If you're a gentleman looking to counteract the effects of ageing, a new study on sheep may have the answer – but you're going to have to say goodbye to your family jewels in return for a slowdown of your DNA's ageing process.
"Both farmers and scientists have known for some time that castrated male sheep live on average much longer than their intact counterparts," explained first author Victoria Sugrue, an anatomy PhD student at the University of Otago. "However, this is the first time anyone has looked at DNA to see if it also ages slower."
Key to the study – more key than knife-wielding boffins lopping sheep's bollocks off hither and thither, anyway – was the concept of an "epigenetic clock," a means of measuring the ageing of creatures' DNA. In sheep, the researchers found, the clock ticks slower for castrated males than those left intact in the nether regions.
"We developed a way to measure biological age in a broad range of mammals – we have looked at over 200 species so far and discovered surprising commonality in which animals age," said Steve Horvath, professor at the University of California in Los Angeles and inventor of the epigenetic clock concept. "But the sheep study was unique in that it specifically isolated the effects of male hormones on ageing."
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The researchers hope their work will have wider implications, though possibly not that it may encourage anyone interested in radical life extension into a little self-surgery with the kitchen scissors – especially as it has not yet been determined whether the same effect can be seen in humans.
Nevertheless, the study is being positioned as a key finding for the mechanisms of what scientists term "male-accelerated ageing". "We found that males and females have very different patterns of DNA ageing in sheep," team co-leader Tim Hore, PhD, claimed, "and that despite being male, the castrates – wethers – had very feminine characteristics at specific DNA sites.
"Interestingly, those sites most affected by castration also bind to receptors of male hormones in humans at a much greater rate than we would expect by chance. This provides a clear link between castration, male hormones and sex-specific differences in DNA ageing."
Hore also highlighted Shrek, a Cental Otago merino sheep who evaded musterers for six years – growing a 27kg fleece in the process. The castrated sheep lived to the age of 16: "By the time Shrek was caught he was already 10 years old – roughly the maximum age of the most long-lived sheep on a commercial farm," Hore explained. "I think at least part of Shrek's fame was simply that he lived so long – something which almost certainly wouldn't have happened if he was not castrated."
The full paper has been published in the journal eLife, but El Reg disavows any responsibility should readers decide to take experimentation into their own hands – or, indeed, trousers. ®