Every action, no matter how altruistic it might seem, has an egoistic or biological motive (except involuntary actions, of course).
While egoistic motives are always focused on us and our good, this is not always the case with biological ones. There are situations when nature "betray" us. In war, for instance, our nature might force us to sacrifice ourselves for the bigger group of brothers in arms.
These are two soldiers I found, who threw themselves on the enemy machine-guns to protect other soldiers (in Russian language):[You must be registered and logged in to see this link.][You must be registered and logged in to see this link.]
I think this kind of behavior is directly related to hormone called [You must be registered and logged in to see this link.]
and is triggered to protect the evolutionary more important individuals (similar to mother-child bond). "For the greater good".
In other words, nature, on the contrary to what most people think, concerns only about the survival of the species. An individual is of second importance and is important only because it is a part of the species.
Another example of this is [You must be registered and logged in to see this link.]
. It is a common phenomenon in nature which shows that if it adds to the good of species, fit individuals might eat sick, young, small or simply - inferior ones. This not only feed the superior ones, but also increases the probability that those disadvantageous genes won't appear in other generations. If only this could be applied in human context. Che.