HOMO sapiens is the only species with a history. In the mere 200,000 years of our existence, we have gone from upright apes with a few hand-axes and spears to a species that spread from Africa to occupy nearly every habitat on Earth, building a world replete with technologies most of us don’t even understand.

By comparison, our close genetic cousins, chimpanzees, still sit on the ground cracking nuts with stones, as they have for millions of years. History for other animals really is, as British historian Arnold Toynbee said, “just one damn thing after another” – and the same “thing” at that.

Our achievements pose a challenge to Darwin. His great theory of evolution by natural selection provides a sophisticated view of how species adapt to their environments. But how are we to explain the existence of petrol engines, cameras, pasta machines, yo-yos, religion and the arts? Even if we concoct stories to explain how these artefacts might improve our survival, why have only humans produced them?

These questions make up, in Kevin Laland’s eyes, the “unfinished symphony” of his new book. He wants to know exactly what it was about humans that set us on a trajectory of cumulative and accelerating technological innovation, the limits of which we are still exploring.

We know it must have been small in genetic terms because we share around 98 per cent of our protein-coding gene sequences with chimpanzees, and more than 99 per cent with the hapless and extinct Neanderthals. And yet there seems to be an unbridgeable gap between our evolutionary potential and theirs. Indeed, there seems to be a gap between us and all other species.

“The history of technology is not one of great leaps of insight but small, often accidental modifications”

The usual human conceit is that we are simply more intelligent: our big brains allow us to figure things out. But this view is exaggerated. Looking at the evolution of technology, it did not happen with great leaps of insight, but small and often accidental modifications to existing ideas. Thomas Edison’s notebooks show he tried thousands of materials, including platinum and bamboo, before alighting on a carbon fibre as the filament for his light bulb; Henry Ford didn’t invent the assembly line; even Isaac Newton acknowledged that he stood on the shoulders of giants.

Laland, who is a behavioural and evolutionary biologist at the University of St Andrews, UK, organised a tournament in which 100 computer programs competed over many rounds of interactions to survive in an ever-changing environment.

Programs could combine strategies of copying and innovation in whatever ways they liked. Startlingly, the winning program almost exclusively copied others. The program that relied almost entirely on innovation finished close to last.

Our view of ourselves as progressing through a series of light-bulb moments of inspiration is being replaced with the idea that what our species is really good at is imitation. We can search among a sea of what might be little more than random ideas others have tried, picking the ones that seem to work best. It is a form of survival of the fittest ideas that mimics biological evolution, but because ideas can quickly spread from one mind to another, the pace of our cultural evolution vastly outstrips the plodding rate of most genetic change.

However, there is more to this story. Copying is fraught with errors. If left uncorrected, those errors will accumulate on top of other errors, and this will eventually bring the cultural evolutionary train to a halt, at least for things more complicated than those you might be able to learn on your own. This is a fair description of most other animals’ technologies – chimpanzees, for example, probably rediscover the art of nut cracking every generation, perhaps benefiting only from having their attention called to it from watching others. Lacking a mechanism to reduce copying errors, the chimpanzees are stuck at this level of sophistication.

Our solution, in Laland’s view, was to teach. Teaching can transmit new information, but it is also an error-correction mechanism that allows more sophisticated practices and technologies to be passed on and accumulate.

Some animals do display rudimentary forms of teaching – such as when adult meerkats disable the stinger on a scorpion to allow their offspring to experiment with it at low risk – but only humans practise the systematic teaching of complex actions. Laland even suggests that our human capacity for language evolved not for the economic and social reasons many others suggest, but as an aid to teaching: language arose as something akin to an aural DNA.

It’s surprising how little was needed to accelerate our development: who would have thought that the ability to copy others could get us so far? What’s more, the cultural environment this cognitive shift produced has fostered other adaptations. There is a growing recognition that, compared with other species, humans are less a product of their genes than our genes are a product of living in the presence of the cultures we have created.

If Laland is right, language provides a striking example. Another is psychology and social behaviour that is uniquely centred around group living. Around 70,000 years ago, our capacity for culture propelled us out of Africa by allowing us to acquire the knowledge and technologies necessary for survival in new environments.

“Language may have evolved as an aid to teaching: as something akin to an aural DNA”

Humans eventually occupied nearly every environment on Earth in small tribal societies with their own languages, customs and beliefs. So important were our groups to our survival that we developed a tendency to treat other members almost as honorary relatives: we came to risk our well-being and even our lives for our tribes, for example, when going to war. No other species does these things, apart from the social insects – the ants, bees and wasps – whose unusual reproductive systems mean that the members of a hive or nest are brothers and sisters.

Our cultural adaptations have equipped us for the modern world, but have also left legacies. Today, the advance of culture and the changes it has wrought in us have yielded a species that is curiously in and out of its time. Remarkably, our ancient allegiance to our group has been able to scale up as our increasingly sophisticated cultures grew in size from the small societies we evolved in, to the larger, modern groupings of villages, towns, cities and even nations with millions of people. The emotion of watching your nation triumph over another in a sporting contest is an atavism from an earlier age, and it allows us to live relatively peaceably and productively alongside people who are effectively strangers with a shared identity.

That same atavism must now confront a globalised world (also a product of cumulative culture) in which we routinely mix and live alongside people whose cultural roots and identities may be distant from our own. In spite of the tensions this can cause, when measured across the world, human societies are becoming more, rather than less, peaceful, continuing a trajectory that began at least 10,000 years ago when humans began to live in larger groups.

The simple and yet unexpected story of our species’ success shows how H. sapiens gives up the secrets of its success slowly and only after painstakingly detailed work by academics. Laland’s book shows how those evolutionary biologists, anthropologists and social scientists are currently leading the way in unlocking those secrets. Darwin’s Unfinished Symphony is accessible to the general reader and well researched. It is an enjoyable and valuable place to begin or to top up your understanding of our enigmatic existence.

This article appeared in print under the headline “A series of fortunate events”

Cultural force: the Munduruku halt work on a dam in Brazil (Image: Taylor Weidman/LightRocket via Getty)

IMAGINE the fate of identical twins separated at birth, one reared among the indigenous Munduruku of Brazil, the other in the UK. Despite being genetically identical, they will be culturally as different as night and day: indeed, up until recently, the Munduruku used to decapitate their enemies and live a stone-age existence in the Amazonian rainforest.

The striking cultural differences between these twins can only happen to humans. That’s because unlike all other animals, we have two distinct and fully fledged systems of inheritance: one genetic and one cultural.

Our genetic inheritance affects our physical and psychological make-up, including our intelligence. But our cultures give us our languages, religions, belief systems, technologies, lifestyles and ways of life. They even determine who we fight or kill in wars. You could say it is our cultures that determine who we are – the “I” or “me” we see when we look inside ourselves.

Most of the time our genetic and cultural inheritances both work to enhance our Darwinian fitness – our survival and chances of reproduction. In fact, having these two relatively independent streams of inheritance has been key to human success.

Where most biological species are confined to the small areas of the world to which their genes are adapted, humans have been able to occupy nearly every habitat on Earth by adapting at the cultural level. Thanks to culture, we are as varied in our technologies and lifestyles as collections of different biological species.

But in his engaging new book Mixed Messages, anthropologist Robert Paul argues that, owing to their independence, our genetic and our cultural inheritances will often be in conflict. He even goes so far as to say “their agendas are… at cross purposes”.

To illustrate his point, Paul describes a cultural practice among the Mbaya people of South America that gets them to eschew sex, procreation being seen as a vulgar practice, beneath the dignity of this locally dominant tribe. Forgoing sex creates a dilemma for the perpetuation of the group, so Mbaya society has acquired the additional cultural belief that adoption of children from nearby tribes is a good thing.

The Mbaya’s solution is a practical one, but on closer inspection we realise it allows the cultural system to survive at the expense of its biological carriers. Mbaya culture floats along on a steady stream of unrelated genes, all the while maintaining Mbaya society as a cultural, if not genetic, entity.

The celibacy practices of some Catholic orders, or of the fundamentalist Shaker people in the US, aren’t really any different – they too survive by attracting a steady stream of new, genetically unrelated adherents.

The Mbaya’s behaviours are startling to us because they are so obviously maladaptive. But they are only maladaptive from the perspective of genetic inheritance; the culture is flourishing. So why, Paul asks, do we give priority to the genetic system over the cultural one? Doing so treats genes as the real inheritance while our cultures are relegated to being mere passengers on the genetic train.

It’s true that cultural information largely piggybacks on our biological existence. But neither one deserves to be privileged: both inheritances are just streams of information flowing down the ages.

“Neither of our inheritances deserves privileging: both are streams of information flowing down the ages”

Our genes evolve ways to create and then use our bodies as a form of transport into the next generation. Our cultures are freer, readily able to effect their transmission by jumping from mind to mind rather than having to reproduce and then wait for a body to mature and have sex. Both genes and culture outlive their human hosts.

While neither form of inheritance has a literal agenda, it is this difference in routes of transmission – one via bodies, the other by symbols and word of mouth – that grants our cultural instructions greater scope for harming our genetic interests. Like the spread of a virus, whether it is getting you to whistle Dixie or give up sex, cultural traits can oppose your genetic interests so long as they can jump to a new mind before the host mind dies or somehow nullifies the trait. Adopting children, as the Mbaya do, is just a way of creating new host minds to colonise.

Still, just how common is it that our cultures succeed in opposing the interests of our genes? Here the jury is decidedly out. Some think it common – such as when we die defending our country, which lives on in our absence – while others think it likely that in most cases a genetic advantage can be found.

Language, for example, can be used to trumpet your actions far beyond those who witness them. This could mean, for instance, that the reputational glory attaching itself to one of Japan’s fabled kamikaze pilots was passed along to family members, enhancing the survival of genes they shared with the pilot, even if the copies residing in the pilot were less fortunate.

So, who are you? The choices are stark. Are we robots controlled by our genes, primed to have sex as a way of ensuring their representation in future generations? Or are we robots of our cultures, possessed by thoughts that can even get us to risk our lives to promote the survival of our “tribe”?

The answer will only cheer the existentially minded: we can in turns be both of these things. Paul’s rich exploration of the myriad ways that genes and culture can collide make his book well worth reading.

This article appeared in print under the headline “Who are we really?”