(p. 1) Philosophical issues
Evolutionary psychology has its origins in the merging of two intellectual streams that have, in the past, largely been only tangentially related: evolutionary biology and psychology. We make a strong case here for maintaining the broadest possible remit for this nascent discipline, arguing that attempts to confine its interests to specific aspects of cognition or behaviour fail to appreciate both the lesson and the opportunity that Darwinian evolutionary theory offers us. The essence of the approach on which we have premised this volume is that the evolutionary approach is not a competing sub-discipline within psychology, but rather provides a framework for integrating psychology's diverse sub-disciplines and uniting them with those streams of organismic biology that concern themselves with behaviour—a programme that Celia Heyes (2000) has referred to as ‘evolutionary psychology in the round’.
In the long run, the essence of any such development must focus on understanding the role of culture in the human condition. However spectacular and fascinating the cultural behaviour of animals like whales and primates may be, it is self-evidently not in the same league as that of humans. Equally, however, it is not enough simply to say that humans are different, and leave it at that. We need to understand how and why humans are so different from other animals. Plotkin reminds us that part of that difference lies in the capacity for shared knowledge, for recognizing socially constituted facts (what the philosopher John Searle refers to as ‘institutional facts’) and using these in the construction of our social relationships. A dollar bill is not just a unit of currency, it is also an agreement among a group of individuals to use it as the basis for trading relationships. However, the capacity for shared knowledge does not occur in a psychological vacuum: it depends on the prior existence of cognitive mechanisms capable of supporting such functions. We know almost nothing of what these cognitive mechanisms might be, though it is widely accepted that theory of mind and other facets of ‘mentalizing’ (see Baron-Cohen, Section IV) constitute the core.
The central importance of culture is also taken up by Mameli. One of the important issues he emphasizes is the fact that cultural transmission allows the transgenerational transmission of knowledge. In this way, humans shape the environment in which their children develop, thereby both speeding up the process of learning how to cope with the vagaries of the environment and structuring the social context in which the individual lives and makes its evolutionarily valent decisions. These, as Mameli reminds us, are all but unstudied aspects of human evolutionary psychology. In effect, humans niche-construct their environment. Laland explores this in more detail. Social learning, as Laland reminds us, is the core to cultural transmission, and the impact of cultural transmission can be so powerful that cultural knowledge can rachet up the impact of niche construction in an evolutionarily (p. 2) very powerful mix. We currently have almost no real understanding of how these processes work, or how they actually affect human reproductive and other decisions, though some initial modelling work confirms that these effects are likely to be very important.
At one level, multi-level selection forms an extension of niche construction theory: by creating higher-order structuring to populations of individuals (i.e. social groups), humans and other social species modify the environment of selection within which they live. Groups buffer individuals against certain selection pressures. Wilson reminds us that this is not naïve group selection, of the kind that bedevilled biology (and especially the study of animal behaviour and ecology) during the first half of the twentieth century. The important difference between naïve group selection and multi-level selection is that the latter emphasizes that it is genetic fitness at the level of individual (or more appropriately, of course, the individual allele) that provides the unit of cost-accounting, whereas the former assumes that it is the group itself. Wilson's point is essentially that selection can act at the level of the group but its consequences fall at the level of the individual. There has, to date, been no study that seeks to explore the consequences of group-level processes for individual fitness. It is a topic that urgently needs addressing.