Wasp-researchers in the Americas ( don't remember if central or south, sorry ) discovered that altruism is generalized mothering.
IF there isn't much need for mothering in this nest, THEN go provide mothering in other nests, even-though wasps are .. aggressively competitive critters according to them.
This isn't the version I'd read before, but it's the same research:
That is 1 evidence-based-science identifying altruism's root.
AwakeSoulism/Buddhism has been insisting that altruism is generalized mothering for 25 consecutive centuries, and the phrase "all our kind mothers" meaning all other Souls/Continuums who're lavishing lessons on us, is the current rendition of that ( though Buddhism's people often forget to differentiate between the local person/mind vs the eternal Continuum that currently is trapped in an individual-life/incarnation )
In the Abrahamic religions, they have a story in Genesis, where women "ate of the fruit of the Knowledge of Good & Evil", which means Morality, and having eaten Morality, they shared it with men.
Mothering the root of it, again.
Of course, religious-men twisted the text to mean that women were "guilty" of "sin" and used that to justify mysogyny for many many millenia, but what should one expect of male-supremacism, when its too-fragile ego feels threatened?
History, Western, Eastern, doesn't suggest that we should expect honest integrity of it, obviously.
( the literally millions of women who were forced to die in India due to that male-supremacism, iirc 1 census pegged it at 30,000,000-ish missing women, and that number wouldn't have gone down recently..
the selective-abortion-of-female-foetuses/babies, in order to protect male-supremacism, including the Chinese woman who died while aborting her 4th or 6th or something daughter, because her husband wanted a son to be their only or 1stborn child..
it isn't just China that selectively exterminates girl-lives, the West shows the same thing, & as a Jewess pointed-out, nobody in Jewish culture celebrates the birth of a girl: only boys.
The Catholic inquisition's holocausting of women..
Hatred of female-lives & female-validity seems to be a deep current throughout humankind's diverse cultures, for millenia. )
3 different views into ancient psychology, and all-3 identify mothering as being the root of altruism..
Having come from an Abrahamic school background, I'm curious about the sources for #3. It is true that the meaning of the story has been twisted to justify misogyny, and that was how it was taught to us back in school.