Relationships: evolutionary explanations Flashcards
What is evolution?
Evolution is the concept whereby genes mutate over time, sometimes giving individuals an advantage when competing for resources like food and mates.
What is meant by natural selection?
the process where inherited characteristics that enhance survival are passed onto the next generation
What is meant by adaptation?
the functional products of natural selection or sexual selection in human evolution
What is meant by reproductive success?
the degree to which an individual is successful in produced offspring that in turn are able to produce offspring of their own. Often a tally of the number of offspring produced by an individual
What is sexual selection?
Ability to attract / find a mate and reproduce successfully. Attributes and behaviours that increase reproductive success are passed on (survival of the sexiest).
Inter-sexual selection:
One sex chooses from a group of prospective mates according to attractiveness. womans choice
Intra-sexual selection:
Members of one sex compete for access to the other sex.
Explain why inter-sexual selection is the prefereed strategy of the female
Females make a greater investment of time, commitment and other resources before, during and after the birth of their offspring.
Females may be quite fussy, and wisely choose a partner who can offer resources (food, territory and protection).
This will enhance the female’s reproductive success, as any child she bears will have a greater chance of survival due to resource availability (and consequently, passing these genes on).
In modern times, this need for resources might not necessarily be food and shelter, but might be translated into money and status, and men with ambition and industriousness.
Optimum strategy - select a genetically fit partner who is able and willing to provide resources. This leaves the males competing for the opportunity to mate with the fertile females.
This leads to the ‘sexy sons hypothesis’ - female mates with a male with desirable characteristics, and this ‘sexy’ trait is inherited by her son, increasing the likelihood that successive generations of females will mate with her offspring.
Explain why intra-sexual selection is the prefereed strategy of the male
This is the preferred strategy of the male - quantity over quality.
It refers to the competition between (intra) males to be able to mate with a female.
The winner of the competition reproduces and gets to pass on to his offspring the characteristics that contributed to his victory (e.g., strength, heigh, facial features).
This strategy has given rise to dimorphism in humans - the obvious differences between males and females.
For example,
In any physical competition between males… size matters.
Larger males have the advantage and are therefore likely to mate.
On the other hand, females do not compete for reproductive rights so there is no evolutionary drive towards favouring larger females.
Waist- hip ratio preference and research?
Research suggests that males will show a preference for a female body shape that signals fertility.
Singh (1993, 2002) studied this in terms of waist-hip ratio (WHR).
Up to a point, males generally find any hip and waist size attractive so long as the ratio of one to the other is about 0.7.
Name and outline 5 male mating strategies
Courtship Rituals – Allows showing off genetic potential and resources.
Size – Bigger body sizes demonstrate physical strength and an ability to protect partner and offspring from threats.
Sperm Competition – Men have evolved to have bigger testicles and faster swimming sperm.
Mate Guarding – Keeping a close eye on partners to prevent unfaithfulness.
Sneak Copulation – Being unfaithful - can be beneficial to both parties?
Name and outline 3 female mating strategies
Handicap Hypothesis – Some women may pick men with handicaps as it shows an ability to thrive despite adversities. May explain why some women are attracted to men who take drugs and drink a lot.
Sexy Sons Hypothesis – Females select males they deem physically attractive as they are likely to pass this onto their children, increasing the offspring’s chance of reproducing.
Courtship – Dating is an important strategy for females to establish a man’s worth to produce offspring.
Evaluation for evolutionary explanations of relationships: research (Buss)
There is supporting evidence for the evolutionary explanation for partner preferences.
For example, Buss (1989) studied 10,000 adults in 33 different countries and found that men preferred younger, physically attractive females (as signs of good reproductive capacity), whilst females preferred dependable, ambitious and older men with vast resources.
This research implies that the theory may be valid in explaining this integral human behaviour by demonstrating consistent sex differences in partner preference.
Evaluation for evolutionary explanations of relationships: low external validity
The external validity of these evolutionary explanations could be considered to be low.
Generally, these explanations do not take into account same sex relationships or partnerships where children are not desired and thus, cannot be attributed to all individuals.
These explanations of partner preferences can only be used to explain the majority of heterosexual relationships.
Given that these ideas can only be applied to a subset of the population, it could be argued that the usefulness of these theories is limited.
Evaluation for evolutionary explanations of relationships: research from clark and hatfield
Furthermore, Clark and Hatfield (1989) also supports the theory of evolutionary explanations in partner preferences.
Clark and Hatfield sent male and female psychology student across a university campus to approach other students and say: ‘I have been noticing you around campus. I find you to be very attractive. Would you go to bed with me tonight?’
Not a single female student agreed to the request, whereas 75% of males did, immediately.
This research suggests that females are choosier than males when it comes to selecting sexual partners and that the two genders have evolved different mating strategies.
