BIOPSYCHOLOGY 8e John P.J. Pinel

Transcription

1 BIOPSYCHOLOGY 8e John P.J. Pinel

2 Thinking about the Biology of Behaviour: From Dichotomies to Relations and Interactions There is a tendency to think in simple dichotomies when explaining behaviour: Is it physiological or psychological? Is it inherited or is it learned? Both questions are common, yet misguided?

3 Cartesian Dualism Universe Cartesian Dualism: universe consists of two elements: physical matter (body, brain, non-human animals) and human mind (soul, self, or spirit) Human Mind Cartesian Dualism: Mind and brain viewed as separate entities

4 Is It Inherited or Is It Learned? Watson (it s learned), a behaviourist, believed that all behaviour was the product of learning (nurture) - Your environment makes you who you are Ethology (it s inherited), the study of animal behaviour in the wild, focuses on instinctive (nature) behaviours - Instinctive behaviours are not learned (grooming behaviour, urinary posture in male dogs) Nature Versus Nurture

5 Problems of Traditional Dichotomies: Mind-Brain Dualism Problem Number 1 Brain damage has an impact on psychological functioning Or, damage the physical brain and you impair the operation of the mind. Problem Number 2 Chimps show complex psychological (i.e., human ) abilities. That is, evidence of a mind Example: Gallup s research on chimp self-awareness Chimps spontaneously groom themselves and touch red mark on their own faces seen in mirror.

6 Problems of Traditional Dichotomies: Nature-or-Nurture Complex distal and proximal interactions converge to generate behaviour Many factors have an impact on behaviour other than genetics (nature) or learning (nurture) Nurture now encompasses learning and environment A schematic illustration of the way in which many biopsychologists think about the biology of behaviour.

7 Human Evolution: Evidence for Evolution 1 Fossil evidence of evolution 2 Structural similarities among living species suggesting common ancestors 3 Impact of selective breeding 4 Direct observation of evolution in progress: Grant (1991)

8 Human Evolution: Evidence for Evolution Four kinds of evidence supporting the theory that species evolve.

9 Evolution and Behaviour Just as physical features can contribute to fitness (survive and reproduce), so do behaviours Some are obvious the ability to find food, avoid predation, etc. Some are less obvious social dominance and courtship displays Females of a species signal receptivity too:

10 Course of Human Evolution Complex, multicellular water-dwelling organisms first appeared on earth about 600mya Evolution of vertebrates Chordates (450 mya) have dorsal nerve cords Vertebrates are chordates with spinal bones Emerged about 425mya Evolution of amphibians (410 mya) Bony fishes leave the water for brief periods Advantages include fresh water and new food sources (new mates, avoid predation) 400mya their fins evolved into legs, and gills into lungs

11 Course of Human Evolution Evolution of reptiles (300mya) Lay shell-covered eggs; covered by dry scales Can live far from water Evolution of mammals (180mya) Develop mammary glands to nurture young Eventually no longer lay eggs: raise young in mother s body Humans emerge from the order primates Emergence of humankind Humans belong to family hominids, genus Homo First homo species emerged from Australopithecus 2 million years ago Homo sapiens (modern humans) emerged 200,000 years ago KINGDOM Animal PHYLUM Chordate CLASS Mammal ORDER Primate FAMILY Hominid GENUS Homo SPECIES Sapiens

12 Thinking About Human Evolution Similarities among species do not necessarily mean that the species have common origins Not all existing adaptive characteristics evolved to perform their current function Not all existing behaviours or structures are adaptive e.g. spandrels Thinking About Human Evolution Evolution does not necessarily result in perfect design Evolution does not proceed in a single line Humans have only been around for a brief period of time Fewer than 1% of all known species are still in existence

13 Evolution of the Human Brain There is no relationship between brain size and intelligence Brain size is generally correlated with body size (bigger bodies have bigger brains) More informative to look at relative size of different brain regions (such as cerebrums cerebral hemispheres)

14 Human Evolution: Evidence for Evolution The brains of animals of different evolutionary ages. Cerebrums are shown in yellow; brainstems are shown in purple. More cerebrum, more complex behaviours

15 Evolution of the Human Brain The human brain has increased in size during evolution Most of the increase in size has occurred in the cerebrum Increased convolutions in the cerebrum serve to increase the volume of the cerebral cortex Vaginal birth a limiting factor for neonatal skull size

16 Evolutionary Psychology: Mate Bonding Most species mate promiscuously Most mammals form polygynous mating bonds Polygyny works because of costs of parental/ gamete investment She: mate with fit males He: mate with any female Monogamy only works if he and she can raise more fit young than her along.

17 Thinking about Evolutionary Psychology Current aspects of human mate selection appear to be predicted by evolutionary theory Examples: Males on average are larger and more aggressive than females Men tend to value indications of fertility Women tend to value power and earning capacity Physical attractiveness predicts which women bond with men of high status Mate attraction strategies: for women, physical attraction; for men, displaying power and resources Men are more likely than women to commit adultery (and value chastity)

18 Thinking about Evolutionary Psychology Keep Thinking: Your ideal mate Mate guarding Chastity Adornment Indicators of youth/fertility Indicators of strength/ resources