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.
Non answer. While I didn't direct the original post to you, maybe you can take a crack at the questions. Be as specific as possible to avoid any possible misunderstanding.
What nonsense!
This definition will determine if a person is a strict naturalist or if they are willing to acknowledge the supernatural. Strict naturalists seem to have a corner on Academia at the moment, which gives the appearance of credibility. However, this data point is changing rapidly.
You're on your own here.
Nope...too busy trying to learn how to catch flies.
You need to be careful on these threads. The evolutionists here are ruthless. I typically don't bother posting on these threads because no "discussion" really takes place -- just evolutionist back-patting.
Typicaly evolutionist hatred. Nice. Looking for a chuckle and a back-pat from a fellow evolutionist?
It all comes down to that, doesn't it? Any theory other than evolution is incompatible with your worldview. So your clinging to evolution is not primarily based on evidence, but on your atheistic worldview.
I would argue that nature does not create or possess intelligence. Therefore any evidence of intelligence we come across in nature would have originated from a supernatural intelligence.
In other words "Life was created".
There are no other "theories" on the diversity of life we find on this planet. Theories are based upon evidence. Evidence is something that can be observed/handled/tested by more than one person and have the same results. Because of its nature, evidence is physical, not supernatural. You can attempt to base ideas on the supernatural, but until someone else can test those ideas and come up with compatible results, your theory is so much vaporware.
To put it succinctly, a neutral third party could not be expected to accept your version of events without some corroborating evidence. "A 2500-year-old Bronze Age creation story" is not evidence.
"They try to use evolution to explain how primates use their eyes and limbs, to conceal the fact that evolution can't explain how they got eyes and limbs in the first place."
Ok, how did they get eyes and limbs?
Not hatred. If someone feels qualified to comment upon the veracity of a well-accepted scientific theory, one must be prepared to back one's assertions up. Asking for a detailed explanation of that person's understanding of the theory is not hatred, but rather an effort to determine the person's level of knowledge.
This is an unsupported assertion. As I said, you are going to have to supply evidence that would corroborate your claims.
Wow, is this a new record? YECer for sure by post 5, probable in post 3....
"Any theory other than evolution is incompatible with your worldview."
ZAP and a day of rest isn't a theory. It is a faith. Faith is incompatible with scientific theory.
Not to mention mushrooms.
Babies do not have fears of snakes and spiders. These fears reach their peak about age three, when kids are likely to wander away from their parents.
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