Wednesday 8 October 2008

Cat evolution - learning from human evolution

We might learn some lessons about the future of domestic cat evolution from human evolution. It has been argued that human evolution has three components, natural selection, mutation and random change. 

My cat! As at 2022.

Cat evolution must it seems be dependent on the same components. It has been further argued by Professor Steve Jones that human evolution is slowing down because men are becoming fathers at a younger age. The mean age for becoming a father in the West is 29 years of age. At that age there would have been about 300 cell divisions from sperm that made the man to the sperm he passes on. Each division offers the chance of a mutation, the product of a defect in the process of cell division. At aged 50 a man would have had 1000 cell divisions, more than three times the opportunities for a mutation to occur. 

 Natural selection is losing its impact as people live to advanced age. 98% live to aged 21 now whereas in the past half of the children would die before the age of 20. There is relatively little natural selection going on. Finally, the concept of random change has been reduced to a global mass because of the size of the human population. If the world population was about 500,000 as it would be if there was no agriculture there would have been a greater chance of random change. According to Professor Jones this is because genes are accidentally lost. How does this translate to domestic cat evolution? 

We can see the change in the appearance of the cat from the classic small wild cat such as the American bobcat or Scottish wildcat and the modern domestic cat. If we apply the above criteria to the cat world, what do we come up with for cat evolution? Well, the domestic cat population is high and feral cats inhabit all parts of the world; they are very able breeders and mothers. Feral cats although wild cats if truly feral are still domestic cats lost betwixt the world they should inhabit, the human home, and the wild which they left some 9,000 years ago when they became domesticated. 

Their high numbers would support the view that less random change is likely to occur in the future. As to fathers; what is the age of stud boys? My view is that the feral cat population is vastly bigger than the domestic cat population worldwide so the feral cat population should be the pool from which to decide what happens in an evolutionary sense. As feral cats breed young this would also lead to the suggestion that there is less likely to be a genetic mutation on the above criteria. Cat breeders like genetic mutations as it throws up the opportunity for a different cat breed, something new. 

The rare mutations that have occurred have not been ones that have enhanced survivability, quite the contrary. Classic mutations are the Rex coated cats, such as the Devon Rex, due to a defective recessive gene and the curly eared cat the American Curl. Sometimes breeders try to add one mutation to another for yet more change. This is generally resisted by associations as it is false and likely to produce ill health. Is there an argument that cat breeders should breed from stud boys who are in over 7 years of age? (see age comparison chart). 

 The same could not be said however about the third criteria, natural selection. Feral cats die young, which provides more opportunity for natural selection to take effect. Perhaps in 5,000 years we will see a super feral cat, one that is more a wildcat, better able to survive in the urban jungle. A special kind of urban cat. Natural selection is the area where cat evolution will take place. This is what Australians fear (see Savannah cat ban in Australia is wrong). 

A super feral cat would be a very efficient killer and push out native species. This is a worry in Tasmania where the Tasmanian Devil, their well-known dog like mammal famous for having the worlds strongest bite pound for pound is becoming extinct due to facial cancer and the void filled by the feral cat (see desexing feral cats) Cat evolution to home page This short post on cat evolution was provoked by a Times October 7th 2008 story.

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