Population growth and ethnic mix, and Star trek

When I was born in the UK in 1960, the world population was almost exactly 3Bn, 50M of whom had been born in the UK. Today, the world holds 6.7Bn people, 55M of whom were born in the UK (figures from World Bank and UK Office of National Statistics). So the number of people born in the UK has gone from 1.67% of the world to 0.8% today. That means the UK accounts for less than half the proportion of the world's population than when I was born. This pattern is followed throughout western Europe and indeed the rest of the developed world, because people have fewer kids as they get richer.
The other side of these same statistics is that as people get richer, their descendants account for a lower share of tomorrow's human population. Misquoting Jesus a bit, 'the poor will inherit the earth'.  The poor have more kids, who also have lots of kids, until at some point, they start getting richer. While poor people's descendants remain poor, they will continue to increase their representation in the human gene pool.

On today's trend, a wealthy UK family would see their offspring reduce to half of their original number in 5 generations, while a Nigerian family (average 6 kids today) would see their increase to 240 times as many, so will be 480 times better represented in the gene pool. So in strict evolutionary terms, being poor is a huge advantage. No-one expects that Africa will actually experience this level of growth in the future - average family size is already falling rapidly (down from 8 to 6 in two decades in Nigeria). But there is still a huge difference between African and European countries. This asymmetry in fertility rates means that the ethnic mix of tomorrow's world will be very different from today's.

While low reproduction rates mean that predominantly white Europeans are heading towards possible extinction over the next two or three centuries, Africans will increase greatly in number. So will South Americans, while Indians and Chinese will account for much the same proportion of the future world's population as today. So, as a Star Trek fan, it seems that the crew is all wrong. Almost all of Kirk's crew are white Americans, with a token russian, african, asian, and an alien. Later casts aren't much different apart from having a few more aliens and an android. In reality, the 2030 enterprise will be staffed almost entirely by AIs and robots, the human crew will almost all be people of Asian, African and South American descent, and there will hardly be a white face in sight. As Spock would say, fascinating.