Evolutionary Socio-biology

Study Finds Sexism Rampant In Nature



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"When we first decided to examine attitudes and behaviors toward gender roles among non-humans, we were wholly unprepared for what we would find," said Jennifer Tannen, leader of the UCSD research team, a joint venture between the school's zoology and women's studies departments. "Females living in the wild routinely fall victim to everything from stereotyping to exclusion from pack activities to sexual harassment."

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"To mate, the male Galapagos tortoise simply immobilizes the female with his weight, which, as far as I'm concerned, qualifies as non-consensual sex," Tannen says. "Female southern elephant seals gather in large groups during mating season, and each group has a small handful of males who control them like a harem. It's sick."

This is good satire, I love The Onion News.  

It is interesting to note that nothing can technically be called 'rape' in the animal kingdom despite some unusual sexual practices exhibited by many species. This goes for Tazmanian devils as well.

what do you mean? no accounts of forced intercourse in nature?

Well, it's difficult to tell, after all they can't scream 'no' 'help' or 'get the fuck away' but they do court and make sounds that we can reasonably guess to mean something along the lines of pain or pleasure, and the difficulty with that is, it can often be confusing which is which.

Cats, for example, have kinky mating habits. The male has a kind of barb on his junk that might be mistaken for causing pain but actually excites with pleasure. The female cat cries out bloody murder but apparently likes it. As the male grabs her by the neck she snaps and bites---it sounds like a porno clip. And remember, the female cat only allows or 'notifies' the male(s) when she is ready.

Or we'll take dogs as another example, I get rapes by doggies all teh time! But humping is more of a gentle, playful kind of thing where if you tell the dog no or another dog tells them no they get the point pretty quickly. And if I were to imagine an instance when a male approached an unwilling female the female would probably be able to stand her ground and hold herself to her wishes since often the variations in size between the sexes in that species aren't so great. I've seen chihuahuas humping Rottweilers while the bigger dog just stands there and doesn't even notice...lol...

But overall, animals 'typically' don't have the same type of respect violations like humans do. They tend not to be stupid enough to consider forced sexual intercourse as a beneficiary evolutionary reproductive method. Thankfully there are a handfull of humans out there that don't either.

Holy mary mother of god!

The science and philosophy just keep on flowing.

Dolphins have been observed a number of times to copulating 'in formation' with a receptive female. Humans would call this 'gang rape' but in the wild it's probably more like hedging bets or something actually beyond the comprehension of most humans who have learned to 'just say no'.

ah yes, cats are the most weird ones. I remember seeing them mate, I heard the same screams as the times I tortured the cats by throwing them around the garden or pulling their tails.

They will remember what you did and scratch you whilst you sleep...

Typical...of pussy.

Σατυρ wrote:

Typical...of pussy.

I steer well clear of pussies and those who like to torment them. You won't find me swimming with dolphins either.

Rape is common in nature and a variety of animal species hence why rape is natural.

To describe anything as not being natural is a naturalistic fallacy.

Moral and ethical philosophers can eat their own hearts out reading this.

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Not meat-hunting per se, but meat-sharing machiavellianism that led to evolved brains.

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"When, why, and how early humans began to include meat in their diet is at the heart of our quest to understand our origins. Diet affects every aspect of an animal’s lifestyle, and the way in which food is acquired is influenced by a crucial set of adapta- tions without which the animal would not survive another day. In the case of early humans, we can be sure that their diet consisted mainly of plant foods, for which they foraged all day long just as modern apes do. We can be confident of this because our ancestors lacked any anatomical specialization for catching large prey, such as carnivorelike canine teeth or powerful claws. The only other evidence of the plant portion of the diet is the microscopic wear made by tough seeds and fibrous foods on fossilized teeth. These microwear patterns can reveal the type of plant diet eaten by long-extinct species by comparing the tooth wear patterns to those of living primates whose diet is well known. Unfortunately, we have little direct evidence of the plant food diet of early hominids. A few archaeologists, such as Jeanne Sept of Indiana University, have tried to reconstruct the likely vegetation landscape that early hominids would have relied upon, but since eating most plant foods does not require any tool use (one exception might be digging for subter- ranean tubers), little evidence exists of those habits. The primary evidence that we have in the fossil re- cord for the advent of meat eating is the appearance of crude stone tools, beginning in East Africa in the mid-Pliocene period about 2.5 million years ago. Before this time, if emerging humans were making and using tools, they were made of materials such as wood or bone that did not preserve in the fossil record. As to what extent the earliest hominids were eating meat without the assistance of tools, such as the chimpanzee scavenging opportunity de- scribed above, we have no archaeological record at all.

The evolutionary transition from an herbivorous primate to a more carnivorous one involves a major shift in how an animal is built as well as how it must behave. The digestive tract, armaments for prey capture, and the biting strength of the jaws are features that change when an herbivore becomes a carnivore. In human ancestors, cleverness and co- operation may have evolved to a point at which planned cooperative hunting replaced stealth and sheer attacking power. Sociality, better weapon manufacture, and larger brain size may thus be traits that arose in response to the need to find and capture prey. We assume, but do not know, that early hominids gradually became omnivores by in- cluding some meat in their diet, and that the per- centage has generally increased in our more recent ancestors. Paleoanthropologists Pat Shipman and Alan Walker identify several traits that must have changed when hominids became more predator than prey.2 These include developing ways of butchering animal products; the lengthening of the small intestine while the large intestine became shorter; an increase in leisure time as the time needed to forage for plants decreased; and attaining a low population density, since predators typically sit atop the food chain and can only live at sparse densities lest they overeat their prey supply. Some of these hypothesized shifts, such as the type of di- gestive tract, are untestable. Shipman and Walker suggest that the adaptive shift happened relatively recently in human history.

There are some good reasons to think that humans began to include meat in their diets routinely at a very early stage of evolution, and that their ape precursors were already eating meat when they could get it. Chimpanzees routinely include small animals in their diet.

Omnivores tend to be opportunistic, grabbing a small animal or scrap of meat whenever it chances along.

According to Dart, the australopithecines were “confirmed killers . . . that seized living quarries by violence, battered them to death, tore apart their broken bodies, dismembered them limb from limb, slaking their ravenous thirst with the hot blood of victims and greedily devour- ing livid writhing flesh.”4 The writer Robert Ardrey picked up on this idea and ran with it in more vivid fashion in a series of popular books that depicted evolving hominids as bloodthirsty creatures.
Anthropologists ever since have been obsessed with human carnivory, despite the fact that none of the anatomy in early human skeletons reveals any adaptations for being predatory or carnivorous.

How the meat was procured is as important as when it began to be a food item. Prey had to be caught and killed, or carcasses had to be scavenged. It is important for us to discover whether our own lineage arose with the help of a hunting ancestry or a scavenging way of life, since each of these modes requires a different set of behavioral adaptations. Did bands of early humans courageously attack and slaughter large and dangerous game, or did they nervously creep up to decomposing, nearly stripped carcasses to glean a few scraps of meat and fat?

Anthro- pologists Richard Potts and Pat Shipman studied the bones of prey animals at Homo habilis sites. On the bones they found cut marks made by ancient sharp-edged tools as well as tooth marks made by the gnawing of long-extinct lions, hyenas, and leop- ards. When they examined them more closely, they saw that on some of the bones, the human-made cut marks were on top of the carnivore bites—evidence that humans were cutting flesh from the bones sometime after they had already been chewed by a predator. The implication was clear: the role of hominids was that of scavenger of the carcass of the prey, rather than hunters.10

This discovery represented a dramatic reversal in our thinking about the lives of early humans. To be a scavenger rather than a hunter affects every as- pect of daily life. Instead of depending on the ability to chase down and kill elusive prey, a scavenger needs to find the kills made by hunters, then sneaks up to a carcass and cuts off bits or chunks before being detected. Many scavengers, such as vultures and jackals, are tolerated by larger carnivores at a kill: would early hominids have been?

Early humans may have filled a scavenger niche in African forest-grassland ecosystems between one and three million years ago.

Kills would have been quickly processed by the hunters, but sufficient nutrients remained in the carcass long enough to support a scavenger who relied on finding dead animals for dinner. These kills would provide little muscle tis- sue but much bone marrow and brain matter, and these are rich sources of fat and protein provided the scavengers can break the bones to get to the bounty. Scavenging was a reliable enough way to obtain large quantities of good nutrition, making hunting unnecessary. Scavenging may have been a dietary niche into which early hominids shoehorned themselves.

However, other studies have questioned whether African habitats could sustain a creature that subsisted on scavenged meat. Even Blumenschine’s study in support of the scavenging hypothesis indicates that scavenging yields a lower return per carcass due to the already-defleshed na- ture of many carcasses. This translates into fewer opportunities for chunks of the carcass to be transported to some other place for butchering or consumption.

One of the most important hypotheses put forward related to the scavenger hypothesis is that early hominids began to use a home base. This idea was first suggested by archaeologist Glynn Isaac in the 1970s. He studied deposits of fossilized bones and stone tools on hominid landscapes, and inferred that ancient humans might have brought captured meat back to a central place for butchering it and doling it out, in much the same way that some hunting and gathering peoples do today. Ancient home bases used by hominids to cache food and center their daily activities would certainly have been a benchmark in human evolution, since great apes do not return to a home base of any sort at night, merely making new nests wherever they find themselves when dusk falls. If early hominids were carrying butchered carcass meat back to a cen- tral place, many fundamental changes in their life- style might have accompanied the pattern.

Most models of the origins of early humans depict them as weaklings struggling to survive in a world that was so inhospitable that only by dint of their cleverness could they get by at all. Only a few current researchers have challenged this view. Henry Bunn of the University of Wisconsin looks at early humans and sees creatures small in stature but strong enough to have overpowered lions and hyenas to take the carnivores’ kills away from them.16 We know that wild chimpanzees will attack and ha- rass leopards they encounter as they travel through the forest, and they are not even armed with weap- ons when they do so. So it is not unthinkable that early humans might have outright charged at big carnivores sitting on their kills in order to drive them off and claim the meat as their own. Such pi- racy requires a different set of adaptations than pas- sive scavenging, in that the ability to detect a car- cass is only the first stage of obtaining it.

Bunn also points out that whereas advocates of the scavenging niche hypothesis consider hunting and scavenging as separate foraging strategies, this dichotomy is false. There are few carnivores that hunt but do not also scavenge. Hyenas are actually ef- ficient and avid hunters, while lions pirate kills away from other predators more often than they make the kill themselves. Both hyenas and lions are better characterized as hunter/scavenger carnivores than as members of only one category. Of course, each early hominid species was unique and possessed a set of adaptations that may not have occurred in any other primate, but the likelihood that any early human species scavenged exten- sively without hunting at all is quite small. It is easy to imagine a roving group of Homo habilis searching all day for fruit, and in the course of their foraging came upon either the carcass of a recently killed antelope or a very-much-alive fawn. That they would eagerly eat one but not the other seems very improbable.

Meat is such a valued resource that early humans would have eaten it at each and every opportunity. Or would they? The same ingredients that make meat such an important commodity for carni- vores—a compact parcel of amino acids and calories—may also make it unpalatable, even toxic, if consumed in substantial quantity by a noncar- nivore. University of Michigan archaeologist John Speth has challenged the conventional wisdom that large amounts of meat would have been eaten by early hominids. Speth points out that among mod- ern hunter-gatherers, foods that are high in protein are not utilized heavily during periods of food scar- city, which is just the time when one would expect they would be used most. This is not because meat is unavailable during this time; instead, foragers seem voluntarily to limit their consumption. Speth argues that both modern people and early homi- nids are constrained in their meat consumption by the toxic, even lethal, effects of consuming too much protein.18 Meat is a source of both protein and calories, but only about 50 percent of one’s daily caloric intake can come from meat. Above this limit, the liver is unable to metabolize the excess amino acids, and the body is unable to flush itself of the waste products of meat consumption. This can lead to liver and kidney impairment or failure, having lethal consequences. Furthermore, the threshold may be lower than 50 percent for pregnant females. This, according to Speth, suggests that carcasses, whether hunted or scavenged, would have been eaten for their fat and calories rather than their protein.

There is another source of animal fat and protein that is much less glamorous but perhaps more available. Modern apes and human foragers eat insects and insect larvae whenever they can obtain them. Jane Goodall first documented chimpanzees making and using simple tools—twigs or blades of grass stripped clean and probed into the tunnels of termite mounds to coax the protective soldiers to clamp onto the tool and be extracted. Using this technique, chimpanzees rou- tinely consume thousands of termites per day in some seasons (most often of the genus Macro- termes). There is a fascinating difference between the sexes in tool using. Females are much more dili- gent than males; William McGrew found that ex- tended bouts of termite-fishing were done twice as often by females as by males.

Fully modern Homo sapiens in Europe ate not only meat of ungulate mammals but also products of the sea and lakes. Their mainstay was Europe’s big mammals of the time: bison, reindeer, red deer, wild horse, and ibex. These are large, herding, poten- tially dangerous animals, whose killing would require a major cooperative effort. Reindeer in particular were a favored prey on the plains of northern Europe. Hunters appear to have targeted reindeer at northern climes, while those in warmer, southern climates exploited a wide range of animals and plants in their environment. In either place, we know that these hunters were armed with sophisti- cated weapons, spears, darts, perhaps bows and ar- rows, harpoons, and other sorts of projectiles. This gave people the ability to bring down creatures at which they could only stare longingly earlier in prehistory. Humans living 20,000 years ago had also learned to plan their hunts in advance, and to drive game through narrow bottlenecks in the landscape where they could be more effectively ambushed. They may also have known the annual migratory cycles of the hoofed game and followed them, or planned their hunting calendar around the much- anticipated movements of game through their area. Hunting by more modern men thus becomes routine, strategic, and well coordinated rather than op- portunistic. To understand the importance of this shift, we must consider the meat-eating behavior of modern foraging people.

Why would human hunter-gatherers search for sources of meat while chimpanzees do not?

The answer may lie in the availability of meat in a tropical forest, and how humans compared to chimpanzees travel in order to locate their food. Meat, whether it is living animals or the carcasses of dead ones, is almost certainly more widely and unevenly scattered on the landscape than plant foods. Even a rare and sought-after species of fruit will be found more easily and predictably, simply because the fruit tree is stationary and usually bears its bounty at predictable times. Prey animals move around, and even dead ones lie out of sight while their bodies decompose into inedibility. Meat sources must be located and reached fairly reliably and quickly. Great apes certainly have the cognitive ca- pabilities to remember where they have recently seen good food of any kind and know when and where to look for desired plant foods. But getting there is a different story. Chimpanzees travel quadru- pedally on the forest floor; very little travel is done overhead in the trees. On the ground, chimpanzees knuckle-walk, a mode of travel that is inefficient compared to the gait of other large-bodied mammals. Even though chimpanzees may walk several miles per day in the wild, they are generally traveling to known locations of fruit trees and don’t knuckle-walk aimlessly around the landscape. Chimpanzees are not well suited for the sort of low-reward, long-distance searching that finding meat would entail.

Human foragers possess the bipedal posture and gait, enabling us to walk slowly but efficiently for many miles. Many human foragers travel farther on a foraging day than chimpanzee parties ever travel. The origins of our bipedal posture are not well un- derstood, but walking upright has made all the difference in many aspects of our behavior, and meat-eating may be one of these.

Humans travel long distances efficiently to find food, then cooperate to increase individual re- turn rates, and also employ weapons as killing tools. What do chimpanzees do when they hunt that human foragers do not? Foremost, chimpan- zees make use of the forest canopy and their won- derfully adapted-for-climbing anatomies. They can mount an attack on monkeys high above the forest floor that would be out of the reach of human hunters armed with arrows. Chimpanzees also pos- sess their own weaponry: long canine teeth that can puncture the skull of a small monkey, pig, or antelope. Although chimpanzees use tools effectively for eating insects and also incorporate branches and rocks into their charging displays, they virtually never use these tools to help kill the animals they are pursuing. Humans, on the other hand, routinely use bows and arrows, blowguns, nets, clubs, and spears to facilitate making the kill.

Sharing, far from al- truistic, may reflect evolved aspects of social manipulation. Sharing may also have evolutionary roots in the concept of tolerated theft. If what you have is more than ample, then the cost of losing some of it to a persistent beggar may require less energy than the expense of trying to keep it. So surrendering a bit of your prize may be tactical avoidance. More- over, the apparent generosity of foragers may be matched by their persistence in soliciting. Of course, people trade goods for services all the time. In Western industrial society, those in positions of power are often able to use their status to negotiate terms of trade that are favorable to them. Dealing from strength is a common feature of a cash econ- omy. If someone needs to borrow money from you, you agree to make the loan contingent on a promise that it be paid back in full, plus interest. This inter- est is a reflection of the economic power of the lender.

But in foraging societies, egalitarianism and an apparent lack of hierarchy are the rules that people live by. Why do great apes and nearly all modern people live in rigidly hierarchical societies, while foragers do not appear to possess the concept of hi- erarchy? Christopher Boehm has considered this question and what it may mean for the way in which cultural mechanisms of change can influence biological evolution. He reasons that the prevention of hierarchy formation is enforced from those who are in nonleadership positions, but that leadership does exist, albeit controlled from beneath. Boehm refers to the manipulative use of the leader by his followers as a reverse dominance hierarchy and considers it to characterize most foraging societies. Through their conscious rejection of the dominance status of anyone who tries to tout his own accom- plishments, foragers succeed in bringing the would-be alpha quickly back to earth, statuswise. Consensus is all, and in this striving to achieve con- sensus Boehm sees the roots of modern culture, able to override the biological evolutionary process. David Erdal and Andrew Whiten also see the roots of our behavior in the food sharing of foragers, but in a different light. They consider food sharing to be a learned tradition that is grounded in an evolved disposition to share. They approach the forager food-sharing paradox from a biological perspective contrasted with Boehm’s more cultural-determinist view. Erdal and Whiten suggest that at some point in human evolution, the cognitive ability to enforce a reverse dominance hierarchy arose, which in turn placed a great natural selection value on the ability to be politically astute in dealing with group mates

Many animal behavior researchers attribute the increase in the size of our brain to increasing natural selection pressures that favored socially and po- litically adept group living. Primates that could best manipulate their social surroundings to their own advantage reap more mates and leave more off- spring. This is of course also a time-honored pattern used by political leaders throughout human history. This school of thought—“Machiavellian intelligence”—has risen to prominence in the past de- cade, stemming from seminal writings in the 1960s and 1970s by scholars such as psychologist Nicholas Humphrey and primatologist Alison Jolly. There can be no more basic goal of social life for an intelligent creature than to get one’s fellow group members to do what you want them to do without knowing that they are being manipulated. Males enlist the help of other males to overthrow an alpha whom neither could hope to challenge alone. Once the alpha has been toppled, the fragile coalition of low-rankers may fall apart, each left to his own devices to hold onto the power that they both gained but could not successfully share.

Intentionally deceiving a colleague is another piece of evidence that animals are socially very smart. Lying is not a uniquely human trait. Cheney and Seyfarth saw vervet monkeys give false alarm calls, apparently to divert group mates’ attention from food resources the group was trying to share.9 When some primates copulate, the male (and some- times the female) gives copulation calls—loud shrieks that attract attention from all around. Low-ranking male rhesus macaques do not give these calls as often as high-ranking ones, presumably to avoid being bashed by a high-ranking male who does not approve of the mating. But low-ranking male chimpanzees have been seen trying manually to prevent their lips from parting in order to sup- press copulation calls—an apparently conscious and forethinking attempt to deceive.

The brain increased incrementally in size through- out nearly all of primate evolution. Then, since the time of Homo erectus and the gradual transition into modern humans some 200,000 years ago, human brain size exploded. This explosion happened at a time when humans were probably living in small bands, leading a nomadic or seminomadic life of hunting and gathering. They were also probably evolving a qualitatively different and more ad- vanced form of language and speech than had exis- ted in earlier hominids. It may be that the brain size increase that took place during this time was due to the value of a larger and more sophisticated brain for survival and reproduction. As the complexity of human societies grew, so did the pressure that natu- ral selection brought to bear on the ability to be socially and politically clever. The result is a species in which frequent small deceptions, planned maneuvers of one’s mates, and general politicking skills count for more in nearly all arenas of life than do physical size, strength, or agility.

The roots of intelligence may lie in a combination of ecological complexities, the value of foresight in making and using tools, and the value of being socially intelligent. Teasing apart these factors is, however, a difficult practice when one is without fossilized soft tissue such as brains. British pri- matologist Robin Dunbar compared data from the life histories of a range of primate species to ex- amine how the ecological function of intelligence stacks up against its political value. He found that the size of the neocortex and the size of the social group in which the primate lives were highly corre- lated across the primate order. A monkey that lives in a group of fifty instead of a group of five must be able to hold in its head the knowledge of a much more complex web of social relationships. It is like playing chess versus tic-tac-toe. Dunbar found no relationship between brain size and the size of the home range used by a primate, suggesting that the physical environment’s complexities had not led to big brains. Nor did the extent to which the species used “extractive foraging” (tool use) to obtain food correlate with cortex size. Dunbar’s findings sug- gest that while the first push toward a larger brain may have been the result of a patchily distributed, high-quality diet and the cognitive mapping capa- bilities that accompanied it, the evolution of the very large brain of the higher primates was primarily due to its value in social intellect. There are many confounding factors here, since lower primates such as prosimians usually live in small groups while monkeys and apes reside in bigger groups. This may simply reflect their evolved pre ispositions for particular grouping patterns.

There is another factor that is ignored by most advocates of the social intelligence school of thought. Although brain sizes can be measured, plotted, and correlated against the mating system and grouping pattern, whether higher primates really have much more complicated social lives is less clear. Does the raw number of potential social relationships dictate a more complex social life? We assume so but have few pieces of empirical support for the idea. This is important in considering how the modern human brain came to reach its current size.
The modern human brain is on average three and a half times larger in volume than a chimpanzee’s.

But what evidence is there that early human societies were more complex than modern chimpanzee societies? If group size is the primary factor, then how do group sizes compare between foraging people and chimpanzees or bonobos? The evidence is weak, since we cannot as- sume that ancient humans lived in bands that were comparable to those of modern human foragers. There is wide variation in group size among mod- ern foragers and also among chimpanzees.

If the increase in primate brain size through evolution has social intellect as its root, then we must be able to explain the dramatic in- crease in brain size in the very recent past of Homo sapiens based on a measurable increase in social complexity.

Deacon shows that much of the variation in brain-to-body size among primates may be due to natural selection operating on body size rather than natural selection producing a certain, larger brain size. He accuses the bigger-is-always-better advocates of perpetuating an obsolete evolutionary ladder concept of brain size, one that is both methodologically and logically flawed. We would not say that just because an ani- mal has bigger eyes or longer legs, all animal species could be ranked based on visual acuity or running speed. In the same way, we should not be trying to do so based on the relative size of a species’ brain. Whatever the key influences have been on primate brain size, the much more recent expansion of the human neocortex is the most difficult to account for. The selection factor may have been language, which is without fossil evidence and is therefore in the realm of informed speculation." [Craig Stanford, The Hunting Apes: Meat-Eating and the Origins of Human Behaviour]

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"Among the behaviors that are of most interest is food sharing. This is due to the cooperation and reciprocal altruism that sharing entails. In the face of much evidence that animals tend to act in their own self-interest first and foremost, we try to explain why sharing exists and how it could evolve. From a Darwinian perspective, the sharer ought to reap more than he invests, for without that selfish impetus he would not share. The difficulty in imagining the evolution of sharing among both humans and other animals is that such cooperative behavior is difficult to establish. Sharing is especially difficult to maintain in the face of those who selfishly cheat. If one individual cheats the system by reaping the benefits of sharing without contribut- ing, that cheater will benefit. If sharing is at all genetically influenced, the cheaters will end up leaving more offspring in the next generation, and the cheating trait would spread, leading to the collapse of cooperative sharing.

In the pattern of sharing we see the roots of both sides of our altruistic and selfish natures. The art of the deal among sharers is to give a bit less than you receive. Giving just enough to perpetuate the rela- tionship with the fellow sharer is often the goal. This subtle form of cheating is common among sharers of many primate species, including hu- mans. Whether it is subject to penalty or correction is largely determined by the relative status of the giver and sharer.

In such instances sharing may appear reciprocal to the casual ob- server when in fact the powerful are manipulating others to their advantage. For example, in the recent history of the Kasakela chimpanzee community at Gombe, the alphas have not necessarily been highly skilled or avid hunters. They are always, however, avid meat eaters. The dominance status of the alpha male allows him to appropriate carcasses with im- punity from other hunters. The others, though more skilled at capture, are less able to defend their catch due to their socially subordinate position. At both Gombe and Mahale, sharing is nepotistic and the sharer reaps political rewards, while at Ta ̈ı sharing of meat is more often reciprocal among the hunt participants. These two sharing traditions, one Ma- chiavellian and the other more reciprocal, have ap- parently arisen in response to aspects of the local relationship between chimpanzee and colobus. Christophe Boesch has argued that at Ta ̈ı the enor- mous height of the rain forest canopy to which the colobus retreat makes cooperation in hunting essen- tial, with the result that helping out is rewarded later. At Gombe, with a lower forest structure and greater ease of hunting, such cooperation is not necessary and so no such reward system has developed.

I suggest that the ability to make use of meat for nutritional purposes is facilitated in a social primate by a relatively high degree of intelligence, because of the complexities of sharing the meat of other animals. Being a sharer requires a level of encephalization that is seen only among the great apes and humans.

Sharing and egalitarian relationships are two hallmarks of the foraging people of the modern world. The open reciprocity that occurs routinely in these human societies is rare among nonhuman primates. There is a stark contrast between the egali- tarian nature of hunter-gatherer bands and the strongly hierarchical structure of the great-ape soci- eties. Yet when we consider modern people in virtually all industrialized societies, we see status and hierarchy as the rule of life. David Erdal and Andrew Whiten of the University of St. Andrews in Scotland have depicted the evolution of hierarchy as a U-shaped curve, with the early rise of hierarchical society followed by a drop in status seeking among early humans.31 Hierarchical behavior returns only recently among modern people, perhaps when subsistence foragers became settled as agriculturalists and began living in larger groups.

In the egalitarian relationships that exist among foragers, we may see the shaping of the origins of the human mind. Alliance formation, always im- portant among nonhuman primates, assumes even greater weight among humans because of the value in cooperating to obtain meat. Such coalitions in chimpanzees allow males jointly to challenge those much higher in the dominance hierarchy. Christo- pher Boehm of the University of Southern Califor- nia suggests that in the course of human evolution, the political savvy that stems from the need to form alliances contributed to the rise of human intel- ligence. In humans, the ability to destabilize domi- nance hierarchies was the basis for the system of dominance reversal that characterizes hunter-gath- erers.32 Egalitarianism is a system in which the self- interests of the individual are at times submerged in order to benefit the group. There is no leader; the impulse to lead or to achieve social status is beaten down by verbal harassment from everyone else. In the same way, the behavior of foraging people strongly discourages getting too much of anything at the expense of the other, including too large a share of meat after a kill is made. So the goal is not to get ahead oneself, but to ensure that no one else gets ahead. If the social intelligence required to nav- igate a social hierarchy is considerable, the political cleverness required to live within a nonhierarchical system may be even greater. One must be acutely aware at all times of one’s own needs, gains and losses, and be able to compare them to those of many other comrades. Erdal and Whiten see this process leading to increasing plasticity of behavior, both enabled by and leading to a larger and more powerful brain. In the behavioral options available to a social strategist in an egalitarian setting, we may see the foundations for modern human cogni- tion. The paradox is that within the past several thousand years we have seen a return to hierarchi- cal societies, complete with chieftains, social castes, and social institutions based on social or economic status. Nearly all these systems are male-dominated patriarchies. In patriarchal systems, males control essential resources and use them to control females and reproduction.

Man the Hunter argued in part that human brain size and cognitive skills were enhanced through a long evolutionary history pursuing prey, with all the communication and coordination skills that hunting may place at a premium. This is partly correct; social hunting does place a premium on intel- ligence. The premium is exacted, however, in the realm of the sharing, control, and distribution of meat after a kill rather than in the pursuit of the prey. In the doling out of the meat we see signs of strategizing and politicking that go far beyond those seen in predatory behavior. The evolutionary legacy of our hunting and scavenging past lies therefore not so much in the hunt but in the division of spoils. While there appears to be little continuity in the hunting tendencies of ancient and technologi- cally simple modern people, there is a vital link in the use of meat as a currency, a valued good. This link is found in the behavior of apes and people when the sharing of meat occurs, or when food is used to manipulate the behavior of others. In the distribution of meat in apes, as in other social arenas, we see control and power at the heart of both male and female patterns of behavior. In the attempts by either sex to tip the balance of power, we may be seeing the roots of human gender relations. When meat becomes a resource that is not only a food but also a social currency—a way to help you obtain what you want in the group—we are seeing the emergence of barter, currency-based human social systems.

In human and some other primate societies, meat eating is about politics as well as nutrition. The control of a valued resource is about power. When the two sexes are involved in the power struggle, the physically dominant sex often controls a resource and therefore controls female reproduction as well. Sexual politics plays a key role in chimpanzee meat eating just as it does in some traditional human so- cieties. Relationships between the sexes are part and parcel of the capture and sharing of meat, since in nearly all human and nonhuman primate soci eties in which the meat of mammals is eaten frequently, males hunt for it more often than females. We see gendered carnivory in human, ape, and monkey societies. In chimpanzee society, both males and meat occupy a hierarchy: males domi- nate one another, and all males dominate all females. Meat is so highly desired that the whole community will devote hours to catching it, even though most female and immature community members end up with only tiny scraps. No other food commands such devotion. The hierarchy of meat appears to be closely linked to the hierarchy of males, in that it is almost always males that capture meat, putting them in the role of providers for other community members, including females.

In many traditional human societies, men hunt but women procure most of the protein and calories for their social groups through their gathering of roots, fruits, and small animals. This behavior has led some anthropologists to claim that the importance of hunting and meat eating was more mythi- cal than real, since men’s efforts, while it received much attention from a previous generation of re- searchers, did not account for much nutritionally. But this misses the key point about meat eating. The fact that meat is so highly valued even when it com- poses a small part of the diet is powerful testimony to its value as social currency. Men are able to use meat to enhance status, show beneficence, and even to obtain more sex by having caught meat. Nutrition is not irrelevant to meat’s value at all; it is essential in that it makes the meat something worth bragging about, begging for, and manipulating with. But the use of meat has gone well beyond this; the !Kung do not sit and haggle for hours over the ownership of a pile of berries, but they will do so over the carcass of an antelope. The value of meat is a matter of perception by group members. It is irrelevant that plant foods are as valuable a resource as meat. What matters is that animal carcasses are considered by both men and women as a more valued resource than plant foods.

This difference in the way that plant foods and meat are regarded in both ape and human societies may be related to the difficulty of obtaining meat, and that only one sex—typically males—controls meat. A fundamental premise of the origins of pa- triarchy is that when men gain control over re- sources that women need, they use it to control and coerce them. Male dominance is a near cultural uni- versal; this is accepted by both feminists and socio- biologists, as well as by scholars who are both. This does not mean that all societies are in all ways patri- archal; women have spheres of influence that may simply differ from the arenas in which men rule. There are some societies, including those of the tra- ditional foragers, which are more egalitarian than others. There are, however, no true matriarchies. Feminist scholars usually depict male domination of women as arising in historic times, due to the social contexts of our own recent prehistory. Few, however, acknowledge the possibility that male dominance may have far more ancient origins. Per- haps this is because if patriarchy has its roots in the Miocene or Pliocene instead of the past few thou- sand years, it implies an evolved Darwinian basis of patriarchal systems. Among other primates, male dominance is usual, though not universal. Where it occurs, it is based on a combination of greater male size and strength, male coalitions, and a lack of strong female-female alliances.

In all primate species, including ourselves, there are sexual conflicts of interest over male desires for access to reproduction. Females become not the goal of patriarchal domination itself, but rather the means to its end, which is reproductive success. This evolutionary view of human gender relations is quite different from a feminist perspective, which more often considers the goal of male domination to be an end in itself.1 It was once thought that women were subject to male control in most cul- tures because of limitations imposed by their repro- ductive biology. Women were thought to be intrin- sically barred from ruling due to their physiology. This antiquated view still finds an audience with those who question whether women can serve as combat soldiers or governmental leaders due to their menstrual cycles. Modern feminist thinkers have seen the control of reproduction as the male goal in human societies. Female reproductive biology may limit women from playing controlling roles in some societies, but this is due more to male oppression than to women’s lack of ability or desire to rule. This analysis has not often been properly grounded in the study of nonhuman primate societies. If we ask how patriarchies came into being in the first place, a feminist approach might be to sug- gest males’ greater physical size and strength. Some psychological need to dominate might also be in- voked. But any biologist knows that male size and strength are not an end, but a means to an end, namely the control of female bodies and their repro- ductive output. Competition among males, and fe- male choice of male mates with particular physical features, led to the 10–15 percent size difference between ancestral human males and females.

Two biological anthropologists who are both fem- inists and sociobiologists, Sarah Hrdy and Barbara Smuts, have been exceptional in offering biological levels of explanation for human gender relations. In separate studies, both suggest that the same Dar- winian principles that govern the conflicting inter- ests of the sexes in all primate social systems may prescribe male coercive behavior toward females in humans. They point out the logical inconsistency of feminist analyses that posit the same rationales for male dominance in an attempt to explain how such systems came into being, without asking why they exist at all. The “why” of patriarchal systems can be addressed with the extension of feminist theory to evolutionary paradigms.

Some recent authors have recognized that sociobiological analyses of gender relations, far from offering sex- ist, simplistic views, reveal the complexities in human behavior. Females are not passive receptacles of male reproductive desires. They are active strate- gists in pursuit of their own interests and often are the driving forces behind the social system itself. Males may likewise be caregivers rather than warriors and headmen. However, each sex has repro- ductive interests at stake in social life, and these may clash. There is no direct genetic basis for patriarchy; they arise from the biological conflict of interests between males and females of all primates, including men and women.

If patriarchies are about male dominance and the control of female reproduction, then we should con- sider how males acquire power. This may point to the role that meat eating and meat sharing plays in patriarchal systems. One way this occurs in nonhu- man primate groups, human social groups, and probably in our ancestors’ social groups, is through sheer size and strength. Sexual dimorphism is the product of sexual selection favoring male attributes; in species where being large helps in the mating game, we see outsized males with impressive canines and musculature. The level of dimorphism in modern human populations is about 10 percent in stature and somewhat more in weight. This differ- ence is very similar to the magnitude of size difference between males and females in both chimpanzees and bonobos, but vastly less than that seen between the sexes among gorillas and orangutans. The degree of size dimorphism suggests the inten- sity of male competition for mates, but the fit is not always clearly tied to the social system. The largely solitary orangutan, for instance, shows the greatest degree of male-female size dimorphism, exceeding 50 percent. Males may sexually coerce and brutalize females. Females are not passive, and may refuse to mate with a male no matter how imposing he is, though she may subject herself to violent attack by doing so.

A second way that males obtain power is through strategic alliances. This is true for both human and nonhuman primate societies. Male coalitions may form to control access to females, or to prevent other males from having access to them, or to defend territories that contain desired females. Anthropologists Joseph Manson and Richard Wrangham have theorized that primate societies featuring tight male bonds form when the crucial resources are both portable and defensible—such as fe- males—rather than immovable, such as fruit trees. Chimpanzees, bonobos, and many tribal human societies fit this dichotomy. When it is highly beneficial for males to form alliances, there is often a kin-selected benefit that heightens the potential re- wards for cooperating with kin.

The converse effect of male alliance formation is that in many female primate species, females do not form strong alliances. This is especially true among the great apes, in which female alliances are weak in three of the four great apes. Because female apes usually disperse from their natal groups at sexual maturity, they end up living as breeding adults in a new group lacking relatives and close allies.

Smuts suggests that a female’s reluctance to form coalitions to the degree that males do may be based on their own selfish reproductive interests.

The history of gender relations has not been entirely Nature red in tooth and claw. Men and women have long worked toward common goals as reproductive partners, group members, and as parents. However, both biological and social/historical perspectives lead us to believe that each sex is also carrying out a more selfish individual agenda. And in both the evolutionary and social interpretations of patriarchal systems, meat eating has played an important role.

The same gender-biased acquisition and distribution pattern that characterizes these apes also characterizes many human groups. Meat is a difficult-to-obtain resource in both human and many other primate societies, valued out of proportion to its nutritional worth. And as a re- source much in demand by both sexes but typically brought home by males only, it becomes an impor- tant factor in the efforts of males to influence the behavior of females, and vice versa.
Peggy Sanday surveyed a range of traditional societies and concluded that those that eat a diet in which meat plays an important part are more likely to be strongly patriarchal. In some traditional societies, the rules of meat division preclude women from getting as much as men, particularly nutrient-rich portions such as the fat in a carcass. Meat thus has a gendering influence. Adams, in analyzing the distribution of meat and power in human societies, makes essentially the same argument that any ape or human sociobiologist would make regarding meat and patriarchy, but couches her argument entirely in historical and social terms. Adams points out that when males control a resource as highly valued as meat, its worth as a nutrient is largely mythical. Tubers and beans make an equally protein-rich diet. But men eat meat in many cultures in the belief that it gives them the strength that they need for their work. Women are not deemed to require it. Meat is also a nearly universal symbol of masculinity, from Western industrial to forager societies, and the eating of meat is thought to enhance masculinity. The image of a vegetarian weightlifter or football linebacker is paradoxical to most of us—evidence that these values are deeply entrenched in Western culture. Perhaps this is because meat eating is associated with meat getting and the other masculine attributes traditionally connected to hunting.

Instead of a sinister symbol of the cultural influences on patriarchy, meat eating is more likely a behavioral focus around which patriarchies have evolved. Meat has long been a symbol of masculinity only because it served males well throughout human evolution as a political currency that is used to enhance male alliances, snub rivals, and control females

This is not to say that meat eating is the central feature of all male-dominated soci- eties. It can, however, be a defining trait of gender relations in some societies, such as those in which men hunt for a living while women gather.

This brings us back to Man the Hunter. The idea that meat eating may have been a catalyst in human behavioral evolution fell into disfavor due to the backlash against Man the Hunter. The model was pilloried to the extent that it became a forbidden term, one that labeled its adherents as male-biased chauvinists, consciously or unconsciously ignorant of the role of women in human evolution.11 This backlash was fueled by key field data about the role of women and also fit emerging social values that sought to place women in an equable role in society relative to men. Whether the actual role of females in early human prehistory fits our modern Western gender-balanced sensibilities is an entirely different question. While women may collect most hunter- gatherer protein, we should not ignore the fact that men are able to use meat for their own selfish and manipulative political ends.

When a male chimpanzee withholds a scrap of meat from a female until she mates with him, we see the use of meat as a manipulative social tool. The value of the resource to the female may be en- tirely nutritional, but its value to the male is clearly both social and nutritional, in that he may be able to use it as a means to a political and reproductive end. In the same way, the value of a carcass to a lactating woman may be entirely different than its worth to a man. Both ape and human scenarios in- volve the control of a resource, valued perhaps beyond its amino acids or calories.

If females usually live in male-dominated, male resource-controlled groups, how do they obtain what they want in those groups? Female primates, including humans, may need alliances and strategic support to survive and reproduce. One female goal in any species is the successful birthing, rearing, and nurturing of offspring. The successful matura- tion of offspring is a goal in which males are equally interested but in which they tend to invest far less energy and time. Males thwart female ambitions, and they often do so in ways that involve the con- trol of reproduction. Female primates can navigate the complex social web of relationships, male power struggles, and their own power struggles only by being politically clever. The premium placed on social intelligence in females extends to obtaining food, allies, and mates. Gagneux and col- leagues’ recent study of furtive mating outside the community by female Ta ̈ı chimpanzees is a vivid example of strategic reproductive behavior. Obtaining valued food is also strongly influenced by a female’s ability to network within her group. Being fertile, high-ranking, and clever are three important ways that females can obtain meat. Since no female is fertile for more than a small portion of her life, and only a few females can be high ranking, most must rely on their ability to manipulate their social milieu, including the males themselves, at the same time that males are trying hard to manipulate them.

Life in a primate society is thus about power and control, not of females by males, but of each sex by the other. Each side has a valued resource to gain and also has much to lose.

The relationship between hunting and sex is no- where clearer than among the Sharanahua, a people of the Peruvian Amazon basin. According to an- thropologist Janet Siskind, “Put at its crudest, the special hunt symbolizes an economic structure in which meat is exchanged for sex.” (p. 103). Since women produce as much food as men do, this is not likely to be just an economic exchange in which women exchange what they produce for what men produce. It is a culturally mediated system, with an obvious biological effect, in which sex is the incen- tive for men to hunt, and men who are better hunters have a better chance to have wives or mis- tresses. Siskind considers women to be a scarce commodity to be competed over in the Sharanahua, because sex is not free for men and must be won, and because some men have more than one wife, enhancing the impetus to “win” women with prof- fers of meat. This form of barter may be a common occurrence among tropical forest people.

This control game is played out in many nonhuman primate societies as well as in our own human cultures. Machiavellian intelligence applies to both males and females, but it does not necessarily apply to them in the same ways. Males and females have often been likened to separate species, with separate reproductive strategies and different means of meeting the same end of reproducing themselves. They may also have evolved somewhat different sorts of cognition as a result of needing to cope differently with complex social environments. Certainly males and females live in separate social worlds even in the same social group in many species. The same claim has been made about men and women.

I have portrayed the roots of human behavior as manipulation and social cunning that arise from the use of meat in our ancestors. This is very different than saying that, because of a meat-eating past, we have an innately aggressive nature. It should be re- membered that predators, while possessing many adaptations that can be used in aggression within their own species, do not necessarily use them. In fact, many scholars doubt whether the predatory aggression that allows a lion to bring down a zebra or a chimpanzee to savagely rip apart a monkey is even closely related to intraspecific aggression. Ag- gressive behavior within a species may resemble predation, but the resemblance is often superficial. Humans are not demons by nature; in spite of the attention that we focus on human violence, there are thousands of acts of compassion for every act of physical aggression.

The hunting, scavenging, and sharing of meat were fundamental features of the lives of our ances- tors. This does not mean that we are biologically driven to do any of these. The way that we deal with one another in society is rooted in social strate- gies that were molded during a time in our history when getting and using meat was vital. If meat were a currency with a 10,000-generation history in the human family, then the traditions that have developed related to the use of meat are likely to have some evolved basis. By sharing meat we are both altruistic and selfish, as we are in most other arenas of our endeavors. We are not simply compassionate by training and Machiavellian by nature. Nor are we constrained by our past to repeat Machiavellian patterns in the future." [Craig Stanford, The Hunting Apes: Meat-Eating and the Origins of Human Behaviour]

Meat-eating and Evolutionary pattern: Humans < Chimpanzees < Bonobos < Gorillas < Orangutans

Quote :

"The origins of human intelligence are linked to the acquisition of meat, especially through the cognitive capacities necessary for the strategic sharing of meat with fellow group members. Important aspects of the behavior of some higher primates—hunting and meat sharing and the social and cognitive skills that enable these behaviors—are shared evolved traits with humans and point to the origins of human intelligence. This does not mean that there is an instinctive desire to hunt on the part of all modern humans; only a small percentage of people in industrialized countries have ever hunted for anything that’s alive. Instead, the intellect required to be a clever, strategic, and mindful sharer of meat is the essential recipe that led to the expansion of the human brain.

Chimpanzees hunt and eat the meat of a variety of mammals. They are skilled makers and users of tools. These apes and their closest relatives have large brains and an intellect that surpasses that of all other nonhuman animals. They are funhouse mirrors of our ancestry; the same stock produced us, but with a filter of millions of years of adapta- tions that occurred during the history of each lineage. Chimpanzees, along with the other great apes—the bonobo, gorilla, and orangutan—illus- trate how evolution can mold a highly intelligent animal that lives in a complex forest environment and an even more complex society. There is only one animal of greater intelligence, and it also lives in an incredibly intricate web of social relationships, navigating its way through life using group-mates as support systems and as tools to be manipulated. This other animal, of course, is humankind.

Man the Hunter was fatally flawed, first by its emphasis on the role of cognition in meat acquisition rather than meat sharing, and second by its unconscious ignorance of the role of females in the meat-control system. Correcting these two errors leads us to establish a new frame- work in the light of modern evolutionary theory and of current views of the roles of women and men in human societies, past and present. It is not only our anatomy that is the product of evolution. Our soci- ality, the most basic primate behavioral adaptation, is a product of our status as a higher primate. While we learn to be members of one culture or another through learning, our social nature itself is as basic a primate trait as breathing. A whole range of hu- man social behaviors, from mother-infant bonding to corporate striving to choosing a mate to sexual jealousy, is influenced by evolved tendencies to respond within a certain range of emotional and behavioral reactions to particular situations. Eye-brows are raised when we consider human beha- vior to be motivated only by our human species centrism.

This Darwinian paradigm is of fundamental importance in tearing down old perspectives about meat eating and its role in human origins and in forging a new synthesis. Without a framework rooted in the realities of what animals, including human animals, do, we are left with stories told through the ages and all their inherent biases and flavorings.

Chimpanzees are the only great ape to avidly hunt and consume large quantities of meat. They clearly relish meat. After a kill, the younger members of the hunting party will some- times sit below the tree limb on which the hunters are crunching on bones and tearing flesh, hoping for scraps that fall to the ground. After an hour’s wait, these scroungers may receive a few drops of blood or shards of bone.

Unlike other nonhuman primates, the capture of meat may entail cooperation. A highly ritualized sharing of meat occurs after a kill is made. When a lion kills a zebra, the drama of the hunt ends the moment the zebra is killed; a moment after its death the zebra carcass is just lunch. When a party of chimpanzees makes a kill, however, there often en- sues a social frenzy. At one level this is simply about getting a scrap of meat, for which members of the hunting party will beg, borrow, or steal. But under- lying the nutritional aspect of getting meat, part of the social fabric of the community is revealed in the dominance displays, the tolerated theft, and the bartered meat for sexual access. The end of the hunt is often only the beginning of a whole other arena of social interaction.

Before we judge the failure of Gombe chimpanzees to cooperate to indicate a lower state of social evolution, consider the two societies’ styles. Gombe chimpanzees capture meat and share it nepotistically—with close relatives and allies—rather than with their hunting comrades. They also use the meat as a political tool of social manipulation, rewarding allies and snubbing rivals in plain view of those other members of the com- munity to whom they may want to send a message. Toshisada Nishida and his colleagues have found the same sort of nepotistic use of meat among the chimpanzees of Mahale National Park.7 Why should we think that cooperation is a more highly evolved art form than selfish manipulation?

At Gombe, male chimpanzees who have meat will sometimes offer bits to swollen females, in ex- change for which they receive matings. These sex- ual manipulations show both the males’ ability to exert control over female reproductive behavior and possibly females’ abilities to obtain meat with- out needing to kill it themselves.

Female chimpanzees are much less involved in hunts despite relishing meat. At Gombe, fewer than 10 percent of all kills have been made by females over the past twenty years.

Sexuality among bonobos is the most talked about aspect of their social life. Among both chim- panzees and bonobos, adult and adolescent females vividly advertise their fertility for a portion of the monthly menstrual cycle. This advertisement is the sexual swelling, the pink, fluid-filled anogenital sack that inflates for several days on each side at the time of ovulation. It is a billboard of sexual avail- ability, one that excites males and incites competi- tion among them, and may enable a female to size up which male or males are the most desirable. As an aspect of their hypersexuality relative to chim- panzees, female bonobos exhibit a sexual swelling for about two weeks of their six-week cycle. Female chimpanzees swell for about ten days of a shorter five-week cycle. Although chimpanzee births do not occur with any seasonality, swelling cycles are seasonal, peaking in the dry season in western Tan- zania and influencing the pattern of party aggrega- tions. Although the swelling does indicate an ovu- latory state, female chimpanzees and bonobos also experience swellings while they are pregnant or lac- tating, though these nonovulatory swellings are less regular in their frequency and duration. When fe- male chimpanzees or bonobos are swollen, they become highly attractive magnets around which males aggregate, and the females themselves be- come more sociable as well. The result is large par- ties that form and travel together, dispersing once the swelling subsides. Among chimpanzees, when “popular” females are swollen there is a sexual frenzy in the community as the alpha male attempts to preserve a sexual monopoly while the female herself actively seeks out other males, all of whom are interested and may challenge the dominant male for the opportunity to mate with her.

A premise about bonobo sexuality, and of the bonobo’s relevance to understanding human behav- ior, is that bonobos and human females are the only primates who are sexually active outside the time of ovulation. Wild female chimpanzees rarely mate when they are not swollen, though in the confined boredom of zoos they may.

Two female bonobos may enter the same tree to feed and rub their genitals together, apparently as a means of reducing what would oth- erwise be an unacceptable level of social tension between them. Nonreproductive sex clearly plays a strong role in human social bonding and social communication, and is made possible by the con- stant sexual receptivity that characterizes humans. Are bonobo females truly in the same class as hu- mans in terms of nonprocreational sex? The most detailed study of sexual receptivity in wild female bonobos refutes much of the strength of this claim. Takeshi Furuichi found that although female bono- bos do copulate occasionally when not cycling, most copulations (more than 90 percent) occurred when the females were maximally swollen, or nearly so.

One difference involves the presence of swollen females in foraging parties. Among Gombe chimpanzees, at least one female chimpanzee in the community is swollen about 50 percent of the time.

Therefore, only a small percentage of traveling parties contain a swollen female. By contrast, virtually every mixed-sex bonobo party has at least one sexu- ally swollen female.17 This is a very important dif- ference between the two societies: access to repro- ductively active females is much greater for bonobo males than it is for chimpanzee males. This may in turn account for the lower levels of aggression among male bonobos than those reported for male chimpanzees.

Perhaps the most fundamental difference in the behavior of bonobos and chimpanzees is the rela- tionship among females. Chimpanzee society is male dominated; adolescent males rise in rank by first dominating each adult female, and then they enter the bottom of the male hierarchy. Females, be- cause they arrive as immigrants unrelated to other resident females, receive little support from the other females in their community; they are like sis- ters-in-law in a patrilocal household. Female chim- panzees also spend their lives alone much of the time rather than as part of a cohesive group.

Female bonobos also transfer to new commu- nities at adolescence and also may not be imme- diately welcomed by females in the new commu- nity. But much of the similarity to chimpanzees ends here; bonobo females become partners in power, and alliances of females form that in some cases allow them to dominate males. The power base which in chimpanzee society rests solidly with adult males is therefore more female-centered in bo- nobos. However, even this difference between the two ape species may be smaller than previously thought, as female dominance is expressed mainly in feeding situations, in which males defer to fe- males by allowing them to enter good feeding areas first. In exchange for their deference, males receive sex. Thus, what may appear to be female-domi- nated feeding is in fact self-serving deference by males. In all other social arenas, male bonobos are dominant to females. If one considers dominance in the social arena rather than pri- ority of feeding access, the pattern of dominance in bonobos begins strongly to resemble that of chimpanzees.

Gorillas were folivores—leaf eaters that spent their day pushing, bulldozer-like, through impenetrable thickets of wild celery and nettles. They were considered the cows of the primate order, eating to live and living to eat, and able to subsist on browsing a poor diet by virtue of the serpentine digestive systems that curl within their massive bodies. The usual fare might be poor quality, but by the time it passes through the long gorilla gut it is broken down to the max. Again, cows. Gorillas seemed to support the rule that large-bodied primates are likely to eat a poor quality diet while living a low-energy lifestyle, while smaller primates eat a higher-energy diet such as fruit and have a more active lifestyle. In what little time they had left over after all the food finding, eating, and digesting, gorillas seemed to engage in social behavior, most often living in groups composed of one silverback plus his harem of females and their young.

Recent fieldwork conducted elsewhere in Africa has shown that the sedentary leaf-eater portrait of the gorilla that came out of the early days of research, based on that one montane gorilla population, is a wrong characterization of the species. Mountain gorilla behavior does not closely resemble that of its lowland cousins, because the montane form is a remnant population living in a habitat ut- terly unlike that in which most gorillas evolved and currently inhabit. Throughout the towering primary rain forests, the swamp forests, and even in degraded secondary forest patches in Central and West Africa live most of the world’s gorillas. This is the lowland version of the species, and its behavior and ecology are different. Far from the lethargic cel- ery eaters of the mountains, these rain forest gorillas eat large quantities of fruit, and they forage far and wide to find it.

Unlike the constant unpredictability of chimpanzee and bonobo groupings, gorillas live in more co- hesive societies. Gorilla society consists of a small number of adult males to whom are bonded a num- ber of females and their young. These males are the glue of the social group; when a male dies his females generally go their separate ways. The females have the same sister-in-law rela- tionships that we saw in chimpanzees, and sisters may migrate together and end up in the same new group. These maternally related animals tend to support one another in squabbles, whereas unre- lated females would not. Females are far smaller than and subordinate to adult males. But in spite of all appearances, females exert a key influence in the dynamics of gorilla group life; they decide which social group they prefer to belong to, and transfer among groups accordingly. These transfers most of- ten take place following an encounter with another gorilla group. Since gorilla groups do not defend territories, they have home areas that overlap broadly like Olympics rings, and encounters be- tween groups occur often in these overlap zones. The silverbacks square off and defend their females, and it appears that the females meanwhile size up new potential mates in the opposing group. This is a good example of the fallacy of the harem concept; the male may be larger and more powerful, but fe- males are still active strategists in search of their own reproductive ends. Both females and males may emigrate from the groups of their birth. Those males that emigrate rarely enter another established gorilla group. Instead, they wander alone or bond with other bachelor males in search of eager-to-transfer females. When a group loses its silverback, the females left behind stand a grave risk of losing their babies due to infanticide committed by other males. Death at the hands and teeth of another gorilla is one of the leading causes of death for baby mountain gorillas.

We understand… very little about the deep structure of orangutan society. Like gorillas, they exhibit extreme sexual dimorphism; like chimpanzees and bonobos, they are largely fruit eaters; like many primate females, they are choosy about which males they will mate with; and like all apes, they reach maturity and reproduce themselves very slowly. But unlike other apes—indeed all other higher primates—orangutans are mainly solitary, associating with others mainly to mate. Fe- male orangutans hold territories on which they for- age, their dependent offspring in tow.

Adult male orangutans come in more than one size. Resident males, who attempt to monopolize a number of females, tend to be large and use long- distance calls to drive away intruding males, attacking their rivals on sight. But their size also means that they are slow, and the large area conscribed by their territory cannot be effectively monitored for all of an individual’s females at all times. This leaves the door open for transient males. These floaters were long thought to be adolescents, which was assumed to explain their smaller size and lack of the fleshy facial appendages that characterize full adults. But years of observation have shown that even after many decades some subordinate males still retained an immature appearance. This pseudo immaturity may be strategic; appearing to be immature and nonthreatening in the presence of an intolerant dominant male may allow the small males to gain access to females. Once they have located fertile females that belong to the resident male, these small floater males sometimes engage in a hei- nous reproductive tactic. They attempt to force themselves on the unwilling female, in what orang- utan biologist John Mackinnon called rape.

Although adult males also occasionally resort to coer- cive sex, forced copulation appears to be a mating strategy used mainly by immatures or transients, al- though the perpetrators are not necessarily success- ful at mating with the adult females they coerce.

This social system of territorial lone females, pos- sessive resident adult males, and smaller transient males has defied full description for decades. What is the basic social unit of orangutan society? There may be no social unit beyond a single female and her young, surrounded by possessive but promis- cuous floating males. However, there may also be a larger meta-unit that resembles an attenuated ver- sion of a chimpanzee community, in which individual females have a relationship with particular males that inhabit the same forest area. It will take further decades of field research to fully expose this larger network of relationships if they do exist.

These four great apes seem at first glance to have very little in common: one solitary, one harem-style polygynous, one living in communities glued by re- lated males, and the other in communities in which female bonds may provide the glue. But underlying this variety is a deep pattern, first pointed out by Richard Wrangham in two influential papers pub- lished twenty years ago. In each of these species, as in the societies of nearly all primate species, females are a driving force. Females need particular re- sources in life, foremost among them food for their own reproductive health and for their gestating or maturing offspring. By living among female kin, the harmful effects of food competition are mitigated, since it is better to share key resources with close relatives than with nonrelatives. Female orangutans and chimpanzees have opted to forage for these re- sources on their own, probably because their ripe fruit diet is best suited to individuals or small par- ties eating small patches of food that could not feed a larger group. Hence, fragmenting into small sub- groups as chimpanzees, bonobos, and perhaps low- land gorilla do, or just foraging alone as orangutans do, is an adaptation to feeding by females. But if females come and go as they please, how can a male hope to monopolize them for mating? Individual male orangutans try to monopolize several females for mating, but they cannot have exclusive sexual access because of their slowness and the large size of female territories. A silverback gorilla attempts to keep control over a group of females, many of whom have little to do with one another. These fe- males transfer out of his group and into the groups of rival males. One lone male does not seem to be able to control the behavior of several females very effectively.

Male chimpanzees take a different approach; they form coalitions, often of relatives, that attempt jointly to control females. And to some extent this works, because in chimpanzee society females are not particularly supportive of one another in times of trouble, including sexual coercion. In bonobo so- ciety, however, females have power and they are able to broker relationships with males to some extent.

Female bonobos are better able to assert themselves over male attempts at control- ling them than any of the other apes, and perhaps for this reason male coalitions are not so marked among bonobos as they are among chimpanzees. Among the four great apes, males try to control fe- males—that is, their movements and their behavior during estrus—but females are difficult to control because they are following their own reproductive agenda. The female agenda is to forage for food alone or in small groups so as to minimize competi- tion for food with other group members.

Far from the passive, submissive female of the old stereotypes, female great apes are active players in the mating game. They may travel miles to obtain desired matings furtively, as shown recently in the Ta ̈ı chimpanzee study by Gagneux mentioned ear- lier. The finding of Gagneux and colleagues that more than half of the offspring had been fathered by males from outside the social group implies that females were sneaking off to find other males from other communities to father their offspring. Since male chimpanzees are highly territorial, this is no small feat, and it is a testimony to the females’ de- sire to expand their pool of potential fathers and perhaps future male allies by mating outside their own groups.

A second unifying feature of great ape society is the tendency for females rather than males to emigrate from the group in which they were born. In most of the higher primate species, males emigrate at sexual maturity while females remain in the natal group. In a majority of primate species, the group is composed of a core of female relatives surrounded by a coterie of unrelated immigrant males. This is what gives the lie to the old stereotype of the male-centered, male-dominated monkey group. To the contrary, group life more often centers on the lives of the females, who travel where they need to in order to find food. Males, determined to obtain mating opportunities whenever possible, seek membership in female groups. In exchange for the sexual access to females that they receive from this membership, males provide some measure of secu- rity against attacks by predators. They also protect the group’s females against marauding infanticidal males from outside the group. And they may also help the females gain access to and defend desired food trees.

It used to be thought that this Old World monkey pattern was true for nearly all primate species. We have learned over two decades of primate study that there are many primates that do not fit this fe- male-bonded pattern; in many species, females and males both transfer. But there is a minority of spe- cies in which males are typically philopatric (living their lives in the group into which they were born) and the females are migratory. This is the ape pat- tern, and although it is based on only four species it does suggest that our last common ancestor with the modern apes also lived in groups composed of related males and unrelated, migratory females. When females transfer between groups, they exert their choice of mates. Thus, in the living apes, females are far from being passive recipients of male reproductive ambitions. Rather, they engage in strategies that optimize the quality and quantity of males at their disposal.

If the relationships within groups of great apes are strongly influenced by female distribution in spite of male attempts to control female behavior, what about the relationships among groups? None of the apes live peacefully as neighbors. Chimpanzee intercommunity aggression is violent, even le- thal, as events at Gombe and Mahale in the 1970s revealed. Even among bonobos, although females seek out males from other communities with impunity, most encounters between male neighbors are tense and aggressive. Male orangutans defend their females against intruding males, and silverback male gorillas have been seen fighting savagely over control of a group. Joseph Manson and Richard Wrangham consider this issue in comparison to the kinds of intergroup relations that most traditional human societies have. They considered females, whether human or ape, to be valuable alienable resources for which males should and do compete intensely. This competition places male cooperation at a premium, since each male benefits by being part of a strong alliance. They conclude that this set of benefits leads to males (and men) tending to remain in their natal area and obtaining females (women) from other neighboring groups. Since males who remain in the home group tend to be related to one another, the incentive to compete rather than cooperate may be lessened.

Chimpanzees are alone among the four species of great apes in being frequent predators. We have no reason to believe that the digestive systems of the other apes could not process meat protein. Yet it is not consumed by gorillas at all, and by orangutans and bonobos only rarely. Meat, bone, and viscera surely have the same nutritional value to a bonobo as they do to a chimpanzee, so why don’t bonobos hunt avidly? We used to think that gorillas were obligatory leaf eaters and so perhaps lacked the di- gestive capabilities to process meat, but the studies in West and Central Africa have shown them to eat a fairly chimpanzee-like diet in much of their range. There is no record of any gorilla consuming the meat of other mammals, though insects and small invertebrates are consumed readily. Surely bonobos and gorillas ought to make use of such a valuable resource whenever possible.

Consider the different reasons that the other apes might not be avid meat eaters. First, there may be basic ecological factors: some apes live in forests in which suitable prey are not available. This is rarely the case except where humans have hunted all the smaller mammals out of existence, in which case the apes’ existence itself is probably threatened. It is certainly not the reason that bonobos do not hunt very often; red colobus and other monkeys are found in the same forest inhabited by these apes.

In fact, a stunning observation of the relationship be- tween bonobos and potential monkey prey was made by Jorge Sabater Pi and his colleagues in the Lilingu forest. They witnessed bonobos capturing small guenon monkeys, but rather than eating them the bonobos used them as playthings. After catch- ing a monkey, rather than apply a killing bite and consume it as a chimpanzee would, the bonobos would carry the monkeys for hours and played with them as though they were dolls.27 Besides monkeys, bonobo habitats in which human poach- ing has not been intense also contain small duiker antelope, a favorite food for chimpanzees, plus a variety of small mammals. It does not appear that bonobos fail to hunt due to lack of potential prey.

Chimpanzees make good use of their tree-climbing abilities, their powerful arms, and their large ca- nine teeth when grabbing and subduing a monkey. The prey is usually a young monkey that is grasped by the hands, pinned to the branch, and bitten through the rear of the skull or neck. Bonobos cer- tainly have the same adaptations for catching and killing prey as chimpanzees—as their use of mon- keys as playthings attests—and yet rarely make use of them. But orangutans may be too slow to chase down prey: in their forest canopy, they would en- counter mostly fast-moving animals such as squir- rels and monkeys. This may be why orangutan meat eating is limited to the occasional squirrel found in tree cavities while foraging for fruit.28 Cer- tainly the gorillas’ size might not allow them to ma- neuver quickly enough to catch an antelope, but the circumstances under which prey are usually met suggest otherwise. If a duiker crosses a trail in front of a gorilla, the ape need only make a headlong rush to capture its quarry. Duiker have been seen crossing a gorilla’s path, but the gorilla’s reaction is one of disinterest.

A third possibility is that the other apes do not hunt due to energetic constraints. The calories that a mountain gorilla might have to expend to pursue and catch a duiker might negate the caloric value of the meat. I don’t find this a very plausible explana- tion for their failure to hunt because chimpanzees still do so. My work at Gombe has shown that the energetic balance involved in hunting rarely tips in favor of a nutritional motive. Most members of the hunting party receive very little meat for their ef- fort, and the number of chimp-hours expended on the hunt plus the long begging and sharing session that follows it can be enormously costly relative to the quantity of meat that is usually available.29 The most typical catch is a one-kilogram baby monkey, divided among up to twenty hunters. So chimpanzees engage in an energy-expensive behavior, and most fail to recoup their caloric investment. Granted, the nutrient value of meat is different from its pure caloric value; perhaps the value of some saturated fat and animal protein outweighs the rela- tively few calories that lean monkey meat provides.

These three explanations for why the other apes don’t hunt are all in some way ecological, tied to the interaction between the hunter and its physical en- vironment. But what if the motivation to hunt or not hunt is not determined by the physical environ- ment, but by a social one? Social factors are clearly implicated in chimpanzee hunting behavior. We know that the size and composition of the foraging party determines whether its members will under- take a hunt when they meet a group of colobus monkeys. The number of hunters strongly influences whether a hunt will be successful.

Beyond social factors, there is culture. The cultural diversity seen among chimpanzee societies supports an emerging realization that populations across Africa at least superficially resemble very simple human societies in their variety of learned, enculturated features. The culture of hunting is one such learned tradition.
In forests where there is no [meat] abundance, the culture might never have developed, and chimpanzees might therefore not recognize antelope as po- tential food. We see examples of this in the failure of Ta ̈ı chimpanzees to attack pigs when they are en- countered, or when Gombe chimpanzees show little interest in fresh carcasses of antelope they encoun- ter in the forest. Presumably, once the innovation of meat eating has taken place, it will spread among the members of a chimpanzee community, and into other communities with the departure of emi- grating females. But cultures live and die, and it is equally likely that a learned desire for meat could be extinguished only to reemerge later. In this way some populations might hunt only particular species, or even not hunt at all, due only to the halting process of the birth and death of cultural traditions.

Finally, we must consider whether my original hypothesis is valid. Among the other apes, hunting is an unimportant part of society compared to the role it plays in chimpanzees. Since both gorillas and orangutans have been watched by human researchers for decades for long periods at close range in different types of habitat, we can safely say that gorillas do not eat meat, and orangutans do so only rarely. But nearly everything we know about bonobos comes from two study sites in the Democratic Republic of Congo, both of which have had impediments to observing hunting over the years." [Craig Stanford, The Hunting Apes: Meat-Eating and the Origins of Human Behaviour]

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"This partly has to do with the larger cranium and the relationship of the cranium to the jaw, as well as being related to the position of our eyes and the way we speak and communcate. The muscles that close the jaw pass under the zygomatic arch and up towards the cranium. The zygomatic process -- the cheekbone -- serves to strengthen the arch. It also serves as an attachment for several facial muscles and with the frontal bone and eyebrow ridge forms a strong protective enclosure for the eyes. Human faces are remarkable in their expressivity and if you hold a finger to the side of your face and speak, you'll feel several muscles attached to the cheekbone operating.

That makes it clear that the  evolutionary influences on the development of these structures are immensely complex, because so many factors are in play, so I would doubt if there was any one specific 'advantage'; rather a whole array of factors that led to improvements. This generally holds true of evolutionary development and you need to think holistically about it."

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"The researchers, David Carrier and Michael Morgan of the University of Utah, theorized in a previous paper that humans’ ability to clench their hands into fists was natural selection’s way of making hands into better weapons. (Slap fights just weren’t cutting it anymore.) And if early humans had similar punching preferences as current humans do, the face was a prime target—a 1998 study of male assault victims found that 68.5 percent of injuries were facial.

Interestingly, the face bones that are most likely to fracture in homo sapiens—including cheekbones, mandibles, noses, and orbital bones—“tend to exhibit disproportionally large dimensions in australopiths, often equal to or exceeding values reported in much larger-bodied male gorillas,” the study reads. “Regardless of the evolutionary reasons for these features, the facial skeleton of australopiths was well proportioned to withstand strikes.”

Previous theories of why the face developed this way focused on chewing, and the ability to crush hard foods and grasses. But the researchers point out that some studies suggest australopiths may not have had that many hard foods in their diets after all, and that these facial features didn’t experience much strain during chewing. Perhaps, they think, since males exhibited these characteristics significantly more than females, “the proportions of these parts of face may be a result of sexual selection on fighting performance.”

Once we get into the homo genus, the robustness of the australopiths is reduced. Cheekbones are thinner, and faces are just smaller overall. The evolution toward a more vertical face, which we still see in humans “reduced the rotational moment on the skull from a blow” to the mandible, so we’ve still got that going for us. But the researchers posit that we may not need the facial structures of australopiths as much anymore because there has been a “more-or-less continuous reduction in upper body strength” throughout the evolution of the homo genus.

Still, the study notes that wide faces in human males are still associated with violence and fighting ability. So if you’re engaging in fisticuffs with a guy who looks a little prehistoric, it might be safer to aim for his stomach.

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"Science confirms what 10 minutes gazing at Chris Hemsworth's chiselled features will tell you – a person's face is the primary way that we judge attractiveness. Our eyes are trained to be drawn to the masculine features of strong cheekbones and square jaw lines in the male face.

Along with Chris, one glance at Hugh Jackman or Henry Cavill and you'll see the same pattern of striking cheek and jawbones.

Turns out, we're not just being superficial. What's happening here is our evolutionary instinct judging the genes of facial features because they communicate good health.

Why? Hemsworth's well-defined cheek and jaw line means the bones of his face are properly developed. These bones also house many of the crucial structures that support our airways, like the nasal sinuses, palate, tongue and throat. When they're underdeveloped, airway issues like mouth breathing and sleep apnoea can starve the body of oxygen, leading to chronic health problems. And that just wouldn't work for Thor.

The other features that these bones affect are the teeth. Yep, if you suffered through braces as a kid or had impacted wisdom teeth, this means you. People with well-formed facial bones provide enough space to have straight and strong smiles. Whilst this in itself is a feature we find attractive, it's closely related to appearance of the face.

When a dentist sees crooked smiles and impacted wisdom teeth, they also see long, skinny faces with underdeveloped chin and jaws. All of these signs point to facial bones that don't support airways… and are probably why a good smile is seen as an attractive feature.

WE ARE WHAT WE EAT

What's most interesting though is that the facial development is closely linked to what you ate when you were growing up. Bone growth occurs in response to muscular mechanical forces. Just like body builders who make strong, dense limbs to lift enormous weights, our shift from a naturally tough diet to soft processed foods prevents normal jaw and skull growth."

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