by posted on 30/1/2023 14:29
(credit: Unsplash/Henrik Hansen)
Research conducted by Carnegie Mellon-University of Pittsburgh in the United States found that people still have the genes to be hirsute (having long, wiry, thick hair).
About a million years ago, humans lost most of their body hair, a key moment in evolution that involved major changes in the same gene pool as other mammals such as dolphins, mole rats and elephants.
A team of scientists from the university’s computational biology doctoral program conducted a study, published in the journal eLifecomparing human genes with those of 62 other mammals, including elephants, manatees and armadillos, looking at how hair loss evolved in different species and at different times.
“The initial loss of hair in many species was probably very adaptive,” says Clark Nathan, a geneticist at the University of Pittsburgh. “When you think about it, it’s clear that a dolphin swimming in the water, or a whale or a porpoise, would be much slower. They need to be simplified. They don’t need that hair cover anymore,” she explains.
The work also identified new genes and gene regulators linked to body hair, a finding that may one day be used to treat genetic conditions from baldness to cancer.
This resurgence of a trait in unrelated lineages is known as convergent evolution. In the case of hair growth, it evolved independently at least nine times along different branches of the mammalian family tree.
The researchers found that the genetic changes in the hairless species mostly resulted from mutations in the same sets of genes. Many of these mutation collection genes were related to the structure of the hair itself, such as genes that code for keratin proteins, the sequences that regulate hair growth.
“As animals come under evolutionary pressure to lose hair, the genes that code for hair become less important,” explains Clark.
“That’s why they speed up the rate of genetic changes that natural selection allows. Some genetic changes may be responsible for hair loss. Others may be collateral damage after hair stops growing.”
Although we still retain many of our ancestral genes that code for fur, the regulatory selectors have been “silenced” by the accumulation of these mutations.
Hair loss during treatments
The team also identified hundreds of new hair-related regulatory genes and some potential new hair-coding genes. This can be important for people trying to regain hair lost due to disorders or chemotherapy.
“There are quite a few genes that we don’t know much about,” says Amanda Kowalczyk, a member of the research team. “We think they could have a role in hair growth and maintenance.”
The ensemble approach can also be applied to different features of convergent evolution. Now they use a computerized method to screen for other health conditions.
“This is a way to identify the global genetic mechanisms that underlie different traits,” Clark concludes.
