Wilson and colleagues are to be congratulated for their interest in developing a science of intentional change, which is a critical component of human evolution. They make the excellent point that all too often the biological sciences and the behavioral sciences seem to be miles apart in how they approach human phenotypic variation – a separation that even makes its way down into individual disciplines. To extend the point they make with respect to divisions within psychology, the various social and behavioral sciences in general share an interest in phenotypic change, but each at a different scale of analysis. To grossly oversimplify, psychology tends to focus on the individual, anthropology on small groups and communities, and sociology and human geography on populations. Perhaps the widest lens is used by macroeconomics, which renders human societies as abstract mathematical systems that are brought full circle through highly simplified assumptions about the behavior of individuals. Having these different scales of analysis is a strength, but it also presents a challenge for finding a unified approach to human behavior, which, despite comprehensive reviews in this journal (e.g., Gintis Reference Gintis2007; Mesoudi et al. Reference Mesoudi, Whiten and Laland2006) and elsewhere (e.g., Laland & Brown Reference Laland and Brown2011; Mesoudi Reference Mesoudi2011; Mesoudi et al. Reference Mesoudi, Whiten and Laland2004), has been difficult to achieve (Gintis Reference Gintis2009b).
I suggest there is an important component of the discussion that has been left out of the blueprint for consilience, at least in its explicit form. That component is niche construction, which is the process whereby organisms, through their activities, interactions, and choices, modify their own and one another's niches, thereby acting as codirectors of their own evolution as well as that of others (Odling-Smee et al. Reference Odling-Smee, Erwin, Palkovacs, Feldman and Laland2013). The discussion by Wilson and colleagues is wonderfully preadapted for niche-construction theory. In fact, much of what they state or imply constitutes the basics of the approach. I paraphrase and slightly expand three of their points:
-
1. Evolution is the overarching process by which organisms change in relation to their environments, not only by genetics but also by mechanisms of phenotypic plasticity that evolved by genetic evolution, including some that count as evolutionary processes in their own right.
-
2. Complex special-purpose adaptations that arise through genetic evolution result in nongenetic mechanisms of inheritance that are capable of rapidly adapting organisms to their current environments.
-
3. Many species have the capacity for open-ended learning at the individual level, but humans have an elaborate capacity at both the individual and the social levels as a result of culture, which can be defined as information capable of affecting the behavior of individuals and which they acquire from other individuals through any of a number of social-learning pathways, including teaching and imitation (Richerson & Boyd Reference Richerson and Boyd2005).
Wilson and colleagues rightly point out that the conventional view of evolution is that species, through the actions of natural selection, come to exhibit those features that best enable them to survive and reproduce in their environments. Under this perspective, “adaptation is always asymmetrical; organisms adapt to their environment, never vice versa” (Williams Reference Williams1992, p. 484). Alternatively, niche construction creates adaptive symmetry by using and transforming natural selection, thus generating feedback in evolution at various levels (Laland & Sterelny Reference Laland and Sterelny2006). To quote Levins and Lewontin, “The organism influences its own evolution, by being both the object of natural selection and the creator of the conditions of that selection” (Levins & Lewontin Reference Levins and Lewontin1985, p. 106). Niche-constructing species play important ecological roles by creating and modifying habitats and resources used by other species, thereby affecting the flow of matter and energy through ecosystems. This process, often referred to as “ecosystem engineering” (Jones et al. Reference Jones, Lawton and Shachak1994), can have significant downstream consequences for succeeding generations, leaving behind an “ecological inheritance” (Odling-Smee Reference Odling-Smee and Plotkin1988).
One key emphasis of niche-construction theory – certainly one that sets it apart from the conventional view of evolution – is the role played by acquired characters in transforming selective environments. This is particularly relevant to human evolution, where our species has engaged in extensive environmental modification through cultural practices. This is why humans have been referred to as the “ultimate niche constructors” (Odling-Smee et al. Reference Odling-Smee, Laland and Feldman2003, p. 28). Humans can construct developmental environments that feed back to affect how individuals learn and develop and the diseases to which they are exposed.
There is good reason to think that selective feedback from human cultural activities to human genes – as well as to those of other species – may be a general feature of human evolution. Given that geneticists have identified several hundred human genes subject to selective sweeps over the last 50,000 years or less, it may be that gene-culture coevolution is the dominant form of human evolution (Feldman & Laland Reference Feldman and Laland1996; Laland et al. Reference Laland, Odling-Smee and Myles2010; Richerson et al. Reference Richerson, Boyd and Henrich2010). If so, then there is all the more reason to adopt the kind of analytical framework advocated by Wilson and colleagues, perhaps with an explicit role for niche construction and the emphasis it places on the power of human agency as an evolutionary process (Kendal Reference Kendal2011; Laland & O'Brien Reference Laland and O'Brien2010; O'Brien & Laland Reference O'Brien and Laland2012).
Space precludes a side-by-side comparison, but Wilson and colleagues' Figure 1, which illustrates interventions by developmental phase, and their Table 2, which lists community interventions and policies, would be right at home in any study conducted by niche-construction enthusiasts. With slight modification, their Figure 1 becomes a construction chain – a flow diagram that summarizes the immediate and downstream consequences of an act of niche construction and its consequences for other processes, operating at other levels and feeding back into the phenotypes, and often the genotypes, of the actors. It does not matter whether one is talking about planting yams in West Africa, which has tremendous downstream consequences in terms of the balance between malaria and sickle-cell disease (O'Brien & Laland Reference O'Brien and Laland2012), or Wilson and colleagues' development of community policy to lower juvenile drinking, which has similar consequences in terms of fetal alcohol syndrome, crime, and a rash of other problems. What matters is that we understand that they are both instances of human niche construction and that neither can be understood simply in light of classical evolutionary theory.
You have
Access
Wilson and colleagues are to be congratulated for their interest in developing a science of intentional change, which is a critical component of human evolution. They make the excellent point that all too often the biological sciences and the behavioral sciences seem to be miles apart in how they approach human phenotypic variation – a separation that even makes its way down into individual disciplines. To extend the point they make with respect to divisions within psychology, the various social and behavioral sciences in general share an interest in phenotypic change, but each at a different scale of analysis. To grossly oversimplify, psychology tends to focus on the individual, anthropology on small groups and communities, and sociology and human geography on populations. Perhaps the widest lens is used by macroeconomics, which renders human societies as abstract mathematical systems that are brought full circle through highly simplified assumptions about the behavior of individuals. Having these different scales of analysis is a strength, but it also presents a challenge for finding a unified approach to human behavior, which, despite comprehensive reviews in this journal (e.g., Gintis Reference Gintis2007; Mesoudi et al. Reference Mesoudi, Whiten and Laland2006) and elsewhere (e.g., Laland & Brown Reference Laland and Brown2011; Mesoudi Reference Mesoudi2011; Mesoudi et al. Reference Mesoudi, Whiten and Laland2004), has been difficult to achieve (Gintis Reference Gintis2009b).
I suggest there is an important component of the discussion that has been left out of the blueprint for consilience, at least in its explicit form. That component is niche construction, which is the process whereby organisms, through their activities, interactions, and choices, modify their own and one another's niches, thereby acting as codirectors of their own evolution as well as that of others (Odling-Smee et al. Reference Odling-Smee, Erwin, Palkovacs, Feldman and Laland2013). The discussion by Wilson and colleagues is wonderfully preadapted for niche-construction theory. In fact, much of what they state or imply constitutes the basics of the approach. I paraphrase and slightly expand three of their points:
1. Evolution is the overarching process by which organisms change in relation to their environments, not only by genetics but also by mechanisms of phenotypic plasticity that evolved by genetic evolution, including some that count as evolutionary processes in their own right.
2. Complex special-purpose adaptations that arise through genetic evolution result in nongenetic mechanisms of inheritance that are capable of rapidly adapting organisms to their current environments.
3. Many species have the capacity for open-ended learning at the individual level, but humans have an elaborate capacity at both the individual and the social levels as a result of culture, which can be defined as information capable of affecting the behavior of individuals and which they acquire from other individuals through any of a number of social-learning pathways, including teaching and imitation (Richerson & Boyd Reference Richerson and Boyd2005).
Wilson and colleagues rightly point out that the conventional view of evolution is that species, through the actions of natural selection, come to exhibit those features that best enable them to survive and reproduce in their environments. Under this perspective, “adaptation is always asymmetrical; organisms adapt to their environment, never vice versa” (Williams Reference Williams1992, p. 484). Alternatively, niche construction creates adaptive symmetry by using and transforming natural selection, thus generating feedback in evolution at various levels (Laland & Sterelny Reference Laland and Sterelny2006). To quote Levins and Lewontin, “The organism influences its own evolution, by being both the object of natural selection and the creator of the conditions of that selection” (Levins & Lewontin Reference Levins and Lewontin1985, p. 106). Niche-constructing species play important ecological roles by creating and modifying habitats and resources used by other species, thereby affecting the flow of matter and energy through ecosystems. This process, often referred to as “ecosystem engineering” (Jones et al. Reference Jones, Lawton and Shachak1994), can have significant downstream consequences for succeeding generations, leaving behind an “ecological inheritance” (Odling-Smee Reference Odling-Smee and Plotkin1988).
One key emphasis of niche-construction theory – certainly one that sets it apart from the conventional view of evolution – is the role played by acquired characters in transforming selective environments. This is particularly relevant to human evolution, where our species has engaged in extensive environmental modification through cultural practices. This is why humans have been referred to as the “ultimate niche constructors” (Odling-Smee et al. Reference Odling-Smee, Laland and Feldman2003, p. 28). Humans can construct developmental environments that feed back to affect how individuals learn and develop and the diseases to which they are exposed.
There is good reason to think that selective feedback from human cultural activities to human genes – as well as to those of other species – may be a general feature of human evolution. Given that geneticists have identified several hundred human genes subject to selective sweeps over the last 50,000 years or less, it may be that gene-culture coevolution is the dominant form of human evolution (Feldman & Laland Reference Feldman and Laland1996; Laland et al. Reference Laland, Odling-Smee and Myles2010; Richerson et al. Reference Richerson, Boyd and Henrich2010). If so, then there is all the more reason to adopt the kind of analytical framework advocated by Wilson and colleagues, perhaps with an explicit role for niche construction and the emphasis it places on the power of human agency as an evolutionary process (Kendal Reference Kendal2011; Laland & O'Brien Reference Laland and O'Brien2010; O'Brien & Laland Reference O'Brien and Laland2012).
Space precludes a side-by-side comparison, but Wilson and colleagues' Figure 1, which illustrates interventions by developmental phase, and their Table 2, which lists community interventions and policies, would be right at home in any study conducted by niche-construction enthusiasts. With slight modification, their Figure 1 becomes a construction chain – a flow diagram that summarizes the immediate and downstream consequences of an act of niche construction and its consequences for other processes, operating at other levels and feeding back into the phenotypes, and often the genotypes, of the actors. It does not matter whether one is talking about planting yams in West Africa, which has tremendous downstream consequences in terms of the balance between malaria and sickle-cell disease (O'Brien & Laland Reference O'Brien and Laland2012), or Wilson and colleagues' development of community policy to lower juvenile drinking, which has similar consequences in terms of fetal alcohol syndrome, crime, and a rash of other problems. What matters is that we understand that they are both instances of human niche construction and that neither can be understood simply in light of classical evolutionary theory.