That the defining feature of humans — our large brains — continued to evolve as recently as 5,800 years ago, and may be doing so today, promises to surprise the average person, if not biologists."We, including scientists, have considered ourselves as sort of the pinnacle of evolution," noted lead researcher Bruce Lahn, a University of Chicago geneticist whose studies appear in Friday's edition of the journal Science."If this argument is right," write Goodland and Anhang, "it implies that replacing livestock products with better alternatives would be the best strategy for reversing climate change.
The more damaging elements of the meat and dairy industry are effectively government-sponsored: millions of pounds of taxpayers' money is spent propping up factory farms and subsidising the import of animal feed that's been grown at the expense of forests." Justin Kerswell, campaign manager for the vegetarian group Viva!, said: "The case for reducing consumption of meat and dairy products was already imperative based on previous UN findings.Using DNA samples from ethnically diverse populations, they identified a collection of variations in each gene that occurred with unusually high frequency.In fact, the variations were so common they couldn't be accidental mutations but instead were probably due to natural selection, where genetic changes that are favorable to a species quickly gain a foothold and begin to spread, the researchers report.Lord Stern of Brentford, author of the 2006 review into the economic consequences of global warming, added his name to the call last week, telling a newspaper interviewer: "Meat is a wasteful use of water and creates a lot of greenhouse gases.
It puts enormous pressure on the world's resources." Scientists are concerned about livestock's exhalation of methane, a potent greenhouse gas.Cows and other ruminants emit 37 per cent of the world's methane.A study by Nasa scientists published in Science on Friday found that methane has significantly more effect on climate change than previously thought: 33 times more than carbon dioxide, compared with a previous factor of 25."There's a sense we as humans have kind of peaked," agreed Greg Wray, director of Duke University's Center for Evolutionary Genomics."A different way to look at is it's almost impossible for evolution not to happen." Still, the findings also are controversial, because it's far from clear what effect the genetic changes had or if they arose when Lahn's "molecular clock" suggests — at roughly the same time period as some cultural achievements, including written language and the development of cities.According to Goodland and Anhang's paper, which has not been peer-reviewed, scientists have significantly underestimated emissions of methane expelled by livestock.