26. Cooperation

When people consider what it is that makes humans unique, they are likely to come up with a rangeof characteristics such as walking around on two legs, having big brains, and our language andculture (van Straalen, 2018). Famously, Desmond Morris in his book The Naked Ape (Morris, 1967),concluded that humans’ most obviously striking trait compared to other mammals is ourhairlessness! But arguably the most vital of our unique traits is our unusually strong willingness tocooperate, often in notably large numbers. As a result of the importance and prevalence of[[cooperation]] to the human species, some go so far as to call humans [[ultrasocial]] (Campbell,1983). It is likely this ultra-cooperativeness helped humans to both survive the challenges of theAfrican savannah, where our species evolved, and then our rapid expansion across the globe(Townsend et al., 2023).However, despite this clear benefit to human success, it is all too common for discussions ofcooperation to begin by calling it a puzzle (e.g., Henrich & Muthukrishna, 2021) or a problem (e.g.,West et al., 2011). It is the case that [[natural selection]] is generally a process of [[competition]]between individuals, and a trait that reduces an individual’s chances to reproduce will be selectedagainst. Cooperation seems costly to reproductive fitness and often benefits other individuals, sosurely it is selected against? This is the source of the notion of cooperation as a puzzle. Yet in theevolutionary sciences there has been a lot of work undertaken to understand how behaviours thatappear to undermine the fitness of cooperators could have evolved. In this chapter, we will explorethe various approaches that human evolutionary scientists have developed to understandcooperation as a trait and to account for how humans can be as cooperative as we are.