Nexus - 0904 - New Times Magazine-pages

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have two sets of chromosomes, one from each parent. The at rest to 150 bpm during a chase. Its top speed is 70 miles per number of chromosomes varies as widely as in plants (humans hour, while a thoroughbred tops out at around 38 mph. Nothing have 46), but there are always only two sets (humans have 23 in on a savanna can outrun it. It can be outlasted, but not outrun. each). Cheetahs are unique because they combine physical traits of The only "tools" available to Neolithic herdsmen were those two distinctly different animal families: dogs and cats. They available to farming kinsmen: time and patience. By the same belong to the family of cats, but they look like long-legged dogs. crossbreeding techniques apparently utilised by farmers, wild ani- They sit and hunt like dogs. They can only partially retract their mals were selectively bred for generation after generation until claws, like dogs instead of cats. Their paw pads are thick and enough gradual modifications accumulated to create domesticated hard like a dog's, but to climb trees they use the first claw on their versions of wild ancestors. As with plants, this process required front paws in the same way a cat does. The light-coloured fur on anywhere from hundreds to thousands of years in each case, and their body is like the fur of a short-haired dog, but the black spots was also accomplished dozens of times in widely separated areas on their bodies are inexplicably the texture of cat's fur. They con- around the globe. tract diseases that only dogs suffer from, but they also get "cat Once again, we face the problem of trying to imagine those first only" diseases. herdsmen with enough vision to imagine a "final model", to start There is something even more inexplicable about cheetahs. the breeding process during their own lifetimes and to have it car- Genetic tests have been done on them, and the surprising result ried out over centuries until the final model was achieved. This was that in the 50 specimens tested they were all, every one, was much trickier than simply figuring out which animals had a genetically identical with each other! This means the skin or strong pack or herding instinct that would internal organs of any of the thousands of eventually allow humans to take over as cheetahs in the world could be switched with "leaders" of the herd or pack. For example, the organs of any other cheetah and not be it took unbridled courage to decide to bring rejected. The only other place such physical a wolf cub into a campsite with the intention | All examples of plant and _ | homogeneity is seen is in rats and other ani- of teaching it to kill and eat selectively and animal "domestication" mals that have been genetically altered in to earn its keep by barking at intruders (adult . . . . laboratories. wolves rarely bark). And who could look at are incredible In their (Cue the music from The Twilight Zone...) the massive, Fearsome, tempered aurochs own right, but perhaps 4 Cheetahs stand apart, or course. but at and visualise a much smaller, much more . . * lomesticated animals have traits that are not amiable cow? Even if somebody could have the most incredible is explainable in terms that stand up to rigorous visualised it, how could they have hoped to the cheetah. scientific scrutiny. Rather than deal with the accomplish it? An aurochs calf (or a wolf embarrassment of confronting such issues, cub, for that matter), carefully and lovingly scientists studiously ignore them and, as with Genetic tests have been done on them, and the surprising result was that in the 50 specimens tested they were all, every one, genetically identical with each other! raised by human "parents", would still grow up to be a full-bodied adult with hardwired adult instincts. However it was done, it wasn't by crossbreeding. Entire suites of genes must be modified to change the physi- cal characteristics of animals. (In an interesting counterpoint to wild and domesticated plants, domesticated ani- mals are usually smaller than their wild progenitors.) But with animals, some- thing more...something ineffable... must be changed to alter their basic the mysteries of domesticated plants, explain them away as best they can. For the cheetah, they insist it simply cannot be some kind of weird genetic hybrid between cats and dogs, even though the evidence points squarely in that direction. And why? Because that, too, would move cheetahs into the for- bidden zone occupied by You Know What. The problem of the cheetahs’ genetic uniformity is explained by something now known as the "bottleneck effect". natures from wild to docile. To What it presumes is that the wild chee- accomplish it remains beyond modern tah population—which must have been abilities, so attributing such capacity to Neolithic humans is an as genetically diverse as its long history indicates—at some recent insult to our intelligence. point in time went into a very steep population decline that left All examples of plant and animal "domestication" are incredible only a few breeding pairs alive. From that decimation until now, in their own right, but perhaps the most incredible is the cheetah. they have all shared the same restricted gene pool. There is no question it was one of the first tamed animals, with a Unfortunately, there is no record of any extinction events that history stretching back to early Egypt, India and China. As with would selectively remove cheetahs and leave every other big cat all such examples, it could only have been created through selec- to develop its expected genetic variation. So, as unlikely as it tive breeding by Neolithic hunters, gatherers or early farmers. seems, the "bottleneck" theory is accepted as another scientific One of those three must get the credit. gospel. The cheetah is the most easily tamed and trained of all the big Here it is appropriate to remind scientists of Carl Sagan's cats. No reports are on record of a cheetah killing a human. It famous riposte when dealing with their reviled pseudoscience: seems specifically created for high speeds, with an "Extraordinary claims require extraordinary evidence." It seems aerodynamically designed head and body. Its skeleton is lighter apparent that Sagan learned that process in-house. than other big cats; its legs are long and slim, like the legs of a It also leads us, finally, to a discussion of humans, who are so greyhound. Its heart, lungs, kidneys and nasal passages are genetically recent that we, too, have been forced into one of those enlarged, allowing its breathing rate to jump from 60 per minute "bottleneck effects" that attempt to explain away the cheetah. JUNE - JULY 2002 NEXUS ¢ 57 www.nexusmagazine.com