Divining Human History with DNA
Everyone knows about how genetics is changing how we look at and treat human disease. But what may be less appreciated is what it can tell us about human history.
From studying human genetics, we know that all humans started out in Africa. We also know that early humans interbred with Neanderthals and Denisovans before wiping them out. Now a new study looking at cow DNA is teaching us about our agricultural history.
Scientists compared DNA from 8,000 year old cow bones to 20 or so different modern cow breeds from all over the world. When they plugged their data into various computer models, the one that made the most sense had modern cows coming from about 80 wild founders around 10,000 years ago.
Not only does this help explain why cows all look so much alike, it also tells us that our ancestors only managed to domesticate cows once. This is despite the fact that ancient, wild cows (called aurochs) were wandering all over Africa, Asia, and Europe at the time.
The obvious conclusion is that domesticating a cow is really hard. And this makes sense if you think about the animals.
No, I don’t mean placid Bessie out in the pasture. Ancient cows were huge, ornery creatures that would have been hard to capture alive and hard to breed. Archeological evidence suggests it took hundreds of years or more of breeding to get animals that were smaller and more docile.
Archeological evidence also helps us pinpoint where the first domestication probably happened – the Middle East. But because archeological data is often incomplete, it can’t tell us whether this was the only cattle domestication event in human history. We need genetics to confirm this (or at least to confirm that modern cows came from a single domestication event).
Genetics is providing insight into human history that we could not have gotten in any other way. We can see that humans lost their fur and gained darker skin around 1.2 million years ago. And we can see that our original pale skin from back when we were hairy came back into fashion in Europe about 6000-12,000 years ago.
And cows aren’t the first animal’s DNA to tell us something about ourselves either. By looking at lice DNA, scientists think that humans first started wearing clothes about 170,000 years ago.
It is amazing what we can learn about our history from looking at the DNA of ourselves and our associated creatures. Soon we’ll learn even more. As the price of deciphering our DNA goes down, the number of questions we can answer will go up dramatically. The only thing that will keep us back is figuring out the best questions to ask.