Primate Evolution

Question 1

What is the problem with Paleoanthropology?

Answer 1

Behaviors don’t fossilize

Question 2

What indicators of ancient behaviors do we have?

Answer 2

Dentition
Fire?
Hyoid bone => spoken language?
Tools (but bias! not all tools)
Findings in caves
Burials => symbolic thought?

Question 3

Why did we acquire the traits we have?

Answer 3

• shared ancestry
• convergent evolution

Question 4

Which 4 groups of monkeys exist?

Answer 4

Prosimians (e.g. Lemurs)
New world monkeys (e.g. Callitrichids)
Old world monkeys (e.g. Maccaques, Babboons)
Apes

Question 5

What do all primates (more or less) have in common?

Answer 5

• long gestation
• forward facing eyes
• grasping hands and feet
• hind limb driven locomotion
• olfaction replaced by vision
overlapping visual field helps with depth perception
• small litters
• long juvenile period, long lifespan (K-selected)
• rel. large brain
• increased dependence on learning and behavioral flexibility

Question 6

Consequences of diet for home ranges

Answer 6

Leaves: easy, small home ranges
Fruits: seasonality and distribution = cognitive challenge, large homeranges bc. lower availability

Question 7

Territorial primates

Answer 7

If benefits > costs:
benefits => protect lim resources
costs => must defend area (collective action problem (free riders) => coordination)

Non-overlapping home ranges
Aggressive

Contest competition (clumped food distribution)

Question 8

Scramble competition

Answer 8

distributed foods
intake not correlating with dominance

Question 9

When does dominance emerge?

Answer 9

If contest (clumped food sources) is high enough

Question 10

Dominance

Answer 10

Can lead to dominance hierarchy

Benefit: if repeated interactions = no escalation needed
=> signals
=> energy cheap and efficient way of dealing with conflict

Costs: requires
• individual recognition
• repeated interactions
• Memory

Question 11

Primates as prey

Answer 11

Vulnerable if small and terrestrial
=> terrestrial primates tend to be larger and live in groups

Question 12

Group living

Answer 12

Detection
Deterrence (collective defense)
Dilution

Question 13

A couple of vigilant marmosets can be compared to

Answer 13

coupled oscillators, where the interval of how long an individual can eat uninterruptedly is elongated

Question 14

What is the optimum group size?

Answer 14

where predation risk and feeding competition/disease avoidance converge
=> point where benefits and costs optimally integrated

But in primates optimum is unstable => groups tend to be bigger and then split

Question 15

Group living

Answer 15

Mix of competition and cooperation

Question 16

Why do dominant females in small groups usually rear more offspring?

Answer 16

more nutritional resdources

Question 17

What are the trade offs in female reproduction?

Answer 17

• own growth vs reproduction
• current or nex offspring
• quantity or quality

Question 18

What is lactational amenorrhea?

Answer 18

Period when female is weaning infant

Not in humans and callitrichs
=> cooperative breeding

Question 19

Why is sexual selection stronger on males?

Answer 19

Bc. reproductive success is more variable in males

Question 20

What are the implications of infanticide affecting reproductive success?

Answer 20

• should only occur if group has been taken over
• only unweaned (still drinking milk from mother) infants should be targeted
• not done by sexually active males in a group
• the ones that kill will later mate with females