We are born selfish. Self-interest is the actuating force for economic activity. Without the rules and laws, sanctions and taxes of the state, we would descend into a war of all against all. Evolutionary science and political economy – from Adam Smith and Thomas Hobbes, to Milton Friedman and Richard Dawkins – tell us selfishness is our default mode.

What if they were completely wrong? Science increasingly suggests they are.

Evidence from evolutionary biology and psychology, anthropology and game theory shows our uniquely sophisticated capacity for co-operation is at the heart of our evolutionary success. Science is telling us we are co-operators.

We breed babies that develop slowly and need a lot of care. According to Sarah Blaffer Hrdy, professor of anthropology at the University of California, mothers in hunter-gatherer tribes needed help, especially from older women, to cope with child-rearing and to supplement the food brought back by hunters. The babies most likely to survive would have been good at eliciting support, showing pro-social tendencies and emotions.

For most of human history the only sure way to get food on a regular basis was to be co-operative: if a hunter returned with nothing they would rely on sharing food brought in by other more successful band members. Richard Wrangham, professor of biological anthropology at Harvard, argues that we evolved large brains because our ancestors worked out how to cook food to make it more digestible and so to provide more energy. Hunting, cooking and eating together required tolerant temperaments and skills of co-operation.

Michael Tomasello, the co-director of the Max Planck Institute for Evolutionary Anthropolgy in Leipzeig, who has spent a lifetime studying altruism among babies, has found that infants willingly co-operate with people they do not know. They tend to share goods like toys and food; they help by fetching out-of-reach objects for people; they are helpful and informative, even with strangers.

The Swiss economist Ernst Fehr has conducted thousands of experiments with people, called social dilemma games, to test their willingness to share money with other people. In general only 20% and at most 30% play these games selfishly; 50% to 60% play co-operatively.

Samuel Bowles and Herbert Gintis, the world's leading researchers into reciprocity, led teams to study co-operation among 16 of the last hunter-gatherer societies in the world and found that the closer we get to a state of nature the more co-operative we become. They summed up the new science of co-operation thus: "Many economists, biologists and others will assert, as they have for at least a century, that altruism beyond one's immediate family members is highly exceptional and ephemeral. The experimental evidence of the last two decades tells strongly against that view."

Our evolutionary success depends on our ability for complex problem-solving, from how to hunt giant mammoth together to organising mass healthcare services – and all complex problem-solving depends on co-operation. Martin Nowak, professor of biology and mathematics at Harvard, argues that co-operation is the hidden, driving force of evolution: "Co-operation was the principle architect of 4 billion years of evolution. Co-operation built the first bacterial cells, then higher cells, then complex multicellular life …Co-operation can draw living matter upward to higher levels of organisation. It generates the possibility for greater diversity by new specialisations, new niches and new divisions of labour. Co-operation makes evolution constructive and open ended … We need to do even more to create an environment where co-operation can flourish if we are to reap its creative benefits."

These sciences are helping to show how co-operation can be sustained through norms of fairness, sanction against free riders, direct communication among co-operators and creating opportunities for people to acquire social standing by being co-operative.

Co-operation – far from being quaint and anachronistic – could come to be seen as successful and modern, aspirational and dynamic. The web and social media are working in favour of co-operation, amplifying and reinforcing relationships. Sharing and co-operation are increasingly central to consumer culture – witness the rise of Groupon and airbnb. Collaboration and co-operation lie at the heart of our most innovative activities in science, culture and business. The reform of the welfare state hinges on breathing life back into its withered sense of reciprocity. The revival of politics probably rests on what the Canadian political philosopher Mark Kingwell calls co-operative citizenship: citizens learning to engage with one another to find solutions as much as with the government.

New forms of co-operation will be needed at every level of our lives, from the global challenges of financial instability, climate change and resource depletion, to the growing recognition that most of what matters most to us – love, care, friendship, respect, trust – come from relationships.

All of which leads to a simple prediction: the societies that succeed in the decades to come will be fair and relatively non-hierarchical because they will be better at co-operation that those are divided and unequal.

• Charles Leadbeater is author of It's Co-operation, Stupid, published by the thinktank IPPR

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http://www.theguardian.com/commentisfree/2012/mar/07/selfish-cooperation-existence