By Jody Harrison

IT is a question that is perhaps as old as man himself… why some go bald, and how hair loss might be reliably reversed.

Now Scottish scientists say they have identified the genetic culprit responsible, and it’s all to do with a complex conjunction between latitude, sunlight... and whether or not a prospective baldy sprouts on a mountain.

Unfortunately for anyone facing the prospect of a receding hairline, the baldness-related mystery solved by researchers only concerns plants, particularly those which grow on upland slopes.

And despite the established convention of the animal kingdom that hairier equals warmer, in plants the opposite is true.

Scientists at the University of Edinburgh have been studying a puzzle which has long baffled botanists – why some plants on high mountainsides have hair, while their low-lying cousins are smooth.

Alpine species of snapdragon are covered in a downy fluff across much of their stalks and leaves, given them a far more hirsute appearance than their lowland cousins, which remain hairless.

A study of the genetic make-up of these plants has revealed that those growing on higher elevations have evolved the ability to disable a gene which prevents them from growing hair, and is switched on in plants living at lower altitudes.

It is believed that the reason behind this is to do with protection from the sun, as the small hairs may act like UV sunscreen to protect alpine plants growing in full sunlight on lofty, exposed cliffs.

Low-lying plants might not need to make the hairs because of the relative abundance of shade in valleys, protecting them from harmful rays.

Although unlikely to help reverse hair loss in people, the study may yet have other beneficial results.

Researchers hope their insights could aid the production of useful chemicals secreted by the hairs of some plants, including the antimalarial drug artemisinin, and the substance that give herbs and hops their flavours.

Researchers named the bit of genetic code responsible for the plants’ hair growth the “hairy” gene and were able to isolate it by crossbreeding alpine and lowland species together.

They scientists were able to answer the question of which plant came first – the hairy or the bald variety.

It is thought the fact that the gene is switched off to allow hair growth indicates it evolved after the plants colonised upland areas, and was already present when snapdragons began to appear in the valleys.

The findings show that the first snapdragons – which grew around 12 million years ago – were bald, and that newer, alpine species evolved as a result of mutations that deactivated the gene.

Professor Andrew Hudson, of the University of Edinburgh’s School of Biological Sciences, who led the study, said: “This exciting discovery gives us a chance to find out the rest of the genetic toolkit that controls plant hair growth.

“It could also help us work out why exactly being hairy is an advantage for alpine plants.”