Arthritis gene aided spread of mankind
A SINGLE gene that made it easier for early humans to colonise Europe and Asia also causes arthritis, researchers claim.
The gene, which causes people to be more compact, became more common when early humans moved out of Africa.
Being smaller helped humans cope with colder temperatures because it meant less body area to keep warm.
However, the downside is that someone with the gene is twice as likely to develop arthritis as someone without it.
The findings highlight the role that genetics plays in the painful condition – which is often thought of as a disease caused by ‘wear and tear’ on joints.
Around a half of all European and Asian people carry the gene, which is ‘relatively rare’ in most Africans.
Researchers at Stanford University School of Medicine and Harvard University said the gene ‘ has been repeatedly favoured [by natural selection] as early humans migrated out of Africa and into colder northern climates.’
Dr David Kingsley, professor of developmen- tal biology at Stanford, said: ‘Even though it only increases each person’s risk by less than twofold, it’s likely responsible for millions of cases of arthritis around the globe.
‘ This study highlights the intersection between evolution and medicine in really interesting ways, and could help researchers learn more about the molecular causes of arthritis.’
A more compact body structure due to shorter bones could have helped our ancestors better withstand frostbite and reduce the risk of fracturing bones in falls while slipping on ice, the researchers speculate.
These advantages in dealing with chilly temperatures and icy surfaces may have outweighed the threat of osteoarthritis, which usually occurs after prime reproductive age.
Dr Kingsley added: ‘The gene we are studying shows strong signatures of positive selection in many human populations.’
The research has been published in the online journal Nature Genetics. The gene, called GDF5, was first linked to the growth of bones in the early 1990s.
Researchers found a variant that is very common in Europeans and Asians but also rare in Africans.
‘Millions of cases around the globe’