Mirna Salim
Introduction
Cats have been living with us for thousands of years. As opposed to other domestic animals like cows and sheep that provide as with food and other raw materials, it has never been clear the main reason why human domesticated cats. Some schools of thought believe that cat was domesticated to help human eradicate rodents which were destroying crops. However, others believe that cats were domesticated just to be pets, to keep human company. This research will not major in the reason as to why cat was domesticated, but rather will focus on the origin of the domesticated cat, the gene deference between the domestic cat and the wild cat; and if there was no difference, the research will establish the methods human beings used to select the cats they domesticated and left the wild ones.
For a long time, more than 10,000 years, cats have lived with us (Linseele, Neer & Hendrickx 2007). However, there is no clear indication on to how they originated and the way human selected them for domestication. There are very little physical observable differences between the wild cats and the domestic cats. The variation must be very small because we can observe that both the wild and the domesticated cats are still mating to produce either domestic or wild cats. With this characteristic, one can say that, unlike dogs and other domestic animals, cats are still semi-domesticated. It is almost impossible to naturally breed a dog with their sister wolfs. However, genetic fingerprinting between the wild cat and the domesticated cat has shown some variations. The genes that control fear, memory and kitty vary a lot between the two types of cats. This research therefore endeavours to establish the origin of cat domestication, their relationship with the wild cat and how the human selected them from the wild cat for domestication.
The Origin of the Domestic Cat
There have been different theories on when and where cat was first domesticated. A number of researchers suspect that the current domestic cat originated from the only one wild cat species called, Felis silvestris. What was not consistent was that this species is represented all over the world hence we can’t assume that initially they were confined to a specific corner of the globe. Therefore, one cannot unequivocally ascertain which wild cat was from which the tamed ones originated. For a long time, researchers believed that the first domestication of cats started in Egypt around 3,600 years ago (Linseele, Neer & Hendrickx 2007). Contrary to this view, some researchers believe that cats were domesticated simultaneously in different region at the same period of time. Another study shows that early Chinese farmers must have domesticated cats around 5,000 years ago. This therefore means that the cats were domesticated more than once in various periods of time. An archaeological extraction in Quanhucun, a small village in China revealed the pelvis and mandibles of cats which dated 5300 years ago. The bones were excavated from a site which was evidently occupied by human being with human boned dating the same period (Driscoll, Macdonald & O'Brien 2009).
In 2002, Dristcoll started to do a research in order to tack the question on the originality of the domestic cat. He assembled 979 samples of both domestic and wild cats. His hypothesis was that the genetic composition of wild cat will vary from one geographical area to the other. His argument was that the wild cat needs to adapt to the environment so that they can survive in the wilderness. On the other hand, he believed that the domestic cats may not exercise such levels of adaptive radiation because their environment is modified by the human they are living with. His focus was to compare the various DNA structures. If he found out that the DNA structures of the wild cats vary from one geographical area to the other; and that the DNA composition of the domestic cat varies slightly with those of the wild cat, then he would easily conclude the origin of the domestic cats.
In his analysis which was published in 2007, Driscoll and other colleague, O’Brien focused on two main DNA. The DNA of the mitochondria, this was because this DNA is passed from parent to offspring. The second DNA they focused on was called microsatellites. These DNA are short and have repeated sequence in the nuclear; they were used to determine the effect of geographical difference on the characteristics of the cats. Using computer software, they were able to assemble the different ancestry for the 979 species under investigation (Driscoll, Macdonald & O'Brien 2009). The next question they had to ask themselves was either the different cats lived in the same geographical position or there were variations.
There were five ancestries which were identified from the research. Out of the five species, four of them were identify to represent four known species of the wild cat originating from four distinct geographical locations. The first lineage was Felis silvestris lybica. The origin of this wild cat was traced from the Middle East. The second one was Felis silvestris ornata which originates from central Asia; Felis silvestris cafra which dwells in Europe; Felis silvestris silvestris which dwelled in Chinese mountain; and Felis silvestris margarita which represented hundreds of the domestic cats which were sampled, including both the mixed and pure breed from all over the globe (Linseele, Neer & Hendrickx 2007).
After identifying the various origins of the cats, the next step was to ascertain whether the cats were really domesticated from the wild cat species or there was a special species which was chosen for domestication. By using genetics, one can identify whether a given species of organism was domesticated from an available wild species or the species were genetically tamed even before they were selected by humans. Geneticists can study the evolutionary events in a specific genetic mutation over time. When an organism exhibits steady continuous genetic mutations which accumulate over a specific period of time, then one can conclude that the organism was modified from the wild ancestor to the current tamed animal (Linseele, Neer & Hendrickx 2007). By using this method, the time tickled so slowly that the result shown that the cats were just domesticated around 10,000 years ago. The only remaining method to ascertain the time of domestication was by studying archaeological records.
In 2007 Jean-Denis Vigne who used to work with the Paris National Museum of Natural history excavated their remains of cats that shown the earliest archaeological evidence of cat domestication. The site was in Cyprus, Mediterranean and the archaeological evidence shown that the remains of the cats found were in a human settlement site which also had the remains of humans dating the same period. The archaeologists discovered the remains of a human being of unknown sex laid in a shallow grave with iron tools and stone tools lying next to the remain. Just a few centimetres away, the remains of a 13 months old cat was found lying on the same orientation as that of the human (Mullikin 2007). Archaeological evidence has shown that cats are not natives of Mediterranean Island, it can therefore be concluded that the cat was carried by a human being, in a canoe, to the island. The deportation of the cat to the island and the burial of the cat just next to human was an indication that cats and men started living together more than 10,000 years ago.
Evidence that Cat was Really Domesticated
There are irrefutable evidences that cat and human have been sharing the same roof for more than 10,000 years from now. Both mutational gene sequencing and archaeological fossil dating can confirm to this. The only knowledge so far which has still been lacking is how human domesticated these friendly animals. A research undertaken by Driscoll (2007), led to the analysis of the cats’ genomes which has so far brought about some surprising clues. This research was published in November 2014 by the National Academy of Science.
Cats, unlike dogs, have a relatively recent history with human. Domestication of dog was estimated to have occurred around 30,000 years ago. Cats can be said to be semi-domesticated compared to their dog counterparts. As stated before, cats just split from their ancestral wild cats around 10,000 years ago. However, the DNA evidence of their domestication can be vividly observed. Scientists have studied the genome of the cat and spotted the genes which have been altered as a result of staying with human beings (Bar-Oz Weissbrod & Tsahar 2014). This was done by comparing the genomes of the wild cats and the domesticated cats and identifying the evidence of gene mutation which occurred due to the domestication. The main genes which were observed to have been altered were the genes that controlled fear, memory and reward-seeking (Hu 2014). Reward seeking was an important gene in that the main reason why the cat and man came together was for the cat to prevent rodents from destroying grains while it seeks for man’s reward on shelter and food.
The National Human Genome Research Institute undertook a research on the genomes of cats. The research was meant to establish the characteristics of hereditary diseases in cats which were also found in men. These diseases included metabolic diseases and neurological disorders. To get a better understanding of the genetic composition of the cats, genome sequencing was undertaken so that only pure breed cats. The physical characteristics which were focused on included the docility of the cat, the facial structure, the hair colour and the texture and colouring pattern. The team focused on specie of cat called Birman. The main characteristic of Birman was that they had white paws. The research indicated that there are only two genes difference between the colour of the paw and that of the entire body of the cat (Bar-Oz Weissbrod & Tsahar 2014). This was an indication that men selectively domesticated the cats which white, and the changes in colour only took place within a very short period of time. This was therefore an indication that human selectively chosen certain characteristics in a cat before they domesticated them. Not all the wild cats were favourable for domestication.
Why did Humans Domesticate the Cats?
The characteristics of cats do not give them the candidacy for domestication. Unlike most of the domesticated animals which operate in groups, cats are often found in solitary. This therefore poses a great difficulty in collecting the cats for domestication. These animals that travel in herds and flocks are already used to operating in cheeks and jaws; therefore, when they are domesticated, it is easy for them to get used to the confinement. On the other hand, most domesticated animals feed on readily available vegetation; cats however are strictly carnivores hence it may pose difficulties in feeding them.
During the Neolithic Period which occurred between 9,000 years to 10,000 years ago, all the animals which were sufficiently flexible were forced to go look for food. The house mice, shown by the archaeological evidences, could not compete with the wild mice (Montague et al 2014). They therefore were forced to move to search for food in homes of human. As a result of invasion by the mice, grains were destroyed and humans were forced to look for alternatives ways of getting rid of the mice. Cats were feeding from the mice for a long time before, it can therefore be concluded that the cats came to human homes to kill and feed on the mice. Man, on realizing that cats were important in getting rid of the mice, they selectively domesticated some species of the cat that they believed had tameable and favourable characteristics. Due to natural selection, some cats become more favourable for domestication while the remaining ones were left in the wilderness. The mode of selection to this new niche was by possessing the docile gene. Humans only selected cats which could be easily tamed and leave those which were too wild to be tamed. Those that possessed little docile genes were left in the wilderness to fend for themselves.
People viewed cats as harmless animals, and as a result they allowed them to just stay close to them. Some researchers believe that these cats possessed some physical characteristics which were appealing to the humans. These characteristics involved round eyes, snub face, and “cute” features among others. Another factor which was considered by man was tolerance, The European and the Chinese mountain cats were too intolerant to be domesticated.
Evidence of Cat Domestication
In order to prove that the cat was domesticated, research has been conducted on the genome of both the domestic cat and its wild feline counterparts. By conducting research on the entire genome of a domestic cat that was based on a female Abyssinian referred to as cinnamon and the genome of 22 other pure breed cats from six other breeds and four other wild breeds the Studies into the comparison of domestic cats genomes and those of wild felines indicate the genetic underpinning for domestication (Czernik 2015).
The studies also indicate that unlike dogs cats are the only semi-domesticated and it is only recently that a split appeared between domestic cats and wild cats and even though some cats still breed with their wild relatives DNA evidence of their domestication has largely developed (Czernik 2015).
According to research when one compares the genomes of domestic cats with those of wild cats, he or she is able to notice that when compared to the genomes of wild cats, the genome of domestic cats showcased evidence of recent selections in those genes that are linked to memory, stimulus-reward learning and fear conditioning (Montague 2015). It is important to note that all these factors are related to the evolution of tameness. According to the scientists behind the research in the genome of cats evolved in this way because in order for the cats to be domesticated they would have needed to be less fearful of individuals and new places and they would also need to remember the people taking care of them.
Certain variations that were discovered in domestic cats are important in helping to explain certain aspects of the cat’s biology such as the genes of the cats which are involved in metabolism, increased visual and auditory acuteness in the cats and the cat’s sense of smell which is completely different from those of their canine counterparts (Grimm 2014). Unlike humans and cows genome studies have indicated that cats both wild and domestic have lipid metabolizing genes which change at a faster rate than can be explained. These lipids help in maintaining the cat’s hypercarnivorous diets by breaking down fats (Grimm 2014).
It has been proven that cats perceive sound in an ultrasonic sound range, and they are usually less active at dusk and more active at dawn (Serpell 2000). This factor was linked to a group of genes that helped in the development of the cat’s sense of hearing and seeing. The genes were more advanced and more complex than those found in humans, dogs, and cows. Studies also determined unlike dogs cats rely less on smell to hunt for their food. Thus, they have fewer genes that are associated with the smell (Serpell 2000). However, it has been proven that cats have genes which are related to an alternate form of smell. These genes are responsible for the detection of chemicals that are referred to as pheromones. The pheromones allow mostly solitary animals to track and find opposite sex animals of the same species during mating season.
Studies have also proved to a T that all domesticated cats are descendants from the Near Eastern and North African subspecies of wildcats. Further research to the domestication of this cats indicates that it occurred 10 800 years within the area of the Middle East.
Evidence also indicates that cats were not only domesticated once, but they were domesticated twice. The second time a cat was domesticated was from a different species referred to as the leopard cat. The second domestication is said to have occurred in China approximately 5000 years ago. The Recent discovery of small cat bones located at several Neolithic sites only goes to support the claims that indeed cats were domesticated a second time. Conducting of a geometric morphometric analysis of the feline bones that were collected from the site concluded that the cats bones originated from a different species of wild cat scientifically referred to as Prionailurus bengalensis or the wild cat in layman terms (Vigne, Evin, Cucchi, Dai, Yu, Hu & Dobney 2015). According to researchers, the can easily be bred in captivity and nature and physical condition of the cats disposition indicated that the remains of the cats found in the Neolithic sites were under the process of domestication. However, genetic analysis of most modern cat's today including those in China indicates that there are no direct descendants of the leopard cat species which was domesticated in China. Thus, the big question is what happened to the domesticated leopard cats of China? Research indicated that the cat may have returned to the wild search of food during the periods of the great droughts that faced China. However, some researchers believe that domestication made them extremely dependent on humans and thus could not survive on their own without human assistance. Thus, most of the leopard cats of China are said to have gone extinct because they could no longer hunt for themselves. However the Bengal domestic cat was a breed of cat that was modeled after the leopard cat species and some scientists are trying to reintroduce them back into the society (Driscoll, Clutton-Brock, Kitchener, & O'Brien 2009).
References
Driscoll, C.A., Macdonald, D.W. and O'Brien, S.J., 2009. From wild animals to domestic pets, an evolutionary view of domestication. Proceedings of the National Academy of Sciences, 106(Supplement 1), pp.9971-9978.
Montague, M.J., Li, G., Gandolfi, B., Khan, R., Aken, B.L., Searle, S.M., Minx, P., Hillier, L.W., Koboldt, D.C., Davis, B.W. and Driscoll, C.A., 2014. Comparative analysis of the domestic cat genome reveals genetic signatures underlying feline biology and domestication. Proceedings of the National Academy of Sciences, 111(48), pp.17230-17235.
Driscoll, C.A., Menotti-Raymond, M., Roca, A.L., Hupe, K., Johnson, W.E., Geffen, E., Harley, E.H., Delibes, M., Pontier, D., Kitchener, A.C. and Yamaguchi, N., 2007. The Near Eastern origin of cat domestication. Science, 317(5837), pp.519-523.
Hu, Y., Hu, S., Wang, W., Wu, X., Marshall, F.B., Chen, X., Hou, L. and Wang, C., 2014. Earliest evidence for commensal processes of cat domestication. Proceedings of the National Academy of Sciences, 111(1), pp.116-120.
Mullikin, J.C., Hansen, N.F., Shen, L., Ebling, H., Donahue, W.F., Tao, W., Saranga, D.J., Brand, A., Rubenfield, M.J., Young, A.C. and Cruz, P., 2010. Light whole genome sequence for SNP discovery across domestic cat breeds. BMC genomics, 11(1), p.1.
Bar-Oz, G., Weissbrod, L. and Tsahar, E., 2014. Cats in recent Chinese study on cat domestication are commensal, not domesticated. Proceedings of the National Academy of Sciences, 111(10), pp.E876-E876.
Linseele, V., Van Neer, W. and Hendrickx, S., 2007. Evidence for early cat taming in Egypt. Journal of Archaeological Science, 34(12), pp.2081-2090.
Vigne, J. D., Evin, A., Cucchi, T., Dai, L., Yu, C., Hu, S., & Dobney, K. 2015. Earliest" Domestic" Cats in China Identified as Leopard Cat (Prionailurus bengalensis). PloS one, 11(1), e0147295-e0147295.
Czernik, S. 2015. The Domestication Effect: Increasing Phenotypic Similarities in Newly Domesticated Species (Doctoral dissertation).
Montague, M. J. 2015, January. Comparative Analysis of the Cat Genome Reveals Clues to Feline Domestication. In Plant and Animal Genome XXIII Conference. Plant and Animal Genome.
Grimm, D. 2014. The genes that turned Wildcats into kitty cats. Science, 346(6211), 799-799.
Tamazian, G., Simonov, S., Dobrynin, P., Makunin, A., Logachev, A., Komissarov, A., & Koepfli, K. P. 2014. Annotated features of domestic cat-Felis catus genome. GigaScience, 3(1), 13.
Serpell, J. A. 2000. 9 Domestication and history of the cat. The domestic cat: The biology of its behaviour, 179.
Driscoll, C. A., Clutton-Brock, J., Kitchener, A. C., & O'Brien, S. J. 2014. The taming of the cat. Scientific American, 300(6), 68-75.
