Life History and Development

Question 1

What is the concept of pervasive tradeoffs?

Answer 1

There are fixed pools of energy, where when energy is directed towards one thing, that energy is taken away from another

Question 2

What are the 3 key trade-offs in life history?

Answer 2

1) Number vs quality of offspring
2) Age vs size at maturity
3) Current vs future reproductive function

Question 3

What are the 3 main things that resources are directed toward?

Answer 3

1) Growth
2) Reproduction
3) Maintenance

Question 4

What makes humans unique from other primates?

Answer 4

Humans live past reproductive age (post-reproductive/post-menopause lifespan)

Question 5

What is the grandmother hypothesis?

Answer 5

States that humans live past reproductive age because grandmothers provide care for their grandchild, therefore increasing their survival and her own fitness

Question 6

What are the characteristics of a juvenile (5)?

Answer 6

1) Weaned
2) Sexually immature
3) Independent locomotion
4) Can survive without caregiver
5) Not full-sized

Question 7

What is the sequence of life history?

Answer 7

1) Gestation
2) Infancy (period of weaning)
3) Juvenile
4) Adulthood (marked by first reproduction)

Question 8

What is the Charnov model?

Answer 8

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

Question 9

What are the advantages of early vs late reproductive age?

Answer 9

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)

Question 10

What determines the reproductive age of species?

Answer 10

The external environment and the risk of death, where high risk = more beneficial to reproduce earlier

Question 11

How do lifespans of arboreal species compare to terrestrial species?

Answer 11

Arboreal species have longer lifespans

Question 12

What are the 2 hypotheses for long juvenility?

Answer 12

1) Ecological risk hypothesis
2) Need to learn hypothesis

Question 13

What does the ecological risk hypothesis state?

Answer 13

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

Question 14

What are the predictions associated with the ecological risk hypothesis?

Answer 14

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

Question 15

What is the evidence for “juveniles of species with reliable foods should grow faster than species with unreliable foods”?

Answer 15

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

Question 16

What does the need to learn hypothesis state?

Answer 16

Social complexity takes a long time to learn, therefore juvenile period allows for acquisition of adult competence

Question 17

Is the need to learn hypothesis mutually exclusive with the ecological risk hypothesis?

Answer 17

No

Question 18

What is the evidence associated with need to learn hypothesis (2)?

Answer 18

1) Orangutans achieve adult-like ingestion rates shortly after weaning
2) Adult competency is reached before adulthood in chimpanzees

Question 19

What is the difference between juvenile chimp males and females when it comes to termite fishing?

Answer 19

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

Question 20

What is social play?

Answer 20

Includes rough and tumble (RT), wrestling, tag, chasing, etc.

Question 21

What does social play serve as?

Answer 21

Prep for adult life

Question 22

What are the 2 hypotheses regarding the function of social play?

Answer 22

1) Motor-training hypothesis (enhance motor skills)
2) Social relationships hypothesis (enhance social skills)

Question 23

What are the predictions associated with the motor-training hypothesis?

Answer 23

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

Question 24

What are the predictions associated with the social relationships hypothesis?

Answer 24

If adult male-female bonds are prevalent (e.g., in Gorillas), Juvenile females should play more with males than females

Question 25

How is the size of wild primates measured?

Answer 25

Using photogrammetry with fixed parallel lasers as calibration

Question 26

Where does the energy budget for locomotor play come from?

Answer 26

Locomotor play trades off with growth (increased locomotor play results in decreased growth rate)

Question 27

What was initially thought about the source of energy for play?

Answer 27

Thought that play was “extra energy” that primates could burn off without consequence

Question 28

Where does the time come from for locomotive play?

Answer 28

It comes from the resting budget (i.e., time resting is reduced in exchange for play)

Question 29

During increased food availability, what do the sexes tend to allocate the extra energy toward?

Answer 29

1) Immature females invested in increased growth rates
2) Immature males invested in locomotor play

Question 30

What is the relationship between motor skill acquisition time and play?

Answer 30

Motor skill acquisition occurs faster with more play

Question 31

Describe the growth differences between males and females

Answer 31

Males tend to grow slowly but continuously through their life, while females grow quicker but stop after a certain period