We are not just one species. As history teaches us, we can and will see, treat and kill humans from other races, other tribes, other religions, other ideologies or other what ever what, as pests, which we can and should kill, if the opportunity and necessity to do so rises.
We should, as William Catton stated in his book "Overshoot: The Ecological Basis of Revolutionary Change", see Nazi Germany as a bizarre prelude of what may happen in the 21. century.
In German there is a book form the Swiss professor of history, Christian Gerlach, with the Title "Krieg, Ernährung, Völkermord. Forschungen zur deutschen Vernichtungspolitik im Zweiten Weltkrieg" (War, Food and Genocide. Research on the German extermination policy in WW2").
According to this, after the lost air-battle over Britan, in Sommer 1940, the German Government was faced with very serious resource and food problems. Although they controlled large parts of continental Europe(!), a German undersecretary of food and agriculture in 1940 seems to have calculated, that Germany would have to surrender within in only two years because of food shortages, if no new resources would be found. Futher more, the Hitlers government seems to have been very afraid of a repeat of the famine of of 1917/18, which seems to have been one of the main reasons of the German revolution in November 1918.
Indeed, the Nazis did very much to please the German people with welfare laws (many of them, as the wartime law which granted free health insurance for elderly people, in fact lasted for many decades.)
As Gerlach could prove with his research, the mass killings done be the Germans in WW2, and the death camps like Auschwitz, started in 1941, after food shortages had become a real threat. When the Germans attacked the USSR in 1941, their objectiv was not only to conquer oilfields, but also to conquer arable AND to kill huge parts of the Soviet people by hunger.
Killing tens of millions of people by hunger did not work as planed. The Russians and other people in the USSR seemed to have been able to survive (How they did it should be one great lesson to learn from history). But the Germans were able to kill by hunger in POW-camps. This is one answer to the questions why so incredible many Soviet soldiers died in German POW-camps.
As Gerlachs work shows, the mass killings of Jews too started after the attack on the Soviet Union, in summer 1940. Perhaps for this one should remember, that there too was some strong antisemitism in the Soviet Union and other none German parts of Europe. How ever, the mass killings of Jews too served as a seemingly successful strategy to get rid of "useless" consumers of food which helped to improve the food supply and thus the political stability in Germany itself. Furthermore, by killing the Jews, other resources possessed and consumed by the Jews could be freed and distributed to "more worth full" Germans and their allies.
Thus WW2 and its at least the attacks and crimes of the Germans after 1940, should better not be seen as singularities done by some mad ideologists, but as actions of a well educated, very modern people seeing themselves threatened with resource shortages and famine.
From that viewpoint, it may be a very bad idea to give women equal rights and opportunities to lower their fertility. Instead raising the fertility results in a surplus of young men and thus in warriors, which may be the most important asset when it comes resource wars. Indeed, Europe will be taken over within the next decades by Muslims and by Africans. Europe will die from complexity, loss of faith, in relation to Africa and the Middle East much to low birthrates (and thus to few sons), and to much reliance on technology.
The white Europeans may face the fate, Hitlers government had planed for the Jews. Although, instead building death camps with all the work and organization they would need, the Europeans, and maybe the Americans too, can best be killed by an EMP-attack with just a few nuclear warheads, or even simpler, by just waiting for a real huge sun storm. After that, those other people with their unequal, poor educated but very fertile women can and will conquer Europe with ease - and will show mankind, that education, schools, universities and equal rights and opportunities for women are not good in the longer term.
The Boko Haram (boko = school, Haram = not good) people, the Pashtun Taliban and the like and their descendants with their simple lifestyles will survive, but we white Westerners, with all our education, technology and knowledge will be defeated and die in the golden, comfortable and obviously very attractive death camps we have build ourselves, while we thought we were building smart and sophisticated social democratic, liberal states and organizations of states.