Genetic scientists have long been interested in how Homo sapiens lost their fur, and now a new study, published in eLife, could provide a clue.
The study has gone in search of the genetic basis of our body baldness and found that we actually still have the full set of genes needed for fur, however, “they have been silenced.”
In search of the root of all hairlessness, the researchers behind the new study conducted a one-of-a-kind analysis, looking at the genetic codes of 62 mammals to see which segments of the genome appeared to be crucial for “optimal fluffiness.”
In addition to tagging genes known to influence hair growth, the analysis found new ones, as well as hundreds of hair-related regulatory elements, that influence gene expression.
Here, the phenotype of an animal can be influenced not only by “epigenetics” (the study of changes that activate or inactivate genes without changing the DNA sequence), but also by regulatory elements that act on their expression.
It may explain why some animals may have the genes for a certain phenotype, like humans who have the genes for a full body of hair, but instead express a different one, like us and our relative nakedness.
The genes and regulatory elements identified in the study encode all aspects of hair growth, from the shape of the shaft to the pattern of development. Importantly, the researchers were able to identify genomic regions related to hair growth that had evolved at a faster or slower rate, leading to possible explanations for how and when some mammals became hairless.
In mammals, there are varying degrees of hairlessness. You might think that humans are quite bald, until you look at, say, dolphins.
Such convergent evolution may be driven by regulatory elements that turn genes off in disparate groups of animals, which is what the researchers were looking for when they conducted this study.
Using a computational approach, they identified shared genes in mammals that evolved to be hairless and found that regions previously responsible for fur sprouting were accumulating mutations at different rates compared to their diffuse relatives.
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