The Club of Rome gave that fear its most influential form with the publication of The Limits to Growth. Few could have foreseen how deeply the computer simulations produced by Dennis Meadows and his 17-member team would shape global politics. Half a century later, the report’s catastrophic scenario of overpopulation, and the conviction that it must be prevented at almost any cost, has become something close to dogma in affluent Western societies.

The chain of assumptions set out at the time, from overpopulation to malnutrition, resource scarcity, environmental damage and man-made climate change, has since settled in the minds of many politicians and much of the media as a vision of inevitable apocalypse. The fact that prominent figures such as Elon Musk publicly challenge the Club of Rome’s warnings has done little to change that. In Musk’s view, humanity’s real danger is not overpopulation, but “an aging and shrinking world population” and a kind of human implosion.

The Blind Spot in the Demographic Debate

As it becomes increasingly clear that food shortages and poverty in populous societies can be brought under control worldwide through technological progress, politics has neglected what is currently causing the greatest problems in young, growing societies: a surplus of young men without prospects.

“Where there are too many young men, people get killed”, the German sociologist and demography researcher Professor Gunnar Heinsohn once put it bluntly. He is regarded as the founder of the youth bulge theory, which links a large surplus of young people to social breakdown and violence. In 2003, Heinsohn set out his findings on societies prone to civil war in Söhne und Weltmacht: Terror im Aufstieg und Fall der Nationen (Sons and World Power). His argument was that conflict becomes likely when ambitious young men vastly outnumber the respected social positions available to them.

In a 2006 interview with the Swiss newspaper Neue Zürcher Zeitung (NZZ), Heinsohn, who has since died, explained what he called a world formula. He had taken the idea from the French scholar Gaston Bouthoul, developed it further and supported it empirically through an analysis of 70 countries.

His conclusion was that wherever women had six to eight children on average over decades or even centuries, meaning three to four sons, things almost invariably became “dangerous”. Only one son, or at most two, could be given respected positions. The third and fourth brothers were no less ambitious, and they were in their prime fighting years. They would therefore either emigrate or seize their place by force. The result was crime, civil wars, genocides against minorities, revolutions, international wars or colonization. The cycle continued until the male surplus had been killed off and the birth rate began to fall again.

The War Index

Heinsohn sought to explain how a region where the guns had only recently fallen silent could suddenly descend into civil war. His answer was a set of mathematical probabilities that he called the “war index”. It compares men aged 55 to 59, who are approaching retirement, with males aged 15 to 19, who are just entering the struggle for status and survival. According to Heinsohn’s calculations, Germany had a score of only 0.66 in 2015, when it opened its borders to migration from Arab and African states. For every 1,000 older men, there were 666 younger ones.

In the Gaza Strip, by contrast, the war index at the same time was about 10 times higher, at a factor of six. For every 1,000 older men, there were 6,000 younger ones. The same was true in Afghanistan. In Nigeria, the index stood at a factor of five.

Heinsohn’s research, which also looked at societies hundreds of years in the past, challenged the common narrative that wars are triggered by religion or hunger. His argument was that war and violence are not caused primarily by income inequality, but by demographic imbalances and too many underoccupied young men.

Violence, in this view, erupts where young males form a large surplus. Heinsohn defined a youth bulge as a situation in which 15- to 29-year-olds made up at least 30% of a society’s male population. He saw this as a major source of crisis in the Arab world, including the Palestinian territories. His 2003 prediction that these crisis zones would erupt from 2011, because the relevant age structure was already taking shape, has since proved accurate. Even the so-called Arab Spring could be anticipated using this method.

Europe’s Own Surplus Sons

Europe’s bloody history can also be read through this lens. According to Heinsohn, the continent experienced a youth bulge for almost 400 years from 1500 onward, after the plague had previously reduced the population dramatically. Birth rates in medieval Europe remained high, often at seven to eight children.

The resulting surplus of sons was followed almost inevitably by civil wars, revolutions and Christian-motivated campaigns of extermination. The Spanish colonizers who carried out genocides and massacres in South America were known as Secundones, the second-born. They were the surplus brothers who had nothing to lose at home and much to conquer abroad. Switzerland, in turn, exported its sons as mercenaries to other peoples and to the Vatican’s Swiss Guard.

As early as 2015, Heinsohn calculated the Arab world’s conflict potential for policymakers. At the time, he said, the region had 300 million sons under the age of 15. Over the following 15 years, they would reach the 15-to-30 age bracket.

“At best, 100 million of them will find a place at home. But 200 million form a potential for violence. Most likely within their own countries, but possibly also internationally”, Heinsohn said at the time, describing a future that has now become the present. He added that sexual frustration could also play a role, “if in the society concerned sex is available only as a reproductive act within marriage, but marriage first requires a social position to have been achieved”.

When Demography Reaches Europe

While left-wing politicians are eager to deny any connection between migration flows from African and Arab states and rising crime in Europe, police statistics tell a different story. In passing, they also posthumously confirm Gunnar Heinsohn’s thesis.

The “surplus sons” of these societies have long been making their way to Europe. European countries also record women and children among refugees, but the overwhelming majority are precisely those young men who see no future in their own countries and therefore head north. If one of them succeeds, for example, in establishing himself permanently in the German welfare state, he can generate more income each month than his first-born brother in Afghanistan or Syria earns in an entire year.

The increased aggression, but also the sexual frustration of these men, is reflected in the crime statistics of their host countries, where they are heavily overrepresented in violent crime and sexual offenses. In Germany, for example, the category of murder and rape has risen by 70% since 2015. Syrians and Afghans are 10 times more likely to be suspects than German citizens. A policy that brings large numbers of young men from potentially violent cultures into the country, without language skills, vocational qualifications or stable employment, and concentrates them in specific places over a short period of time, quite naturally increases the risk of violent conflict.

Those who enter a country only to appear in its crime statistics do not solve a demographic problem. They create one. The price is increasingly paid by women as victims of sexual violence, while native men are also more often targeted in violent attacks. Countries such as Sweden and Denmark have meanwhile responded with strict limits on new immigration and policies aimed at returning as many migrant offenders as possible.

If Europe’s leaders had listened at the time to experts such as Heinsohn, the continent could have spared itself the continuing wave of terror and violence by perpetrators with a migration background through a restrictive immigration policy.

The West’s Missing Sons

Understanding demographic processes and their effects on security, as well as on a country’s ability to defend itself, casts the birth deficit of Western societies in another alarming light. Europe is no longer capable of defending itself. Or, to put it in Heinsohn’s terms: the West has, on average, only one son, and it does not want to lose him in war. Other societies have three or four surplus sons and still an heir left at home. The willingness to unleash global conflicts rises with a society’s willingness and capacity to sacrifice its sons.

The left-wing pacifism of the West is therefore less heroic and moral than its representatives like to claim. With a birth rate of only 1.4 children per woman, people are far more reluctant to give up their average 0.7 sons than they were during World War I and World War II.

Heinsohn’s analysis of his own German people was correspondingly sober. If Germany had reproduced at the same rate as the Palestinians in the Gaza Strip, he calculated, there would today be not 80 million Germans, but 550 million, including 80 million young men with the potential for conflict between the ages of 15 and 30.

What would Germans do with them? Heinsohn posed the logical question: “Do you believe the 80 million young German men would be 10 times as pacifistic as the seven million we have today? Or would they not be far more likely to throw bombs in Prague and Gdansk and Wroclaw and, like the Palestinians, say: that is our territory, it was taken from us because of historical events for which we are not responsible?”

It's the demography, stupid!