biopsychology 8e john p.j. pinel · copyright © pearson education 2011 course of human evolution...

BIOPSYCHOLOGY 8e John P.J. Pinel

Copyright © Pearson Education 2011


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

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Universe Human Mind

Cartesian Dualism

Cartesian Dualism: universe consists of two elements: physical matter (body, brain, non-human animals) and human mind (soul, self, or spirit)

Cartesian Dualism: Mind and brain viewed as separate entities


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


Problem Number 2 Problem Number 1

Brain damage has an impact on psychological functioning

Or, damage the physical brain and you impair the operation of the mind.

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.

Problems of Traditional Dichotomies: Mind-Brain Dualism


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.


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Fossil evidence of evolution

Structural similarities among living species suggesting common ancestors

Impact of selective breeding

Direct observation of evolution in progress: Grant (1991)

Human Evolution: Evidence for Evolution



Four kinds of evidence supporting the theory that species evolve.


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: http://www.youtube.com/watch?v=jJIGGRM3Vq4 http://www.youtube.com/watch?v=qY2f_wQ6CSo


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


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


Thinking About Human Evolution

Thinking About Human Evolution

Evolution does not

proceed in a single line

Humans have only been around for a brief period

of time

Not all existing adaptive

characteristics evolved to perform their current function

Fewer than 1% of all known

species are still in existence

Evolution does not necessarily result in perfect

design

Not all existing behaviours or

structures are adaptive e.g.

spandrels

Similarities among

species do not necessarily mean that

the species have common origins


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)



The brains of animals of different evolutionary ages. Cerebrums are shown in yellow; brainstems are shown in purple. More cerebrum, more complex behaviours


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


Evolutionary Psychology: Mate Bonding

Most mammals form

polygynous mating bonds

Monogamy only works if he and she can raise

more fit young than her along.

Most species mate

promiscuously Polygyny works

because of costs of parental/gamete

investment She: mate with

fit males He: mate with

any female


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)


Thinking about Evolutionary Psychology

Keep Thinking: • Your ideal mate • Mate guarding • Chastity • Adornment • Indicators of youth/fertility • Indicators of strength/resources

biopsychology 8e john p.j. pinel · copyright © pearson education 2011 course of human evolution...

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