Possibly one of my biggest issues with the way evolutionary theory is described in the social sciences today is the characterization of evolutionary biology as somehow being based on the same assumptions as rational choice theory. Here is the first paragraph from a book chapter I saw today which motivated me to write this blog entry...

Evolutionary Theory and Cooperation in Everyday Life

David Sloan Wilson and Daniel Tumminelli O’Brien

"Theories of cooperation in both biology and the human social sciences have had a turbulent history. During the nineteenth and early twentieth centuries, it was common to regard societies as like organisms in their own right. This holistic worldview was largely replaced during the middle of the twentieth century by a more reductionistic view that sought to explain as much as possible in terms of individual self-interest. In evolutionary biology, this trend was represented by the rejection of group selection in favor of “the theory of individual selection” and ultimately “selfish genes.” In the human social sciences, the trend was represented by “methodological individualism” (Sober and Wilson 1998; Wegner 1986) and especially rational choice theory in economics, which assumes that all human preferences can

be understood in terms of individual utility maximization, with the utility usually conceptualized as material gain (e.g., income)."

Grrrrrr. Take a look at the picture (my artistic attempt to wash away 30 years of misunderstanding!) and hopefully you'll see why biologists get so frustrated when people equate their theories to economic rational choice.

Where do I start with this paragraph. Firstly what I do agree with: Of course saying humans behave as rational self-interested utility maximisers is totally silly in many situations (but I am wary to say more - I've spoken to several economists whose sentiments I can empathize with a lot - they tell me how people outside economists construct a straw-man normally called Homo economicus and then go to great lengths explaining why its a mad idea and the people who came up with it are mad (or perhaps just evil)....anyway, rational choice is good in some situations (I'm assured for financial stuff)...but in many other situations (the ones I'm interested in like social interactions) its woefully lacking.

The non-economic social sciences (sociology, anthropology etc.), from the start could see these problems, and clearly as the main areas of their interest fell into the realm where rational choice failed, they disliked the theory intensely. So as the world started to talk in terms of rational choice and individualism I can imagine how irritated whole departments of anthropologists were getting...

It took a lot of empirical evidence before people listened, but fortunately since the mid-90s, the limitations of rational choice are being considered seriously by its supporters. The field of behavioural economics is rapidly expanding and there are exciting and inspiring cross-disciplinary collaborations happening between economists and social science disciplines (economist-psychologist, economist-anthropologist etc).

OK, so what about evolutionary theory. On the surface, it sounds like a similar story is going on...in the 1970s, the collectivist "group-selection" ideas were finally extinguished, and everything was studied in terms of individual maximisation, indeed biologists went one step further and by the end of the 1970s were talking of "Selfish Genes"...opposition to these ideas began to mount, especially with the claims about human behaviour (see the Sociobiology EO Wilson controversy).

Starting in the 1980s and continuing today, these ideas have been challenged and a new way of looking at evolutionary biology from a group - or multi-level - perspective has replaced the old "NeoDarwinian" ideas. In recent years, this has lead to a flurry of Science and Nature papers by leading economists suggesting how human sociality can be understood as a group adaptation.

OK, I'll stop there with my "just-so" story of what "NeoDarwinian" evolutionary biology think.... For anyone interested in this topic most of this historical story will be old news anyway.

I'm not going to have time this evening to go through all the misconceptions in detail - but I'll start with the biggy that got me when I read that chapter I quoted earlier...that evolutionary biology rejected group-think and went for an individualist approach.

Before I go on, if you are interested, I humbly suggest you read this paper I've written with my colleagues at Oxford which we've submitted to the Journal of Economic Literature. It lists in detail many of the misconceptions I'll not doubt find myself writing about on this blog. (Apologies the references are not yet nicely formatted, there were so many we could not be bothered doing it until we were writing the final version). If you would like further reading go there and then see the references therein.

So true or false:

Evolutionary biology sees individuals as fitness maximsers. True.

Evolutionary biologists sees the individuals fitness (number of offspring) as the maximand.

False.

OK, I've got to go make dinner, so I'll have to return to this another day...here is the quick explanation...

Multiple copies of the same gene occur in different individuals in a population (if you are memebers of the same species i.e human, a vast majority of your genes will be identical, afterall we share 97%+ of our genes with a chimp).

Selfish Genes are only “selfish” when seen as a whole (as it is the fitness of the gene, not the fitness of its individual copies that is maximised). The "selfishness" here means maximsing its own transmission, not any other more emotive / morally loaded meaning of selfishness. As genes can be shared between species, for many genes the individual copies over which it maximises can be in a diversity of individuals. It has been shown formally (with maths) that genes (i.e. all copies of a particular gene) can be accurately described as maximsers.

Lets consider now an individual person (or animal if you prefer). That person will have millions of COPIES of different genes. The selfish gene idea never meant to suggest that an individual copy would be expected to behave selfishly. Indeed most gene copies favour cooperation with individuals that also have a copy of the same gene...because doing so maximises the gene fitness. So I stress, cooperation at the individual level is the predicted outcome of us sharing copies of the same "selfish" genes.

Individuals contain many genes leading to complex patterns of cooperation between them. This means individuals are NOT predicted to be rational maximsers akin to economic agents...their genes are (but as genes have copies spread across many individuals the way rational choice-style theory is applied it very different from the way we'd apply it assuming individual people are the economic agents).

How can we the define fitness in a useful way that helps us understand behaviours that individuals (or groups) perform that we are interested in (like human cooperation)? The answer is inclusive fitness. Recently, it has been shown formally (with maths) that it is accurate to say that an individual is adapted to maximse its "inclusive fitness". Inclusive fitness measures the degree to which an individual succeeds in transmitting the genes it bears copies of to future generations. To calculate the inclusive fitness of an individual you need to consider two things: an individual's direct and indirect fitness.

Direct fitness is the number of offspring an individual has (and the fact this is part of the inclusive fitness calcualtion I think added to the misunderstanding that individuals will maximse their fitness like an economic agent maximses utility).

Added to direct fitness is the indirect fitness, which is the number of offspring that others produce as a result of the individual helping them. The number produced it weighted by the relatedness between them.

I'll have to discuss relatedness in detail in the future...but suffice to say - if we share 97% of our genes with non-humans, its highly misleading to say that the indirect fitness component is only relevant when you are looking at close family (like chilren and cousins)...indirect fitness is often VERY important. Furthermore many of the recent models of human cooperation make it very hard to understand its importance and I'vew seen models with statements like "we examine a model of human cooperation evolving between unrelated individuals" actually works because of the indirect fitness benefits...but the way the maths os done makes that too obscure to see. This is obviously important because it means the model conclusions could be misapplied to real-world situations where they could not hold.

OK, thats enough from me, I think my husband is not too keen about my new-found interest in blogging! To conclude I re-stress that evolutionary biologists do NOT think organisms are individual fitness maximisers...indeed I'd like it if anyone could send me an article written by a reputable "NeoDarwinian" biologist who ever stated that.

Goodnight and thanks for reading,

Claire