"Everybody's a Little Racist," goes a popular Broadway song, and this is indeed true. Prejudice is entirely normal, just as the tendency to eat far more food than we need is entirely normal. If these traits had not promoted the survival of our not-so-distant ancestors, they would not have been passed down to us. This does not make evolution an excuse for either trait because both are counterproductive today. We can and should unlearn them, and it is easier to unlearn prejudice than it is to unlearn overeating.

We know today that a diet high in saturated fats, along with obesity, increases our risks for cardiovascular disease, cancer, and diabetes. Why, then, are the appearance and aroma of a marbled juicy steak so appealing to anybody who has not deliberately unlearned, as I did when I got an unfavorable cholesterol test many years ago, our taste for red meat? Why are we programmed genetically to eat something that will shorten our lives?

The reason is that, except among the wealthy, obesity was the least of our problems prior to the Industrial Revolution. Many if not most people were one bad harvest or one bad hunt away from starvation, so a reserve of fat plus a propensity to eat as much as possible when food was available promoted survival and reproduction. This was even more so prior to the development of agriculture roughly 11,500 years ago, when hunter-gatherers had to eat enough to survive on a very uncertain meal schedule. It is why most dogs will similarly eat as rapidly as possible (because something else might take their food) and as much as possible (because they don't know when they will get another meal). We are, for the same reason, attracted to foods that are rich in energy density such as red meat, butter, and cream. All of these contain the saturated fats that cause so much harm to our arteries, but their consumption once promoted our survival when few people lived long enough to develop heart disease or cancer.

Prejudice is Instinctive

It is similarly quite normal to be not only racist, but even distrustful of people outside our own communities and families. How many of us were taught as children, for example, not to talk to strangers? Why do our dogs always bark at strangers? These traits once ensured our survival and promoted the breeding of dogs that would bark or snarl at strangers.

The word for "stranger" was once, in fact, the same word for "enemy." The ancient Indo-European language is very instructive as to the origin of almost all words in Europe and Central Asia. As a simple example, our word "ignite" and the name of the Hindu fire god Agni both come from the Indo-European word for "fire."

The Indo-European word ghos-ti is similarly the root of words like guest, host, hospitable, hostile, hospital, hostel, and hostage. It is also the root of the Greek word xenos or stranger, and xenophobia is fear of strangers. Why would words with almost opposite meanings--guest, host, hospitable, hospital, and hostel on one side, and hostile and hostage on the other--evolve from the same root? All relate to relationships between strangers.

"Prejudice Is Hard-wired Into The Human Brain, Says ASU Study" explains that prejudice is "hard-wired into the human brain through evolution as an adaptive response to protect our prehistoric ancestors from danger," and with good reason. Only within the past couple of hundred years, if even that recently, did most people travel more than 20 miles or so from the places of their birth. It took a long time to go anywhere on foot, or even on a horse if you could afford one. Road were dangerous because most highway robbers were far less polite than the gentlemen one sees in movies, and there were also wolves. This was why only (1) rich people who could afford carriages and armed escorts, (2) merchants, (3) bandits, and (4) armies tended to travel much distance at all.

Some merchants were interchangeable with bandits, and their decision as to whether to trade or to kill might depend on how many weapons you displayed when they showed up at your village. Soldiers also were interchangeable with bandits depending on how recently they had been paid, and how effective their officers were at keeping discipline. They regarded loot as a perfectly legitimate bonus, as shown by Count Tilly's observation during the sack of Magdeburg that "the soldiers must have something for their trouble." Soldiers were even willing to rob and loot their own side if no enemies were available. Hence King Henry V's order during his campaign in France (after consenting to the execution of a soldier who had robbed a church),

"We would have all such offenders so cut off, and we give express charge that in our marches through the country there be nothing compelled from the villages, nothing taken but paid for, none of the French upbraided or abused in disdainful language; for when lenity and cruelty play for a kingdom, the gentler gamester is the soonest winner."

That meant that, unless the new arrivals were your king and his escort, the duke or earl making his circuit of the lands, or a tax collector or similar official, "stranger danger" was exactly that.

If, however, the strangers meant no harm, there had to be rules and rituals for safe interaction. The friendly upraised and open hand once assured somebody whom you met on the road that you were not holding a weapon. The handshake originated when people immobilized one another's right arms to show that they did not wish to fight. Laws of hospitality were inviolate, and they included mutual obligations between host and guest. This was why Macbeth's murder of King Duncan while Duncan was a guest under Macbeth's roof was especially evil. The Old Testament adds that it is forbidden to harm, mistreat, or swindle a guest in your land.

That was Then; This is Now

Very few people in the developed world are now only a meal or so away from starvation, and many are instead hundreds of meals into dangerous obesity. This is because our ancestors developed ways to store food outside their bodies rather than inside their waistlines, which is a practice almost unique to humans. A leopard can carry its kill up a tree to prevent others from eating it, but he or she must eat it before it spoils. Ancient humans, in contrast, learned to smoke and salt meat and fish. The importance of salt for food preservation once made it extremely valuable, and salary comes from the Latin word for salt. Underground storage chambers meanwhile served as refrigerators. Canning and bottling came along a couple of hundred years ago, followed by refrigeration and packaging. This makes it unnecessary and counterproductive to be overweight today.

The Romans' development of an extensive road network along with uniform Roman laws, meanwhile, may have similarly counteracted ethnic bigotry. The only armies were of course Roman legions under very strict Roman discipline, and bandits stayed away if they knew what was good for them. Merchants could travel safely, and there was no need to fear violence from them. There was far less need to regard strangers as dangerous, although this changed quickly when the Empire collapsed; hence the Dark Ages.

Today, of course, we can talk to somebody on the other side of the world from our own homes, and few people live their entire lives within 20 miles of the places of their birth. Strangers, at least those who share almost universal basic values as to how people should behave toward one another, are no longer dangerous. This makes prejudice against people of other ethnicities obsolete and dysfunctional.

This does not mean we don't need police or locks on our doors, because there have always been individuals (even from within our own villages) who will try to prey on others. It doesn't mean we can get disband our armies either. There will always be despots such as the ruler of North Korea along with dangerous ideologies like Nazism, Communism, and what the rulers of Iran, ISIS/Daesh, Hamas, Al Qaida, and Boko Haram call Islam. (I do not call it that, and I consider the Islamic burial of Osama bin Laden disrespectful to genuine Muslims.) The issue in all cases is, however, a despot or a dangerous ideology rather than a race or an ethnicity, and the dangerous ideology may reside in somebody who looks like us, dresses like us, and talks like us.

This is why it is more important than ever to follow Martin Luther King's advice to judge others not by the color of their skin or, by implication, their ethnicity, but rather by the content of their character. Prejudice can and should be unlearned and, because this instinct is far less powerful than the drive to eat, understanding of its origins and an intelligent desire to unlearn it should result in success.

William A. Levinson, P.E., is the author of several books on business management including content on organizational psychology, as well as manufacturing productivity and quality.