Body of a lab retriever, genome of a chihuahua

Taking Sherman, our black Lab for a walk.

The “guy” is built like a Sherman tank; when he runs to fetch a ball, he is a force of nature, anything standing in his way will get knocked to the ground. As we were walking down the bike trail I was struck by the complete lack of self-consciousness of dogs. Chihuahuas, toy poodles, Great Danes and assorted mutts  recognize him as a dog in good standing. They smelled his derrière, wagging their tails in approval. Yet, I am thinking, as I look at their different sizes, shapes, and colors…could they be more different from each other? Compared to this dizzying variety of Canis canis, we, H. sapiens, are boringly uniform. Or are we?

Shake your family tree and a Neanderthal may fall out

Meet your cousin, the neanderthal; see any resemblance?

Yup, we are all Neanderthals to some extent. But before I let the news leave you in shock, let me explain.

As a special issue of Nature devoted to Peopling the world states “Not long ago, the story was simple. A vanguard of modern humans left their African birthplace 50,000–60,000 years ago and quickly conquered Asia. They turned left into Europe some 40,000 years ago, later crossing the Bering Strait and marching southward into the Americas. With their advance, Neanderthals and other earlier peoples dwindled and vanished.

But in the past five years, the picture has grown more complex — and more interesting.”

To which I would add: Amen!

I remember as a high school student being taught about the Mt. Carmel caves in today’s Israel, in one of which Neanderthals lived…practically next door our own forefathers. Being a teenager with a fevered imagination I conjured up images of neighborhood orgies. Impossible, I was told by Mrs. Danin, my biology teacher. On two counts: the Neanderthals preceded the modern humans by thousands of years, 30,000 to be exact. And besides, different species don’t interbreed.

Well, both facts turned out to be non-facts. Using advanced dating technology, we now know that humans got out of Africa as long as 130,000 years ago. And different species do interbreed. And yes, in all likelihood we lived side by side with our Neanderthal cousins for thousands of years. Put two and two together and you have to reach the inescapable conclusion that ancient humans and Neanderthals “slept” together, defense of human-with- human marriage be damned.

As a result, today’s human genome contains 2.5% Neanderthal genes. It is still unclear where the ancient trysts took place and what specific anatomic or cognitive traits these genes dictate, but who cares. This is your genome; get used to it. If I had my choice, I would love to get a Neanderthal gene for resistance to cold. Let the temperature drop below 70 degrees and I have to put on three layers of clothes. Those guys lived through ice ages in Europe clad in animal skin and felt just fine, thank you.

Denisovans

I think this the most remarkable story I’ve heard in a long time. Archeologists and paleontologists were digging in a cave in Siberia and found the bones of a human finger. Imagine their surprise when DNA analysis showed that the finger belonged to yet another species of non-human hominins. They called these people Denisovans, after the region where the cave is. But then, an even bigger surprise: comparison of their DNA with other human populations showed that fragments of their genome are found in aboriginal Australians and New Guineans. I can’t blame the Denisovans for abandoning Siberia and trekking down to Australia. I would do the same if I was in shape. What is amazing though, is that a new cousin-species and its migration was discovered based on DNA recovered from one child’s finger. As my son would say: awesome!

So all you dogs of different sizes, shapes and colors: you have nothing on us. Although we look boringly quite similar to each other, we are more varied in our genetic and cultural background than any other animal on earth. And it shows: we are probably the most adaptable, the most self-aware, and the most intelligent (most of the times) of all species. But alas, we don’t come anywhere close to having your ball-fetching talents.

Fetch!

 

 

 

 

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.

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