Neanderthals and the Addiction to Nicotine

As a writer I sometimes feel like I’ve committed to a lifetime of searching for a new story to tell. I am completely wedded to the plot I’m working on right now (“Oh yeah, Neha – weren’t you supposed to have finished writing the first half of your novel by now?” Shut up, it’s none of your business.) but that doesn’t keep me from thinking of new ideas, new stories, even new genres. The other evening, after a day of hard and frustrating work trying to connect the various narrative strains in my book, I sat down with some green tea (actually it was scotch) and picked up an article on our long-dead cousins, the neanderthals. And one of the things I read in it was that while homosapiens (our great, great, great gran-grans and pop-pops) developed the concept of living in large settlements resembling villages quite early in the game, neanderthals lived in tiny groups that were separated from and not dependent on one another.

Gods! I think there is an alternate universe story to tell here!

I immediately engaged Boyfriend, who likes pointlessly long drawn discussions about completely hypothetical situations more than anyone else I know. I shared some of my scotch with him (actually, he just made himself some green tea), and we plotted the world as it might have been 400,000 years ago, with the hypothetical situation that homosapiens and neanderthals had gone to war with one another. And every scenario we could think of, I ended with gran-gran and pop-pop wiping out the neanderthals.

For some reason, Boyfriend was disappointed by this; he really, really wanted the neanderthals to survive. Maybe the neanderthals fought back when they were attacked, he suggested.

Sure they did. But the homosapiens lived in bigger groups, and their interdependency had probably led to a sense of common identity. They had larger numbers – the neanderthals lived in tiny groups, remember? – and they were fighting for something bigger than just a bunch of strangers not putting out their campfire. (You think flint is easy to find, you motherf***er? [Of course, at the time I doubt motherf***er was really considered an insult. But I digress.])

Well, maybe they were stronger…? Boyfriend suggested feebly, knowing this was barely a possibility. Even in a universe not as hypothetical as the one we were constructing, homosapiens occupied sub-Saharan Africa and parts of Asia – regions with tropical to temperate climates. Neanderthals were scattered across Europe, struggling to fight the cold, hunt for food, and somehow survive. I doubt they were stronger.

At this point, Boyfriend was crestfallen. What’s the point of a hypothetical universe if everything’s the same. Hey – he brightened up – maybe they fought for a bit but then called a truce and lived in harmony ever after?

Haha! Called a truce. You’re funny.

Whatever. You’re right, they probably weren’t very strong, Boyfriend admitted with resignation, and then continued:

“Did you know the gene for nicotine addiction in modern human beings comes from neanderthals?”

Homo sapien sapien, Q.E.D. (Image source.)

Homo sapien, Q.E.D. (Image source.)

Scientists have known for a long time that about 2-4% of the genetic material of average modern human beings (not of African origin – sub-Saharan Africans are believed to have inherited little to no genetic material from neanderthals) comes from neanderthals, mainly affecting skin and hair. A recent study conducted at Harvard University and published in Nature has managed to shed some light on the microscopic aspects of this genetic mixing. It found that the alleles for nicotine addiction, Type 2 diabetes, and Crohn’s disease in the modern human being are a result of interbreeding between neanderthals and homosapiens.

Neanderthals and homosapiens shared common ancestors about 600,000 years ago. But for several thousand years after these ‘cousins’ parted ways, homosapiens lived in sub-Saharan Africa, where they hunted, gathered, and eventually settled and farmed. Neanderthals lived in hostile climates outside Africa, where the barren environment was not really conducive to farming. The study found that by the time the groups of homosapiens who left sub-Saharan Africa met and bred with neanderthals, the two species had already evolved in very distinct ways, and were on the brink of incompatibility. About 300,000 years ago, not very long after this interbreeding, the neanderthals died out.

While there have been indications explaining the neanderthal demise, the Harvard study is among the first to have found evidence across large areas of human DNA that suggest neanderthals may, in fact, have had genetic qualities that were harmful, and that were passed onto the first human beings through interbreeding, but were wiped out of the gene pool over time, through natural selection. The allele for nicotine addiction is among the few that persist in modern humans.

I guess this means all of you smokers out there can no longer be guilt tripped by your friends and family. I mean, you got the genes from the neanderthals. It’s not your fault, right? Right?

Eh. Wrong.

Of course, Fred's insight may be true in ways other than just the human desire to smoke. (Image source.)

Of course, Fred’s insight may apply to things other than just the human desire to smoke. (Image source.)

I am definitely among those people who get inordinately excited about evolutionary biology and genetic findings such as these. But as significant as the results of this study are, we have to bear in mind that considering just how long we (homo sapiens, not just humans) have been around, the ways in which our environment has changed, and the fact that Evolution (as I have pointed out before on this blog) is really slow to catch on, it would be erroneous to attach a relationship of direct causality between the findings of this study and the extinction of neanderthals 300,000 years ago, or diseases and addictions in humans today. While the allele for nicotine addiction can be traced back to neanderthals, that does not necessarily mean neanderthals were smokers or addicts of any kind. In its original carrier, the gene could have been part of a whole other DNA party altogether. Similarly, while the high incidence of Crohn’s disease in people of eastern European descent (considered among the closest to neanderthals) may suggest some causality, this reasoning is immediately challenged by the high incidence of Type 2 diabetes in African Americans, which is likely the result of modern environmental and socio-economic factors. And let’s not forget, we got some good things too, from the neanderthals. Neanderthal DNA is what gives us stronger keratin, which leads to stronger skin, hair, and nails. But again – while this helped the earliest humans survive extreme cold, it is still not strong enough evidence to suggest that the neanderthals had adapted well to the extreme cold they lived in.

So while each of these studies wipes clean a new piece of a jigsaw puzzle, the puzzle itself is so big and so complicated, I don’t know if we’ll ever really find all the pieces. Our species is becoming more enlightened and more informed with every passing minute, but in the words of one recently famous TV redhead, you (still) know nothing, Jon Snow.

Want to know more? Go here. And here, for the study published in Nature.

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