Evolving ideas

November 7, 2009

A Thought About Dual Inheritance Theory

Filed under: Uncategorized — Tom @ 2:11 pm

I recently had reason to re-read Eric Alden Smith’s chapter on Three Styles in the Evolutionary Analysis of Human Behaviour. This chapter was published in 2000 and discussed the relative merits of Evolutionary Psychology, Human Behavioural Ecology and Dual Inheritance Theory (DIT). Some might say that this chapter is now out of date, and that the boundaries between these three sub-disciplines, or styles, has begun to erode with scientists now pursuing particular kinds of question with specific methodologies. Moreover there is some evidence, folk might say, that researchers recognize the need to discuss population level behavioural patterns, in order to proscribe parameters for the more proximate musings of, for example, evolutionary psychologists.

Given the rhetorical nature of the preceding paragraph one might assume that I think the boundaries are eroding. I certainly think that conceptually they ought not to have been there for evolutionary psychology and human behavioural ecology, and I suspect a deep sociological theory will reveal why such issues existed, perhaps revealing an abiding problem of funding and departmental pecking orders. I do, however, think that DIT ought to be seen as a stand-alone activity.

On page 32 Smith outlines the core of DIT. DIT claims that culture exhibits heritability, variation and fitness effects, but that cultural inheritance is different from genetic inheritance. So, neo-Darwinian modelling can be applied to cultural change but with modifications to account for the difference in inheritance. Furthermore, given this distinction between inheritance systems, cultural evolution can lead to genetically maladapted forms. Smith then moves on to claim that DIT can sustain particular forms of group selection:

“Since collective action often involves systems of widespread and indirect reciprocity (e.g. serving as a soldier on behalf of one’s society is reciprocated with various kinds of rewards to the soldier or his kin), it qualifies as a form of social exchange. Boyd and Richerson… have constructed models of cultural group selection of such group-beneficial behaviours. These models show that cultural inheritance plus conformity transmission (‘when in Rome, do as the Romans do’) can in principle create and maintain significant between-group differences despite reasonable rates of migration between these groups, thus avoiding a major obstacle facing classical forms of genetic group selection.

“The mechanisms of group selection most commonly proposed in this regard is group dissolution due to warfare, with refugees from defeated groups being absorbed by allied groups; if culturally transmitted traits that favour socially altruistic traits (e.g. contributing to the collective good of military defense and offense) decrease the probability of group defeat and dissolution, then these could spread by cultural group selection…” (Smith, 2000: 33)

Putting to one side the technical problems of group selection, another way of stating this effect (if it indeed qualifies as an effect) is that a defeated person can be housed within the population that defeated him or her and learn that contributing in a particular way to the group will sustain him or her. We can hypothesize that humans have good learning mechanisms that enable them to conform at the appropriate point.

More critically, if one removes the possibility of changing strategic response for absorbed refugees, the victorious groups will change the ratio of committed soldiers to uncommitted members both through absorption and the natural attrition of soldiers as a consequence of what they do. As these proportions change so will the population dynamics within the group. This is likely to erode between group differences and increase within group variation thus undermining the claimed possibility of group selection.

So, either absorbed refugees can change and conform, in which case the explanatory action is at the psychological level and we are back to normal evolutionary concerns with regard to the selection of such learning mechanism, or they cannot and the constitution of the groups will change and prevent sufficient between group differences for the kind of selection wished for.

My charitable suspicion is that DIT folk heuristically think of groups as organisms with phenotypes, and see them competing in a given ecology with other such individuals. However, once they have modelled some dynamic interaction between such individuals, perhaps in a similarly approximate way that gene-level selectionists might look at individuals, they remember that they are groups, that the inheritance is within and between groups, that it is different from genetic inheritance in many other ways (not least its low fidelity), and so they try and force the group selection point. Indeed, they call it cultural group selection in an attempt to move away from contentious issues in biology.

To conclude, I think that this use of (cultural) group selection by DIT theorists shirks explanatory responsibility. What is interesting is how humans ever begin cooperating in the first instance, how human psychology facilitates the emergence of stable equilibria in a variety of social games. Evolutionary psychology will tell you that evolutionary game theory will predict the emergence of certain strategies that are the product of gene-level dynamics. By establishing these strategies we can then begin to look at the psychological mechanisms that are, by extension, part of this strategic response, and then map the variation in these phenotypes. Such activities are entwined with behavioural ecological concerns about facultative responding to different ecological facts, in order to (try and) maximize fitness. I recognize this is a rather a skimming treatment of the situation, but it serves to emphasize what DIT is not delivering. DIT at best might highlight something to look at – the operation of conformity or some such – but by forcing what is at best an analogy with genetic inheritance, and thereby biological evolution, the discipline misses the intrinsic puzzle of the phenomenon, a phenomenon that evolutionary social psychology can take care of. To this end, DIT is in no sense a style of evolutionary analysis, as Smith has claimed.

(If you want to see how to think about all of the underlying biology properly then you should read West et al. (in preparation). This paper is the best I have read on the topic of cooperation, and deals with the claims from group selectionists decisively and fairly. It deserves to be widely cited upon publication.)

September 21, 2009

The next two posts

Filed under: Uncategorized — Ben @ 9:16 pm

The next two posts our guest posts by John Jacob Lyons.

April 4, 2009


Filed under: Uncategorized — Ben @ 12:25 am

A disclaimer about what follows: this is a substantial digression from any area I might claim knowledge of.

Quantum theory is counterintuitive in interesting ways. Many people emphasise the strangeness of indeterminacy and adduce it to argue that the mind contains or operates special causal levers. I don’t see a great benefit to uncaused causes for a free-will enthusiast or, for that matter, for first-cause mysticisers, so I tend to be sceptical of many popular claims of this nature. Indeterminacy is counterintuitive and interesting but determinacy isn’t a pin in the grenade of rationalism.

Non-locality  – or the capacity for state changes to propagate between entangled particles with no intermediaries and with no delay – has always seemed more interesting to me. This recent popular article emphasises its incompatibility with general relativity. It turns out that non-locality’s absolute simultaneity poses a significant challenge for physics and, given our ideas of the geometry of spacetime, for our understanding of causation.

Reading this stimulates in me the intuition that perhaps locality is in some sense incoherent. Just how close do two objects have to be (à la Zeno’s paradox) for interactions between them to be considered local? Is it necessarily all that peculiar that events in the future might determine events in the past?

I think that our concepts of locality and ontology are linked in such a way that revisions may be required in both. If X and Y make up the entity Z then any properties of Z will be shared by X and Y regardless of where and when X and Y are. This argument makes the description of instantaneousness redundant and I suspect that quantum entanglement is somewhere between the situation just described and one in which X and Y are truly separate entities. Perhaps the problem of non-locality cuts into ontology. I would very much appreciate any more expert thoughts on the matter…

March 27, 2009

Creative thinking

Filed under: Uncategorized — Ben @ 10:46 pm

There is a pattern in the way I respond to world events with high penetrance in the news. I tend to become emotional and ideologically minded, then analytical and anti-ideological. The financial and economic situation is no exception and it seems to offer plenty of opportunities for my sort of confusion. Here is a chance to push a social democratic agenda, to challenge market fundamentalism – the argument for market failure seems compelling. On the other hand, I am losing confidence in the stimulus: both as a concept championed by economic “science” and as a policy carried out by crony capitalists with friends in certain industries. I am entering my sceptical, anti-ideological phase – totally free markets are footling abstractions, real markets are fallible, real regulation inadequate, and the re-colonisation of the markets by governments not entirely benign. The disappointingly minimal conclusion seems to be that highly abstracted financial markets are negative sum or at least dangerously unpredictable (perhaps because of dangerous levels of prediction in them, after Nassim Nicholas Taleb). So while we can say that markets are engines of growth (and defend some level of abstraction in them), none of the big -isms offer much to add to or challenge this view and we must muddle along and cope with some of the absurd consequences of the dominance of betting in our economy (see this article for a specific and complex example).

But this recent piece has got me thinking about whether a more creative response is possible. The open source movement has made inroads beyond software into other social spheres (certainly into science where PLoS journals are flagships) and seems to offer a genuinely novel approach to production. Just as the market solves the tragedy of the commons, so open source approaches offer a solution to the tragedy of the anticommons (wherein production is limited because ownership of necessary components is distributed between companies each of which values their asset(s) at a price commensurate with sufficiency). And since open source approaches are decentralised they seem part of the solution for the burgeoning energy costs of the growing networks that support human society. The reduced transaction costs of the internet seem to offer a way to reinforce cooperation and more research is clearly needed to explore which factors drive and which factors limit this. Perhaps then we can take some of these ideas offline and into the wider world to produce robust and sustainable economies.

August 11, 2007

Induction and scepticism

Filed under: Uncategorized — Ben @ 10:16 pm

I’m just starting to read “The Black Swan: the impact of the highly improbable” by Nassim Nicholas Taleb. So far, so fun (have a read: UK and US). The title is motivated by the fact that it takes only one observation of a black swan to undermine the supposition that all swans are white even though we may have years of observations to back it up. This is the classic problem of induction.

It looks like a major claim of the author will be that the probability distributions that underlie the majority of events in the natural and social world are non-normal and subject to huge sampling error. Hence the problem of induction is a severe one in everyday life. Also this problem is one that lies at the edge of our knowledge since knowledge is most easily acquired about systems with more predictable properties. I might be over-interpreting here, but I suspect that this leads him to conclude that science communication, story-telling about uncertainty, is a flawed activity that will itself promote unpredictability by making people less savvy about risky and rare events in a globalised, mass-media world.

I find it an interesting to think that what we don’t know is somehow different in kind from what we do know. It is certainly good to be humble about the limits of knowledge in general. But I am also suspicious that there may be radical scepticism in here: something one tends to find surrounding poorly-evidenced and contrarian ideas. So I will be looking out for selective use of the unpredictability idea and for alternatives that massage intuitions in the absence of evidence.

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