"Going back in time, the common ancestor must have had a gene at this position from which hair keratin genes of both mammals and lizards evolved," he added. The researchers additionally found that keratin proteins in lizards and humans contain a high content of an amino acid called cysteine. Tracing the history of this acid, the scientists found it didn't just suddenly arise by chance during mammalian evolution, but instead was inherited from the ancient common ancestor. The particulars of this important animal relative remain unknown, but scientists can make some educated guesses. "Probably it was more similar to a lizard than to modern mammals or birds," Eckhart said. "It is likely that this ancestor had claws, which it may have used for climbing." The first mammal emerged sometime later, likely between 160 and 220 million years ago. Since the researchers believe hair keratins evolved earlier than hair itself, some of the first mammals could have sported a warm, furry coat. Genes for hair loss are also in the news, as another scientific team recently found a gene linked to human baldness that can be inherited from an individual's mother or father. Previously, yet another gene associated with hair loss was identified, but it only passes down through the maternal line. "This (latest finding) helps to provide an explanation for the similarity between father and son," said Markus Nöthen, who led the study and is a professor at Bonn University's Institute of Human Genetics and the Life & Brain Center. Nöthen explained that the discovery not only explains why bald fathers often produce sons who later experience hair loss, but also why men often take after their maternal grandfathers, at least in terms of hair. Eckhart and his team are currently trying to find the mechanism that allowed mammals to use keratins of animal claws to produce hair. Such studies may not only solve mysteries about how humans and other mammals first evolved, but they might also lead to improved hair growth treatments in future. Related Links: How Did Mammals Evolve? (Smithsonian National Museum of Natural History) |
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