What makes us human ?

I'd say for the first time in history, we have an answer to that question. We understand a little bit about how it is that humans diverged from our last common ancestor with chimps about 4 to 7 million years ago, and what it was that made our species so different from other animals. The answer to that question is that we discovered a new source of information to guide our behavior that untethered us from mere genes, or just what information we could acquire in our lifetimes.

There is some amount of individual learning. Humans have a third source of information or a second source of inheritance that we get from our societies. That's what we call in my field culture. It is the beliefs, the values, ways of thinking, technologies and institutions. It's effectively software that runs on our minds. What makes humans so different from other animals is that we're not just reliant on genetic hardware; we are also able to think beyond our lifetime of experience through accumulated software.

The interesting thing is that if I were to ask you to light a fire and nobody showed you how to do that, you'd actually have a hard time. The ability to make fire and the ability to cook are not in our genome, and they're not discovered every generation through trial and error. Instead, they're passed down culturally.

What's fascinating is the process by which that occurs, because it isn't a process of intelligent design; it's a process of cultural evolution, variation, people trying all kinds of different things. Transmission, as we acquire things from the previous generation, often without really understanding; we have very limited causal models of why we brush our teeth or eat three times a day or sleep when we do and so on. Selective transmission – we don't just learn at random. We try to learn from the people who seem the smartest, who seem the most successful or whom other people are learning from. This is what we call cultural evolution.

Now, that solution is a genetic solution. It is the amount of melanin in your skin that protects you from too much sun but allows you to absorb the right amount. It's not an individually learned solution. It's not a cultural solution. We have new cultural solutions when there are mismatches. If you are, for example, a light-skinned Australian of European ancestry, you need to put some sunscreen on. You're too far south for your genetics. If you are a dark-skinned European, you should probably be consuming some vitamin D. You're not getting enough sunlight for your genetics. What they showed was that when the environment is very stable, even though it varies by the season, it's relatively stable across latitudes. Genes are a good solution for that.

Today, you're eating these red berries that you're genetically adapted to eat, but tomorrow you've got to figure out how to eat the blueberries. That's when you get trial-and-error learning.

An example of this would be something like a cyclical drought. Maybe you haven't experienced the cyclical drought, but your parents or your grandparents have. There are lots of examples of this in the anthropological record, where grandma remembers what the tribe did during the drought because she experienced it as a child. They went left to the forest past the mountain, and she led her tribe to safety.

To understand human behavior, you have to understand that we are the product of millions of years of genetic evolution, but also thousands of years of cultural evolution, as societies adapted to different places around the world – and, of course, our short lifetime of experience. If you understand what determines what someone is going to do or what a society is going to do, you have to understand where they're from. You have to understand what their societies had to deal with. That allows you to understand how much they care about their families, how much they adhere to norms and a whole host of other behaviors. That is the secret to what makes humans so different: we outsourced our cognition to a collective brain. We distributed it, and we stored it as software, not as hardware, not needing to be learned. We are smarter than our short lifetimes should suggest.

What I would argue is we're still living in the shadow of that moment. What that moment was, was the discovery of stored sunlight, effectively. Peat turned into the black rock that we call coal. Later on, oil and natural gas enabled us to travel across the globe, create factories and produce things at a far more efficient rate, because we're able to multiply human ingenuity in that way. That has led to the modern world. It incentivized us to work together in ever larger groups.

Europe, on the back of energy availability and technologies that could put that energy to work, was able to cooperate at a very large scale and outcompete other societies around the world. Now, why did Europe have that technology? Britain had cheap and available coal, but didn't the Dutch also have cheap and available coal? Maybe the Germans did as well? What else might have been going on? Why didn't the Chinese industrialize? Another part of this is what we call a cooperative brain or a collective brain: people's ability to work with one another to discover new solutions.

These undermine higher scales of cooperation. They undermine states, they undermine governments and so on. Now, in Europe, for historical reasons, the Catholic Church ends up banning cousin marriage and changing the European family. What we refer to as a traditional family isn't really a traditional family. Mom and dad and kids with a few uncles and aunts – that's not what humans mostly did. As I said, we were more like family webs. By breaking it down to these nuclear family units, it allowed for a higher scale of cooperation to flourish in Europe relative to a lot of other places around the world. That meant that when Europe discovered that energy, and it had the technology to put that energy to work, it also had the ability to bypass what normally holds them back in terms of cooperation: people lend favors to friends and family because their governments can't provision for them, and the reason their governments can't provision for them is because there's corruption. People are lending favors to friends and family, cronyism, nepotism and so on. You had less of that in Europe initially, which then enabled, on the back of this, the reward for cooperating, this higher scale to emerge. This problem, by the way, still exists in society today and is an ongoing battle in terms of multiculturalism.

It's an evolutionary process where different societies or even different parts of society are running experiments on how to work together, how to live together and where new technologies are. The winners persist over time. The losers don't. The trouble is that some of the lower scales of cooperation can undermine higher scales. Evolution is a constant battle. Understanding this duality between competition and cooperation, and understanding that it's not this inevitable trajectory upward, and it's certainly not the march of man, is probably one of the biggest misconceptions.

Editor’s note: This article has been faithfully transcribed from the original interview filmed with the author, and carefully edited and proofread. Edit date: 2025