From: Preston Garrison (garrisonp@uthscsa.edu)
Date: Tue Apr 29 2003 - 01:29:21 EDT
There was a nice review of the state of the art on this topic in
Nature last week:
NATURE |VOL 422 | 24 APRIL 2003 849
Genetics and the making of Homo sapiens
Sean B. Carroll
Understanding the genetic basis of the physical and behavioural
traits that distinguish humans from other primates presents one of
the great new challenges in biology. Of the millions of base-pair
differences between humans and chimpanzees, which particular changes
contributed to the evolution of human features after the separation
of the Pan and Homo lineages 5-7 million years ago? How can we
identify the 'smoking guns' of human genetic evolution from neutral
ticks of the molecular evolutionary clock? The magnitude and rate of
morphological evolution in hominids suggests that many independent
and incremental developmental changes have occurred that, on the
basis of recent findings in model animals, are expected to be
polygenic and regulatory in nature. Comparative genomics, population
genetics, gene-expression analyses and medical genetics have begun to
make complementary inroads into the complex genetic architecture of
human evolution.
Preston G.
>In the interest of being open-minded about the common descent issue,
>here is a considerably problematic article for the idea that man did
>not descend from monkeys. I can find no alternate explanation, nor
>have I critically analyzed the data. Any comments?
>
>
>"Chromosomal Speciation and Molecular Divergence- Accelerated
>Evolution in Rearranged Chromosomes." Navarro, A. and Barton NH.
>Science 300, p321-324.
>
>Abstract:
>Humans and their closest evolutionary relatives, the chimpanzees,
>differ in ~1.24% of their genomic DNA sequences. The fraction of
>these changes accumulated during the speciation processes that have
>separated the two lineages may be of special relevance in
>understanding the basis of their differences. We analyzed human and
>chimpanzee sequence data to search for the patterns of divergence
>and polymorphism predicted by a theoretical model of speciation.
>According to the model, positively selected changes should
>accumulate in chromosomes that present fixed structural differences,
>such as inversions, between the two species. Protein evolution was
>more than 2.2 times faster in chromosomes that had undergone
>structural rearrangements compared with colinear chromosomes. Also,
>nucleotide variability is slightly lower in rearranged chromosomes.
>These patterns of divergence and polymorphism may be, at least in
>part, the molecular footprint of speciation events in the human and
>chimpanzee lineages.
>
>
>Josh
>
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