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Old 10-15-2014, 02:57 AM
 
Location: Auckland, New Zealand
5,522 posts, read 2,604,874 times
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Is evolution bout luck really? I suppose mostly but adaptations to environment seems a little more complex than a set of variations being more viable. One example that comes to mind is eyesight. All invertebrates stated out with amazing vision. We humans are left with a mere tri-color vision while ungulates and canines are left with bi-color vision. They have lost the red cones. By comparison, turkeys see six different colors! So deer and the like lost their red cones because they became nocturnal (mostly) and red cones don't work in the dark. (They don't see red as red but they do see red as green but not as bright because green cones are less sensitive in the red spectrum. We don't know how they perceive green and blue). This means they don't have yellow, orange or red in their perception, just varying levels of something corresponding to green. On the other hand, they also lost the yellow UV protecting pigment in the eye which allows them to see in the ultraviolet (near ultraviolet actually) which is great for night vision (starlight is high in ultraviolet). But why would nocturnal animals lose something that isn't being used? Humans have lost some color from our ancestral nocturnalism. Just a snippet, the color violet is between blue and ultraviolet yet it has a reddish hue. That's because that wavelength is detected by our red cones as well as our blue cones! Red cone sensitivity drops off to near zero in the blue then picks up again in the violet.

Ruffin_Ready will be able to fill in the gaps and correct the errors. He'll know more about this than I do.

Oh, dogs can't find red balls in green grass! They have no problem finding blue balls in green grass.
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Old 10-15-2014, 11:47 AM
 
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Originally Posted by Cleonidas View Post
Two species that occupy the same niche are necessarily competing with one another when they occupy the same area. If one species has an advantage it will necessarily displace the other absent adaptation. Neanderthals were probably plenty clever, but we know a thing or two about human deviousness and capacity for being very rude, don't we? Does it really matter if a neanderthal male of your approximate age would have been significantly stronger than you if you knew how to fashion an atlatl that was beyond his comprehension?
The theory that the early humans killed off the neanderthals has mostly been ruled out. I get your argument about two species competing with each other. But weren't the different apes also competing with each other? We do have many species of apes and not one or two clear evolutionary winners.
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