Definition Evolutionary Developmental Psychology

The publication of Origin of Species by Charles Darwin in 1859 initiated the beginning of a scientific, cultural and social revolution - one that caused science and society to view the origin of humankind and its relationships with other living beings differently. Not surprisingly, Darwin's ideas have often been compared with those of Copernicus because of their deep impact, not just in science, but in culture and human understanding. As is the nature of science, ideas also change and evolve, and the core of evolutionary thinking since the middle of the 20th century (the so-called New or Modern Synthesis) is actually a mixture of Darwinian ideas about natural selection and contemporary genetic theory, as initially developed by people such as Dobzhansky [1937], Mayr [1942] and Simpson [1944]. Yet, the principal mechanism of evolutionary change proposed by Darwin remains alive, namely natural selection, which involves four straightforward principles: (1) there are more members of a species born in each generation than will survive (i.e., superfecundity); (2) there is variation in physical and behavioral characteristics among individuals within species; (3) this variation is heritable, and (4) characteristics that result in an individual surviving and reproducing tend to increase in frequency in the population, whereas characteristics of nonsurvivors decrease. Evidence from a broad range of disciplines, including biogeography, paleontology, comparative anatomy, embryology and molecular biology [Ayala, 1999; Weiner, 1995; US National Academy of Sciences, 1984] has provided consistent support for Darwin's contention, making the 'fact' of evolution undeniable, with natural selection being the most potent (though likely not the sole) mechanism responsible for changes in species over time [Gould, 2002; Mayr, 1982]. 

Psychological science as a whole - and particularly developmental psychology has not been immune from the findings and theories related to biological evolution. In fact, the origin of developmental psychology as a discipline has often been linked with the evolutionary thinking of the scientific community during the latter half of the 19th century [Delval, 1982, 1988, 1994; Cairns, 1983; Dixon and Lerner, 1992]. However, others have questioned the importance of such a link [Bradley, 1989; Charlesworth, 1992] or proposed that developmental psychologists have misunderstood Darwin's message, resulting in what Morss [1990] called the 'Darwinian myth', or what Lickliter and Berry [1990] referred to as the 'phylogeny fallacy'. Moreover, the main theoretical streams that have led psychological thinking over the last century (behaviorism and cognitive psychology) have focused on levels of analyses that did not make completely necessary reference to either biology or evolution [Hernandez Blasi, 2000], and this includes mainstream developmental psychology. To date, after almost 150 years since Darwin's ideas were published, the influence of evolutionary ideas on developmental psychological theory and research has been weak (although there are some exceptions, for instance, attachment theory, see Bowlby [1969]). Evolutionary thinking has remained within our discipline more as a vague theoretical reference than as an active pool of ideas to serve as a framework for doing research on development. As Charlesworth noted in 1992, 'the revolutionary implications for studying human behavior from an evolutionary point of view are just starting to be realized' (p. 9), and we believe that developmental psychology should partake fully in 21st century Zeitgeist that recognizes phylogenetic influences on human thought and behavior. 

Although few contemporary psychologists, developmental or otherwise, deny the fact of human evolution, there has been (and continues to be) a long-standing resistance in the social and behavioral sciences to the application of evolutionary theory to explain human behavior [Brown, 1991; Geertz, 1973; see Tooby and Cosmides, 1992, for a review]. This stems, in part, from a belief that humans possess a unique set of mental faculties that provides them a degree of intentional control over their behavior, freeing them from the constraints of biology and obviating a need for an understanding of Homo sapiens' phylogenetic history in order to understand its behavior. Relatedly, evolutionary psychology and other biologically based approaches to human behavior smack of genetic determinism and serve, in the minds of some, to minimize the role of culture in influencing behavior. According to Tooby and Cosmides [1992], the standard social science model, which proposed that humans possess no 'nature' but are solely the products of their culture, dominated thinking in the social sciences through the 20th century and made no room for evolutionary thought in explaining human behavior. 

Tooby and Cosmides [1992] discussed at great lengths many of the shortcomings of the standard social science model, and research over the past several decades has clearly shown that humans are not born as blank slates but have biologically influenced constraints that affect their perception, cognition and social and emotional behavior [Bjorklund and Pellegrini, 2002; Gelman and Williams, 1998]. Moreover, contemporary evolutionary psychological theory emphasizes that there is substantial plasticity in development, making any claims of genetic determinism incorrect (see further discussion below). Finally, an explosion of research in comparative psychology has revealed both many similarities and differences in the social and cognitive abilities of H. sapiens and our great ape relatives [Byrne, 1995; Tomasello and Call, 1997; Parker and McKinney, 1999; Suddenhof and Whiten, 2001], supporting the existence of a phylogenetic continuity of mental function. Although such discoveries and insights do not require that contemporary human functioning and development be examined from an evolutionary perspective, we believe that such advances make the time ripe for such an analysis.