What sets humans apart from other animals? Why have we been so successful? Most people would say it's our intelligence. Here I want to argue that the secret of our success is actually culture.
I'm going to use Wikipedia's definition of culture, which has a broader meaning than the everyday use of the word:
information capable of affecting individuals' behavior that they acquire from other members of their species through teaching, imitation and other forms of social transmission
Humans are special because in addition to passing on our genes, we can also pass on cultural artefacts to the next generation. For example, children pickup their parents' language rapidly, with very little formal instruction. No other species can do this to the extent we can.
Let's consider a hypothetical scenario. If one day you find yourself teleported from your comfortable urban home and dropped into the middle of the Amazon rainforest, alone, your chances of survival are bleak no matter how smart you are. You don't know where to find drinkable water, how to make a fire, how to hunt animals, or which plants are edible and which poisonous. And your magnificent IQ won't help you much with these things.
But if you bump into a friendly tribe, your survival odds skyrocket. You learn that drinkable water can be found condensed on large leaves early in the morning. Fire can be made using a bow drill, although it takes weeks of practice before you're able to do it right. Some kinds of worms are edible and nutritious, even though you are initially squeamish about eating them. You watch and imitate the tribes-people, and in a few months you've figured out how to fend for yourself in this harsh environment.
In this scenario, culture was more important to your survival than raw intelligence: immersing yourself in the tribe's culture helped you pick up the skills needed to survive in the harshness of the rain forest. The same is true for almost any other environment. Imagine you want to be a successful investor in Silicon Valley. Perhaps you could use your incredible intelligence to figure out the fundamental principles of investing and go from there. But you will probably have more success simply absorbing knowledge by working with other investors. Your best strategy is to spend more time around other investors and watch them do their job.
One great example of how culture can beat individual intelligence is described in anthropologist Joseph Heinrich's book The Secret Of Our Success. Heinrich talks about the processing of the tuber cassava, also called manioc. Cassava contains high levels of toxins and requires an elaborate process of detoxification before it is safe for consumption. But the effects of the toxins show up after years or decades of consumption, so it's hard to link the eating of cassava to the subsequent poisoning a long time later.
When the Portuguese brought cassava from South America to Africa they didn't bring the detoxification process with them. This led to high levels of cyanide poisoning in the populations that started to consume cassava.
Rationally, using our intelligence, it was hard to see why South American tribes spent so much time processing cassava. But many cultural values don't seem rational because feedback is often opaque and delayed in the natural world. In the short term skipping the processing steps and simply boiling the cassava would save you a lot of time and energy and would seem like the smart thing to do. But it would be a costly mistake. You'd only realise you were wrong many years later, and that's only if you could then make the connection between eating the cassava and the effects of the poisoning.
Culture being more important than intelligence also tells us something deep about our environments, and perhaps even about reality: that there is less of an order and structure to things than we believe. If the world was structured more, intelligence alone would be enough to succeed with first principles thinking. But if the world is more chaotic and arbitrary then you can't figure out most things from first principles. Much of the knowledge needed to succeed in the natural world doesn't arise from general principles but from arbitrary bits of detail that people before you have stumbled upon as they tinkered with their environment. Like, for example, that cassava needs extensive processing to detoxify it. And there's usually too many such bits of detail for you to figure them all out on your own; you have to rely on the insights of generations of people before you.
On the other hand, let's not be too dismissive of intelligence; it does matter, and often quite a lot. If it didn't, we'd simply imitate all the time. Our environments are not just complex, but ever-changing, and we need to innovate to thrive in them. Intelligence helps us innovate. I think really in most environments you want to imitate/inherit 95% of the time and innovate 5% of the time. You imitate 95% of the time because you don't want to discover everything from first principles – it's easier to learn from other people's mistakes than your own. But you can innovate and push the frontier in a few select areas.
You want to inherit 95% of knowledge from your culture: things like language, the existing body of scientific knowledge, etc. Most societies also have educational institutions like schools and universities to help transmit this knowledge efficiently. And you want to push the frontier on the remaining 5%. Which 5% may vary depending on your interests: carpenters would innovate on woodworking, scientists would push their scientific frontiers, and so on. But excessive imitation would also lead to stasis, so you want to make sure that 5% is there. A company that owns a search engine needs to innovate on search, but not on payroll processing for its employees, managing its real estate, or a number of other things.
Newton recognised the value of culture in science. In a letter to Robert Hooke, a fellow scientist, he said:
If I have seen further it is by standing on the sholders of Giants.
The 'giants' were the many generations of scientists and philosophers before him who had incrementally built the body of scientific knowledge his work would be standing on. Standing on these giants, he could see further than any of this predecessors.
We too stand on the shoulders on giants today. Thousands of generations before us have incrementally improved the body of human knowledge: how to grow food, how to build bridges, how to cure disease, how to increase the wealth of nations, and so on. We inherit this culture, make some incremental improvements to it, and pass it on to the next generation.