SPRING - 2011
Let me start our discussion of human evolution with the
observation that although Darwin had little to say about the subject in his
Origin of Species
had already become obvious that if humans had taxonomic relatives, they were to be found
among the great apes.
The taxonomy that followed had humans as a separate family:
Great Apes include the Orangutan, the Gorilla, the Chimp, and this was thought to be the
closest family to humans. The gibbon was placed in its own family, as was the human lineage.
For a long time, it got left that way, but even Linnaeus had his doubts, which he expressed
privately, in letters to friends.
With modern molecular evidence, and a better understanding of the anatomical details for
these various species, it now seems far more likely that humans should be grouped with
Gorillas and Chimpanzees, a tad closer to the latter, with the Orangutan in another family. If
we ignore all the other taxa, we have something more like:
The gibbon is in one family, Hylobatideae, all the others in a single family, Hominidae, with
the orang in one subfamily (Ponginae), and with the gorilla, common chimp and pygmy
chimp (Bonobo) and humans in another (Homoninae). Gorilla, chimps and humans are
placed in three different genera. Voluminous evidence now places humans closest to chimps.
The Fossil Record
– If you look at the fossil record for the great apes and humans, it seems to
go back about 6 Mya, when the Gorilla lineage split off from what was then the chimp-human
lineage. About 4.6-5.0 Mya, hominids split off from chimps, as nearly as we can tell. It has to
Note addition of the
Bonobo (pygmy chimp),
which Linneaus did not
know about, but which
we now do.