Lecture 7 (Bechtold) Flashcards
rate of social monogamy in mammals?
Few mammalian species display exclusive mate bonding
Social monogamy in only 2-3% of mammals
what defines a social/affiliative bond?
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Ability to recognise specific individuals
Recognition associated with positive emotion affect that stimulates proximity seeking, physical interactions that reinforce positive affect and imitation
Physical separation of the individuals causes negative emotions and searching behaviour
Aggression towards intruders that threaten the exclusivity of the bond
Some element of reciprocity
Relationship bonds are long term
Social and emotional dependence between individuals that promotes survival and reproductive success
what is natural selection?
evolutionary forces which favours progression of advantageous traits/ phenotypes (increase likelihood of passing on genotype)
what is sexual selection?
acts on an organism’s ability to obtain or successfully copulate with a mate (often by any means necessary!)
powerful enough to produce features that are harmful to the individual’s survival.
what leads to natural selection?
variation, differential reproduction, and heredity,
what is the effect of bonding on direct fitness?
often bonding is associated with an apparent sacrifice of direct fitness.
advantages to social bonding?
Protection against predators
Food provision
Stress reduction (fear, anxiety…)
Social learning
Social reward/positive affect
Increased chance of reproductive success
Survival/care of young
what are altricial animals?
born in a very “incomplete” state that will take time/care to become fully operational, alert and active with all its senses and actions. mother care critical to survival
what are precocial animals?
refers to species in which the young are relatively mature and mobile from the moment of birth or hatching.
need bonding, ie deer could just walk off and die
Which 3 theories explain monogamy in mammals?
Parental care hypothesis: Benefit of a second parent produces healthier, stronger, smarter offspring.
Discrete range hypothesis: Female become intolerant of other females and occupy non-overlapping territorial ranges. Inability to prevent rival males mating and reduced access to drives monogamy.
Infanticide hypothesis: Males kill the offspring off rival males to bring the female back into oestrus. Long lactation period makes infants vulnerable. Monogamy was driven by the need for males to protect offspring
2 and 3 not mutually exclusive
What is behavioural imprinting?
Phase-dependent and non-associative learning.
no positive or negative feedback, learnt regardless.
ie duckies
What is Filial imprinting?
young animal learns the characteristics of its parents
What is Fraternal imprinting?`
learns the characteristic of its own species
What is sexual imprinting?
young animal learns the characteristics of a
desirable mate
example of early life imprinting in birds
Lorenz used the graylag goose to demonstrate imprinting (He took over the maternal role for a group of goslings). also rubber ball worked.
In birds, cross-fostering leads to imprinting on first object or individual that they see, leading to fixed social and sexual preferences.
This sexual imprint is pre-programmed and occurs at an early stage in development.
mammals and imprinting?
Mammals are more complex and flexible…
but sexual imprinting still occurs
Sheep and goats (cross fostering suitability)
Genetically similar enough to breed and produce infertile offspring (vary rare ‘Geep’)
So amenable to cross fostering (allow the mother goat to accept and rear baby sheep and visa versa)
Cross fostering experiments in sheep and goats
Kendrick 1998
mix goat kids and lambs with other species foster mother –> juveniles allowed to mix socially with members of
their own genetic species as they grew up.
Play and grooming behaviour resembles that of adopted mother (AND NOT THEIR GENETIC SPECIES)
Aggression, climbing, feeding vocalisation unaffected and resembled genetic origin
Cross fostering and sexual preference?
Male sheep/goats always chose the adopted species for mating, consistent for 4 years.
Female sheep/goats revert to their own species after initially choosing foster.
Therefore males imprint strongly on their maternal species, females much less so
Sheep and facial recognition?
Right temporal and medial frontal cortex cells respond more strongly to a familiar face.
This region of the brain is also implicated in humans with facial recognition
Male goats and sheep select their foster species over genetic (Oedipus boi). Females are much less selective when cross fostered
Parental influence on mate choice in humans?
Women born to older fathers give stronger attraction ratings to older men.
Big study found no evidence for effect of father on female partner choice but some evidence for men choosing women that looked like their mother (yuck)
reverse sexual imprinting in humans?
the Westermarck effect (after Edvard Westermarck)
Desensitized to later close sexual attraction
individuals develop sexual aversion with other individuals that were raised in the same peer or family group; stronger for women than men (parental investment, inbreeding avoidance)
Westermarck effect has since been observed in many places and cultures i.e Amish
Primate bonding strategies
FOR PRIMATES:
Olfactory recognition and olfactory inputs are downregulated; recognition is based on integration of multimodal sensory cues; increased redundancy in hormonal priming for motivated behaviour; increased importance of social learning
Small mammal bonding strategies
requires individual recognition by olfactory cues (also auditory, visual)
activation of neural mechanisms concerned with social reward by these cues
gender-specific hormonal priming for behavioural output
