For most of the time that humans have existed as a species, we lived in small hunter-gatherer groups. The best available evidence, from modern-day hunter-gatherers such as those in New Guinea, from anthropological and archeological evidence, is that we mostly acted like chimpanzees in our relationships to other groups. For human hunter-gatherers and chimps, territory is their lifeblood, and competition over it is deadly serious. If caught alone by a patrol in another tribe’s territory, death is a definite possible outcome.
In such an environment, it made perfect sense to evolve a fear of people from other tribes. They would be identified by not looking like us, not dressing like us, and worshipping different gods. Those millions of years of evolution put the fear of different others in us. That fear would keep you alive. In that kind of environment, it would also be important to evolve a quick response, quickly fall in line behind the leader when the tribe is threatened.
That same environment, surprisingly, accounts for our patriotism, altruism, and willingness to sacrifice for members of our tribe. If a gene developed that made people willing to sacrifice for the good of the tribe, then that tribe and that gene would be more likely to survive and populate future generations.
So it was a double-edged sword, on the one hand hostility, fear and mistrust of others not like us, but also altruism and unity toward those we consider like us.
Unscrupulous politicians have always been willing to capitalize on the unfortunate side of that double-edged sword. This was put on paper most famously in 1513 by a philosopher named Machiavelli, who described that the easiest way to make sure to get loyalty from your constituents is to convince them that a small group of people who are different than them in some easily identified way (for example, Jews, illegal immigrants, trans people) are a threat to them, and you are the only person who sees the threat and will protect them. That unites your constituents and causes them to fall in line right behind you. A Presidents popularity always gets a big initial boost in times of war.
Of course, the easiest way to do this is to pick out a relatively powerless minority group to target. This way, you don’t have to make yourself the enemy of some powerful group you yourself have to fear, and you don’t have to overcome rational fear in your constituents to mount this “defense.” Most importantly, you will be the only one talking about this threat, because this powerless minority group poses no real threat, and that means that when you demagogue people into fearing them, you will be the only one seen as a protector.
But the politician who does this must be without bothersome conscience, because he or she will without doubt make life harder for the targeted minority group and will often lead to violence and killing of innocent people in those groups. Not necessarily as a direct effort, as in historical genocides, but sooner or later the politician will have blood on his hands from increased suicides, and violence against the minority group by those more unbalanced among his constituents. This is why Machiavellianism is today used as a synonym for manipulative, dangerous, and unscrupulous leadership.
An educated electorate is crucial for a constitutional democracy such as the US. It is important for the voters to be educated on the importance of avoiding demagogues getting power using Machiavellianism. Since 2016 it is obvious that we as a country have fallen down in our responsibility to do that kind of education.
Education should start with the difference between anecdotal evidence and objective evidence. With enough instances to choose from, you could find an example to prove whatever you want to prove anecdotally. Government is too large and over-reaching, government is too small and doesn’t do enough, because you can always find someone doing something stupid on both sides of the argument.
When Mr. Trump started his campaign, he did It by saying that illegal immigrants bring crime, that they are murderers and rapists. And he could find numerous examples of immigrants who did commit murder and rape. But that proves nothing because in a large enough group there will be some murderers and rapists. You could make the same point about Scandinavians using that kind of anecdotal evidence. The empirical, objective evidence would be what the rate of murder and rape is in illegal immigrants compared to native born. Those studies have been done and they show that immigrants commit crime at a lower rate than native born.
Relative to undocumented immigrants, US-born citizens are over 2 times more likely to be arrested for violent crimes, 2.5 times more likely to be arrested for drug crimes, and over 4 times more likely to be arrested for property crimes. (Light, MT et al., 2020. Comparing crime rates between undocumented immigrants, legal immigrants, and native-born US citizens in Texas. Proceedings of the National Academy of Sciences, 117 (51) 32340-32347)
The reason is obvious. For illegal immigrants, there is a bigger penalty for crimes, they have more to fear, because they must fear being deported back to whatever desperate, dangerous circumstances made them uproot their lives and leave everything they knew in the first place.
If we lived in small tribes all our lives with continuing conflict with the other tribes, there would be no question about what we consider our group, and no choice. The struggle to help our tribe survive would give our lives instant meaning. Life being simpler might have had some advantages. But the big advantage that we have today over our ancestors is that we have choices about what we want to consider our group, whether we consider that group our nuclear family, our extended family, members of our profession, our religion, our country, all humanity, or all intelligent life. We can decide who we want to extend friendship and altruism to, rather than have that choice forced on us.