Monday, May 4, 2009

Human Chimp Homology


The next few posts are presented to help you prepare for the AP exam. This first post addresses the homologies between humans and chimps. Recall that homologies are traits that are derived from the same ancestral form - they have a shared ancestry.

First of all, here is a brief timeline:
40 mya - primates diversify
15 mya - the great apes (Hominidae) diverge from the lesser apes
10 mya - the chimp human line diverges from the gorilla line
7 mya - the line that leads to humans diverges from chimps
4.4 mya - hominin bipedalism

Second, many of the human/chimp homologies relate to their arboreal origin.
Forward facing eyes
Stereo vision
Grasping hands, opposable thumb
Sensitive, dexterous fingers with nails rather than claws
Fully rotating shoulder
Extended care of young

Last, homologies not related to arboreal living
DNA sequence similarity (approximately 98%)
Chromosome banding similarity
Evidence for chimp chromosome #s 12 and 13 fusing to form human chromosome #2

More later,

Mr. Baker


Bulgan said...

Do we have to memorize and know all of these for the exam?

Mr. Baker said...

Not all, but knowing a couple will help.

Mr. Baker