Last updated on April 24, 2014 at 1:21 EDT
Giraffe South Africa
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Giraffe, South Africa

July 25, 2012
A giraffe at the Kriega Nature Reserve in South Africa. Scientists long have suspected that the sex chromosome that only males carry, the Y chromosome, is deteriorating, but until now, no one has understood the evolutionary processes that control this chromosome's demise. Now, a pair of Penn State scientists, including a National Science Foundation graduate research fellow, has discovered that the Y chromosome is evolving at a rapid rate, resulting in a dramatic loss of genes that eventually could lead to the chromosome's complete disappearance. Credit: Anton Nekrutenko, Penn State University