In “Why we gave up prehistoric night life for social life” (MSNBC, November 9, 2011), Wynne Parry reportsm “Research indicates search for food drove us into daytime living 52 million years ago,”
Researchers from the University of Oxford delved into our evolutionary history by building a family tree for 217 primate species whose social habits are known. Working backward from the present, they found that early primates were nocturnal animals that lived solitary lives until about 52 million years ago. Our early ancestors apparently transitioned to life in large groups at the same time they shifted to becoming active during the daytime.
From here, other social structures evolved, such as isolated pairs and harems, in which a single male lives with multiple females.
If there is any evidence for this historical transition in lifestyles, the researchers do not say what it is. We also learn, they ran into problems because
… it became trickier when focusing on the great apes — chimpanzees, gorillas, orangutans and us — because each organizes itself differently, she said.
Humans are the most flexible of all. Human societies have social structures resembling, at least to some degree, those found throughout the primate world, including living in pairs or harems or, in some traditional societies, in families structured around related members of one sex — sisters, mothers and daughters or brothers, fathers and sons.
In other words, beyond the obvious, we have little or no idea what a protohuman group’s social structure would be. It took two minutes for news staff to find an example of a still nocturnal primate, the tarsier, within whose species social arrangements vary between group and solitary living. Humans, as such, have pretty much organized their societies in ways that they believed, rightly or wrongly were best. And the fact that they believed that is no demonstration that it is best. Those ancient peoples would turn up again, if they ever do, as fossils, whether their choices were was good for them or not.
A mathematical model convinced the researchers that group living coincided with a move to daytime living, which presumably settles the matter. If there is anything to settle.