Book preview: Cats and people have shared the planet for at least two separate ice ages


How far back do people and cats go?

Too far for a written record of their origins. Still, we need to get both species onto the scene before describing how cats were domesticated.

In lieu of human writing or art, today’s experts use fossils and molecular markers to “read” the past. They’ve found that most modern land mammal groups have survived multiple ice ages.

The relevant deep-freezes for us are the last one–the Wisconsin/Würm glaciation (named after where it was first identified)–and the one before that, the Illinois/Riss.

There was more than one ice age?

Short answer: There have been dozens. It all began, for complex reasons that aren’t yet fully understood, two and a half million years ago. This was around the time that our close ancestors and those of the domestic cat first appeared.

Details: Against a background of 4.5 billion years’ worth of Earth history, the ice ages aren’t that big a deal. Our planet has seen colder, as well as warmer, times.

But 2.5 million years is too long a stretch for most of us to grasp, so let’s put a face on this story–a round, furry little face.

We’ll have to start a little farther back to bring in this character. The oldest Felis fossil comes from Kenya and is about 4 million years old.

What sort of world did this little cat live in?

A satellite view of Pliocene Earth would have shown subtle changes here and there, but the big shocker to modern eyes would have been the poles. Antarctica was freckled with bare ground, and the North Pole was open water!

Despite a lack of ice, this wasn’t the greenhouse of dinosaur times. Global temperatures were only about 10° F warmer than they are today, and there was somewhat more rainfall.

The planet was cooling down and drying out, though. These changes were so gradual at first that today’s paleoclimatologists have difficulty reconstructing them.

Then, about 2.5 million years ago, Earth crossed some unknown climate threshold and things started to happen quickly. Glaciers appeared in the Northern Hemisphere, and the northern Pacific Ocean cooled dramatically.

Soon, great ice sheets formed, spread out over the northern continents and then, after thousands of years, melted away, only to return and repeat the cycle many millennia later.

As continental ice sheets initially took shape and steppe lands became more common, the first members of our own group Homo (though not yet sapiens) appeared in Africa, where they had to contend with lions, leopards, hyenas, and at least three different kinds of sabercat.

Farther north, in what is now Italy, there was a smaller cat–Felis lunensis. This two-million-year-old feline has left only a few fossils there and elsewhere in Europe, just enough to show that it was a lot like modern wildcats, except for the size of its teeth.

Ice ages, of course, affect evolution in complex ways (see Hewitt in the source list below for more details).

Gene pools mix and ecosystems change each time the ice advances or retreats because animals (and plants) must move out during a glacial period and then move back in when things get warmer.

This happened in Europe over and over again, but apparently Felis lunensis was tough enough to stick around–true wildcats initially appeared there.

Where do people and domestic cats come in?

Short answer: Cats are descended from wildcats, which evolved in Europe around 400,000 years ago and later travelled into Africa and the Middle East. The most recent common human ancestor lived in Africa around 157,000 years ago, during the Illinois/Riss glaciation (the next to last ice age). Cat domestication then began in the Middle East some 10,000 years ago, when African wildcats and people met there shortly after the Wisconsin/Würm ice age (the last one) ended.

Details: Towards the end of an ice age roughly 400,000 years ago, in the Middle Pleistocene, some European small cats–either Felis lunensis or intermediate species–transitioned into the modern wildcat, Felis silvestris, “the cat of the forest.”

Europe remained the center of wildcat evolution through complex glacial-interglacial events that followed, as well as the eventual Illinois/Riss ice age. Then a few wildcat fossils start showing up in 130,000-year-old African and Middle Eastern rocks.

In the meantime, Homo sapiens appeared in Africa, possibly as early as 300,000 years ago, though that’s controversial. Molecular studies (Fu and others, in the source list below) date the most recent common ancestor for all modern people to 157,000 years ago, during Illinois-Riss times.

There is no consensus on how people spread out over the world. The movements of wildcats out of Europe aren’t clear, either, but by 50,000 years ago, European wildcats had colonized the Middle East. Thirty thousand years later, as the Wisconsin/Würm glacial maximum began to ease off, long-legged, sleek African wildcats stalked into that region and replaced the older species.

Then, some 14,000 years ago, the last great ice sheets melted away. Part of the Middle East was now a parkland of nut trees, with wild varieties of wheat and other nourishing foods, including wild peas and lentils.

Such a fertile crescent attracted plant-eaters (and their predators), as well as hunter-gatherers. These people first lived in base camps, but life here was so good that they settled down, inventing agriculture and domesticating animals and plants.

The camps became farms and settlements–rich hunting grounds for the African wildcat, who probably moved in close, just as it still does today.

Human and cat saw each other and assessed one another’s strengths and weakness, seeing some benefit in establishing a connection. The two species then came together, at least 10,000 years ago, to form a close bond that still is present today.


Featured image: European wildcat, Felis silvestris, by Tambako the Jaguar, CC BY-ND 2.0.


Sources:

Antón, M. 2013. Sabertooth. Bloomington: Indiana University Press.

Belknap, D. F. 2018. Quaternary. https://www.britannica.com/science/Quaternary#ref921947 Last accessed September 21, 2018.

Callaway, E. 2017. Oldest Homo sapiens fossil claim rewrites our species’ history. https://www.nature.com/news/oldest-homo-sapiens-fossil-claim-rewrites-our-species-history-1.22114 Last accessed September 22, 2018.

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, Supplement 1. 106: 9971-9978.

Fu, Q.; Mittnik, A.; Johnson, P. L.; Bos, K., Lari, M.; and others. 2013. A revised timescale for human evolution based on ancient mitochondrial genomes. Current Biology, 23(7): 553-559.

Hewitt, G. 2000. The genetic legacy of the Quaternary ice ages. Nature, 405(6789): 907.

Kurtén, B. 1965. On the evolution of the European wild cat, Felis silvestris Schreber. Acta Zoologica Fennica. 111:3-29.

Lisiecki, L. E., and Raymo, M. E. 2005. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ180 records. Paleoceanography. 20, no. 1.

Lyle, M.; Barron, J.; Bralower, T. J.; Huber, M.; and others. 2008. Pacific Ocean and Cenozoic evolution of climate. Reviews of Geophysics. 46: RG2002,

McHenry, H. M., and Coffing, K. 2000. Australopithecus to Homo: transformations in body and mind. Annual Review of Anthropology, 29(1): 125-146.

Prothero, D. R. 2006. After the Dinosaurs: The Age of Mammals. Bloomington and Indianapolis: Indiana University Press. Retrieved from https://play.google.com/store/books/details?id=Qh82IW-HHWAC.

Randi, E., and Ragni, B. 1991. Genetic variability and biochemical systematics of domestic and wild cat populations. (Felis silvestris: Felidae). Journal of Mammalogy. 72(1):79-88.

Tallavaara, M.; Luoto, M.; Korhonen, N.; Järvinen, H.; and Seppä, H. 2015. Human population dynamics in Europe over the Last Glacial Maximum. Proceedings of the National Academy of Sciences. 112(27):8232-8237.

Werdelin, L.; Yamaguchi, N.; Johnson, W. E.; and O’Brien, S. J.. 2010. Phylogeny and evolution of cats (Felidae), in Biology and Conservation of Wild Felids, eds. Macdonald, D. W., and Loveridge, A. J., 59-82. Oxford: Oxford University Press.

Yamaguchi, N.; Driscoll, C. A.; Kitchener, A. C.; Ward, J. M.; and Macdonald, D. W. 2004. Craniological differentiation between European wildcats (Felis silvestris silvestris), African wildcats (F. s. lybica) and Asian wildcats (F. s. ornata): implications for their evolution and conservation. Biological Journal of the Linnean Society. 83:47-63.

Zachos, J.; Pagani, M.; Sloan, L.; Thomas, E.; and Billups, K. 2001. Trends, rhythms, and aberrations in global climate 65 Ma to present. Science, 292: 686–693.

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