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Snakes as agents of evolutionary change in primate brains (2006)

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Current hypotheses that use visually guided reaching and grasping to explain orbital convergence, visual specialization, and brain expansion in primates are open to question now that neurological evidence reveals no correlation between orbital convergence and the visual pathway in the brain that is associated with reaching and grasping.

An alternative hypothesis proposed here posits that snakes were ultimately responsible for these defining primate characteristics. Snakes have a long, shared evolutionary existence with crown-group placental mammals and were likely
to have been their first predators.

Mammals are conservative in the structures of the brain that are involved in vigilance, fear, and learning and memory associated with fearful stimuli, e.g., predators. Some of these areas have expanded in primates and are more strongly connected to visual systems. However, primates vary in the extent of brain expansion. This variation is coincident with variation in evolutionary co-existence with the more recently evolved venomous snakes.

Malagasy prosimians have never co-existed with venomous snakes, New World monkeys (platyrrhines) have had interrupted co-existence with venomous snakes, and Old World monkeys and apes (catarrhines) have had continuous coexistence with venomous snakes.

The koniocellular visual pathway, arising from the retina and connecting to the lateral geniculate nucleus, the superior colliculus, and the pulvinar, has expanded along with the parvocellular pathway, a visual pathway that is involved with color and object recognition. I suggest that expansion of these pathways co-occurred, with the koniocellular pathway being crucially involved (among other tasks) in pre-attentional visual detection of fearful stimuli, including snakes, and the parvocellular pathway being involved (among other tasks) in protecting the brain from increasingly greater metabolic demands to evolve the neural capacity to detect such stimuli quickly.

A diet that included fruits or nectar (though not to the exclusion of arthropods), which provided sugars as a neuroprotectant, may have been a required preadaptation for the expansion of such metabolically active brains. Taxonomic differences in evolutionary exposure to venomous snakes are associated with similar taxonomic differences in rates of evolution in cytochrome oxidase genes and in the metabolic activity of cytochrome oxidase proteins in at least some visual areas in the brains of primates. Raptors that specialize in eating snakes have larger eyes and greater binocularity than more generalized raptors, and provide non-mammalian models for snakes as a selective pressure on primate visual systems.

These models, along with evidence from paleobiogeography, neuroscience, ecology, behavior, and immunology, suggest that the evolutionary arms race begun by constrictors early in mammalian evolution continued with venomous snakes. Whereas other mammals responded by evolving physiological resistance to snake venoms, anthropoids responded by enhancing their ability to detect snakes visually before the strike.

Comments

seems like a cool subject except evolution is theory. its never been proven, there has never been one case of speciation ever documented. and you would need 2 cases simultaneously for any new species to propagate. like I said evolution is BUNK..........peace

dudeface wrote:

seems like a cool subject except evolution is theory. its never been proven, there has never been one case of speciation ever documented. and you would need 2 cases simultaneously for any new species to propagate. like I said evolution is BUNK..........peace

ok, state and prove your claims... let's debate and see why it is that you don't know the conterxtual differences in ther use of the word "theory"
A Scientific theory has empirical evidence to back it up.... back up your claim please :-)

that basically would take to long. I don't believe lying luciferian freemasonic Nazis. pretty simple. theory does not mean fact or truth.............period.........peace

https://www.youtube.com/watch?v=DtCIp9sgiE0

dudeface wrote:

that basically would take to long. I don't believe lying luciferian freemasonic Nazis. pretty simple. theory does not mean fact or truth.............period.........peace
https://www.youtube.com/watch?v=DtCIp9sgiE0

As i mentioned a Scientific theory is backed up by research and objective evidence which can be tested and repeated.
Big claims require big evidence... over to you

dudeface wrote:

seems like a cool subject except evolution is theory. its never been proven, there has never been one case of speciation ever documented. and you would need 2 cases simultaneously for any new species to propagate. like I said evolution is BUNK..........peace

have a wee peak here maybe
https://www.youtube.com/watch?v=DrgR_tSVdLU

good day.......ya that's funny, mutation is not evolution. words have meaning. not what you think they mean and evolution is nothing more than adapted mutations to a particular environment. white moths changing to black moths because the trees bark got darker is a mutation. there was no change from a fish to a monkey. again the repeaters carry on repeating. you seem really intelligent but don't let your ego stop you from admitting you have been fooled. they lie about so many other things but they never lie about science. you PROVE TO ME SPACE IS A VACUM.....YOU CANT YOU HAVE NEVER BEEN THERE. so you rely on lying luciferian freemasonic Nazis who say its so. you say repeatable and blah blah........ but YOU repeat the experiment that proves gravity, dark matter, space, going to the moon, black holes............you cant. you repeat. sorry my fellow human I believe nothing and know things...........belief is the enemy of knowing............peace

dudeface wrote:

good day.......ya that's funny, mutation is not evolution. words have meaning. not what you think they mean and evolution is nothing more than adapted mutations to a particular environment. white moths changing to black moths because the trees bark got darker is a mutation. there was no change from a fish to a monkey. again the repeaters carry on repeating. you seem really intelligent but don't let your ego stop you from admitting you have been fooled. they lie about so many other things but they never lie about science. you PROVE TO ME SPACE IS A VACUM.....YOU CANT YOU HAVE NEVER BEEN THERE. so you rely on lying luciferian freemasonic Nazis who say its so. you say repeatable and blah blah........ but YOU repeat the experiment that proves gravity, dark matter, space, going to the moon, black holes............you cant. you repeat. sorry my fellow human I believe nothing and know things...........belief is the enemy of knowing............peace

wow. no.. WOW.. what an utter self assured and very wrong person. why not change your name to W. Wrongy Wrongenstein? :-)
you make me laugh!

Okay; then in your belief system, how do you explain the wide variegation of plant and animal species? If there is no evolution, what accounts for the explosion of life all over the planet?
Note that I am not attacking; I am genuinely asking for your perspective. It's a serious question that a lot of serious minds have pondered. You can't just swipe your hand at it and expect everyone to stand up and take notice.

euxconcen wrote:

Okay; then in your belief system, how do you explain the wide variegation of plant and animal species? If there is no evolution, what accounts for the explosion of life all over the planet?
Note that I am not attacking; I am genuinely asking for your perspective. It's a serious question that a lot of serious minds have pondered. You can't just swipe your hand at it and expect everyone to stand up and take notice.

Straw man
you are starting from the false premise that there is no evolution. there is an abundance, in fact a preponderance of evidence and see if you can persuade , showing facts, figures and evidences of your case

My question was directed at dudeface, not you, pax.
It's impossible for me to have made a straw man argument at this stage.
Let the conversation grow first.

euxconcen wrote:

My question was directed at dudeface, not you, pax.
It's impossible for me to have made a straw man argument at this stage.
Let the conversation grow first.

hands up to that one.. i dumbassed it!

good day............ya its not really a belief system. I either know or don't know. as far as beliefs I have only one......there is a creator of this "realm" we live in. I cannot prove many of the "scientism" theories that are driven into my brain as a child through school, TV, news and movies and even most books. I question everything and try to be autodidactic in my thought processes. coming to my own conclusions by removing the lies and then whats left must be the truth. not a theory. theory DOES NOT mean truth. I'm sorry it doesn't. people have been taught theories are reality and true. things like black holes and dark matter are good examples. they are as fake as santa claus. millions of light years away and we can tell you everything about them.....poppycock. people look up to see whats down.
as to the abundance of life in this realm...........the creator made them as they are, all of them. and then let the earth machine on its way and gave you the 2 best gifts ever........life and freewill...............its all about freewill. every decision you make takes you either closer to light ..........or dark. the meaning of life is living.
but unfortunately luciferian freemasonic Nazis have hijacked the natural machine and since they cant control mother nature they are trying to destroy the natural system and create a false dark un natural system they can control. SCIENTISM. satanic/luciferian believers have nothing to do with God and Satan......its a self serving religion, they are the god and its me me me.
so basically earth is the center of everything. not a speck of dust in infinite nothingness. EVERY ancient culture had an enclosed earth cosmology. every one. and for you or anybody to believe that in the last 100 years we came up with the answer to everything is arrogance at its peak and the reason for our downfall we witness now ...............DONT FORGET TO WEAR YOUR 4 MASKS........peace

thanks, Langeille, for your SOLID uploads

PS - I have extensively researched the mythology of serpents. Let me know if that topic interests you

That definitely interests me, euxconcen. I'd appreciate any uploads you can do.

okay! am working on it, cheers

I would like to see the upload

cool video! thanks for sharing that, cheers