This may be a distant consideration for most but, as a serious sufferer of arthritis myself, I found the following hypothesis about its source very intriguing.
During the winter of 2008, I was forced to walk two miles in deep snow. The temperature was about - 25°F. I don't know what the Wind Chill was, but it was blowing. I had no gloves and a light coat with no pockets.
My hands should have been solid blocks of ice but, curiously, they weren't. I think I now know why.
Mother Nature, she'll always surprise you.
The Mutation That Helped Ancient Humans Survive Frostbite Probably Gave Us Arthritis
PETER DOCKRILL
4 JUL 2017
http://www.sciencealert.com/the-mutation-that-helped-ancient-humans-survive-frostbite-also-gave-us-arthritis (http://www.sciencealert.com/the-mutation-that-helped-ancient-humans-survive-frostbite-also-gave-us-arthritis)
QuoteWhen humans began their slow migration out of Africa some 100,000 years ago, they carried with them the genetic seeds necessary to help survive the bitter chill of Europe and Asia.
But, unknowingly, in the same genes lurked a painful burden that afflicts millions today – with a new study finding that a gene variant that helped our ancestors survive extreme climates and frostbite also increases the likelihood of developing arthritis.
According to researchers at Stanford and Harvard universities, a variant of the GDF5 gene – which is associated with bone growth and joint formation – has two effects on those that carry mutations of the gene: it reduces bone length (and, subsequently, height), and it can almost double the chance of osteoarthritis.
"It's clear that the genetic machinery around a gene can have a dramatic impact on how it works," says one of the researchers, human evolutionary biologist Terence Capellini, now at Harvard University.
"The variant that decreases height is lowering the activity of GDF5 in the growth plates of the bone. Interestingly, the region that harbours this variant is closely linked to other mutations that affect GDF5 activity in the joints, increasing the risk of osteoarthritis in the knee and hip."
In the new study, the team identified a previously unknown region of DNA surrounding the GDF5 gene. Within this region – called GROW1 – the researchers found a nucleotide change that is prevalent in Europeans and Asians, but which rarely occurs in Africans.
The thinking goes that this genetic change – which is found in half of Europeans and Asians – was favoured when modern humans made the trek out of Africa between 50,000 and 100,000 years ago, conferring some kind of physiological benefit to the migrants on the trail.
"Because it's been positively selected, this gene variant is present in billions of people," says developmental biologist David Kingsley from Stanford University.
"So 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."
More at the link.....