Developmental Theory

The English naturalist Charles Darwin's principles of natural selection provide the theoretical foundation for the biological sciences and are frequently used to address issues in the medical and social sciences. Evolutionary theory can also be used to understand human development in general and children's academic development in particular.

Life History

Biologists study development by documenting species' life history. Life history refers to the typical ages associated with developmental milestones, such as length of gestation, age of weaning, and life span. Certain life history patterns have been found in many different species. For instance, a long developmental period is common for species that have large brains and sophisticated cognitive skills, and live in complex social groups. The implication is that the demands of living in a complex social world resulted in evolutionary expansions of the developmental period and brain size, and resulted in more complex social-cognitive abilities. The larger brain supports complex social-cognitive abilities, such as language in humans. The long developmental period allows the individual to engage in activities that refine social and other (e.g., foraging) skills.

Human life history. The same life history perspective has been applied to human development and is understood in the context of hunter-gatherer societies, that is, societies that are similar to those in which humans evolved. In these societies, there are five distinct periods in the human life cycle. Infancy is the time of breast-feeding, and lasts until the age of three years. Childhood begins with weaning and lasts until age seven. During this four-year span, children are still heavily dependent on parents, but are becoming increasingly independent. Juvenility ranges from seven years until the onset of puberty, which often does not occur until the mid-teens in hunter-gatherer societies. Adolescence is the time of physical maturation, and adulthood is the period of mature reproductive activities. These include finding a mate and providing for the well-being of children. Each of these periods is characterized by different social relationships and degree of cognitive maturity.

Social development. Social relationships in infancy and childhood function to allow normal physical development (e.g., rapid brain development) and to reduce mortality risks. In hunter-gatherer societies, a high percentage (50%) of children die before reaching juvenility. Social relationships and other activities during juvenility involve a preparation for later survival-related (e.g., hunting) and reproductive activities. Social relationships in adolescence and adulthood are focused more directly on survival and reproduction.

The primary relationship during infancy and childhood is between the child and his mother, although the father is also heavily involved in some cultures. The nature of this relationship is termed attachment. Attachment-related behaviors, such as separation anxiety, keep the child close to his parents and thus safe. Play becomes an important activity during childhood, and models adult activities, as in play parenting. During juvenility, the focus of social relationships shifts from parents to peers. Peer relationships mirror and thus provide a context for practicing adult social activities. As an example, boys engage in play fighting and organize themselves into large groups that then compete against other groups of boys. These activities result in the practice and refinement of the social and cognitive skills associated with primitive warfare.

Adolescence is defined by the physical changes that prepare the individual for reproductive activities, such as bearing children or competing for mates. During this time, juvenile play activities become increasingly adult-like. Early adulthood is the reproductive period and in hunter-gatherer societies usually begins in the late teens for girls and a few years later (sometimes much later) for boys. In hunter-gatherer societies, many men will have more than one wife and thus continue to reproduce into old age. Older women, in contrast, focus their activities on raising their later-borne children and investing in the well-being of grandchildren.

Cognitive development. In hunter-gatherer societies, people have to learn how to deal with other people; use the local ecology to find food and medicine; navigate from one place to another; and use tools. The cognitive skills that allow people to engage in social activities and maintain relationships are called folk psychology. These skills include language, understanding body language and facial expressions, as well as theory of mind. Theory of mind is the ability to make inferences about what other people are thinking or feeling and predicting their later behavior. The cognitive skills that allow people to understand the behavior, growth patterns, and potential uses of plants and animals for food and medicine are called folk biology.Folk physics includes the ability to move about in the physical environment, remember the location of things in the environment, and know how to use objects as tools.

The basic skeletal knowledge that supports these cognitive abilities appears to be innate, but must be fleshed out during development. Infants, for instance, automatically attend to human voices and faces, and toddlers easily learn human language through innate brain and cognitive systems that guide children's attention to other people and process social information (e.g., language sounds). However, these brain and cognitive systems are immature, and require extended exposure to language, human faces, and so forth to develop appropriately. Children's play and other activities, such as exploration of the environment and objects, provide the experiences needed to flesh out these innate skeletal systems. The result is an elaboration of the systems that support folk psychology, folk biology, and folk physics. The elaboration results in the adaptation of these brain and cognitive systems to local conditions, such as the local language and the plants and animals in the local ecology.

Implications for Education

The folk psychological, biological, and physical knowledge that emerges through an interaction between innate brain and cognitive systems on the one hand and children's play and exploration on the other is not sufficient for living in industrial societies. In industrial societies, schools exist to facilitate the acquisition of competencies, such as reading, that are essential for living in these societies, but are not part of our evolutionary heritage. Several educational issues arise from this perspective.

Academic development. The evolved cognitive competencies that comprise folk psychology, biology, and physics are called biologically primary abilities, and skills that build upon these primary abilities but are principally cultural inventions, such as reading, are biologically secondary abilities. The mechanisms by which evolved systems are adapted to produce secondary competencies are not yet fully understood, but involve, in part, co-opting primary systems for secondary learning, and access to knowledge built into primary systems.

As an example of co-opting, consider the relation between language, a primary ability, and reading, a secondary ability. The acquisition of reading-related abilities, such as word decoding, involves co-opting language and language-related systems, among others (e.g., visual scanning). The result is that these systems can be used for purposes for which they were not designed. For instance, individual differences in the sensitivity of kindergarten children's phonological processing systems, which are part of the language domain, are strongly predictive of the ease with which basic reading skills are acquired in first grade. In other words, the evolutionary pressures that selected for phonological processing, such as the ability to segment language sounds, were unrelated to reading, but these systems are used, or co-opted, when children learn how to read.

As an example of using implicit knowledge for secondary learning, consider that the development of geometry may have been initially based on access to knowledge built into the primary navigation system. In cataloging the basic principles of classical geometry, Euclid started with self-evident truths–implicit navigational knowledge–and then proceeded to prove the rest by logic, that is, by means of fundamental theorems. For example, the implicit understanding that the fastest way to get from one place to another is to go "as the crow flies," was made explicit in the formal Euclidean postulate, "a line can be drawn from any point to any point," that is, a line is a straight line. The former reflects an evolved but implicit understanding of how to quickly get from one place to another and is knowledge that is built into the brain and cognitive systems that support navigation. The latter was discovered, that is, made explicit, by Euclid. Once explicit, this knowledge was integrated into the formal discipline of geometry and became socially transmittable and teachable.

Motivation to learn. Another implication of the evolutionary perspective is that the motivation to acquire school-taught secondary abilities is based on the requirements of the wider society and not on the inherent interests of children. Given the relatively recent advent of near-universal schooling in contemporary societies, there is no reason to believe that all children are inherently motivated to acquire the skills that are taught in school, nor is school learning likely to be inherently interesting or enjoyable. Stated differently, an important difference between primary and secondary abilities is the level and source of motivation to engage in the activities needed for their acquisition.

This does not preclude the self-motivated engagement in some secondary activities. Many children and adults are motivated to read. The motivation to read, however, is driven by the content of what is being read rather than by the process itself. In fact, the content of many stories and other secondary activities (e.g., video games) appears to reflect evolutionarily relevant themes that motivate engagement in these activities, such as social relationships and social competition. Furthermore, the finding that intellectual curiosity is a basic dimension of human personality suggests that there will be many intellectually curious individuals who will pursue secondary activities. Euclid's investment in formalizing the principles of geometry is one example. However, this type of discovery typically reflects the activities and insights of only a few individuals, and the associated advances spread through the larger society only by means of informal (e.g., newspapers) and formal education. The point is, the motivation to engage in the activities that will promote the acquisition of secondary abilities is not likely to be universal.

Instructional activities. The basic brain and cognitive systems that support the acquisition of primary abilities are inherent, and children are inherently motivated to seek out experiences, through social play, for example, that ensure the appropriate fleshing out and development of these systems. In contrast, there is no inherent structure supporting the acquisition of secondary abilities, nor are most children inherently motivated to engage in the activities that are necessary for secondary learning. Although this conclusion might seem self-evident, it runs counter to many assumptions about children's learning in contemporary education; for example, that children are inherently motivated to learn secondary abilities and will do so through activities that involve play and social discourse.

Thus, from the evolutionary perspective, one essential goal of schooling is to provide content, organization, and structure to the teaching of secondary abilities, features that have been provided by evolution to primary abilities. It cannot be assumed that children's inherent interests (e.g., social relationships) and preferred learning activities (e.g., play) will be sufficient for the acquisition of secondary abilities. Instruction must often involve engaging children in activities that facilitate the acquisition of secondary abilities, whether or not children would naturally engage in these activities. This does not mean that play and social activities cannot be used to engage children in some forms of secondary learning. It does, however, mean that it is very unlikely that the mastery of many secondary domains (e.g., reading or algebra) will occur with only these types of primary activities. In fact, research in cognitive and educational psychology indicates that some forms of secondary learning will require activities that differ from those associated with fleshing out primary abilities. These would include, among others, direct instruction, where teachers provide the goals, organization, and structure to instructional activities and explicitly teach basic competencies, such as how to sound out unfamiliar words or manipulate algebraic equations. In closing, the evolution of brain, cognition, behavior, and motivation has profound but largely unrecognized implications for educational theory and practice.