Humans still have genes for a full fur coat, scientists find: ScienceAlert

Humans still have genes for a full fur coat, scientists find: ScienceAlert

Humans still have genes for a full fur coat, scientists find: ScienceAlert

Fur is a defining characteristic of being a mammal. But bald is beautiful for several mammalian weirdos, including dolphins, mole rats, elephants, and of course humans. Without forgetting a practical adaptation.

Yet all of our ancestors had a lot of fur. According to a new study of relatively hairless mammals, we still have the means to be shaggy. These genes, it seems, have simply been turned off.

In their hunt through nearly 20,000 coding genes and 350,000 regulators, compared to 62 different mammalian species, University of Pittsburgh geneticist Amanda Kowalczyk and her team have uncovered a mechanism behind these fascinating parallel changes.

This re-emergence of a trait through unrelated lineages is known as convergent evolution. In the case of hairless, it evolved independently at least nine different times along different branches of the mammalian family tree.

The selection pressures for this lack of hair are just as varied as the species that have lost their down. For elephants, it’s a way to lose heat faster; for marine mammals, being smoother means less resistance to movement in water; and for us, well, there are possibly several contributing pressures, including thermoregulation and parasite reduction.

Despite these differences, Kowalczyk and his colleagues found that genetic changes in furless species mostly resulted from mutations in the same sets of genes.

Many of these mutation-collecting genes were linked to the structure of the hair itself, such as genes that code for keratin proteins, sequences that regulate hair development.

“As animals come under evolutionary pressure to shed their hair, genes coding for hair become less important,” says Clark Nathan, a geneticist at the University of Pittsburgh.

“That’s why they accelerate the rate of genetic changes allowed by natural selection. Some genetic changes could be responsible for hair loss. Others could be collateral damage after hair growth stops.”

Although we still retain many of our ancestral fur-coding genes, their regulatory dials have been turned off by the accumulation of these mutations.

The team also identified hundreds of new hair-related regulatory genes and some potential new hair-coding genes. These can prove important for people trying to recover hair lost due to disorders or chemotherapy.

“There are quite a few genes that we don’t know much about,” Kowalczyk says. “We believe they may play a role in hair growth and maintenance.”

The team’s approach could also be applied to different converging evolutionary traits. They are now using their computer-assisted method to look at other health issues.

“It’s a way to determine the overall genetic mechanisms underlying different traits,” Clark concludes.

This research was published in eLife.

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