Evolutionary Theory Flashcards
define biological evolution
changes that take place in the genetic and physical characteristics of a population or group of organism over time
define evolutionary psychology
an approach that explains behaviour and the development of the mind in terms of their function of adaptiveness. It investigates how an organism’s evolutionary history contributes to the development of behaviour patterns and cognitive strategies related to reproduction and survival during its lifetime.
2 explanations of behaviour according to biologists and psychologists:
ultimate causes
proximate causes
define ultimate causes as an explanation for behaviour
events and conditions that have slowly shaped the behaviour of our species over successive generations
It refers to explanations associated with evolution. It is the study of why this or that behaviour evolved and what was the adaptive function it served.
This is what Darwin’s theory of evolution is about - it looks for the ultimate cause explanations. This type of explanation focuses on processes that occurred a long time ago
define proximate causes as an explanation for behaviour
immediate environmental variables that affect behaviour
It refers to the biological processes operating in the organism at the time the behaviour is observed.
This explanation focuses on the present variables that affect the behaviour.
define adaptation
the ability of generations of species to adapt effectively to changes in the environment
define natural selection
the process whereby some variations in species will be transferred from one generation to the next but others will not
explain Darwin’s beliefs about natural selection
An animal that possesses a characteristic that helps it to survive or adapt to changes in its environment is likely to live longer and produce more offspring than animals that do not have this characteristics. The animal that produces more offspring spreads its genes and that adaptive characteristic becomes more frequent in next generations.
define variation
Organisms show variations (e.g. individual differences in the behaviours they exhibit) due to variation in the genes (e.g. spontaneous mutations that code for manifestation of such behavioural differences).
Personality and intelligence varies across people because of the variation in the genes they have.
define adaptive behaviours
Some changes in genes helps an organism to survive and reproduce by promoting adaptive behaviours, while others hinder it from surviving and reproducing, by producing maladaptive behaviours. What counts as adaptive also depends on the ecological niche an organism is in. e.g. it may pay to be neurotic if your environment has dangers so taking care to watch out for bad things is beneficial
define inheritance
Genes are transmitted from parent to offspring via inheritance. Hence the genes that end up getting transmitted from generation to generation are those that help organisms survive and reproduce. Today, they genes we have, are those that helped our species survive and reproduce in the past and have kept being useful. Thus one can say that different sets of genes end up in competition with one another for which best help the organism to survive.
define competition
If there is a scarcity of food in the environment, this creates competition between animals with the less fit individuals losing the struggle for life. Fast wolves are able to capture more prey than slower ones so fast wolves will tend to outlive and out-reproduce slower wolves if a wolf’s tendency to run fast is a genetically controlled trait, it will be passed onto its offspring and these offspring will be more likely to catch prey and therefore live longer and have more opportunities to reproduce.
explain the adaptive traits of a giraffe as an example of natural selection
Originally the necks of giraffes were not long but more exceptional giraffes had necks longer than average ones. Those that had a slightly longer neck survived by winning in the struggle for existence. Generations of those giraffes survived.
explain the steps of natural selection
- some individuals have better characteristics e.g. are able to obtain more food
- these become stronger and healthier
- they therefore have more offspring
- the next generation has a higher proportion of the more advantageous characteristics
- many generations later, the whole species has changed to the new form
define reproductive success
the ability of an individual to produce offspring
the number of viable offspring it produces relative to the number of viable offspring produced by other members of the same species
explain the interpretation of ‘survival of the fittest’
‘survival of the fittest’ does not always mean survival of the most physically fit or strongest but reproductive success. Physical strength is only one factor that may contribute to such success.
In humans, good looks, charm and intelligence play an important role in an individual’s ability to attract a mate and reproduce.
Evolutionary theorists assume that many features related to human cognition, motivation, personality and behaviour are the result of natural selection. They are adaptations, inherited solutions to the survival and reproductive problems posed by the environment.
define genotype
unique genetic make-up of an organism
it is inherited and influences the form, functioning and behaviour of the individual
define phenotype
physical characteristic of an organism
produced by the interaction of its genotype with the environment
how does competition affect survival of species?
Over time, competition for food and other resources will allow only the best-adapted phenotypes and their corresponding genotypes to survive, thereby producing evolutionary change.
define sexual selection
Some traits exist because they give the individual that possesses them an advantage over others in the competitions for mates.
example of sexual selection in peacocks
peacocks have extravagant tails which reduces the rate of survival due to reduced manueureability, reduced power of flight, easily spot by predators, high energetic cost however, this is compensated for by the increased advantage in reproduction as they attract mates with their long, colourful tails.
define sociobiology
the systematic study of the biological basis of all social behaviour
Sociobiologists are especially interested in understanding the evolutionary roots of our modern-day social actions, especially related to reproduction and parenting
questions that sociobiologists have:
Are there biological determinants of physical attractiveness?
What are sexual and mating strategies of males and females?
Does altruism exist and why?
features of male attractiveness
- Height
- Relatively broad shoulders and slim waist - inverted triangle - waist-to-shoulder ratio = 0.75 or lower
- Chest muscularity to some extent
- Normal level of testosterone: broad jaw, strong brow
features of female attractiveness
- Low waist-to-hip ratio = 0.7 - signal of fertility, physical health and not being already pregnant
- Signals of youth and health: full lips, clear smooth skin, lustrous hair, symmetrical face, round breasts
explain features of male sexual selection
- look for quantity
- want a mate who maximises their chances of having healthy offspring so prefer younger mates
explain features of female sexual selection
- look for quality
- want a mate who maximises their chances of having healthy offspring so prefer older partners
- fewer opportunities to reproduce so are more selective in their choice of mate
- females have to sacrifice a big portion of their own metabolic resources to nourish the offspring during the 9-month long pregnancy and there are risks that accompany pregnancy and childbirth including physical discomfort and possible death
- females also must devote their metabolic resources after the offspring is born due to breast-feeding
explain Buss’ study into sexual selection (1989)
men from 37 different cultures preferred a mate who was younger than they were, whereas women preferred men around 3 years older than themselves.
Younger women are more likely to have healthy children and older men are more likely to have the resources to provide for children.
differences between male and female sexual selection
consequences of having a child are greater for females so females are more selective in their choice of mate
females produce only a select number of ova a month whereas men produce vast quantities of sperm
bigger parental investment for females
how do women assess potential partners?
- Their quality of genes - good health, intelligence, strength etc
- Whether they will devote resources to their children and will not leave to produced next children elsewhere.
what qualities do women look for in a mate?
- Economic resources
- Social status
- Ambition
- Dependability and stability
- Intelligence
- Compatibility - potential for sustaining the relationship
- Love
- Commitment
- Size and strength
- Good health
how do men assess potential partners?
- Men want to detect if their potential partner will provide them with a fast production of offspring and be faithful to them.
what qualities do men look for in a mate?
- Youth
- Beauty - health and fertility
- Faithfulness/ fidelity
male infidelity
Among women, emotional infidelity signals the long-term diversion to the other woman. They risk the diversion of their mate’s energy, commitments and investments to rival women. This is particularly threatening in environments where offspring suffer in survival and reproductive currencies without investment from both parents.
Men and women differ in forgiveness and termination
Women break up if emotional infidelity occurs
female infidelity
Among men, sexual infidelity could jeopardise paternity certainty. The attendant reproductive risk is investing effort in a rival man’s child rather than his own. Thus, men should be more jealous in reaction to sexual infidelity.
Men and women differ in forgiveness and termination
Men break up if sexual infidelity occurs
define inclusive fitness
natural selection favours organism, which maximise replications of their genes not only directly by reproduction but also indirectly by helping those with whom they share genes (Hamilton, 1964)
how is altruistic behaviour beneficial?
Why individuals often behave in an altruistic or selfless way, which may appear to be contrary to their own genetic or reproductive interest.
We are more willing to behave altruistically towards close relatives than towards strangers - kin selection.
evolution and trait theory
Humans are social creatures and live in groups.
Certain personality traits allow members to cooperate to achieve goals and sort out problems. In different environments, different traits may lead to success.
