The Early Years of Social Engineering
People have been breeding animals and plants, at first semi-accidentally and later more purposefully, for many thousands of years, but our first experiments in that direction may have been a factor of ten or so earlier.
One of the great puzzles of human evolution is human generosity and other altruistic behavior. The theory of evolution predicts that selfishness usually pays off at the level of the gene and above. If a behavior lowers one's fitness at the profit of someone else, any genes that permit or encourage it ought to be selected against.
Darwin simply wondered how he could ever reconcile his new theory, which was so “individualistic,” with the fact that patriotic young men so willingly went to war to sacrifice their lives for their countrymen. They were sacrificing not only their lives but also the lives of their future progeny, who otherwise would be inheriting these generous tendencies. The great naturalist was confounded.
Darwin had in mind the fact that free-riding cowards would be avoiding these same risks and that their greater numbers of surviving offspring would be inheriting the same selfish tendencies. In short, following his theories, generously self-sacrificial patriotism should always be on the wane, while dispositions to hold back and stay safe should always be proliferating. This meant that over the long run any tendencies to sacrifice personal interests for the good of the group should be automatically suppressed by natural selection—yet in practice young men were going to war, and many were doing so eagerly.
Boehm, Christopher (2012-05-01). Moral Origins: The Evolution of Virtue, Altruism, and Shame (p. 12). Basic Books. Kindle Edition.
Boehm's theory is, in effect, that human groups selected for cooperation by systematically punishing or excluding non-cooperators. This sort of behavior is only possible for those with brains large enough to understand who the non-cooperators are and social enough to cooperation with other to punish non-cooperation. He and other ethnographers have observed this sort of behavior in modern or recent hunter gatherer societies, and their is reason to think it is universal among them. This and other considerations suggest ancient origins.
We were our own first selective breeding experiment.