X-Ray Reveals Mysterious Component of Human Hair
But the IRF4 variant that favors grey also produces fair hair, he cautioned, so tinking with the gene could also mean fewer blondes.
In the study, published in the peer-reviewed journal Nature Communications, Ruiz-Linares and three dozen colleagues investigated the genetic triggers for facial hair, the prevalence of "mono-brows", hair colour and shape, balding and greying.
This is well-traveled ground scientifically, but the size and original design of the research yielded a trove of new results.
Another gene, PRSS53, for example, was found to influence curliness, shedding light on the evolution of hair shape that led to straight hair in East Asia and among Native Americans.
Plucking Lots of Hairs Grows More Hairs
A variant of a third gene, PAX3, was strongly associated with "mono-brow", the tendency - especially among men - for eyebrows to be joined by a bridge of facial hair.
To undertake the analysis, scientists did a so-called genome-wide association scan (GWAS) of 6,630 volunteers in Brazil, Colombia, Chile, Mexico and Peru, matching similarities in their DNA with physical traits.