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What applies to oxen also applies to scaling up human beings. The chart in the doctor's office suggests appropriate weights for a person of a specific height. These weights, somewhat specious, are calculated by cubing the increase in size for each increment. And the rules hold well even in extreme cases. Robert Wadlow, a well-known British giant of the preWorld War II era, measured 6 feet in height (1.8 meters) and weighed 169 pounds (76 kilograms) as a twelve-year-old. Shortly before his death at twenty-one years from an accidental fall, Wadlow had reached 8 feet 6 inches (2.6 meters). His height had increased by a ratio of 1.4 to 1 since his measurement at age twelve. The ratio cubed is 2.98. If scaling worked perfectly, his weight at death should have been 2.98 X 169 pounds (or 76 kilograms) = 504 pounds (228 kilograms). In fact, Wadlow weighed 491 pounds, or 222 kilograms. The estimate was off by a little less than 3 percent.

Given the huge mass of an aurochs, holding the animal in an enclosure would have required very cleverly designed, strong fences, even if all the animal did was lean against it. Sheer weight, of course, does not necessarily make an aurochs more dangerous, but mass in motion does. The aurochs' increased height meant increased leg length and a longer step compared to a modern bovine. Animals of the same body type tend to gallop at the same rate (strides per minute), but the distance covered in that minute by each stride is what makes the "speed." That is why ostriches run faster than pheasants, and horses always beat ponies to the finish line. The speed of an aurochs is truly difficult to estimate, but it is surely greater than that of a fighting bull, a bison, or an African Cape buffalo. Bison can run up to 35 miles an hour (56 kmh). Two or three tons of aurochs would have come hurtling at Neolithic man (or a fence) at some 45 miles per hour (72 kmh), courtesy of its longer legs. The speed matters even more than the weight. Being hit by a freight train going 1 mile per hour (1.6 kmh) might leave one slightly bruised at the point of contact, but a skinny messenger speeding along on a bicycle can kill someone on impact. It's the combination of weight and speed--the kinetic energy, calculated at one-half of the weight times the square of the speed--that kills, not the mass by itself or the motion alone.

Typically, paleontological calculations are made using
heights, since a single leg bone is all that is needed, not a whole skeleton. But for very rotund and short-legged animals, like the hippopotamus, differences in total body length (head plus body) work the same magic as height in other mammals. With extinct animals, a researcher would use the length of a vertebrae or two and a skull to estimate the total length. The pygmy hippo averages about 5 feet 9 inches (1.75 meters) in length and weighs some 700 pounds (270 kilograms). The full-size hippo averages 15 feet (4.6 meters) in length, or 2.6 times its pygmy look-alike. The average regular hippo comes in at 8,800 pounds (4,000 kilograms). Using the formula of cubed proportionality, you would get a predicted weight based on the pygmy of 8,500 pounds (3,860 kilograms) for the standard hippo.

The massive size of the aurochs adds to the mystery of how our ancestors, sometime in the Neolithic Era, managed to scale down the aurochs into domestic cattle that were much smaller than most of today's breeds and induce them to put up with close contact with humans. The usual explanation is that somehow we managed to selectively breed them to the desired size, just as we made wolf-dogs smaller.

One theory is that after the last ice age, the aurochs naturally shrank, and humans domesticated the diminished animals. The scattered bones of aurochs suggest that the ones found in the Paleolithic (old Stone Age) assemblages of human garbage were some 10 percent larger than aurochs from early Neolithic (new Stone Age) trash heaps. In other words, over some 600,000 to 750,000 years from the earliest age of stone tools to some 10,000 years ago, the aurochs shrunk in size by 10 percent.

In the next two or three thousand years, by the Late ("Pottery") Neolithic, cattle "(Bos taurus)" suddenly appeared. They were one-third to one-half as tall as the ancestral aurochs, had small horns, and, more important in genetic terms, the horns were "variable" horns. They had become a new species. This occurred over a very short period of time. Of course, this change didn't solve the problem of how to get started working with a three- to four-ton beast that is quick-footed and furious.

To selectively breed animals of any kind, one has to have control over them and particularly over their sex lives. How this was done with such a huge beast is mysterious.

According to their earliest fossil bones, cows were comparatively diminutive and easily distinguishable from aurochs. Remarkably, there are no known intermediates between the big aurochs, the slightly smaller ones later, and the modern cow. Such is true with many evolutionary series but uncommon with a relatively recent event. Still, most paleobiologists continue to theorize that with the end of the last ice age, the aurochs became much smaller without human intervention, as a result of no longer needing great bulk for temperature regulation. (Northern animals tend to be larger than similar species from temperate zones; and often within species, say white-tailed deer, animals from along the U.S.--Canada border tend to be much larger than their counterparts in Louisiana or Mississippi.) But this is hardly convincing: The Aurochs' most similar contemporary, the European bison, or Wysent, didn't shrink an inch when the last ice age ended.

One intriguing possibility is that humankind occasionally encountered miniature aurochs. There are two documented events in the history of the genus "Bos" to look at for evidence. First, in Central Europe, aurochs' skulls have been found that are "about one-third below the normal size, but do not differ from ordinary skulls in other respects." Scientists under the sway of old-fashioned, slow-but-steady evolution dismissed these mini-aurochs as aberrations, perhaps resulting from malnutrition, although there is little evidence anywhere in biology that malnutrition diminishes an organism by 33 percent. The worst sort of nonfatal human malnutrition might produce an adult between 4.5 and 5 feet tall (1.37 to 1.52 meters), a diminution of less than one-fifth the size of normal human beings. This is hardly the reduction in size seen in the mini-aurochs fossils. Furthermore, a starved animal--human or otherwise--would not have the normal bones found in the diminished aurochs. If a smaller animal was born in captivity, it might well survive better on its restricted diet. This would be a form of (artificially induced) natural selection. But it is the "born in captivity" that is so problematic, given the size of the wild animal. In places in the world where tribes are isolated and food is scarce, some naturally selected pygmy humans have evolved. But by no means do they approach the relative smallness of the post-Stone Age cows compared with aurochs. The famous African pygmies range from 4 to 5 feet tall (1.2 to 1.52 meters), a mere decrease of at most 20 percent compared with other humans. That doesn't approach the more than 50 percent decline in height from aurochs to Aberdeen-Angus.

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