Long process of taming

2 May 2023

The path to the livestock we know today from their wild ancestors was a long one. Paleoanatomist Joris Peters studies the rich and varied relationship between human and animals, that shaped both. A portrait from the magazine EINSICHTEN.

For a long time in our history, humans walked alone. No dog, no cat, no hamster, no goldfish in a bowl. People were not surrounded by barns, sties, pens, coops, or pastures populated with cattle, pigs, sheep, and chickens. But when and why did the now millennia-old relationship between humans and animals actually began, which is sometimes characterized by deep affinity, but more often by cold economic calculation? Did Homo sapiens just decide one day to drive the wildness out of the creatures? Current research is able to answer the latter question with a clear No. “With some justification, we could ask the question as to who actually tamed whom,” says Joris Peters, Professor of Paleoanatomy at LMU’s Faculty of Veterinary Medicine. “Moreover, domestication was a long process, which took a very different course depending on the species.”

Portrait of Prof. Dr. Joris Peters

Domestication began out of opportunistic considerations, says Joris Peters, not with the clear objective of breeding, for example, domestic cattle from aurochs.

© Oliver Jung/ LMU

What nature asks of us

Read the answers in the new issue of our research magazine EINSICHTEN at | © LMU

The wolf became a companion for humans at a very early stage: hunters and gatherers attached the first packs to them 15,000 or even more years ago, and so the dog has accompanied us as our first pet since Paleolithic times. But this marks it out as an exception, as the process of domestication for animals such as pigs, sheep, goats, and cows can be evidenced some 10,500 years ago on the Upper Euphrates in modern-day Southeast Anatolia, when people settled permanently in the northern Fertile Crescent. Chickens, by contrast, were tamed much later. They descend from the red junglefowl (Gallus gallus), which was domesticated in Southeast Asia in the early second millennium before Christ. The domestic chicken then reached Europe around 2,800 years ago.

To reconstruct the domestication history of various species, researchers are largely reliant on archeological finds in the form of bones and teeth. “I can only analyze what excavations turn up,” explains Joris Peters. This can be complemented by molecular biological analyses, provided that any proteins or genetic material can be recovered from the bones after such a long time. “The climatic conditions for the preservation of DNA are good in Central Anatolia, but very poor in Southeast Anatolia due to the higher average temperatures, which cause the degradation of ancient biomolecules in bones – and it’s precisely there that our theories place the earliest origins of livestock domestication.” Overall, there are many gaps in our picture of the domestication process, which in the past researchers were apt to paint as much more straightforward and goal-directed than it really was.

Researchers now view domestication as a process by which, over the course of many generations, humans entered a permanent and reciprocal relationship with some animals. In the beginning, it was an animal which came up to humans and not vice-versa. “There are in fact animals that almost naturally enter such relationships,” says Peters. “These species are more or less attracted by human settlements – if we disregard the wolf, which is a special case, this was an important precondition for domestication.” As such, the domestication of farm animals such as cattle, sheep, goats, and pigs was contingent upon once mobile hunter-gatherer groups becoming at least partially settled.

Human settlements offer sources of food

“Settlements were attractive for a range of synanthropic species – that is, animals who live closely alongside and benefit from humans – from the beginning,” explains Joris Peters. People created fields around their dwelling places and laid in stores of grain, legumes, and other dry foods inside their settlement. They also threw out their waste nearby. Species like the wild boar were drawn especially to the fields and rubbish heaps, while the food stores attracted rodents, with the result that wild cats expanded into new hunting grounds in human proximity. “When humans began to cultivate wild grains and work the first fields, they created a niche for other animals,” explains Peters.

Wild sheep and wild cattle came to graze on the planted and harvested fields. In comparable fashion, although considerably later, wild chickens ‘discovered’ the rice fields of Southeast Asia as a new food source, after rice cultivation had established itself there in the course of a population influx from the Yangtze River Basin. “For wild animals, having access to an abundant and enduring food source appears to have been worth the risk of being close to humans.”

A new relationship to humans: from prey to livestock

To protect their harvests, humans hunted the unwanted competition – and ate their kills as a welcome meat source. Deliberate placement of waste piles could also entice prey. “A novel human-animal relationship was thus gradually established, and the animals may have lost some of their reserve when scavenging for food near a village,” notes Peters. “Over time, they probably also began to live there more or less permanently and ultimately to reproduce there.”

While animals grew accustomed to the advantages of life in human proximity despite being hunted, people learned to appreciate life at close quarters with animals and caught ‘living stores,’ which at some point ended up in permanent exploitation and ultimately livestock farming. Once the animals were in human custody, the availability of animal resources became more predictable. If people kept the walking resource supplies in their own settlement, then they could control the range of their movements and thus, in the case of penned wild sheep and goats, could curtail their habitual peregrinations between summer and winter pastures.

It is still unclear, however, how exactly the transition went from hunting to enclosure, and therefore the first step to livestock farming. “Presumably it began with young animals – which would after all be easier to capture and handle than adults,” says Peters. This seems plausible especially in the case of wild cattle. “Who would be able to – or indeed want to – look after a fully grown aurochs every day – beasts that weigh around 600 to 900 kilos and have massive horns?”

Bony work

Paleoanatomist Joris Peters is reliant on archeological findings in the form of bones and teeth. “I can only analyze what excavations turn up.”

© Oliver Jung / LMU

Genetically isolated from members of same species living in the wild

In the course of time, humans discovered additional advantages of domesticated animals, such as the nutritional value of milk and the useful work to which they could be put. Slowly, the new way of life took root. “The people in the core regions of domestication in the upper Euphrates basin probably exchanged knowledge from an early stage,” observes Peters. “After all, the same thing happened with tools and religious ideas across hundreds of kilometers.” To what extent animals were traded at the beginning remains unclear, but later this became common practice, as the spread of domestication and livestock husbandry shows.

Equally, it is difficult to pin down the time from which we can properly speak of domesticated animals. For this to be the case, a population must have genetically isolated itself from its wild counterparts. As soon as this connection is severed and the animals kept by humans basically reproduce among themselves, a new subpopulation is created. But in the early period of domestication, there was initially no clear dividing line between wild and farm animal populations: Crossbreeding repeatedly occurred, because animals out on pastures mated with their wild relatives, whether contrary to the farmers’ wishes or because the farmers deliberately got themselves gene flow from the wild.

At the beginning, there was a tremendous amount people had to learn about livestock farming: How do you keep animals in captivity? What keeps them healthy? Can you breed them in captivity? “There are almost 20 livestock species around today, but people probably tried in vain to domesticate other species, failed attempts of which we know nothing at all,” says Peters. And even if it worked, these humans were still a long way off effective livestock farming.

Researchers have shown that humans had problems particularly in the early phase of domestication by studying evidence such as the bones of sheep and goats from the period between 10,300 and 9,800 years ago: “We suspect that animals were initially kept in spaces that were much too confined – probably in the inner courtyard of houses – and were given suboptimal diets.”

As a result, the animals suffered from degenerative joint damage; diseases and parasites were able to spread; there were miscarriages and increased mortality among young livestock – the herd shrank. This probably made it necessary to capture new young from the wild. As finds dating from a few centuries later reveal, farmers had learned some things about how to keep animals in the interim: For species with powerful natural urges to roam such as sheep and goats, the practice of pasturing over large areas became established.

It took a long time before livestock as we understand it today came into being. “Certainly, many generations of animals and people interacted until livestock and wild animal populations were isolated from each other – domestication is a process that must have lasted hundreds of years,” says Joris Peters. “And this process grew out of opportunistic episodes, not with the clear objective of breeding domestic pigs from wild hogs.”

Skull bone of a bird

© Oliver Jung / LMU

Tombstones for dogs with poetic epitaphs

A special case is the wild cat, which was valued as an effective rodent hunter – but lived alongside, as opposed to with, people for a long time. “Why would anyone domesticate an animal that carries out its useful function without having to be looked after?” And so the domestic cat appeared late on the scene, and breeding cats as a pet with many different races is a modern phenomenon. Nevertheless, utility considerations did not always come first in the history of domestication: Chickens were not eaten initially outside of their natural geographic range, for example, but honored as a ‘bird of light’ and buried after death on account of their splendid plumage and the crowing of the rooster.

Gravestones for dogs from Roman times – featuring poetic epitaphs written by their grieving owners – also testify to a special human-animal relationship, which was colored by more than economic considerations and presumably has a very ancient history. “Emotional bonds in pre- and early history are relatively difficult to infer from the archeological find context and without written evidence,” explains Peters. “But there are indications nonetheless – such as the skeletons of buried individual animals that were very old and long past being able to work or reproduce.” When people’s own survival is dependent on animals, observes Peters, the boundary often blurs between utility considerations and emotional significance, which is bound up with attending to the daily needs of the animals and giving them medical care.

Our livestock are not necessarily reliant on these ministrations, as demonstrated by feral populations of horses, pigs, dogs, or chickens. “It depends on how strongly people have selected characteristics in a breeding line that make it more difficult for the creatures to survive in the wild,” says Joris Peters. “But some domestic animals have always escaped and have often been able to reestablish themselves in the wild.” Frequently, they develop similarities again with their wild relatives – precisely those traits that will help them survive in the wilderness.

Text: Nicole Lamers

Prof. Joris Peters | © Oliver Jung / LMU

Prof. Dr. Joris Peters is Chair of Paleoanatomy, Domestication Research and History of Veterinary Medicine at LMU and Director of the Bavarian State Collection for Palaeoanatomy. A Belgian zoologist born in 1958, Peters was appointed professor at the Faculty of Veterinary Medicine in 2000, where he later initiated the interdisciplinary ArchaeoBioCenter working group. Since 1 January 2022, he has also been General Director of the Bavarian Natural History Collections (SNSB).

Read more articles of the current issue and other selected stories in the online section of INSIGHTS/EINSICHTEN. Magazine.

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