Life History and Development Flashcards
What is the concept of pervasive tradeoffs?
There are fixed pools of energy, where when energy is directed towards one thing, that energy is taken away from another
What are the 3 key trade-offs in life history?
1) Number vs quality of offspring
2) Age vs size at maturity
3) Current vs future reproductive function
What are the 3 main things that resources are directed toward?
1) Growth
2) Reproduction
3) Maintenance
What makes humans unique from other primates?
Humans live past reproductive age (post-reproductive/post-menopause lifespan)
What is the grandmother hypothesis?
States that humans live past reproductive age because grandmothers provide care for their grandchild, therefore increasing their survival and her own fitness
What are the characteristics of a juvenile (5)?
1) Weaned
2) Sexually immature
3) Independent locomotion
4) Can survive without caregiver
5) Not full-sized
What is the sequence of life history?
1) Gestation
2) Infancy (period of weaning)
3) Juvenile
4) Adulthood (marked by first reproduction)
What is the Charnov model?
Basic life history model that
1) Assumes animals have a fixed pool of energy which is a function of its body size
2) States energy can either be allocated towards growth or reproduction, but not both
What are the advantages of early vs late reproductive age?
1) Delaying maturity can improve offspring survival and increase number of offspring
2) Delaying for too long can result in death before reproduction (extrinsic mortality)
What determines the reproductive age of species?
The external environment and the risk of death, where high risk = more beneficial to reproduce earlier
How do lifespans of arboreal species compare to terrestrial species?
Arboreal species have longer lifespans
What are the 2 hypotheses for long juvenility?
1) Ecological risk hypothesis
2) Need to learn hypothesis
What does the ecological risk hypothesis state?
Juvenile primates are inept at protecting themselves from predation but also at high risk of starvation, therefore lower growth rates is beneficial in distributing metabolic costs over an extended juvenile phase
What are the predictions associated with the ecological risk hypothesis?
1) Juveniles should have lower foraging efficiency than adults
2) Juveniles should suffer higher mortality from starvation
3) Juveniles should suffer more predation
4) Juveniles of species with reliable foods should grow faster than species with unreliable foods
What is the evidence for “juveniles of species with reliable foods should grow faster than species with unreliable foods”?
Gorillas are supplied with more abundant/rich foods than chimpanzees, and we see that:
1) First birth age is younger in gorillas
2) IBI is shorter for gorillas
3) lifespan is shorter for gorillas
What does the need to learn hypothesis state?
Social complexity takes a long time to learn, therefore juvenile period allows for acquisition of adult competence
Is the need to learn hypothesis mutually exclusive with the ecological risk hypothesis?
No
What is the evidence associated with need to learn hypothesis (2)?
1) Orangutans achieve adult-like ingestion rates shortly after weaning
2) Adult competency is reached before adulthood in chimpanzees
What is the difference between juvenile chimp males and females when it comes to termite fishing?
1) Females use a similar technique to their mother, while males play at the termite mold
2) Females are more proficient fishers
3) Females start to fish at a younger age
What is social play?
Includes rough and tumble (RT), wrestling, tag, chasing, etc.
What does social play serve as?
Prep for adult life
What are the 2 hypotheses regarding the function of social play?
1) Motor-training hypothesis (enhance motor skills)
2) Social relationships hypothesis (enhance social skills)
What are the predictions associated with the motor-training hypothesis?
If male RS depends on size and fighting ability = males need more motor training than females
2) Juvenile males play more than juvenile females
3) Juvenile males play more with males than females
What are the predictions associated with the social relationships hypothesis?
If adult male-female bonds are prevalent (e.g., in Gorillas), Juvenile females should play more with males than females
How is the size of wild primates measured?
Using photogrammetry with fixed parallel lasers as calibration
Where does the energy budget for locomotor play come from?
Locomotor play trades off with growth (increased locomotor play results in decreased growth rate)
What was initially thought about the source of energy for play?
Thought that play was “extra energy” that primates could burn off without consequence
Where does the time come from for locomotive play?
It comes from the resting budget (i.e., time resting is reduced in exchange for play)
During increased food availability, what do the sexes tend to allocate the extra energy toward?
1) Immature females invested in increased growth rates
2) Immature males invested in locomotor play
What is the relationship between motor skill acquisition time and play?
Motor skill acquisition occurs faster with more play
Describe the growth differences between males and females
Males tend to grow slowly but continuously through their life, while females grow quicker but stop after a certain period
