The Evolutionary Approach to Psychology

HUMAN EVOLUTION So how did we get here?

Carl Sagan’s Universe Calendar “Big Bang”January 1 Milky WayMay 1 Solar SystemSeptember 9 Life on EarthSeptember 25 Humanlike Primates December 31, 10:30pm Human Evolution

Scale: Millions of Years BP Australopithecus Homo habilis Homo erectus Human Evolution

Homo habilis 612 cc brain first toolmaker Projecting jaw, brow ridge probable meat-eater possibly arboreal no speech Finds in east Africa indicate that Homo habilis was not very different from Australopithecus the in terms of body size and shape Human Evolution

Homo erectus The earliest Homo erectus remains indicate rapid biological change: H. erectus was considerably taller than H. habilis. 994 cc brain size (compared to 612 for H. habilis) Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya. Human Evolution

Homo erectus, Australopithecus & Homo sapiens Human Evolution

Homo erectus Why was H. erectus so successful? Less hair on body Wearing of furs = ability to live further north Quick adaptation to environment without physical changes Culture Organisation for hunting Ability to protect against predators Control of fire Used stone tools e.g. hand axes Human Evolution

Homo neanderthalensis Discovered in the Neander Valley near Dusseldorf, 1856 Massive brain--about 1,400cc on average Large torso, short limbs, broad nasal passages Later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth The skull of the classic Neandertal found in 1908 at La Chapelle-aux- Saints. Human Evolution

Neandertal Culture Homesites – In caves, also in the open (near rivers, framed with wood and covered with skins) Burial – Is there evidence of purposeful burial and ritual? Language – Could Neandertals talk or not? Tools – Mousterian tradition Top: Reconstruction of Neandertal burial from Shanidar cave Bottom: Mousterian tools Human Evolution

What happened to Neandertals? H. neanderthalensis coexisted with H. sapiens for at least 20,000 years, perhaps as long as 60,000 years What happened? Neandertals interbred with H. sapiens Neandertals were killed off by H. sapiens H. sapiens drove Neandertals into extinction by competition Human Evolution

Homo sapiens Archaic – 100,000 to 35,000 years BP Sometimes called Homo sapiens and Homo sapiens neanderthalensis Modern – 35,000 years BP to present Anatomically modern Sometimes called Homo sapiens sapiens Human Evolution

H. sapiens Culture Shelters Some made with mammoth bones Wood, leather working; carpentry Tools From cores to blades Composite tools Bow and arrow Domestication of dogs Gathering rather than hunting became the mainstay of human economies. Straw Hut Mammoth bone hut Hand tools Human Evolution

H. sapiens Culture Cave paintings Mostly animals on bare walls Subjects were animals favoured for their meat and skins Human figures were rarely drawn due to taboos and fears that it would somehow harm others Cave paintings from 20,000 years ago from Lascaux, in southwest France Traces of art found in beads, carvings, and paintings Female figurines 27,000 to 22,000 years B.P. Called ‘Venuses’ these figurines depicted women with large breasts and broad hips Human Evolution

THE EVOLUTIONARY APPROACH Approaches in Psychology

Evolutionary psychology is an approach to psychology Knowledge and principles from theories of evolution are applied to research on the structure of the human mind The Evolutionary Approach It is not an area of study, like ‘memory’ or ‘social behaviour’. It is a way of thinking about psychology that can be applied to any topic within it.

Darwin’s Theory of Evolution Natural selection “Natural selection is the gradual process by which nature selects the forms most fit to survive and reproduce in a given environment.” Charles Darwin The Evolutionary Approach

Reproduction ensures the continuation of genes responsible for fitness. It is the characteristic rather than the individual that is selected by nature. Natural selection occurs when: A characteristic appears The characteristic is genetically transmitted The gene is adaptive The Evolutionary Approach

Sexual Selection The selection of characteristics that are concerned only with reproductive success Females are the selectors whilst males compete for her attention. Males produce thousands of sperm and invest little in each ‘reproduction’ Females invest a great deal as they produce fewer eggs Therefore females select their mates strategically!!

Evolutionary psychologists explain human behaviour in terms of ultimate rather than proximate causes. Proximate explanations emphasise here-and-now influences on a person’s behaviour Ultimate explanations focus on how these behaviours may have been adaptive in a species’ evolutionary past. The Environment of Evolutionary Adaptation (EEA) This is the environment to which a species is adapted and the set of selective pressures that operated at this time In terms of human evolution, this is generally accepted as to 3 million years ago when our ancestors lived in mobile hunter-gatherer groups on the African savannah The Evolutionary Approach

The Modular Mind The modern mind comprises specific mental modules (hard-wiring in the brain) that would have evolved in response to the specific problems faced by our ancestors in the EEA. Our ancestors are our ancestors precisely because they adapted successfully to these problems and passed the same mental modules on to their descendants (us). The Evolutionary Approach

The Selfish Gene Why do animals act altruistically when it would appear ‘sensible’ in terms of survival, not to risk their life for another? Inclusive fitness. Animals pass on copies of their genes not only directly (i.e. through their own offspring) but also indirectly (i.e. by giving aid to other genetic relatives). The total number of genes passed on directly and indirectly adds up to an individual’s inclusive fitness. Kin Selection The tendency to help those with whom we share genes (our gene pool) is known as kin selection. As we share 50% of our genes with our children and siblings, 25% with our grandchildren and nephews/nieces and just 12.5% with our cousins, kin selection should explain the likelihood of help being given to each ‘level’ of genetic relative. The Evolutionary Approach

A non-conscious process No one stopped and said, “How can I maximize the number of genes I pass along to the next generation?” Our past and present natural yearnings simply reflect the genes’ way of making more genes. The Evolutionary Approach

Increases our knowledge of Nature-Nurture with discussions on genes and how they are vulnerable to environmental changes. (X) Evolutionary reductionism – assumes that behaviour must have at some time must have been adaptive and therefore inherited (X) Ignores cultural transmission of behaviour The Evolutionary Approach