As with “the selfish gene”, kin selection is a valid perspective which manages to become misleading by missing the point of what it is trying to explain. The idea behind it, developed by J.B.S. Haldane and W.D. Hamilton in the late 1950's and early 1960's, is simply that the behaviour of a great many organisms include the risk or sacrifice of the individual for the benefit of relatives – for instance, alarm calling in squirrels (which puts the caller at greater risk from predators), or sterile worker bees who will never breed. According to conventional Darwinian thinking, natural selection should (supposedly) eliminate such behaviours (at least when considered from the gene-centric view), so kin selection was introduced to explain the apparent anomaly.
But there is no anomaly to explain here: the assumption that natural selection cannot favour the risk or sacrifice of individuals rests on a chain of inferences linking behaviour to strict genetics, which as already discussed is a flimsy argument. When we think of “advantages persisting” instead of “selfish genes”, it becomes clearer that co-operation will not be eliminated by natural selection – it will in fact be selected for whenever it is advantageous. As Peter Kropotkin observed in the 1890s, co-operation and mutual aid contribute significantly to the survival of species, since a group of animals can achieve more than the individual members can on their own. The rise of humanity as a species appears to have been significantly facilitated by its capacity to act as a group.
The power of co-operation even extends into the world of plants: Allen Herre and Elizabeth Arnold discovered that plants defend themselves from fungal infection by hosting a population of symbiotic fungal lifeforms (known as endophytes). Throughout the natural world, examples of beneficial co-operation – symbiosis – can be found. In almost every environment, one can find examples of genetically distinct organisms which co-operate, and thus gain advantages in survival and reproduction.
Furthermore, as Lynn Margulis has explicated, all multi-cellular life operates as a consequence of symbiotic co-operation between micro-organisms which have become so reliant upon one another that we mistake their colonies for individual animals. This viewpoint, which is referred to as endosymbiotic theory, originates in the work of the Russian botanist Konstantin Mereschkowski, who in 1905 observed that cell division in chloroplasts mirrored that in free-living cyanobacteria.
You and I are the product of co-operation between billions of cells (closely related to bacteria) which came together to act as one – the mitochondria (cellular powerhouse) and other organelles in each of your cells descend from bacteria which began to work closely together between 1.6 and 2 billion years ago. This astonishing evolutionary development, along with other symbiotic adaptations, have had as great a role in the development of life on Earth as competition between species.
On the macroscopic scale in which we are more familiar, the existence of social animals who co-operate for mutual benefit is another overt sign of the benefits of co-operation. Although it is misleading to conflate biological mechanisms with behaviour, the hormone and neurotransmitter oxytocin appears to be the constitutive mechanism by which trust operates. Almost all vertebrate species possess a chemically similar protein, which appears to have originally been involved in water regulation. From amphibians onwards, however, there has been a trend of increasing capacity for trust between animals – something we are most familiar among mammals, who form packs and other groups for mutual benefit, but which is also found in the flocking of birds, and even in reptiles and fish. Oxytocin and other related proteins also seem to play a critical role in the formation of families (a large quantity of oxytocin is released during childbirth), one of the most important survival benefits found in the natural world.
The extent to which co-operation affords advantage is apparent in the prevalence of mutual aid in the ocean. Coral reefs, which are nature's cosmopolitan cities, contain species such as cleaner wrasse (pictured above) and cleaner shrimp which remove parasites and dead tissue, even from within the mouths of other fish who do not harm the cleaning animal. Recent observations have shown dozens of sea snakes co-operating not only with each other but also with goatfish and trevally in an astonishing display of multi-species collaboration, dramatically depicted in the recent Planet Earth nature documentary. This is not to deny that competition between and within species does not also occur, nor to claim that savage acts do not happen in the natural world, but there is no reason (other than a metaphysical commitment) to deny that symbiosis and other forms of co-operation are also a key part of the story of life.
All of which goes to demonstrate why co-operation is so well represented throughout biology: it is an advantage so powerful, whenever species stumble upon it, it tends to persist. Rather than trying to shoehorn this observation into older models (as with kin selection), perhaps we might consider a new story which captures the incredible role of co-operation in evolution. Simple lifeforms co-operate because it's in their mutual benefit, and advantages tend to persist, but more complex life (such as humans) co-operate not just because it is immediately advantageous but also because we have inherited a biological mechanism which facilitates the formation of trusting relationships – primarily with our relatives, but potentially with anyone. The story that trust is an advantage runs contrary to the usual mythologies of evolution, but it is just as valid, and far more optimistic.
Alternative myth: Trust is an Advantage
Next Week, the Final Part: Myth #5: Survival of the Fittest