Debunking the selfish myth

Do you ever feel that people are inherently selfish? From rivalry in business to the adversarial focus of the mainstream media, competition appears to be king in modern society. But new research suggests that cooperation wields a greater evolutionary advantage

“Nothing makes sense in biology except in the light of evolution” said Theodosius Dobzhansky in his 1964 address to the American Society of Zoologists. Why do giraffes have long necks? Why do deer have antlers? By being able to reach better leaves to eat or fight off rivals, animals with these characteristics are likely to live longer and have more opportunities to reproduce than those who don’t. Their offspring and descendants who inherit (or perhaps improve on) these traits will also reproduce more, gradually squeezing out those who are weaker. In the end the whole species is forever changed. This is the survival of the fittest – any adaptation that brings an immediate reproductive advantage will become more common over time, eventually taking over completely.

selfish-heartDespite this seemingly logical argument, cooperation and altruism are in fact quite common in the natural world, from apes to honeybees. Amazingly, even some single-celled organisms have evolved to be altruistic. Brewer’s yeast (the stuff that makes your beer fizzy can excrete enzymes that convert chemicals in the environment into food. This provides sustenance for itself and surrounding cells so the colony can grow. But making these enzymes takes time and energy, which could have been spent on reproducing. There are some mutant ‘cheating’ strains of yeast who don’t bother contributing and instead simply steal food from those who do. By benefiting without paying the cost, the cheats can breed faster. We might think then that evolution would favour these cheaters, allowing them to increase in frequency until there are no altruists left, leaving a smaller population comprised entirely of antisocial cheats. But this does not happen: the altruistic yeast somehow resist invasion by cheats.

What makes this so interesting is that these simple organisms lack the cognitive ability to enact many of the behaviours that are thought to help maintain cooperation, such as punishing cheaters or preferentially helping cooperators. This shows that it must be possible for altruism to emerge from some fundamental process. Recent research has proposed a surprising explanation for this phenomenon, that cooperation is favoured by chance.

Altruism and cooperation are common in the natural world

Every biological population is subject to random fluctuations. For instance, although we can calculate the average birth rate in a country, each day there will always be deviations from this average. These deviations from the norm have a proportionally bigger effect in small populations rather than larger ones (think of the impact of a single birth on the population of a village compared to a city). Because cooperation allows a population to grow larger by working together, it turns out that the impact of random fluctuations is biased in favour of promoting altruism.

For the yeast, a sudden chance increase in the cheater population is bad news. There will no longer be enough food and so the population will decrease. The absolute size of the increase in the cheat population is therefore curtailed by the lack of food. Conversely, an equally likely chance drop in the number of cheats corresponds to an increase in the proportion of cooperators, and thus to the availability of food. This allows the total population to increase, amplifying the positive effect for the cooperators. In this way cooperators gain a small advantage from each random fluctuation, gradually allowing them to counter the reproductive speed of the cheaters. The statistical advantage gives the cooperators the strength in numbers needed to resist invasion by cheats, making altruism more likely to evolve in the long run.

Biological evolution is sometimes used as a template for how certain areas of human activity might function – a ‘survival of the fittest’ dynamic that efficiently finds the best solutions. But in biology the process of evolution is blind to the future, and so may select short-term selfish behaviours that give instant rewards, even if this means the long?term fate of the population is dire. But humans have the capacity to see our downfall unfolding. We can choose to change the rules of the game to improve our fate.

Dr George Constable is a researcher at the University of Zurich and Dr Tim Rogers is a research fellow at the University of Bath.

Not in our nature? Altruism and cooperation in numbers



Infographic design: Studio Blackburn

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