Lecture 7 Flashcards
what are the Benefits of group life:
Direct access to mates
increased acquisition and control of resources
protection from predation through the “three D’s:” detection, deterrence and dilution
what is detection
(can detect the predators)
what is deterrence
(detters any attack from predators)
what is dilution
(diluting the effect, reducing the effect, that a predator can have on a group… the bigger the group the less an attack will impact them)
what are the Drawbacks to group life
increased likelihood of disease transmission
dramatically increased competition for resources and mating partners
what are the Types of Primate Social Organization
solitary
females and offspring form tight groups and the males are left no the outside
pair-‐bonded (monogamous)
one female, many males (polyandry)
one male, many females (one-male polygyny)
many dominant males, many females (multi-male polygyny
How does sexual reproduction and sexual selection factor into the social lives of primates in within these groups?
Understanding sexual reproduction and care for offspring within primate societies can shed light on the evolution of human social development
Why wouldn’t males always be more involved in child-rearing?
The benefits of child-‐rearing must be weighed against the benefits of continuing to mate with available females.
Cost vs. benefit
Absent fathers are selected for when two conditions are met:
- there is widespread availability of, and access to, additional females
- females within the group are generally able to raise offspring as well as when both parents are present
Why are females the only sole caregivers?
- The investment of time and energy related to pregnancy
2. The ability to lactate
Primate gestation periods are, compared with those of most mammals, relatively long, from between 59 days to 9 months
This is due primarily to:
1) size of the mother
2) brain development of the infant
do Most primate young remain dependent for longer periods
Most primate young remain dependent for longer periods than do the young of most mammals
what is lactational amenorrhea
reducing or eliminating their fertility from between one to three years
do female primates experience lactational amenorrhea
yes
Why are long pregnancies, long periods of infant dependency and lack of fertility while nursing selected for?
- Primate young require additional attention
2. Most nonhuman primates can continue reproducing very late in life
Phenotypic differences between males and females within a species are characterized as what
sexual dimorphism
what is sexual dimorphism
an adaptive response to competition between males for access to females.
The degree of difference between males and females relates directly to what
the type of social organization present
Sexual dimorphism is most exaggerated within what kind of group
one-male polygynous primate groups.
This is due to regular challenges to the resident dominant male by itinerant “bachelors
these groups are forming and then try and break in and overthrow the alpha male
Among solitary primates, the degree of sexual dimorphism is;
high
degree of sexual dimorphism is low where
it is low among polyandrous New World monkeys;
what is sexual dimorphism like within groups comprised of multiple males and multiple females
it varies a lot
why? there is no competition, the animals do not care who has the offspring, as long as everyone pitches in and help to raise them when they come
Pair-‐bonded species, such as gibbons, have the ______ degree of sexual dimorphism among primates.
lowest
what is the degree of human sexual dimorphism like
The degree of human sexual dimorphism is relatively low; among primates, it lies between that of pair-bonded and polygynous species.
This indicates that some degree of regular competition for mates has played a significant role in human social development.
what is Infanticide
is the purposeful killing of infants within a group
infanticide is often part of the transition of dominance within a group; new dominant males will kill infants to;
1) free mothers for procreation
2) ensure that all infants within the group are his
Dominant females in _______ groups will sometimes commit infanticide for similar reasons
polyandrous
Dominant females in polyandrous groups will sometimes commit infanticide for similar reasons, why is this
they want to ensure the they know who the father is so they can get investment…
The complex social relationships that typify primate social organization are closely related to what
cognition
Natural selection favors the ability to what from peers
Natural selection favors the ability to both innovate and learn innovative techniques from peers
