April 29, 2010 | David F. Coppedge

Clock Gene Same in Humans and Birds

Science Daily, this “not only sheds light on how our internal annual body clocks function but also shows a key link between birds and mammals that has been conserved over 300 million years.”
    Mammals, including humans, have a hormone released by the pituitary gland that controls melatonin levels – known to affect the body’s response to light and dark cycles.  When days start getting longer and nights shorter, a second hormone becomes activated.  Scientists at University of Edinburgh have identified the genes behind the hormones and are beginning to understand how they interact.  The first gene may only switch on in the presence of the second gene.  In this way, the second gene regulates, or switches on, the first gene as day length increases.  The hormones, in turn, control multiple bodily responses related to seasonal change, such as “hibernation, fat deposition and reproduction as well as the ability to fight off diseases.”
    The scientists noted that one of the same genes, named EYA3, is present in birds as well as in mammals, and plays a similar role in both.  Given that they inhabit the same planet, this should not be all that surprising.  But the article twice put an evolutionary spin on this observation, claiming that it is “showing a common link that has been conserved [i.e., unevolved] for more than 300 million years.”

Evolution is fluid, except when it is conserved.  Evolution is rapid, except when it is slow.  Evolution shows diversity, except when it shows commonality; it shows homology, except when it shows analogy.  See “The Story of Evolution” (12/19/2007 commentary) for even more opposite things evolution explains.  Evolution is even numerically quantifiable.  Through evolution we can observe “rate heterogeneity,” (03/26/2002), a biological version of Skinner’s Constant.*  So you see: Darwin’s theory is at once most elegantly mathematical and versatile.  Is there anything that evolutionary theory cannot explain?
Yes; explanation itself.  Then the rest of the theory implodes.

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