War and Plague is how the human race solved overpopulation before

What overpopulation is changes depending upon the availability of resources.

For example, the planet never had over 1 billion people before the 20th and 21st century because it literally could not support that with farming techniques without Gasoline, Diesel, and water powered electricity. It simply couldn't be done before that.

However, now we have between 7 and 8 billion people which causes extinction of species after species of plants and animals around the world ongoing. And as long as our populations grow, more and more species will inevitably die now from Global Climate change (mostly getting hotter around the world year after year). So, species who live in a certain water and heat index can no longer survive without that niche and they die and there are then none or almost none left with only a few left in zoos maybe who are cared for by zookeepers so they don't die.

However, humans down through the centuries used various methods to solve overpopulation.

Individualism wasn't as big a thing around the time of Christ. So, when there were wars one nation would literally kill every man, woman and child (except for some of the women they bred with) so soldiers took some of the women as wives and slaves.

So, wars became a way to solve resource problems. And also they killed all the men and boys so there would never be retribution and revenge at any point in the future. And they took them breedable women and impregnated them to raise more fighters to defend their newly taken lands.

This is exactly what ISIS is doing now. It is right out of the old testament of what countries did then.

The other thing that solved overpopulation was various kinds of plagues that hit all over the world. Most of this was caused by too many people living too close together without sanitation or hygiene.

However, solving this problem like the world has now creates other problems, because now overpopulation is killing literally all species on earth.

So, how do we solve our overpopulation problems before groups like ISIS all over the world start to solve these problems for us through genocide and mass murder that is more reminiscent of the times of Christ and before than anything else?