Thursday, 2 September 2010

we are all apprentices

It is long, so here is a précis:

Evolutionary psychologists seek to explain the origins of universal human traits, like markedly high intelligence, language, tool-use, and social structures. The details of these explanations vary greatly in timing and detail (e.g., was it cooking food or an environmental shift that made the difference?) but almost all such explanations begin with some common assumptions.

First, "human evolutionary change has been self-generated through positive feedback." This kind of structure helps to explain why the traits of interest are unique to humans and universal among them. The elements of the feedback loop are (a) complex social environments and (b) high cognitive ability. Notice how this works: selection for co-operation also selects for free-riders. But the drag of free-riders selects for vigilance. And vigilance is accomplished with higher intelligence. Higher intelligence allows for greater social complexity (and co-operation). And so on.

Second, "adaptive response to our complex environment depends on innate, evolved, special purpose cognitive mechanisms, for it is only such mechanisms that enable us gather and deploy the information on which action depends." This is commonly known as the "modularity hypothesis," "the idea that our minds are ensembles of innately equipped special purpose devices; devices which adapt us to the challenges posed to our foraging Pleistocene ancestors; challenges which largely persist today. Our minds are integrated arrays of devices each of which solves a particular problem with remarkable efficiency." (e.g., face recognition or cheater detectors.) 

It is this second piece of the puzzle Sterelny takes issue with. In order for such modules to evolve, the information structure would have to remain stable for long periods of time. In some cases, this might be reasonable -- crudely (and slightly off-topic), tigers have always been about the same size and speed, so a tiger-avoidance module could stabilize. But many important features of our information environment have changed drastically, and too rapidly for (genetic) evolution to keep pace. We have become more sedentary and traded field for market and rocks for iPhones. "To the extent that the modularity hypothesis explains competent response to information-hungry problems by appeal to pre-loaded information, it is poorly posed to explain competent response to evolutionarily novel challenges."

Sterelny wants to trade out "modules" for "skills." Skills look a lot like modules: they are task-specific and fast. But there is a big difference: skills are learned wholesale, they are not modules just waiting for parameters to be set:
High volume, high fidelity, inter-generational cultural learning coevolves with social foraging. There is feedback. As the fidelity of social learning improves, social foraging becomes more effective, for technology and technique improve across the generations. As social foraging becomes more profitable, adults can more effectively support the next generation while they acquire skills and information. This loop depends on the fact that humans organise the learning world of the next generation. Humans (like many other organisms) modify their own environment. One important form of human niche construction is informational engineering. Humans of one generation act in ways that transform the learning environment of the next generation. Cultural learning is obviously central to human social life. But most cultural learning is hybrid learning; it is culturally enhanced trial and error learning. Very few humans acquire significant life skills just from instruction and demonstration; very few learn skills by unassisted exploration. Human children explore and experiment on their physical and social environment. But they often explore environments which have been shaped to make it easier or safer for them to acquire critical capacities.

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