When driving across a European border, some of the most charming sights are the cobwebbed customs facilities, abandoned since 1995. You can drive from the Arctic Circle to within sight of Morocco without ever having to slow down for a passport check. To many, this is what “Europe” means: a single continent, whole and free, whose members trust each other enough to get rid of their borders.

The Arab Spring is having a number of unforeseen consequences. In Donald Rumsfeld’s words, most are “known unknowns”: we knew it was going to get messy. We just weren’t sure what kind of mess it would generate. We mostly still don’t know. But Europe has already reacted in unpleasant ways. France and Italy, spooked by thousands of illegal migrants seeking to flee North Africa’s turmoil for safer shores, are pushing for new rules that would allow EU member states to suspend passport-free travel between themselves should “truly critical” spikes in illegal immigration occur.

Europe has faced huge influxes of refugees before, notably during the wars in Bosnia, Croatia or Kosovo. Compared to those hundreds of thousands, the few who have actually managed to cross the Mediterranean to flee from Ghaddafi’s Libya and the chaos of post-revolutionary Tunisia are a tiny number. The Eurozone crisis, unemployment, and rising Islamophobia have conspired to make today’s Europe a less welcoming place.

But something else is at play. In Europe, an atavistic fear of the “other” has become respectable again. For many liberal commentators, its rise is an “unknown unknown”. But that is a mistake. It is an eminently predictable consequence of Europe’s decision, after the Second World War, to actively discourage any public discussion of the factors driving human evolution. Nazis tried to justify their policies (to themselves and others) with scientific-seeming distinctions between ‘Menschen’ and ‘Untermenschen’. Misusing the biological concept of ‘evolution’ was crucial to Nazi discourses about race, and played a huge ideological role in the Holocaust.

In Europe, tut-tutting the public discussion of human evolution put paid to the most pernicious racialist ideas. But it came at a cost. Europeans have no mental constructs to understand why the immigrants that manage to reach their shores, far from being a threat, are a blessing that should be welcomed with open arms.

People, long struck by the similarity between the bodies of animals and humans, developed the concept of the soul to draw a clear line between the two kinds of creatures. But modern science shows that their commonsense inference was right. Humans are just one animal species among many, and are subject to the same evolutionary forces. Genetics, neuroscience, statistical analysis, linguistics and anthropology are mapping out consistent explanations of how uniquely human traits such as language, religion or music evolved.

Far from endorsing Nazi views of a hierarchy of human races, our expanding knowledge shows how similar we all are in everything we do. There are no major racial differences between humans. But this is not the same as saying that there are no differences between particular groups of humans. On the contrary, people have adapted to their environments and continue to do so. Human evolution may even be speeding up. It just has nothing to do with their skin colour.

For example, the lung capacity of Sherpas and Qechuas is about 25% bigger than the human average. This is an essential adaptation to the low oxygen content of the atmosphere at the high altitudes of their homelands. Pygmies’ small size is advantageous in dense forest and scrub (and could well be a consequence of their early fertility, another adaptation to their unique environment:  reproducing as quickly as possible makes sense in areas teeming with parasites). The tall, thin shape of Somalis maximises the shedding of body heat in their hot, arid homeland. Europeans evolved lactose tolerance in adults once they domesticated milk-giving animals, and may have evolved whiteness to boost their skin’s vitamin D production. This became necessary as agricultural plant-based foods replaced the vitamin D-rich meat-based diet of hunter-gatherers. We know more and more about how humans evolved since they left their African homeland. Humans, like animals, evolved to adapt to their new environments, and keep on doing so.

This should not be controversial, but in Europe it is.  Most of the research, literature, and pop-science books dealing with the topic are American. There, a healthy debate is reducing those who hold racist ideas to an increasingly irrelevant minority. But in Europe, omerta about human evolution is beginning to have perverse consequences. Nazi ideas may have been driven underground, but they have not died out. With science about human evolution gagged, ideas that are pernicious or just plain wrong are spreading, unchallenged. Portraying immigrants as a threat becomes easy. This is a pity, because there is a strong evolutionary case to be made for increased immigration.

Science has eviscerated toxic canards such as “some races are better than others”, the standard answer in centuries past to what Jared Diamond dubbed the “Australia question”: Why was Australia was colonized by Europeans, and not the other way around? Today we know that this has nothing to do with race and everything to do with geography. Research also shows that there is no correlation between ethnic groups and intelligence. The subtle differences that some researchers have measured disappear once factors such as foetal and childhood health, nutrition and disease exposure are taken into account.

But that is not the same as saying that there can be no differences between particular groups of humans. The Bachs were exceptional musicians, much better at music than the average German. The Rothschilds were brilliant financiers, much better at banking than the average Jew. Kingsley Amis and his son Martin are great novelists, again much better than the average Englishman. The Kennedys and Bushes are very good at politics. In each case, a particular talent has been passed down several generations within a single family.

The family environment does of course play a big part. Children growing up in a house filled with music, politics or books will have a strong head start. But that’s all they will get: a head start. Without talent, a politician’s scion might be elected to the school board, but is unlikely to make it to the Senate. A musician’s son might become an obscure music teacher, not a composer whose oeuvre survives centuries. And there are enough examples of financiers’ children frittering away the family fortune. Something else, clearly, is going on.

Dog lovers know that dogs of a given type share a basic temperament, despite having individual personalities. Breeders selected these temperaments. Humans are not bred. But the same selective forces are at work. A brilliant man will tend to pick a wife from another brilliant family, often from the same cultural and social background. A brilliant woman will do the same. Humans, too, are subject to selective pressures.

One of the best examples of such pressures operating recently and at large scales is the balance between individualism and collectivism in different countries. Where you fall on that political debate – whether you want the freedom to do your own thing, even at the risk of not getting much help from the state in case of failure, or instead prefer more social insurance, even at the cost of higher taxes and more restrictions – is a decent indicator of which side of the Atlantic you come from. This is not to say that there are no conservatives in Europe or socialists in America. But, over the past century, European societies have on average been significantly more collectivist, and America more individualistic.

With the exception of Native Americans and the descendants of African slaves, all Americans today are either voluntary immigrants or the descendants of voluntary immigrants. They, or their ancestors, took a bold decision: to leave home, hearth, family, friends, language, culture and climate behind to try their luck in a distant, unknown continent. Before modern times, this literally meant breaking off all contact with the past. There were no planes, no telephones, and often not even any postal mail. There were few pictures and little objective information about the new world. “America” was a mirage, a dream, a gamble from which there was no coming back.

Many were driven away by war, pogroms, or extreme poverty. But it was unusual for whole families to leave. Some members, often most, always chose to stay. Those who chose to go had something in common, irrespective of their wide variation in cultural backgrounds. Immigrants to America self-selected themselves for drive, for enterprise, for decisiveness – in short, for individualism.

We Europeans are the descendants of these immigrants’ brothers, sisters, cousins and friends. Our ancestors are those who were paralysed by fear, timidity or simple inertia. Caution, not boldness, is the name of our game. We like to belong, not to stand out. Notice how Europe’s most popular political movements of the last 150 years – communism, Zionism, socialism, social democracy, fascism, national socialism etc. – all have a collectivist foundation.

Yes, we Europeans are a different breed. Americans and Europeans have different temperaments, and those temperaments are the result of a selection event.

Perhaps, I hear you mutter. But what has that got to do with illegal immigrants in Europe?

Europe is facing two interlinked crises, a demographic one and an economic one. We’re not having enough babies to pay our pensions. And Europeans are, on average, famously bad at being entrepreneurs. So bad that the big EU push to change this, the so-called Lisbon Strategy, is itself a failure. European leaders, wringing their hands, sometimes fall prey to harebrained schemes to boost innovation or get women to have more babies.

Yet the solution stares them in the face. It is clinging on for dear life to a leaky boat somewhere in the Mediterranean as I write these words, trying to break into fortress Europe.

The face of that solution is almost certainly that of a younger man, one who probably comes from the Sahel. He had to decide to leave his home and family. He had to have the drive to find, in some of the poorest countries on earth, the four or five thousand dollars demanded by human smugglers. He ran a high risk of being abandoned by unscrupulous guides in the Sahara, which means that he either managed to cross it on foot or died trying. If he survived, he probably got robbed and beaten by Morroccan or Libyan security once he reached these countries and may well have been driven back into the Sahara, dumped in the middle of nowhere with little water and no food. He had to survive in North Africa by his wits, sometimes for years, as an illegal ‘abid’ –  an Arab slur that means both black African and slave. He had to find fresh money to buy a place on that leaky boat. And, once he made it to Spain or Italy, he had to run quickly from the beach to avoid being caught by border guards, despite his exhaustion and disorientation.

By the time this man turns up as an illegal immigrant in one of Europe’s cities, he is – by definition – one of the very best. He had to run through a ferocious selective process that eliminated the vast majority of those Africans who dream of Europe. He had to be more clever, stronger, more resistant, more entrepreneurial, fitter, and smarter to make it. He stands out among the cautious Europeans not because of his race, but because of his drive. He will make a go of it, and him and his descendants are likely to do better than the European natives.

Across Europe, immigrants on average achieve higher educational goals, are more entrepreneurial, and build many of the continents’ new businesses. The immigrant corner shops found everywhere in western Europe, run by the first wave of migrants, are open 14 hours a day or more every day of the week. Nothing is wasted. People may sleep on the floors of their shops to save money on rent. The money is used to support family members left behind and to send kids to school. The pressure on these kids to succeed is ferocious, and once grown up many will join the professions. Their children, in turn, are providing some of the business titans, top-level writers, journalists and politicians that make Europe so culturally exciting.

Europeans are oblivious to this. Their image of the typical immigrant is that of a young thug, selling drugs or off to do jihad, beating his burqa-wearing sisters, living off welfare with a large family in a ghetto in which “real Europeans” are not welcome.

Those who fight against this racist prejudice almost all come from the left, the political tradition that most strongly rejected any hint that evolution operates among different human groups. They should see that, far from opening the road to a return of Nazi ideas, embracing these ideas might give them an amazing weapon to battle immigration phobia. Immigrants are good for Europe’s future, in the scientific sense as well as the political one.

“Fight Fortress Europe” photograph courtesy of Joel Schalit.