Note: This post still contains a lot of oversimplification for the sake of explaining a few things.

Welcome back to our discussion of the geographic dispersion of humanity. On Tuesday, we discussed how two great barriers–the Sahara desert and the Himalayas + central Asian desert–have impeded human travelers over the millennia, resulting in three large, fairly well-defined groups of humans, the major races: Sub-Saharan Africans (SSA), Caucasians, and east Asians.

Of course, any astute motorist, having come to a halt at the Asian end of our highway, might observe that there is, in fact, a great deal of land in the world that we have not yet explored. So we head to the local shop and pick up a better map:

Our new map shows us navigational directions for getting to Melanesia and Australia–in ice age times, it instructs us, we can drive most of the way. If there isn’t an ice age, we’ll have to take a boat.

The people of Melanesia and Australia are related, the descendants of one of the first groups of humans to split off from the greater tribe that left Africa some 70k ago.

As the name “Melanesian” implies, they are quite dark-skinned–a result of never having ventured far from the equatorial zone.

Today, they live in eastern Indonesia, Papua New Guinea, Australia, and a smattering of smaller islands. (Notably, the Maori of New Zealand are Polynesians like the Hawaiians, not Melanesians, descendants of a different migration wave that originated in Taiwan.)

There is some speculation that they might have once been wider-spread than they currently are, or that various south-Asian tribes might be related to them, (eg, “A 2009 genetic study in India found similarities among Indian archaic populations and Aboriginal people, indicating a Southern migration route, with expanding populations from Southeast Asia migrating to Indonesia and Australia,”) but I don’t think any mainland group would today be classed as majority Melanesian by DNA.

They may also be related to the scattered tribes of similarly dark-skinned, diminutive people known as the Negritos:

However, the Negritos are a very small set of tribes, and I am not confident that they are even significantly related to each other, rather than just some short folks living on a few scattered islands. We must leave them for another day.

The vast majority of Aborigines and Melanesians live in Australia, Papua New Guinea, and nearby islands. They resemble Africans, because they split off from the rest of the out-of-Africa crew long before the traits we now associate with “whites” and “Asians” evolved, and have since stayed near the equator, but they are most closely related to–sharing DNA with–south Asians (and Indians.)

So we have, here, on the genetic level, a funny situation. Melanesians are–relatively speaking–a small group. According to Wikipedia, thee are about 12 million Melanesians and 606,000 Aborigines. By contrast, Tokyo prefecture has 13 million people and the total Tokyo metro area has nearly 38 million. Meanwhile, the Han Chinese–not a race but a single, fairly homogenous ethnic group–number around 1.3 billion.

Of all the world’s peoples, Melanesians/Aborigines are most closely related to other Asians–but this is a distant relationship, and those same Asians are more closely related to Caucasians than to Aborigines.

As I mentioned on Tuesday, the diagram, because it is 1-dimensional, can only show the distance between two groups at a time, not all groups. The genetic distance between Caucasians and Aborigines is about 60 or 50k, while the distance between Asians and Caucasians is around 40k, but the distance between Sub-Saharan Africans and ALL non-SSAs is about 70k, whether they’re in Australia, Patagonia, or France. Our map is not designed to show this distance, only the distances between individual pairs.

Now if we hopped back in our car and zoomed back to the beginning of our trip, pausing to refuel in Lagos, we’d note another small group that has been added to the other end of the map: the Bushmen, aka the Khoi-San people. Wikipedia estimates 90,000 San and doesn’t give an estimate for the Khoi people, but their largest group, the Nama, has about 200,000 people. We’ll estimate the total, therefore, around 500,000 people, just to be safe.

The Bushmen are famous for being among the world’s last hunter-gatherers; their cousins the Khoi people are pastoralists. There were undoubtedly more of them in the past, before both Europeans and Bantus arrived in southern Africa. Some people think Bushmen look a little Asian, due to their lighter complexions than their more equatorial African cousins.

Genetically:

So the total distance between Nigerians and Australian Aborogines is 70k years; the distance between Nigerians and Bushmen is at least 100k years.

When we zoom in on the big three–Sub-Saharan Africans, Caucasians, and Asians–they clade quite easily and obviously into three races. But when we add Aborigines and Bushmen, things complicate. Should we have a “race” smaller than the average American city? Or should we just lump them in with their nearest neighbors–Bushmen with Bantus and Aborigines with Asians?

I am fine with doing both, actually–but wait, I’m not done complicating matters! Tune in on Monday for more.