The ectodysplasin pathway is highly conserved across vertebrates the same genes do similar things in humans and mice and zebrafish. For that reason, and because its effects on skin, hair and scales can be observed directly, it is widely studied.
This evolutionary conservation led Yana Kamberov, one of two first authors to reason that EDARV370A would exert similar biological effects in an animal model as in humans. Kamberov developed a mouse model with the exact mutation of EDARV370A a difference of one DNA letter from the original, or wild-type, population. That mouse manifested thicker hair, more densely branched mammary glands and an increased number of sweat glands.
"This not only directly pointed us to the subset of organs and tissues that were sensitive to the mutation, but also gave us the key biological evidence that EDARV370A could have been acted on by natural selection," said Kamberov.
The findings prompted the team to look for similar traits in human populations. When co-first author Sijia Wang and the team including collaborators at Fudan University examined the fingertips of Chinese volunteers at colleges and farming villages, they found that the sweat glands of Han Chinese, who carry the derived variant of the gene, were packed about 15 percent more densely than those of a control population with the ancestral variant.
At the same time, collaborators at UCL were working to zero in on when and where the mutation arose.
Computer models suggest that the derived variant of the gene emerged in central China between 13,175 and 39,575 years ago, with a modal (most likely) estimate of 30,925 years.
Researchers concluded the derived variant is at least 15,000 years old, predating the migration from Asia by Native Americans, who also carry the mutation.
That time span suggests that different traits could have been unde
|Contact: Clare Ryan|
University College London