Posted on 07/20/2006 6:58:11 AM PDT by PatrickHenry
The ability to spot venomous snakes may have played a major role in the evolution of monkeys, apes and humans, according to a new hypothesis by Lynne Isbell, professor of anthropology at UC Davis. The work is published in the July issue of the Journal of Human Evolution.
Primates have good vision, enlarged brains, and grasping hands and feet, and use their vision to guide reaching and grasping. Scientists have thought that these characteristics evolved together as early primates used their hands and eyes to grab insects and other small prey, or to handle and examine fruit and other foods.
Isbell suggests instead that primates developed good close-up eyesight to avoid a dangerous predator -- the snake.
"A snake is the only predator you really need to see close up. If it's a long way away it's not dangerous," Isbell said.
Neurological studies by others show that the structure of the brain's visual system does not actually fit with the idea that vision evolved along with reaching and grasping, Isbell said. But the visual system does seem to be well connected to the "fear module," brain structures involved in vigilance, fear and learning.
Fossils and DNA evidence show that snakes were likely the first serious predators of modern mammals, which evolved about 100 million years ago. Fossils of snakes with mouths big enough to eat those mammals appear at about the same time. Other animals that could have eaten our ancestors, such as big cats, and hawks and eagles, evolved much later.
Venomous snakes evolved about 60 million years ago, raising the stakes and forcing primates to get better at detecting them.
"There's an evolutionary arms race between the predators and prey. Primates get better at spotting and avoiding snakes, so the snakes get better at concealment, or more venomous, and the primates respond," Isbell said.
Some primate groups less threatened by snakes show fewer signs of evolutionary pressure to evolve better vision. For example, the lemurs of Madagascar do not have any venomous snakes in their environment, and in evolutionary terms "have stayed where they are," Isbell said. In South America, monkeys arrived millions of years before venomous snakes, and show less specialization in their visual system compared with Old World monkeys and apes, which all have good vision, including color.
Having evolved for one purpose, a good eye for color, detail and movement later became useful for other purposes, such as social interactions in groups.
Isbell is currently working on a book about primate origins, including her snake hypothesis.
That kind of stuff isn't newsworthy. Happens all the time.
If you want to convince me, you'll have to show me a real miracle, like a statue that cries real tears.
When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked Him to forgive me.
-- Emo Philips
A monkeys anus is an 'evolutionary adaptation" as well a monkeys fingers. They developed to fling feces at evolutionists.
I hope by this post that we have now reached the nadir of creationist "argument".
From here it can only go up!(but not in the sense of actually evolving, you understand, just up.)
I thought the opposition was being more intelligent than usual. Monkey feces is a step up.
"Wow. I am astounded. Tell me how. Give details.
"
Oh, it's easy. You just say, "Let there be whatever, and whatever appears." It's a snap if you're omnipotent, you see. Sadly, I'm not omnipotent. At my age, I'm lucky I'm any kind of potent.
Ablatives will be found in excess in the taxonomic keys.
I was walking across a bridge one day, and i saw a man standing on the edge, about to jump off. So I ran over and said "stop! don't do it!" "Why shouldn't I?" he said. I said, "Well, there's so much to live for!" He said, "Like what?" I said, "Well…are you religious or atheist?" He said, "Religious." I said, "Me too! Are you christian or buddhist?" He said, "Christian." I said, "Me too! Are you catholic or protestant?" He said, "Protestant." I said, "Me too! Are you episcopalian or baptist?" He said, "Baptist!" I said, "Wow! Me too! Are you baptist church of god or baptist church of the lord?" He said, "Baptist church of god!" I said, "Me too! Are you original baptist church of god, or are you reformed baptist church of god?" He said, "Reformed baptist church of god!" I said, "Me too! Are you reformed baptist church of god, reformation of 1879, or reformed baptist church of god, reformation of 1915?" He said, "Reformed baptist church of god, reformation of 1915!" I said, "Die, heretic scum", and pushed him off.
-- Emo Phillips
"At my age, I'm lucky I'm any kind of potent."
LOL Yeah Buddy. Me too!
"OK, evolutionists, let's hear your howls of protest and derision."
I don't necessarily believe that is the exact reason for vision changes. Seems maybe a better explanation (and I have no proof of this) is that eyesight may have gotten better because certain foods that they adapted to eat blended with the environment, so that was necessary. But it doesn't matter because it is all part of intellectual discussion/debate. It also is not religion. Religion has nothing to go on. Science has millions of years of fossil evidence. Faith isn't science. It is blind hope for people who feel really guilty.
"and the dead walking the Earth that accompanied Jesus' death."
Sounds like Monday morning at my office!
Gone on vacation, hold the fort down. SeeYa.
Placemarker.
 |
 |
 |
They can grow to twelve inches across from leg tip to leg tip:
Now that's one big spider. I hope I never observe one in my lifetime, other than in captivity. I wonder how fast they can move. Every spider I've killed was pretty damn fast, no matter how big, if I didn't get it the first try. And then there are the ones that got away..they were even faster.
Jumping the gun there. The question is how one falsifies the assertion that the supernatural was involved in the first place.
Derision is not logically sufficient.
"How many angels CAN dance on the head of a pin" implies you have a 100% effective angel detector, with no false positives or negatives; and the angels have not developed any ECM, or have signed a unilateral treaty not to use it.
(Stir, stir, stir...)
Cheers!
I understand the Bacchanalia were *very* constraining.
Cheers!
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.