The First Primates Evolve

Living in the trees
60-55 million years ago

Almost immediately after the dinosaurs were wiped out, mammals evolved the ability to nourish their young inside their wombs using a placenta, just like modern humans. Soon, some of these early placental mammals evolved into the first primates. They would ultimately give rise to monkeys, apes and humans. But the first ones were small creatures. The oldest known primate skeleton is of a species called Archicebus achilles, which weighed no more than 30 grams. They lived in the hot and humid rainforests of Asia.

See other: History of Life

The Split From Apes

Our genes start changing
13-7 million years ago

Our ancestors split from their chimp-like relatives over 7 million years ago. At first, they would have looked similar. But within their cells, change was afoot. After the split, the ASPM and ARHGAP11B genes began changing, as did a region called HAR1. It’s not clear what this did, but HAR1 and ARHGAP11B are involved in the growth of the cerebral cortex.

See other: What Makes Humans Human?

Collaboration and Communication

‘Virtually all of humans’ highest cognitive achievements are not the work of individuals acting alone but rather of individuals collaborating in groups. Other great apes, especially chimpanzees, coordinate their actions with others in a number of complex ways—for example, in capturing small animals and in coalitions and alliances in intragroup conflicts (Muller & Mitani, 2005). But humans collaborate and communicate with one another in especially complex ways that go beyond simple coordination, ending up with such things as complex social institutions structured by joint goals, division of labor, and communicative symbols.

The ability to collaborate and communicate with others in sophisticated, species-unique ways is apparent even in prelinguistic human infants […]. In a recent comparative study, human 1-year-olds and juvenile chimpanzees each engaged in a collaborative task with a human adult. When the adult stopped participating, the chimpanzees simply tried to solve the task alone. The human children, in contrast, employed various forms of communication to try to reengage the adult into the task. The children seemed to understand that the two of them had committed themselves to doing this together and it simply would not do if the adult was shirking her duty. The collaboration was structured by joint goals and joint commitments to one another (Warneken, Chen, & Tomasello, 2006). It is not difficult to see in these simple activities the roots of the kind of collaborative commitments and activities that structure human social institutions, from governments to religions.’

– Tomasello. M., Herrmann. E. (2010) “Ape and Human Cognition: What’s the difference?” Current Directions in Psychological Science 19(1) 3-8