Colin Wilson qrites in "A Criminal History Of Mankind":

Dominance is a subject of enormous interest to biologists and zoologists because the percentage of dominant animals -- or human beings -- seems to be amazingly constant. [...] biological studies have confirmed [... that ...] for some odd reason, precisely five per cent -- one in twenty -- of any animal group are dominant -- have leadership qualities." [...]

This animal connection is very interesting.

A corresponded told a following story that originally came from an article in some psychology or ethology magazine.

Baboons are highly hierarchial primates, where a dominant male basically mates with all females, and subdominant animals have no chance. A clan of baboons was observed in a national park. They lived by a hotel within the territory and regularly came to rummage in the daily trash, searching for scraps of food. As always, the dominant males were the first to eat, and others got whatever was left, if any.

One day, something was thrown out that has already gone bad. Dominant males, being first to feed, ate it all up and died. The scientists were very interested in observing what would happen to the population now. But nobody could have predicted the results. In the absence of dominant males, no one stepped up to take their position. The other baboons developed an altruistic society, where everyone was pretty much equal, and tended to the sick and the weak. What's still more interesting that the stray males who have joined the community later have also accepted those rules of the game.

These stories and others, I think, go to show that altruism and selfishness are two separate evolutionary paths.

The problem is that any explanations of altruism in animal studies is either trying to pin down some reason why it still may be USEFUL for the individual and the population in some way, or depict altruistic creatures as dumb or sick or, in general, unfit. Here is an example:

A 2-3 year old lioness 'Kamunyak' had adopted a Fledgling young Oryx calf. The news was treated with a lot of skepticism since an Oryx is a type of antelope upon which lions usually prey. [..] The lioness, nicknamed Kamunyak, or The Blessed One, by locals, had protected her adopted young from danger and had allowed them to nurse from their biological mothers. [..]Three years have passed and astonishingly Kamunyak, (the lioness' Samburu name), had in total adopted six Oryx calves. [..] Sometimes even to her expense as she could not effectively hunt so as to keep guard; a fact that emaciated her to a point of near death. [..]

There are several theories that have been proposed to explain this extra ordinary behavior of the female African lion.

1) The question has been raised whether this could have begun on a hunt with an unusually long game of cat and mouse, where after 24 hours she bonded with the calf. [..]
2) The Samburu people suggested Kamunyak is barren. [..]
3) She could have a serious hormonal imbalance, which is triggering this abnormal behavior with another species. [..]T
4) [..]If a lioness' rank affects their endocrinology perhaps a phantom pregnancy is a possible explanation.
5) [..]Oryx calves are remarkably similar in colour to the tawny coat of an African lion, and it is possible that once the lioness had locked onto the smell of "cub" in the calf then it's lack of a feline physique ceased to matter.
etc

Consider also that Darwin was influenced by Smith and Maltus, i.e. economic and social theories of the time, and as shown by Ernst Mayer, his concept of evolution was essentially deductive. Looks like the very method used in biological studies is influenced by certain ideology that glorifies egoism, and, as a result, doesn't offer a concept of altruism as a choice of intrinsic value. Psychopathology everywhere -- no wonder they like game theory so much in population studies.
Another thing worth mentioning is that many equate egoism with general fitness, which implies that egotistic individuals are somehow better.

This is not necessarily true. As Colin Wilson writes: "Inevitably, a percentage of the dominant [types] have no particular talent or gift; some may be downright stupid.” This agrees with studies of sociopaths, natural human egotists. Their IQ is average or slightly lower, when compared to the population average.

This corresponds to what we see in animal studies. I have read recently in the Atlantic Monthly that because of new information, it is clear that a lot of animal communities a great deal more democratic than was previously thought. The leader, or a dominant, doesn't make decisions on when and where to take off and go to new feeding grounds, or to run away from danger. Animals just do it all together when a certain treshold percentage of individuals wants to turn that way, or when someone senses that something's not right.

Thus the 'leader' does not necessarily LEAD anyone. He is not necessarily smarter of wiser or more resilient. He is just bigger and stronger and gets advantage in mating. And the funny part is that he may be bigger and stronger not because of his genetic fitness, but simply because he has been pushing others out of the way all his life and getting more food than they did.