Comments on: Mammals Evolve Faster in the Tropics, Confounding Scientists http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/ 80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day\'s most compelling topics. Mon, 09 Nov 2009 03:22:11 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: YouRang http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/comment-page-1/#comment-35307 YouRang Thu, 25 Jun 2009 15:22:54 +0000 http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/#comment-35307 Grant H's comment is relevant to the Out of Africa DNA hypothesis. Maybe humans are mobile now, but 50 kyr ago that wouldn't have been true. So there would have been a drive for greater diversity in the tropical populations. Admittedly, the 2 measures of DNA age (ychromosome and mitochondrial chromosomes) have relatively little drive components to them (if any) by virtue of interacting very little with the Red Queen's followers. Aside from all of which, the Red Queen hypothesis is not a theory yet. It might be that the stress response to cool environments is less consistent with variety than the stress response to hot environments. In the study, it might also be that the ancestral population that moved out of the intermediate land that was the homeland to both populations had to be more diverse to respond to a variety of harsher environments in the tropics. I.E. it seems to me that there are more different kinds of climate regions in the tropics than in the temperate zones. (I'm not sure where my climatology book is to verify that.) And as to whether evolution in humans is faster in the tropics: The main driver of human evolution is the human induction of our habitat. IOW there is no particular evolutionary virtue to the ability to run a 9.6 100 m dash. Maybe a few groupies might be seduced (as in Wilt Chamberlain's pointless screwing with 20k women); but it won't last in the long run (since running a 9.61 100 m in the next generation would be no big deal). Grant H’s comment is relevant to the Out of Africa DNA hypothesis. Maybe humans are mobile now, but 50 kyr ago that wouldn’t have been true. So there would have been a drive for greater diversity in the tropical populations. Admittedly, the 2 measures of DNA age (ychromosome and mitochondrial chromosomes) have relatively little drive components to them (if any) by virtue of interacting very little with the Red Queen’s followers.
Aside from all of which, the Red Queen hypothesis is not a theory yet. It might be that the stress response to cool environments is less consistent with variety than the stress response to hot environments. In the study, it might also be that the ancestral population that moved out of the intermediate land that was the homeland to both populations had to be more diverse to respond to a variety of harsher environments in the tropics. I.E. it seems to me that there are more different kinds of climate regions in the tropics than in the temperate zones. (I’m not sure where my climatology book is to verify that.)
And as to whether evolution in humans is faster in the tropics: The main driver of human evolution is the human induction of our habitat. IOW there is no particular evolutionary virtue to the ability to run a 9.6 100 m dash. Maybe a few groupies might be seduced (as in Wilt Chamberlain’s pointless screwing with 20k women); but it won’t last in the long run (since running a 9.61 100 m in the next generation would be no big deal).

]]> By: Grant H http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/comment-page-1/#comment-35268 Grant H Thu, 25 Jun 2009 01:46:55 +0000 http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/#comment-35268 @ tim: I don't believe that would be the case. I would've thought that a percentage of humans globally are quite mobile and I suspect there would be sufficient gene mixing to prevent that scenario. It would be very interesting to find out what the answers to your questions are. But as the article indicates that these evolutionary differences in mammals have only just been established, I imagine you’re questions as yet, have no answers. @ tim:
I don’t believe that would be the case. I would’ve thought that a percentage of humans globally are quite mobile and I suspect there would be sufficient gene mixing to prevent that scenario.

It would be very interesting to find out what the answers to your questions are. But as the article indicates that these evolutionary differences in mammals have only just been established, I imagine you’re questions as yet, have no answers.

]]> By: tim http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/comment-page-1/#comment-35265 tim Thu, 25 Jun 2009 00:16:42 +0000 http://blogs.discovermagazine.com/80beats/2009/06/24/mammals-evolve-faster-in-the-tropics-confounding-scientists/#comment-35265 Is there any evidence that humans living in the tropics are evolving faster than humans living in (1) temperate regions and/or (2) the artic? Also, are humans living in temperate regions evolving faster than those living in the artic? Is there any evidence that humans living in the tropics are evolving faster than humans living in (1) temperate regions and/or (2) the artic? Also, are humans living in temperate regions evolving faster than those living in the artic?

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