Mammalian hair has a surprising evolutionary origin, according to a study published in __PNAS__ this week: the reptilian claw. Evolutionary biologists have long conjectured about the origin of hair -- did this defining mammalian characteristic evolve from features such as scales and feathers, or did it occur much later in mammalian evolution. "Because it's very difficult to find fossils" showing an intermediate stage between scales and hair, said first author Leopold Eckhart from the Medical University of Vienna, "we followed a completely different strategy." Eckhart and colleagues looked at homologous genes in the molecular components of linkurl:hair; and then searched for the homologous genes in the chicken and reptile genomes by mining published data. (The green anole lizard is the first linkurl:full genome; of a reptile published.)
A hair keratin-like protein (labeled red) detected in the growth zone of the claw of the green anole lizard.

Many biologists have thought...
__Image courtesy of Karin Jaeger and Leopold Eckhart, Medical University of Vienna__

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