Question

3. What can you conclude about the evolutionary path between chimps and humans? Do they appear to come from a common ancestor? How can you tell?

Answer 1

Humanity did not evolve from the chimpanzee, which has spent time evolving on its own path for millions of years from our last common ancestor, just as we have. Still, chimps are our closest living relatives.

Genetic evidence suggests the ancestors of humans and chimpanzees diverged roughly 4 million years ago. The relative size of the chimp brain matches most of our extinct relatives, for a long time suggesting our ape cousin might be an ideal place to glimpse humanity's origins.

New evidence suggests, however, that our last common ancestor may not have looked as chimp-like as before thought. The fossil Ardipithecus ramidus, dating 4.4 million years old, which may very well be ancestral to both human and chimpanzee lineages, walked neither like us or chimps, possessing instead an intermediate form of walking.

In addition, Ardipithecus seemed to have possessed canines that are reduced in size, while male chimps have large tusk-like canines used as weapons for threatening and sometimes attacking other males. This may suggest that chimpanzees behaved significantly differently from our last common ancestor.

Humans keep much in common with chimpanzees.

"Emotionally and socially, the psychology of chimps is very similar to humans."

Chimps have shown they can help unrelated chimps and human strangers at personal cost without apparent expectation of personal gain, a level of selfless behavior often claimed as unique to humans. They also display what many scientists dub culture, with groups of chimpanzees socially passing on dozens of behaviors such as tool kits from generation to generation that are distinct from ones seen in other groups.

As gentle as our closest living relatives can be, chimps also can be quite violent in the wild, raping, killing and warring against their rivals. They don't like cooperating with strangers.

Humans and chimps probably last shared a common ancestor between five and seven million years ago.