From feral to floof ball: The incredible evolution of cats

One of the most exciting recent scientific discoveries is the realisation that when natural selection is strong, species can evolve extremely quickly. This topic was on my mind as I reviewed the immense amount of scientific research on Felis catus – the domestic cat – for my new book, The Age of Cats: from the Savanna to Your Sofa. Even though hundreds of millions of free-ranging, unowned cats occur on every continent but Antarctica, there are almost no data on how unowned cats are evolving.

We might predict that evolution is occurring in two ways. One is simply that feral cats could be reverting to the lifestyle of their ancestors, reversing the effects of domestication. It’s not hard to imagine these cats filling the same ecological niche as the North African wildcat and evolving back from whence they came. Alternatively, Felis catus may be striking out in new evolutionary directions. Feral felines occur in many places where there are few large predators. Look at how the coyote has taken advantage of that situation in North America, occupying every imaginable habitat and evolving much larger in size in the absence of wolves that used to keep them in check. Maybe feral domestic cats are doing the same.

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Consider the vast array of habitats occupied by cats in Australia: scorching red deserts, mountains, rainforests and grasslands. As an evolutionary biologist, my first thought is that these cats must be adapting to the different circumstances they experience. Desert cats have probably evolved ways to cope with heat and scarce water, mountain-dwelling populations to the cold and snow. Different prey species require different hunting adaptations; different predators – dingoes, Tasmanian devils, big lizards – require different ways to escape. Walking on sand poses different challenges than climbing on boulder fields.

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A quick survey of the variety of small-cat species illustrates how felines adapt: margays with reversible ankle joints to descend trees headfirst, sand cats with the soles of their feet covered in hair to walk across deserts, fishing cats with webbed toes for the life aquatic, to name a few. Even though Australian cats have been evolving for hundreds, rather than millions, of years, they may have started to evolve in these directions.

We don’t know if this is happening. No one has examined whether physiological adaptations have arisen to live in different climates. Behavioral adaptations for coping with different predators and prey haven’t been studied either. 

One thing is certain, though: ferals do not have any of the extreme traits seen in some breeds. I’ve never seen a feral cat with a smooshed-in face like a Persian, nor the elongated muzzle of the Siamese. No short legs, no hairlessness, no curly ears. The conclusion is obvious: if domestic cats of those breeds were abandoned outside, natural selection would eliminate them.

Worldwide, there have been many reports of feral cats that are both large and jet black. In Australia, hundreds of sightings, have led to speculation of escaped black leopards. In Scotland, black cats called the ‘Kellas cat’ are likely hybrids between house cats and Scottish wildcats, as are the large black cats observed in the Caucasus. Large black cats have also been reported in New Zealand, Hawaii and elsewhere.

Perhaps the most intriguing possible case of feral cat evolution involves another place, where sightings have been substantiated: Madagascar. Cats were introduced centuries ago and, as on islands around the world, they have had a major detrimental effect on native animals, even killing lemurs. Most feral ones in Madagascar look like typical mackerel tabbies, albeit big ones – feral males weigh 12 pounds compared to eight-pound non-feral males.

But there’s an unusual twist – there are two types of feral cats. The more typical ones, just described, and a second, even larger type, with long graceful legs reminiscent of a serval, and a pinched, narrow face. Not only are these ‘fitoaty’ larger than the mackerel ferals, but they live in different habitats, the fitoaty found in deep forest, the mackerels at forest edge and around villages. And there’s one more difference – the fitoaties are entirely black, just like so many other jungle cats. When they first came to the attention of scientists, some thought they might be an unknown species, but DNA tests confirmed their identity as Felis catus. Researchers are currently investigating the evolutionary significance of this elegant forest cat, as well as its impact on the native fauna.

More generally, feral cats are a problem in many parts of the world, but they are also a great, unplanned evolution experiment. Charles Darwin would have been fascinated.

The Age of Cats: From the Savannah to your Sofa by Jonathan B Losos is out on May 11 on £22).You can buy it from The Big Issue shop on Bookshop.org, which helps to support The Big Issue and independent bookshops.

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