What Makes Us Human? Pollard Sci Am
<p>Apr 21, 2011 08:54 PM
 
Katie Pollard... student of David Haussler... article in Sci Amer.
 
We spent the next year finding out all we could about the evolutionary history of HAR1 by comparing this region of the genome in various species, including 12 more vertebrates that were sequenced during that time. It turns out that <b>until humans came along, HAR1 evolved extremely slowly. In chickens and chimps—whose lineages diverged some 300 million years ago—only two of the 118 bases differ, compared with 18 differences between humans and chimps,</b> whose lineages diverged far more recently. The fact that HAR1 was essentially frozen in time through hundreds of millions of years indicates that it does something very important; that it then underwent abrupt revision in humans suggests that this function was significantly modified in our lineage
 
HAR1! is active during develop of the cerebral cortex... that's when it's switched on.
 
HAR1 does NOT encode a protein;
 
protein encoding genes are only 1.5% of our DNA.   the other stuff is regulatory sequences.
 
HAR1 encodes RNA.
 
The secret of rapid change (in an organism) is to have changes in the DNA occur at places where
those changes make an important difference to the orgs functioning.
 
The next example is  FOXP2 gene...  people with mutations cannot make
subtle high-speed facial movements needed for human speech.
 
Neadertals  DO have the modern version of FOXP2.... which emerged > 500K years ago.
 
ASPM...  another gene that controls brain size   (changed since we diverged from chimps).
 
HAR2  may have driven the development of the wrist and thumb...  permitting us to
make and use complex tools.
 
AMY1...  for amylase...  starch digesiton.
 
LCT  lactose digestion.
 
 
 
 
 
 
 
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