So, I was having lunch earlier this week with an old friend of evol-con inclinations, and as conversations with such people do, the conversation turned to What Really Matters – the point of the conversation being to knock the stuffing out of whatever everybody else seems to think matters, and set them straight. We didn’t bother with obvious targets for stuffing-knocking like the Presidential election or gay marriage and went straight for the big stuff. Do schools actually matter, or it basically a combination of babysitting and sorting by IQ, with almost everybody doing their most important learning outside of formal education? Does religion actually matter, or is it an epiphenomenon, accommodating itself to whatever scientific, economic and political facts it has to in order to survive?

My candidate for something that Actually Matters: the demographic explosion in sub-Saharan Africa.

In 2010, the U.N. estimates there were over 850,000,000 people in sub-Saharan Africa. That’s nearly double what the population of the region was 25 years prior, in 1985. By 2035 – 25 years further on – the population of sub-Saharan Africa is projected to nearly double again, to nearly 1.5 billion people. In another 25 years, the population will be nearly 2.3 billion. In 50 years, over 1.4 billion people will be added to the world population from this region.

For comparison, China’s population, estimated at 1.34 billion in 2010, is expected to rise only slightly, to 1.38 billion, by 2035, and then decline to 1.21 billion by 2060. The growth in the sub-Saharan African population is projected to be larger than the entire population of China. The population of Europe is expected to barely change over the period, going from 738 million in 2010 to 702 million in 2060. The population of northern America – the United States and Canada – is expected to grow from 345 million to 466 million. Put together, Europe and Northern America go from 1.08 billion to 1.17 billion. Again, the increase in the the sub-Saharan African population is projected to be larger than this entire region.

This projected increase is not going to happen. There is simply no way that sub-Saharan Africa can sustain population increases of that magnitude. The extremely positive past decade of rapid economic growth notwithstanding, the scale of development required to house, feed, and employ a burgeoning population of this magnitude is unprecedented, and it’s happening in the region of the world with the worst track record of development over the past couple of centuries. You don’t have to have a view on why that track record has been so poor to conclude that meeting the challenge of a near tripling of an already enormous population is probably going to be more than the region can handle.

So it won’t happen. It could fail to happen because birth rates drop suddenly and precipitously. That has happened before, in a wide variety of societies – but primarily in societies that were already fairly urban and/or where the government has been aggressive about promoting population control, and has a reasonable degree of ability to carry out its wishes. It could also fail to happen because of a massive die-off, through some combination of disease, warfare and famine. But the scale of the die-off we’d be talking about would eclipse by more than an order of magnitude anything we’ve seen in recent memory. To posit that the rest of the world would simply sit back and watch it happen is to posit that the rest of the world is going to become much more callous about mass death than it has been.

Or it could fail to happen because, as the sub-Saharan African population explodes, it leaves Africa. But for emigration to make any real difference in avoiding a catastrophe in Africa, it will have to happen on a scale that utterly transforms the recipient societies. Americans periodically get exercised by immigration from Mexico, even though this country has a long and successful history of assimilating immigrants. Europeans, with much less experience of immigration, have experienced a great deal of anxiety, which the major political parties have attempted to suppress without only modest success, about a mostly Middle Eastern and North African Muslim immigrant population that is minuscule relative to the size of the coming sub-Saharan African tidal wave. There is essentially no history of large-scale immigration into China. These regions of the world are projected to total fewer than 2.4 billion people in 2060. About the same population – put together – as sub-Saharan Africa. To absorb a meaningful portion of the African overflow, Europe, North America, and East Asia would have to become substantially African.

None of this is actually news. All I’m saying is that this is Something That Matters, pretty inarguably. The deaths of tens or even hundreds of millions of Africans from war, famine and disease would be a calamity of world-historical proportions. If we in the developed world were simply to look on, that failure to act to save our fellows would effectively define our civilization. If, instead, we absorbed the African population, that would mean a more dramatic demographic transformation of the developed world than we have have ever seen. And if Africa manages to avert calamity by building the infrastructure and the economic capacity to sustain this enormous population, then the African continent will be the dominant force in the world in fifty years. Whatever happens, good or bad, Africa will Matter.