Primate evolution
Sometimes I wonder why I do not sleep at night. Some nights the reason is blazingly obvious — thoughts like the following take root in my mind and will not let go. Recently, I finished reading Guns, Germs, and Steel: The Fates of Human Societies by Jared Diamond. I enjoyed it so such that I plan on reading The Third Chimpanzee : The Evolution and Future of the Human Animal, also by Jared Diamond. Looking at the book on our bookshelf has started me thinking about how humans evolved — specifically, how humans evolved binocular vision with eyes in the front of the head like predators have instead of on the side of the head like most prey animals have. Now, I should state that I accept that chimpanzees are the species that is genetically closest to humans. However, I do not necessarily consider chimpanzees to be predators — although I admit that this subject is not something that I have studied extensively.
Based on these beliefs, I began to wonder where the primate line came from if:
- primates truely are not predators and
- primates have eyes in a predatory configuration.
I know that, given a DNA sequence of all mammalian species on Earth and enough calculation time, one could determine how closely related any one species is from any other species by comparing the overlap in the DNA sequences. Now, the following is what kept me up half the night:
would it be possible to approximate, within a million years or so, how long ago the species diverged? I think that a model could be devised that takes into account:
- the percentage of DNA in common between the species,
- the average amount of radiation that reaches the Earth’s surface,
- the average number of mutations to DNA
that occur per unit of radiation, - the average number of mutations that are passed on, and
- the probability that the mutation will be “beneficial.”
This will probably be something that I will mull over in the back of my mind for several days.
November 29th, 2005 at 9:50 pm
I was going to tell you this tonight, but you didn’t come so: one other possibility beyond their predatory nature is brachiation. Forward-facing eyes is not solely a predatory issue, but a depth perception issue. Predators need it to grab their prey accurately. Similarly, tree- and vine-swinging requires depth perception.
November 30th, 2005 at 11:09 am
But, did depth perception evolve for tree- and vine-swinging, or specifically for predation — with the tarzan abilities coming as an added bonus?
November 30th, 2005 at 12:00 pm
:pulls out voice recorder:
“Monkey tail: help or hindrance?”
:stows voice recorder:
For Ashley’s sake, I will not link to a product page of the recorder I use…
November 30th, 2005 at 10:02 pm
My guess is that it started off in support of vine-swinging and giving better ability to examine things close up with those nifty hands they developed, and later helped in moving them to a more predatory lifestyle.
December 3rd, 2005 at 8:20 pm
The general theory I believe is that primates evolved forward facing eyes so that they can have better depth perception and eyesight which is helpfull for living in trees and picking the freshest fruits.
Although Chimpanzees aren’t carnivores they do have some preditory instincts and have been known too eat other species of primates from time to time so they’re actually a bit omnivorous like us.