Human Evolution + Linguistics = !!!!

This post is a part of the Humanist Community at Harvard’s 2012 Blogathon, a 12 hour blogging marathon by Chris Stedman and Chelsea Link to support HCH’s end-of-the-year fundraiser. Chelsea and Chris are both publishing one new post per hour, for twelve hours straight, and none of the posts have been written or drafted in advance. For more blogathon posts, click here. If you enjoyed this post or any of the others, please consider consider chipping in to support our work.

And now for another moment of awesomeness brought to you by SCIENCE!

One of the coolest things I learned from working as a teaching assistant for a biology course is that there are some pretty incredible parallels between human evolution and linguistic evolution. Prepare your mind, for it is about to be blown.

1. Genetic and linguistic data show that the relationships between both human ethnic groups and language families are nested hierarchies.

Don’t worry, this sounds more complicated than it is.

Basically, if we had a ton of genetic data, we could map every single human who has ever lived onto one gigantic family tree. Within this tree, each person would be a leaf. The other leaves on your branch would be your immediate family members. The leaves on other branches near your branch would be your cousins, second cousins, etc. Your branch would be one among many other branches on a big bough that held your sixth and seventh cousins. As you move inward toward the trunk, you would find your great-great-great-grandparents and your great-great-great-great-great-great-great grandparents and so on, until eventually you would trace the trunk all the way in and down to the first human. This organization – leaves on a branch, branches on a bough, boughs on a tree – is a “nested hierarchy” because it is composed of groups within groups within groups. It’s the pattern you get when you trace back anything that has diversified over time – which means it’s also the pattern you get when you map all of life on Earth into one giant family tree, like Darwin did in the only diagram in On the Origin of Species:

Species make up a genus, genera make up a family, families make up an order, and so on, all the way back to the first little microscopic blob.

Languages follow the same pattern. Norwegian, Swedish, Danish, and others all came from one Germanic dialect; Flemish and Dutch came from another; all came from the same Germanic language, which came from the same Indo-European origins as the Italic languages (like Latin which then gave us French, Spanish, Catalan, etc.), the Hellenic languages (now represented by Greek), and so on. Again, it’s a nested hierarchy:

This is probably the least surprising parallel, but it’s still pretty cool.

2. Silent letters in words are clues to their etymology, just like vestigial organs in organisms are signs of their evolutionary origins.

This particular parallel was pointed out by Charlie D himself. A lot of animals (and plants, but I don’t know crap about plants so I’m going to ignore them for now) have various limbs and things that don’t really serve any purpose – you have extra wisdom teeth and an appendix that does nothing but threaten to explode; kiwibirds have pathetic little wings they will never fly with; etc. We have these things, of course, because our ancestors had fully formed versions of them that they actually used. Our ape-y ancestors probably used their appendices to digest cellulose in plants, which we no longer need to survive. Kiwibirds evolved from birds that flew to New Zealand and then didn’t need to fly anymore. So even though these vestiges don’t do anything for the organisms that possess them, they do serve us as handy hints in tracing evolutionary history.

Similarly, a lot of words have letters that are phonetically unnecessary. For example, why does “leopard” have an “o” in it? We don’t say “LEE-oh-pard,” so why do we spell it that way? Well, the word originated when the Greeks combined “leon” (lion) with “pardos” (panther) to describe the animal that looked sort of like a mix of both. The “o” sound has since been lost, but the word’s etymological history has left its stamp on the spelling.

3. Global patterns of phonemic diversity mirror those of genetic diversity.

This is the really bizarre one.

So, just like your DNA is made up of strings of protein codes called “genes,” words are made up of little sound chunks called “phonemes.” Some languages have lots and lots of phonemes in them, and others have just a few phonemes. The fewer phonemes a language has, the longer its words tend to be, because you need more of them to encode the same amount of information and differentiate words from each other. This is why the fish called a “reef triggerfish” in English (a language with 26 letters) is called a “humuhumunukunukuapua’a” in Hawaiian (a language with only 12 letters).

Now back to genes for a second. Humans originated in southern Africa, where we evolved from chimps (with a lot of now-extinct hominins in between – think Lucy). Some humans stayed in southern Africa – and, ad you may have noticed, their descendants are still there today. Others left and migrated around the world – first to northern Africa, then to Europe, then Asia, the Americas, and Oceania.

Each time humans migrated to a new place, some stayed behind – the groups of humans who founded new societies in new places were always small samples of the groups they had left. The inevitable result of this pattern – called serial bottlenecking or serial founder events – is that genetic diversity is gradually lost with each migration, so that the places where humans went last are inhabited by a less diverse population than the place where we started out.

In case you’re not a statistician, you can visualize this with a bag of marbles of lots of different colors – red, green, yellow, blue, purple, orange, pink, mauve, magenta, white, grey, brown, tan, etc. If I reach in and grab a handful of marbles and drop them into a new bag, chances are I probably didn’t manage to pick up one of every single color of marble that was in the first bag. So the marbles in my second bag will be a less diverse sample of the ones in the first. If I again take just a few from the second bag and move them to a third, I’m going to lose even more colors. The colors are like different genes, and the marbles are people. Except you’d have to pretend the marbles could reproduce with each other, which is kind of disturbing, so don’t think about that part.

Anyway, genetic tests have confirmed that the humans in Oceania are less genetically diverse than Asians, who are less diverse than Europeans, who are less diverse than Africans. Pretty interesting.

But here’s the awesome part. When you map phonemic diversity in languages across the globe in the same way, you get exactly the same pattern:

It turns out that during each migration event, humans not only lost a bit of genetic diversity, but also dropped some phonemes along the way!

So there’s your daily dose of wonder and awe.


Chelsea Link is the Campus Organizing Fellow at the Humanist Community at Harvard.

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