There are two different sides to human nature. Both are important, but the balance between them has huge implications for our wellbeing, culture and future.

One side of our nature is self-interested. This is our in-built instinct to do whatever we can to survive and thrive, often at the expense of others. The other side is co-operative and leads us to help others even when there is no direct benefit for ourselves.

Although Charles Darwin is normally associated with the “survival of the fittest” theory, he also believed that our natural instinct was to care for others. In The Descent of Man he wrote that the communities most likely to flourish were “those with the most sympathetic members”, an observation backed up by research that we are wired to care about each other.

But we have such a strong cultural narrative about the selfish side of humanity that we adopt systems and behaviours that undermine our natural co-operative tendencies. This starts in schools, where the relentless focus on exams and attainment instills in young people the idea that success is about doing better than others. It continues in our marketing culture, which encourages conspicuous displays of consumption and rivalry.

It’s found at the heart of our workplaces, where employees compete with each other for performance-related rewards. It’s behind the self-interested behaviour that makes it so hard to overcome major societal challenges such as climate change.

This “get ahead or lose out” ethos not only fails to promote the better side of our nature, it’s also deeply flawed. In schools, helping young people to develop social and emotional skills doesn’t just enhance their wellbeing, it’s also been shown to boost their performance.

In workplaces, research from Adam Grant, professor of management at the University of Pennsylvania’s Wharton Schoolshows that “givers” - people who help others without seeking anything in return - are more successful in the long term than “takers” - who try to maximise benefits for themselves, rather than others.

For society as a whole, the World Happiness Report 2013, a major global study, found that two of the strongest explanatory factors for national wellbeing are levels of social support and generosity. Our success as a society directly depends on the extent to which we see each other as a source of support rather than a source of threat.

Today is the International Day of Happiness and this year’s theme is “your happiness is part of something bigger”, focusing on the importance of connecting with and caring about the people around us. This matters for sustainability for three significant reasons.

Firstly, it is a timely reminder of the importance of collaboration and the need for systems thinking, both within and across organisations. This is the only way we can solve the major challenges in our increasingly complex and interconnected world.

Secondly, it links to the growing body of evidence including a recent paper from the University of Warwick that shows when people feel happier and more connected they are more productive at work. Dr Teresa Belton, researcher and visiting fellow at the University of East Anglia, has also shown it leads people to behave in more environmentally sustainable ways.

Thirdly, the deeper message behind the International Day of Happiness is the need for a radical shift in the way we measure progress. This moves us away from chasing GDP growth at all costs and towards a more holistic view of wellbeing as the ultimate goal, taking future generations into account too.

This doesn’t just matter for business leaders and policy makers, it relates to the way that we each behave as individuals and how we treat others in our communities and working lives.

Today people all around the world are taking small actions to create more positive connections with others around them, whether at the office, in the shops, on the train or in their neighbourhood. These tiny moments of friendliness and co-operation aren’t trivial and meaningless; they are the vital lifeblood of a good society.

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