Prosociality is fundamental to being human, whether it involves helping others directly, volunteering or making charitable donations. Approximately 10% of the world’s population engages in regular volunteer work. In the USA alone, individuals donated over US $592 billion in 2024. According to the World Giving Index 2025, Africa was ranked the most generous continent relative to income, with people contributing an average of 1.54% of their income, and Nigeria was ranked as the most generous country overall. Nigerians donated 2.83% of their income in 2024.

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Prosocial behaviour is behaviour intended to benefit others1. Helping a neighbour to carry the groceries, being active in a community or donating money to a charity are all expressions of prosocial behaviour.

Prosocial behaviour can also incur costs. This is particularly evident in instances of altruistic action, in which individuals help others without any foreseeable personal benefit — and in extreme cases may even risk or sacrifice their own lives to save others. Such behaviour appears paradoxical from a purely self-interested perspective, which is why researchers are interested in uncovering the evolutionary origins and psychological motivations that underlie prosociality.

Some research suggests that prosocial behaviour may have had an evolutionary advantage, as it may have helped us to survive and raise children in groups2. As social beings, we live in communities, and care not only about our own wellbeing but also that of others. Prosociality is essential for our individual wellbeing3, for group cohesion and group support, and also for ensuring societal cohesion and equity as well as initiating positive change.

To shine a light on the origins, developmental trajectory and societal impact of prosociality, this month we launch a Collection of research articles on prosocial behaviour.

To celebrate one key expression of prosociality — the work of volunteers worldwide — we are launching our Collection on International Volunteer Day, 5 December. International Volunteer Day serves to highlight the work and impact of volunteers and volunteer communities and to ensure their wellbeing4. It was first mandated by the UN General Assembly in 1985, and today the monthly number of volunteers aged 15 years and over is estimated at 862.4 million worldwide. As the UN notes, volunteering is crucial for achieving Sustainable Development Goals such as climate action and good health: it is individuals who contribute to achieving change, and who help to implement solutions on a day-to-day basis.

Many people do good, but what drives people to volunteer and to be prosocial? Researchers have put forward different explanations.

Some are rooted in the biological underpinnings of empathy, a state that often leads to prosocial behaviour, whereas others have focused on the potential evolutionary advantages of prosocial behaviour5. Helping others may have increased the likelihood of receiving help when needed, improving chances of survival.

Beyond direct reciprocity, kin selection and group selection are other evolutionary hypotheses that aim to explain prosocial behaviour. In fact, a point of contention among researchers and philosophers is whether entirely altruistic, prosocial behaviour exists. It is argued that, while not all altruistic or prosocial behaviour might have a direct benefit for the one engaging in it, it might indirectly benefit them. This can come in the form of a ‘warm glow’ — that is, feeling good when helping others. This emotional reward can be a motivator for prosocial behaviour. Being seen as someone helpful is also conducive to our reputation. Helpful people are viewed in a more positive light, and helping others might thus come with benefits in the future. The neighbour who we helped with their groceries might be more likely to take on our packages next time.

Underlying motives also have a role in deciding whether a behaviour is perceived as being prosocial or not. The same behaviour can be seen as helping or just as neutral or even negative, depending on the motives of the actor engaging in it. Some behaviours might benefit others, but they are not executed with this intention and their positive outcomes are merely side effects. For example, someone might be working longer hours to get a bonus, with the side effect that other team members have a lower workload. Their intention was simply personal gain — so this would not be considered prosocial.

Although the question of whether prosocial behaviour exists in a pure form or not might still be subject to debate, it is clear that prosocial behaviour emerges early on in life. Developmental psychology has found that preverbal children as young as eight months old have a sense of justice and punish antisocial others6. This tendency has been found across diverse cultures, and children even sacrifice their own resources to ensure that others are not treated unfairly7. These findings suggest that prosociality might be at least partially innate.

Research on prosocial behaviour is as prevalent and diverse as the behaviour itself. Our Collection aims to highlight some of this literature. We include fundamental work that examines different prosocial paradigms and economic games, as well as research on the developmental trajectory of prosocial behaviour and the understanding of fairness. We also feature studies on the motives for prosociality, and field studies that examine donations and effective altruism (that is, prioritizing causes that achieve the highest effectiveness). For example, did you know that people tend to donate more to people who have the same last name8?

We hope that this Collection will spark curiosity to learn more about this fascinating human behaviour. It might also inspire some readers to engage more in prosocial behaviour themselves. May International Volunteer Day be the start.