Building giants was a necessity for ancient humans. A human tribe was more than the sum of its parts, in physical power, in productivity, and in knowledge.
Given the powers of emergence, large human giants would be forces to reckon with. But unlike ants, humans are more than just cells in competing giants—they’re competing individuals too. So as tribes grew in size, the benefits of strength and capability would be accompanied by the cost of increasing instability. A human tribe is held together by weaker glue than an ant colony, and the bigger the tribe, the harder it is for that glue to hold up. This is partly why complex animals like wolves, gorillas, elephants, and dolphins tend to roll in groups with under 100 members.
Early tribes of humans were probably similar to tribes of other apes—glued together mostly by family ties. Kinship is an obvious natural glue because animals are programmed to be interested in the immortality of those with genes most similar to them—so humans are more likely to cede individual self-interest to a group when that group is family. That’s why today, people are so willing to make huge sacrifices for family members.
Family glue is strongest between parents and children, because genes “know” that copies of themselves live in their container’s direct progeny. Genes also have us selfishly caring about the well-being of siblings and nieces and nephews because a very similar version of themselves lives in them—but we don’t care quite as much about these people as we do about our children. As the distance between blood relations grows, the glue thins. As evolutionist J.B.S. Haldane puts it: “I would lay down my life for two brothers or eight cousins