Cezar Giosan - Cognitive Evolutionary Therapy for Depression: Therapy Manual

In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation.

Charles Darwin, The Origin of Species, 1859

Little did Charles Darwin know, a century and a half ago, that his prophetic words would constitute the foundation of a modern discipline within the broad field of psychology, namely Evolutionary Psychology. Evolutionary psychology examines psychological traits and processes such as memory, perception, or language from a modern evolutionary perspective (Buss, ).

Evolutionary psychology uses an adaptationist approach to understand and explain cognitive structures and argues that different pieces of our cognitive system serve different adaptive functions, which are related to recurrent adaptive problems that humans faced in the ancestral environments (Buss, ).

While the classical approach in psychology, known as the standard social science model (Cosmides, ).

As with adaptations in general, psychological adaptations are intrinsically related to the specific environment in which they evolved, termed the Environment of Evolutionary Adaptedness, or the EEA (Tooby & Cosmides, ). The EEA is not a specific point/place in time, but rather a collection of historically recurring selection pressures that led to an adaptation through natural selection.

Humans, comprising the genus Homo, appeared between 1.5 and 2.5 million years ago, a time that coincides with the start of the Pleistocene about 1.8 million years ago. Because the Pleistocene ended a mere 12,000 years ago, coinciding roughly with the discovery of agriculture (about 10,000 years ago), most human adaptations evolved before or during that period, which, for us, represents the Environment of Evolutionary Adaptedness. Evolutionary psychologists therefore argue that the majority of human cognitive modules are adapted to reproductive and survival problems frequently encountered in the Pleistocene environments (Barkow et al., ). In broad terms, these problems include those of growth, development, differentiation, maintenance, mating, parenting, and social relationships. The argument that our species is adapted to pre-agricultural environments becomes even stronger when we factor in the fact that, just 5000 years ago, only half of the population had fully transitioned to agriculture .

Since our adaptations are suited to the ancestral environments we evolved in as a species, a novel and different environment can result in a mismatch between it and our psychological mechanisms (Irons, ).

The Pleistocene climate was characterized by repeated glacial cycles, during which up to 30% of the planets surface was covered with ice, stretching to North America, Northern Europe, and even New Zealand. Because these periods were characterized by severe lack of food, many extremely large mammals (e.g., the mammoths) went extinct during that time. Another important casualty of those harsh conditions were the Neanderthals, who disappeared around 40,000 years ago.

The modern humans Homo Sapiens appeared in Africa about 300,000 years ago and began to migrate approximately 100,00070,000 years ago, passing through what is nowadays Ethiopia and Yemen, populating Australia, Asia and Europe, and, eventually, crossing the Bering strait and ending with the migration in the Americas, about 20,000 years ago.

Before settling down in the post-agricultural, permanent dwellings, about 10,0005000 years ago, humans lived in groups of hunter-gatherers , who migrated frequently in search for better conditions and resources. Men were the hunters, their main responsibility being, besides protection, to provide protein for their kin. They traveled far distances hunting game, often venturing into unfamiliar, potentially dangerous territories. It was, therefore, vital for them to be able to find their way back, which made them evolve good mapping skills. Women, on the other hand, supplied the role of gatherers, collecting edible foods from the surroundings, such as berries, vegetables, nuts, or sprouts. Since for women, unlike men, the sources of food did not change location from one minute to another (antelopes move around, but banana trees do not), women should have slowly evolved better memory than men for the localization of static objects. This gender difference in cognitive abilities, with women showing better memory for object location, has been confirmed by studies in cognitive psychology (Silverman, Choi, & Peters, ).