Why are Germans so anal about punctuality or Brazilians more likely than Arabs to be accused of showing too much skin? Cultural psychologist Michele Gelfand believes that culture best explains our divisions and conflicts.

We’ve made many strides forward in numerous fields like technology and medicine, but one area of knowledge that needs deepening is that of culture. It’s as old as humanity itself, but we are still discovering how it works. It is culture that holds the key to understanding the structure of our differences as well as our divisions. The solutions to these divisions will not be political or economic, but cultural.

Past cultural explanations didn't go deep enough. They explained things geographically or as a clash of civilizations, but merely saying that there are cultural differences and that these differences matter does not get us closer to the primal underlying structure of cultures and why people act the way they do.

A simple principle can help clarify a great deal of what’s going on in the world. (Think of what gravity did for our understanding of physics, or what germ theory did for the fields of biology and medicine.) In the same way, there’s a simple principle that accounts for the tremendous variation, not only between nations, but also between political parties, social classes, businesses, and households: tight and loose cultures.

Every culture has social norms, but some maintain norms far more carefully than others. Tight cultures are the rule makers: people in these cultures are careful to observe social norms and fear the consequences of deviating from those norms. Loose cultures are the culture breakers. They have cultural norms, but these norms are not as strictly enforced and the consequences for deviating from those norms are far less severe.

In countries like Germany, pedestrians are far more likely to wait patiently at a crosswalk until given the signal to cross—even if it’s late at night and there isn’t a vehicle in sight. In the United States, a looser culture than Germany, jaywalking or crossing without waiting for a signal is far more common. In Brazil, clocks are rarely synced, people are often late to business meetings, and when you want to ensure that people arrive on time, you say “with British punctuality.” Compare that to Japanese culture, a far tighter culture, where the trains are rarely late and, when they are, the conductors issue “late passes” to passengers to give to employers.

Culture matters, but it also matters where the cultural variation comes from.

The handshake is now the most common gesture of greeting in the world. Anthropologists speculate that the practice originated in ninth-century Greece. In that day, it was the way to declare that you were not hiding a weapon and had no plans to attack the person you were approaching. It’s since become a matter of etiquette rather than safety, but we still do it reflexively.

A world without any social norms would spell unlivable chaos for Homo sapiens. Both tight and loose cultures have them and people unconsciously observe hundreds of them every day. We humans are a super-normative species, meaning that we’re wired for creating, maintaining, and following social codes.

Some are explicit, like laws and regulations. Others are tacit but no less powerful, like not staring at others on public transportation or facing the elevator’s door rather than its walls. Many are irrational and make sense only to those under their sway. Have you ever considered, for instance, why a bride would wear white on one of the happiest days of her life or why parents, who instruct their children never to take candy from strangers, let them roam the streets with their friends every October 31, asking strangers for candy? Or why would people chop down a healthy pine tree every December and cover it with ornaments, only to watch it shrivel up in their living room by the end of the month?

To the outside observer, social norms can seem very strange. Another example would be the Kumbh Mela, a religious ceremony in India that attracted 120 million people over a two-month period in 2013. What would impel so many people to sojourn to a place where they bathe in a cold, highly unsanitary river in a city so crowded that people are routinely separated from family members and even trampled? It’s strange and unnerving for some, but for the multitudes that fill the streets and rivers of Allahabad, nothing could be more natural.

Why do humans do these things? Social norms create unity and cohesion. This cohesion allows us to cooperate, and cooperation enables us to do amazing things. Human beings, more than any other species, have the ability to coordinate effectively. It all starts with social norms, these invisible, but powerful and ever-present forces that shape behavior. Infants pick up on them before they can even form words, and we follow them to feel part of a group.

Social norms are the ties that bind us together, and bonding experiences—particularly ones that require enduring suffering together—serve to solidify those bonds. Without these, societies would collapse. They are the secret to humanity’s remarkable feats, but also what leads to our colossal conflicts around the globe.

To map out the tight-loose spectrum meant finding participants from all over the world and from a wide variety of backgrounds. In 2011, the author and a team of researchers administered surveys to 7,000 participants from over 30 countries. The survey questions had been translated into more than 20 languages, and there were vast differences in job, income, gender, age, religion, and social standing. Subjects were asked questions designed to determine the strength of social norms, like whether there were many rules in their culture, whether the consequences for breaking those rules were severe, whether they generally had the freedom to act as they chose, and whether people complied with their country’s norms.

The tightest cultures were Pakistan, Malaysia, India, Singapore, South Korea, Norway, Turkey, and Japan. The loosest cultures were the Ukraine, Estonia, Hungary, Israel, the Netherlands, Brazil, Venezuela, Greece, New Zealand, Australia, and the United States. In general, the tightest nations are South and East Asian, then Middle Eastern, then Nordic and Germanic, and the loosest nations were former Communist Eastern European nations, followed by Latin American nations, Latin-European nations, and English-speaking nations.

The data also revealed that there is far less social latitude in tight cultures, a far narrower range of acceptable options for behavior in parks, cafes, libraries, at shows, on trains, and so on. As mentioned earlier, the tight-loose typology is not an either-or, but a spectrum. Most nations fall between the extremes. And even those nations that are more extreme one way or the other,  have domains and outlets that allow for the “other side” to be indulged.

A notable example of this blowing off cultural steam would be Takeshita Street in Tokyo. In the middle of the capital of straight-laced Japan is a street where people are permitted to break with rigid social norms and dress up like anime heroes, sexy maids, or punk rock stars. In censorious Iran, there is still a thriving community of artists.

Just as there are opportunities to blow off social norms in tight cultures, there are domains of loose cultures that are surprisingly tight: the United States is a fairly loose culture, but is extremely protective of privacy. Israel is an even looser culture, but there is a strong insistence  on the importance of raising big families and serving in Israel’s military. Australians have a famously-laidback temperament, but are readily rankled by anything that seems inegalitarian. Australians pejoratively refer to people who ostentatiously exhibit power and wealth as “tall poppies.”

This pattern is a global one, and it is an ancient one. Anthropologists have investigated millennia-old civilizations and found that they spanned the tight-loose continuum just as modern nations do. The Incas and Goajiro of South America as well as the Azande of Central Africa were very tight cultures. By contrast, the Tehuelche of South America and the Copper Inuit of Canada were loose.

This paradigm is not just global but timeless.

Most people who have visited the small Southeast Asian nation of Singapore find its streets and public transportation systems staggeringly clean. There’s no trash in the streets because of the steep fine for littering, and there’s no gum under tables or chairs because gum is actually illegal. If you’re caught smuggling in gum, you will be fined up to 100,000 dollars or do two years in jail. The trains are pristine, and they run on time. In the rare event of a delay, the conductor offers passengers a heartfelt apology and a thorough explanation. Singapore also has one of the lowest crime rates in the world and is considered a very safe country.

Singapore owes its cleanliness, order, and safety to its strict punishments for violators. In the 1990s, a young American staying in Singapore pled guilty to egging and tagging 18 cars. He was heavily fined, sentenced to four months in jail and six lashes with a bamboo cane. The American media decried the affair, calling it too severe, that Michael Fay was “just a boy.” Bill Clinton petitioned the Singaporean government for clemency. The Singaporean government reduced the sentence from six lashes to four, but insisted that he still be caned for theft and vandalism as the court had ruled.

In contrast to a very tight Singaporean culture, New Zealand culture tends toward the loose extreme. People can open and partake of alcoholic beverages as they drive so long as their blood alcohol level stays below the legal threshold. Gay marriage has been legal since 1994. Prostitution is legal for anyone over 18 years old. New Zealand women have more sexual partners during their lifetime than anywhere else in the world: an average of 20. (The global average is 7.) New Zealanders—or “Kiwis” as they call themselves, a reference for the species of flightless bird native to their island—tend to be very informal. They are not uptight about titles. It’s not uncommon to see people walking through streets and buildings barefoot.

New Zealand is also one of the world’s largest per capita consumers of pornography. Many of their music videos depict suicides, abuse, killings, bombings, and other acts of violence. Protests and civil disobedience are common.

Would you rather live in New Zealand or Singapore? Case studies show some of the liabilities and assets present in both tight and loose cultures. In tight cultures, people tend to be more conscientious, exercise greater self-restraint, and the social order generally operates smoothly. Common liabilities of tight cultures are close-mindedness and cultural stagnancy. Loose cultures have their own assets, like open-mindedness, flexibility, and creativity; and their own liabilities, like impulsiveness, lack of organization, and social unrest.

The survey results of the tight-loose typology are too diverse to fit neatly into the common explanations, like language, religion, or geography. If you remember, Japan, Norway, and Pakistan are among the tightest cultures and Brazil, New Zealand, Greece, and the Ukraine are among the loosest cultures. At both extremes of the tight-loose continuum are a range of regions, languages, and religions.

This does not make these differences arbitrary, however. There are definite reasons for a culture’s particular orientation. Whether ancient or modern, cultures will tighten in anticipation of military threats or in response to an ongoing assault, whether that threat comes from invaders or Mother Nature. An agricultural society residing in a drought-prone region like the Nahua of Central America will have stricter punishments for those who fail to discharge their roles effectively. When the margin of error is razor-thin, it makes sense that a culture would be less indulgent when observing social norms means the difference between life and death.

By contrast, the mostly hunter-gatherer Inuit of North America, are more self-reliant. There’s far less dependence on the collective to ensure that everyone eats. Thus, rigid social norms and severe punishments aren’t needed. Staving off chaos is more difficult in some areas than others.

The historical contexts and challenges of keeping chaos at bay vary from place to place, but they’re everywhere. It occurs often within the United States with looser cultures along the coasts, and tighter cultures in the Midwest and South, but conflicts occur anywhere there are people.

Brexit, the election of Trump, and the rise of other populist leaders throughout Europe—in a word, the nationalist impulse—are all expressions of the desire for a tighter culture. Sometimes  economic uncertainty coupled with rapid technological and cultural changes make too strong a cocktail for a group to handle, and they clamp down on social norms to preserve what remains. Radicalization of Muslims is more likely in a tight Germany than in the loose United States, and those radicalized tend to perceive their new country as intolerant and integration as too difficult.

Culture explains why our world is fraught with conflict, but if culture has created messes, it also holds out hope for our resolving them.

A culture is best served by going for a Goldilocks approach, which is not too tight, nor too loose, but “just right.” The “just right” tension will vary from place to place, but history bears out the problems of being too extreme one way or the other: too loose can mean violence and chaos, and too tight can mean intolerance and suppression.

One example of how knowledge of social norms can be used to mitigate conflicts, one that transcends most borders, is the domain of the internet. Between 2000 and 2016, internet use went from 738 million people to 3.8 billion people. There is great freedom in the online world— arguably too much. The internet is an extremely loose culture, full of trolls, tricksters, cyberbullies, and worse. It is imperative that online culture be tightened. World Wide Web cofounder Robert Cailliau has said as much. Some companies and thinkers are already moving along these lines, with books and guides to online etiquette or “Netiquette” as some are calling it. Facebook executives responded to the abuse of its Live feature by bringing on thousands of personnel to detect and respond to any users using Live to stream acts of assault or torture. Twitter has been developing tools to better detect bot accounts designed to sway political elections. Google is trying to curtail information that they consider false and offensive.

If the internet is in need of tightening, there are other cultural domains in need of loosening. One such domain would be norms surrounding family size. Overpopulation is a pressing concern for the planet. By 2050, there will be almost 10 billion people. By then, the United States’ population is expected to grow by about 100 million and India by almost half a billion. Uganda’s population is predicted to triple. In developing countries, there is little to no pressure placed on citizens to keep families small, which puts strain on families as well as the planet’s resources and stability.

Israel is already a crowded nation, and experts anticipate that its population density will far exceed that of Holland or Japan. Even now, a quarter of complaints to the police are related to noise--par for the course in congested populations. The average number of children in Israel is 3.1, but having seven children is not uncommon among the Orthodox Jews. In Israel, having a large family is a point of pride, and women see it as a duty to community and country. One Israeli politician declared that a woman who is capable of having four kids but doesn’t “is betraying the Jewish mission.”

This may seem odd or even offensive to many, but the historical backdrop of the Holocaust, in which 6 million Jews were obliterated, informs the duty that women feel to restore the population. The immediate context of being surrounded by hostile Arab nations whose citizens are also having big families is another factor that motivates current family practices. There are indigenous groups in Israel now trying to loosen this childrearing domain with the message that the patriotic thing is no longer to have a big family, but to have a small one.

In sum, our lives would be unliveable chaos without social norms. They form the glue that holds a society together. Cohesion makes cooperation possible, and cooperation allows us to accomplish remarkable feats. Awareness of what drives differences equips people to ease the friction between people, organizations, and nations that adhere to social norms differently. Moreover, social norms influence us profoundly, but they are not fate. The examples of online culture and developing nations addressing overpopulation issues remind us that cultures, far from static, can be loosened or tightened to the advantage of their people.