I never knew you are such a pessimist.
Fertility and the resulting population is highly correlated to wealth and education, or the lack of those two factors.
Fertility and living standards: Go forth and multiply a lot less | The Economist
Population and Poverty: New Views on an Old Controversy
Demographics and Poverty | Center For Global Development
Whether you take the view that high fertility causes poverty, or that high fertility is a result of poverty--they travel together. When looking at the global population then, those passing on the most genes are the least wealthy and least educated. That's true if you look at who is producing the most births in the US, India, or Ethiopia. China is a special case with their "one child" policy. But, would you argue that that policy, whatever else you may think about it, has played no role in China's economic growth?
Reality is the inverse of the result we would expect if the "passing on genes" is something the "fittest" are fighting to dominate or claiming as a prerogative of their fitness as demonstrated by their control of the available resources.
I see a creeping movement underway towards more global cooperation. Efforts to control global population are a cooperative effort. Scientific research is carried out and funded by international teams. Getting a handle on the globe's carbon footprint is an international effort. The International Space Station (ISS) is a collaborative effort. Sanctions applied to bad actor nations or ISIS-style groups are a multinational cooperative effort. The economy of any given nation has become more dependent on global factors and with more global inter-dependencies.
The people of the world are busy developing and leveraging shared values. We are communicating with each other in ways never before possible beyond stilted speeches delivered at a UN podium. We certainly have a ways to go before, "What if they gave a war and no one showed up?" can happen but we are moving in that direction. That is nothing to be grim about.