Domestication of the cat - when and how did it happen?

He is distant and cuddly, peaceful and wild, captivating and nerve-wracking. Still, despite its fickle nature, the domestic cat is the most popular pet in the world. Genetic and archaeological findings show that it all started here, in the Middle East about 10,000 years ago

Scientific American

By: Carlos A. Driscoll, Juliet Clutton-Brock, Andrew S. Kitchener, and Stephen G. O'Brien

More than 600 million cats live among humans worldwide. And here, despite the close acquaintance we have with these creatures, we still do not fully understand the riddle of their origin. We domesticated several other wild animals - to enjoy their milk, meat, wool, or their ability to work; But the cats do not contribute to us and nothing in the way of livelihood or work. If so, how come they were such a common addition to the home landscape?

Scholarly explanation has long held that the ancient Egyptians were the first, 3,600 years ago, to keep cats as pets. But genetic and archaeological discoveries in the last five years have changed the picture and yielded new insights both as to the ancestry of the domestic cat and as to the development of its relationship with humans.

The cat's cradle - it all started here, in the Middle East
The answer to the question of where the domestic cat first emerged is not simple, for several reasons. Even though there are researchers who believed that the origin of all races is from one and the same species, Felis silvestris, which is the domestic cat, they could not know this for sure.

Also, this species is not limited to a small corner of the earth. It is represented in animal populations all over the Old World - from Scotland to South Africa and from Spain to Mongolia - and until recently scientists had no way of determining unequivocally which of these wild cat populations displaced the domesticated type.

There are even researchers who have proposed, as an alternative to the hypothesis of Egyptian origin, that the domestication of the cat occurred in several places, and in each of them a different type was created. The problem is that it is difficult to distinguish between the members of the different groups of wild cats as well as between them and the domesticated cats with striped fur, since they all have the same pattern of stripes on their fur, and they easily breed with each other and thus further blur the boundaries between the populations.

In 2000 one of us (Driscoll) decided to tackle the question by collecting DNA samples from 979 wild cats and domestic cats in the southern regions of Africa, Azerbaijan, Kazakhstan and the Middle East. Because feral cats typically defend a single territory their entire lives, he expected that the genetic makeup of wild cat groups would vary by geographic region, but remain stable over time, as it has in many other cat species.

If he could distinguish between indigenous regional groups of cats based on their DNA, Driscoll thought, and if the DNA of domestic cats was closer to that of one of the wild populations, he would have clear evidence of where domestication began.

In the genetic analysis they published in 2007, Driscoll, O'Brien (also one of us) and their colleagues focused on two types of DNA that molecular biologists usually examine to distinguish between subgroups of mammal species: mitochondrial DNA, which is inherited only from the mother, and in repetitive short DNA sequences called microsatellites.

Using standard computer routines, they mapped the lineage of each of the 979 cats tested based on their genetic signatures. More precisely, they measured how similar each cat's DNA was to that of all other cats and assigned those with similar DNA to that group. Then they checked if most of the animals that were associated with a certain group lived in the same area.

The results revealed five genetic clusters, five lineages, of wild cats. Four of the lineages closely matched four of the known subspecies of wild cats and lived in defined locations: F. silvestris silvestris in Europe, F. s. bieti in China, F. s. ornata in Central America and F. s. cafra in the southern part of Africa. But the fifth lineage included not only the fifth subspecies of wild cats, F. s. lybica, but also the hundreds of house cats that were sampled, including purebred and mixed cats from the USA, England and Japan.

In fact, there was almost no difference between the wildcats of the subspecies F. s. lybica, collected in remote deserts in Israel, the United Arab Emirates and Saudi Arabia, and among domestic cats. The fact that domestic cats were found to be close to the F group. s. lybica alone, means that domestic cats originated in a single site, in the Middle East, and not in other places where wild cats are common.

After understanding where the domestic cat came from, we wanted to find out when domestication took place. Geneticists can sometimes estimate when a particular evolutionary event occurred by investigating the amount of random mutations that accumulate over time at a constant rate. But this molecular clock is ticking too slowly to be able to accurately date events that happened in the last 10,000 years, the time when the cat was probably domesticated.

To try and figure out the date of the start of domestication, we turned to the archaeological evidence. A recently discovered find has provided us with particularly useful information.

In 2004, Jean-Denis Vigna, of the Museum of Natural History in Paris, and his colleagues reported the discovery of the earliest evidence that humans kept cats as pets. The find was discovered in Cyprus, where an adult man whose name is unknown was buried 9,500 years ago, in a shallow grave. A variety of objects were placed next to the body: a stone vessel, a lump of iron oxide, a handful of seashells, and 40 centimeters away, in its own tiny grave, an eight-month-old cat laid, like the man, with its head to the west.

Cats are not native to the Mediterranean islands, so the conclusion is that cats were brought to the island in boats, probably from the nearby continent. The bringing of the cat to the island and the burial of a man with a cat together indicate that humans had a special and reasoned relationship with cats nearly 10,000 years ago in the Middle East. This location corresponds to the geographic origin we arrived at through the genetic analyses. It therefore seems that the domestication of the cat occurred at the same time when the first settlements were established in the Fertile Crescent region of the Middle East.

Cat and mouse games?
After deciphering the puzzle of geography and the approximate age of the first stages in cat domestication, we could return to the old question: Why did cats and humans develop a special relationship? Cats are not likely candidates for domestication. The ancestors of most domestic animals lived in herds or herds with a clear hierarchy. (Humans, unknowingly, took advantage of this social structure by taking the place of the ruler in the pack, which made it easier for them to control entire groups.)

These animals were already used to living in crowded conditions, and when we gave them food and shelter, they easily adapted to life in captivity. Cats, on the other hand, are solitary hunters who defend their home territory against other cats of the same species (lions, living in packs, are an exception).
Besides that, most domesticated animals feed on a wide variety of plant foods, while cats are avid meat eaters and have a limited ability to digest other foods, which makes feeding them difficult and expensive. In fact, they have completely lost the ability to digest sugary carbohydrates. And as for the benefit they bring to humans, it is only said that cats do not tend to accept orders. Such features make us believe that the cats, unlike other domesticated animals that man took from nature and bred for certain purposes, chose to live among humans for their own benefit.

Early settlement in the Fertile Crescent 9,000 to 10,000 years ago, during the Neolithic period, created a vastly different environment for wild animals that were flexible and curious (or scared and hungry) enough to exploit it. The house mouse, Mus musculus domesticus, was such a creature. Archaeologists found remains of this rodent, which originated in the Indian subcontinent, in the first wild grain stores in Israel, from about 10,000 years ago. These mice could not compete outdoors with the local wild mice, but found a way to thrive by moving into man's homes and his grain stores.

It is almost certainly clear that the house mice attracted the cats. But the garbage piles on the outskirts of the city were probably an equally strong attraction, as they provided food all year round for those resourceful cats who went out to look for them. In both of these food sources there was a temptation for cats to adapt to life among humans. And in the language of the biology of evolution, natural selection favored the cats who knew how to live alongside humans and thus have free access to the garbage and the mice.

Over time, feral cats that were better adapted to life in a human-dominated environment began to thrive in settlements all over the Fertile Crescent. The natural selection in the new niche probably worked mainly in the direction of domestication, but the competition between the cats also certainly continued to influence their evolution and prevented them from becoming too submissive and obedient animals.

Since these pre-domestic cats undoubtedly had to continue to protect and fend for themselves, their hunting and gathering senses remained sharp. Even today, most domesticated cats are independent animals, able to survive easily even without humans, as evidenced by the large number of wild cats in cities, towns and villages around the world.

Since the little cats cause no real harm, the humans probably didn't care that the cats were around - they may have even encouraged them to stay when they saw that they were preying on mice and snakes. And they may have had other attractive qualities as well. Some experts have hypothesized that the wild cats had pre-existing traits that were suitable for developing relationships with humans. In particular, we endowed these cats with "cute" features - big eyes, a short-snouted face and a high, rounded forehead - which are known to inspire in humans a desire to protect and nurture. It is therefore very likely that there were people who took kittens home simply because they found them captivating, and thus the cat was given its first foothold in the human home.

Why was F. s. lybica the only subspecies of wild cats in captivity? There is anecdotal evidence that certain other subspecies, such as the European wild cat and the Chinese mountain cat, are not so friendly to humans. The South African wildcat and the Central Asian wildcat, on the other hand, are friendlier and could have been domesticated under the appropriate conditions.

But for F. s. Lybica had an initial advantage due to its proximity to the first settlements. With the spread of agriculture from the Fertile Crescent to other regions, the domesticated descendants of F. s. lybica and filled that niche in every area they entered and effectively slammed the door on the local feral cat population. If domestic cats had not arrived from the Middle East to Africa or Asia, it is possible that the local wild cats in those areas would have been attracted to the homes and villages with the development of urban culture.

Ascension of the Goddess
We don't know how long it took for the Middle Eastern house cat to become a pampered domestic companion. Animals may become domesticated quite quickly under controlled conditions.

In one famous experiment, beginning in 1959, Russian scientists, through highly selective hybridization, developed domesticated silver foxes from wild foxes in just 40 years. But without doors or window panes, the Neolithic farmers would have had a very difficult time controlling the mating of the cats even if they had wanted to. It seems reasonable to think that the lack of human intervention in hybridization and the repeated mixing of domestic cats and wild cats acted against rapid domestication and extended the process to several thousand years.
Although there is no certainty as to the exact timeline of the cat's domestication, archeological findings that have been known for a long time shed some light on the process. After the Cypriot discovery, the next clues in their antiquity regarding the connection between humans and cats are a molar tooth of a cat from an archaeological site in Israel whose age is estimated at 9,000 years and another tooth from Pakistan from about 4,000 years ago.

The evidence of full domestication was found in a much later period. A cat figurine made of ivory from almost 3,700 years ago, discovered in Israel, indicates that the cat was a common sight around the houses and villages in the Fertile Crescent even before it arrived in Egypt. This is a reasonable scenario, given that all plants and other domesticated animals (except the donkey) came to the Nile Valley from the Fertile Crescent.

But Egyptian paintings from the New Kingdom period - the golden age of Egypt that began almost 3,600 years ago - are the ones that provide the oldest explicit descriptions of full domestication. These paintings usually show cats under chairs, sometimes wearing collars or leashes, and often eating from bowls or feeding on scraps. The multitude of these paintings indicates that at that time the cats were already in the houses of the Egyptians.

Paintings like these are the main reason why researchers previously believed that ancient Egypt was the place where the cat was domesticated. However, even the oldest descriptions of wild cats found in Egypt are 5,000 to 6,000 years younger than the 9,500 years of the Cypriot burial site. Although the ancient Egyptian culture cannot count the initial domestication of the cat among its many achievements, there is no doubt that it played a central role in shaping the continuation of the process and in the distribution of cats throughout the world.

Indeed, the Egyptians raised the love for the cat to a completely different level. 2,900 years ago, the domestic cat was already the official deity of Egypt in the form of the goddess Bastet, and domestic cats were sacrificed, embalmed and buried en masse in the city of Bubastis, sacred to the goddess. The huge amount, measured in tons, of cat mummies found there indicates that the Egyptians were not content with collecting wild cats but, for the first time in history, actively bred domestic cats.

The cats are conquering the world
For hundreds of years, Egypt imposed an official ban on the export of its revered cats. But nevertheless, cats are found in Greece as early as 2,500 years ago, evidence of the ineffectiveness of export restriction laws. Then, ships carrying grain sailed from Alexandria straight to destinations throughout the Roman Empire, and there is no doubt that they took cats to devour the mice. It is therefore reasonable to assume that cat populations multiplied in port cities and from there spread into the continent.

2,000 years ago, when the Romans expanded the borders of the empire, the cats also expanded their living areas and became a common sight throughout Europe. Evidence of their spread was found at the German site Tofting in Schleswig, from the period between the 4th and 10th centuries, as well as in the growing reference to them in art and literature from that period. (Surprisingly, domestic cats seem to have arrived in the British Isles before the Romans brought them there, a mystery that researchers still cannot explain.)

Meanwhile, on the other side of the planet, domestic cats apparently spread to the Far East almost 2,000 years ago, along the established trade routes between Greece and Rome and between the Far East, reaching China via Mesopotamia and India by land and sea. Then something interesting happened. Since there were no native wild cats in East Asia for the new arrivals to interbreed with, the East Asian domestic cats soon began to evolve along their own path.

There, small and isolated groups of domestic cats gradually acquired unique fur colors and other mutations in a process of genetic drift, in which traits are established in the population that do not necessarily affect the level of adaptation.

This drift led to the appearance of the Kurat, Siamese, Burman and other "natural races", described by Buddhist monks in Thailand in the book Tamara Maew ("Songs of the Cat Book"), probably written in 1350. The ancient origin of these races was confirmed by the results of genetic studies published in 2008. Marilyn Menotti-Raymond of the US National Cancer Institute and Leslie Lyons of the University of California, Davis found in the DNA of European and East Asian domestic cat breeds differences that indicate more than 700 years of independent development in Asia and Europe.

As for the question of when domestic cats arrived in the Americas, we don't know much about it. It is said that Christopher Columbus and other navigators of his time took cats with them on ocean crossings. It is also said that the Mayflower passengers and Jamestown settlers (England's first permanent settlement in the New World) brought cats with them for luck and against pests. The arrival of domestic cats in Australia is even more obscure, although researchers assume they arrived with European explorers in the 17th century. Our group at the US National Institutes of Health is investigating the issue using DNA.

Hybridization for beauty purposes
Even if in the past humans played a minor role in the development of races in the Far East, the efforts aimed at creating new races did not begin until relatively late. Even the Egyptians, who are known to have bred cats on a large scale, do not seem to have done selective cross-breeding to achieve certain appearance traits, perhaps because so many different appearance breeds had not yet been created. In their paintings, both wild and domestic cats have the same striped fur.

Experts believe that most modern breeds were developed in the British Isles in the 19th century, based on the writings of the English natural history master Harrison Weir. In 1871, the first fancy cat breeds - breeds developed by man in order to achieve a certain look - were presented at a cat show held at the Crystal Palace in London (a Persian cat won, although the Siamese also caused considerable excitement).
Today, the Cat Lovers Association and the World Cat Association sell about 60 breeds of the domestic cat. Only about a dozen genes are responsible for the differences between the different breeds in fur color, length and texture, as well as in less prominent features of the fur, such as shades and shine.

In 2007, the complete genome sequence of one Abyssinian cat named Cinnamon was determined, and since then geneticists are quickly identifying the mutations responsible for traits such as scat, the colors black, white and red, long hair and many others. However, apart from differences in the genes of the fur, the genetic variation between the different breeds of the domestic cat is minimal - and can be compared to that between closely related human populations, such as the French and the Italians.

The wide variety of sizes, shapes and temperaments evident in dogs - see Chihuahuas and Great Danes, for example - does not exist in cats. In cats, we see much less diversity because wild cats, unlike dogs - which were bred for tasks such as guarding, hunting and herding since prehistoric times - were not subjected to such aggressive hybridization pressures. In order to enter our homes, they only had to develop a human-friendly temperament.

Are today's cats really domesticated? Well, yes - but maybe only up to a certain limit. Although they are willing to tolerate the presence of humans, most domestic cats are wild and do not need humans to provide them with food and mates. And if other domesticated animals, such as dogs, look very different from their wild ancestors, the average domestic cat largely retains the body plan of the wild cat. However, some morphological differences are evident: slightly shorter legs, a smaller brain, and, as Charles Darwin pointed out, a longer intestine, which may be an adaptation to stolen scraps from the kitchen.

But the evolution of the domestic cat is far from over. Today's cat breeders, armed with the technologies of artificial insemination and in vitro fertilization, are pushing domestic cat genetics into uncharted territory: they are crossing domestic cats with other feline species to create new exotic breeds. The Bengal and cricket, for example, were born from hybrids of a domestic cat with the Asian tiger cat and the caracal, respectively. If so, it is possible that the domestic cat is on the cusp of an extreme and unprecedented evolutionary development to create a composite multispecies whose future will be ours.

Carlos A. Driscoll (Driscoll) is a member of the Oxford University Wildlife Conservation Research Unit and the Genomic Variation Laboratory at the American Cancer Institute (NCI); Juliet Clutton-Brock (Clutton-Brock), founder of the International Council for Archaeozoology, is a pioneer in the study of early domestication and agriculture; Andrew S. Kitchener is Chief Curator of Mammals and Birds at the National Museum of Scotland; Stephen J. O'Brien is the head of the NCI's Laboratory of Genomic Variation. The article was published in the September issue of "Scientific American - Israel", published by Ort