Sunday, 28 February 2016

Bovines: How Cows Were Domesticated

Taurine bull
Cattle (Bos taurus) are among the most familiar of herbivorous domestic animals. According to recent estimates, there are well over a billion of them on the planet today, found almost anywhere that humans practice agriculture. In the west, we are familiar with them as a source of beef or milk, but, in many parts of the world, they are still used primarily as draft animals ("oxen"). Indeed, they are important enough that Christopher Columbus first brought them to America in 1493, on only his second voyage to the New World.

But one unusual thing about cattle is that there is no living wild form of the animal. There are still wolves and wildcats, wild goats, wild sheep, and wild boars... but there are no wild cattle. They're not unique in this respect, to be sure, and there are a few populations of feral cattle around the world (that is animals living in the wild whose ancestors were domesticated), but it's a fairly exclusive club nonetheless. And, obviously, it wasn't always the case.

The animal that cattle were domesticated from was the aurochs (Bos primigenius). This is, incidentally, one of those odd words in English where the singular is the same as the plural; one aurochs, two aurochs. It may help to think of the word as "ur-ox", which is literally what it means [although, see comments for why "ur" might not mean what you think in this context], and, while it isn't standard English, the Germanic plural "aurochsen" is sometimes used to avoid confusion. But,things become rather more muddled when we try to work out the correct scientific name for the animal.

Many scientists, especially those who work in agriculture, rather than zoology, are quite happy to consider the domestic animal to be a different species from its wild ancestor. But, if you don't, which of the two possible scientific names is the "correct" one? Under the standard rules of zoology, if something you previously thought was two species turns out to be just one, then the older name is the one that sticks. Aurochs were first named in 1827, by Ludwig Bojanus, but, unsurprisingly, even the man who invented scientific naming in 1758 knew what a cow was, so the name for the domestic animal is quite a bit older.

So the rules were pretty clear. But a number of zoologists were unhappy about having to use the name of a domesticated animal for a wild one, and requested that the rules be changed to accommodate them. In 2003, the International Commission for Zoological Nomenculature, which is responsible for this sort of thing, agreed, issuing Opinion 2027, which states that, for seventeen species of domesticated animal - and only those seventeen species - the name of the wild animal is the one that counts, even if it's younger.

Thus, if you consider cattle to be the same species as aurochs (and there's nothing in the rules that says you have to), then they are Bos primigenius, not Bos taurus. For what it's worth, the other sixteen species affected are cats, dogs, ferrets, sheep, goats, three other bovines that I'll get to in future posts, horses, donkeys, Bactrian camels, two llama-like animals, guinea pigs, goldfish, and silkworms.

But there's another complication in that cattle appear to have been domesticated at least twice. The sort that most of us in the west are familiar with was domesticated around 8,500 BC somewhere in the general vicinity of Mesopotamia or Turkey. A study published in 2012 shows that the original founding stock may have been as small as 80 cows (and an unknown, but presumably smaller, number of bulls), which suggests a relatively small scale exercise that was hard for the neighbours to duplicate.

Zebu bull
But not impossible, because around the same time, somewhere in northern India, it appears that another group of farmers independently domesticated their own local aurochs. If you consider that domestication is a sufficiently dramatic process that it creates an entirely new species, then logically these animals, zebu, must be their own species, too (Bos indicus). If not, then there are two subspecies of domestic cattle, plus however many extinct subspecies of aurochs here might have been.

If we have to distinguish the two, the western subspecies are referred to as "taurine cattle". It's possible that even they were domesticated more than once, with a third event having occurred somewhere in north Africa, but if so (and it has been disputed), the descendants of those two events are sufficiently mingled now, and of sufficiently similar origin, that they aren't considered distinct. Either way, taurine cattle include a wide range of different breeds, from Aberdeen Angus beef cattle to Friesian/Holstein milk cattle and those short shaggy Highland cattle.

Zebu, on the other hand, are quite clearly distinct. The most obvious differences are the presence of a fatty hump over the shoulders, and usually a large dewlap beneath the throat. Used primarily as beasts of burden, they can also be used as a source of beef and/or milk, but most traditional breeds apparently aren't particularly high quality when it comes to either. Able to effectively tolerate hot, tropical, climes, they are mostly found today in southern Asia and Africa, but the American Brahman breed of beef cattle is a western exception.

Taurine cattle and zebu are also perfectly capable of interbreeding, and there are some breeds today that are descended from both. Few of these breeds are terribly popular, but they can be found in places such as South Africa and Australia; the Australian brangus, for example, is half Angus and half Brahman.

But what of the aurochs, the wild animals from which modern cattle are descended? They lived across much of Europe and Asia, from Great Britain to Korea, although avoiding Siberia and most of Scandinavia, and in the south reached India, the Middle East, and north Africa. Given the wide range of environments that this includes, they must have been reasonably tolerant of different habitats, but they likely preferred woodland, and may have particularly favoured marshy river valleys.

Even before domestication, they were already big animals, with the largest bulls perhaps reaching 180 cm (6 feet) at the shoulder, although the cows would have been significantly smaller. Compared with modern cattle, however, they had relatively long legs and slender bodies, so they presumably weighed quite a bit less than modern breeds, especially of beef cattle. The horns were long and curving, and faced forward, while the head was rather longer than it is in modern cattle. It's likely that the aurochs of India, from which zebu descend, already had a hump, while, judging from cave art, even those in Europe had at least a small dewlap. Not yet having been bred for excessive milk production, the udder of cows was probably small and not especially visible, as it is in animals such as bison today.

Reconstruction of an aurochs bull
The colour is harder to judge when all we have are fossils, but cave art suggests that bulls were dark and cows reddish-brown; both sexes may have had a pale stripe down the middle of the back. Behaviour is harder still to get a handle on, although it's likely that they lived in single-sex herds outside of the breeding season, since this is the usual pattern for herd animals where the males are much larger than the females, as was the case for aurochs.

Aurochs lived in Europe since at least the mid Pleistocene, and in Asia for some time prior to that. Fossils indicate that they were even larger during the warmer parts of the Pleistocene than they are now, shrinking again as the Ice Ages became harsher, due both to a lack of food and competition from humans and the local bison. We have enough genetic material from their remains to show not only that taurine cattle descend from a small initial population, but that there was little, if any, back-breeding with wild animals after that origin.

So what happened to them? In Asia few of them out-lasted the Ice Ages, holding out only in India and the Middle East. The Indian forms were, of course, the ancestors of the zebu, but they seem to have died out not long after the latter were first bred. The last mention of Asian aurochs comes from Assyrian records of the 7th century BC, and they likely disappeared from Africa around the same time. Hunting and competition for prime habitat with domestic cattle appear to have been the main causes of this decline.

In Europe, however, they lasted quite a bit longer, easily post-dating the first taurine cattle. While they disappeared from Britain around 1300 BC, during the Bronze Age, on the continent the Romans used them in arena combats up until around the first century AD. After this, they vanished from southern Europe, but Charlemagne was apparently able to hunt them in the eighth century, and they may have survived in Germany until as late as 1400.

It's hard to tell whether some of the accounts of aurochs from this time really are of those animals, rather than European bison - which were far more common in the past than they are now. But what we do know is that the last aurochs were found in eastern Europe. In 1476, the Polish royal family took possession of what was, by then, the entire worldwide population of the animals, which survived only on their game reserves. A 1564 census conducted on their behalf counted a total of 38 animals, only eight of which were adult bulls.

Further censuses followed, with the number dwindling every time. The last aurochs were found in Jaktor├│w Forest, where the 1630 census reads:

"In the previous report it is written that only one cow was left, but the residents of this village said that she died three years ago."

The skull of the cow in question was stolen by the Swedish army a few decades later, and is now in a museum in Stockholm.

However, for all that the history of the domestication of cattle is at times a complicated one, they are not the only species of bovine to have been domesticated, and some animals that we might vaguely think of as "cattle" are actually different creatures entirely. In these cases, the wild versions still live on, and next time I will be looking at two of them.

[Photos by Charley Quinton, and Scott Bauer of the US Agricultural Research Service, reconstruction by "Aurochs1", all from Wikimedia Commons.]

5 comments:

  1. Point of clarification: the ICZN recommendation for those 17 species is for the wild animals only; domestic cattle remain Bos taurus. The use of the senior Linnaean names for domestic animals did not require a ruling by the Commission; these names are earlier than, or contemporary with, those for the wild taxa and therefore remain valid. There was no need to apply to the Commission for a ruling on their validity, and following the ICZN those names can *only* be applied to domestic or feral forms.

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    1. I thought I'd indicated that with "if you consider them the same species", but if it wasn't clear, that's certainly the case.

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    2. The German name is Auerochse, pl Auerochsen - note the extra e's (which aren't silent).

      But "aurochsen" for the English plural is surely primarily modelled on English ox, oxen.

      The first part of the name isn't the prefix "ur-" but an old Germanic word word meaning, well, aurochs, so the name is etymologically pleonastic: aurochs-ox. (The vowel in the prefix was originally short while that in the aurochs-word it was long; that's why the former remains in modern German while the later has changed to au.)

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    3. The version I had heard (this came from the Oxford English Dictionary) was that the old Germanic word itself derived from ur-ohso, where 'ohso' meant 'ox'. But I freely confess that this is outside my area of expertise!

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    4. Ohso (whence modern English ox) indeed meant "ox". The point I'm trying to make is that the ur- part isn't the same as in Urvogel etc., but an old word that by itself meant "aurochs". So ur-ohso is literally "aurochs-ox".

      (Auerochse is modern German, if that was unclear.)

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