Human Evolution

Question 1

Human Differences

Answer 1

Complex thoughts
Culture
Language
Technology

Question 2

Human Similarities

Answer 2

We are here because our ancestors reproduced

If reproductive success depends on heritable variation in traits, we are still evolving

Question 3

Physical changes often provide species with new adaptive challenges and opportunities:

Answer 3

• Global climate change
• Continental drift
• Geological changes
– New environments can arise (e.g., mountain ranges, desert basins)
– Geology may also change connections between two populations without a large
effect on how they live

Question 4

therapsids

Answer 4

• radiated and dominated many terrestrial environments before dinosaurs did
• largely replaced by dinosaurs in the age of dinosaurs

Question 5

radiation

Answer 5

gain in species diversity

-gives many chances for adaptation

Question 6

contraction

Answer 6

loss of species diversity

Question 7

Reasons for contraction/extinction

Answer 7

– Changing conditions (climate change, continents moving)
– Competition from other clades (therapsids vs. dinosaurs)
– Competition from a successful member (people vs. other hominins)

Question 8

Advantages of previous radiation

Answer 8

• explored more kinds of environments
• found in more different specific places
• had more chances to adapt

Question 9

primates -characterized by… (3 points)

Answer 9

– Highly developed stereroscopic vision
∗ Eyes are close together, face forward, and are used together, allows 3-d visualization
– Versatile limbs
∗ Grasping hands and feet
∗ Nails and fingertips (instead of claws)
– Large brains

Question 10

There are many theories for why primate traits might have been adaptively favored in our ancestor: (5 points)

Answer 10

– Leaping from branch to branch
– Climbing and balancing on trees
– Exploiting new plant resources
– Catching insects
– Adaptive foraging

Question 11

Adaptive foraging

Answer 11

the ability to switch between types of food, and to learn to use new types of food

Question 12

Ape adaptations

Answer 12

• Apes are more adapted for swinging through trees, whereas monkeys are more adapted for climbing and leaping
• More upright
• Better at hanging, bad at sitting

Question 13

Why might apes have diversified, and later been replaced by monkeys?

Answer 13

– Changing climactic conditions
– Changes in plants or insects
– Unpredictable adaptive innovations

Question 14

What if the ape radiation had never happened?

Answer 14

–Less diversity between surviving apes

– Probably no people

Question 15

frugivory

Answer 15

eating fruit

Question 16

folivory

Answer 16

eating leaves

Question 17

insectivory

Answer 17

eating insects

Question 18

Teeth -Importance?

Answer 18

• important for processing food

- help scientists understand what extinct animals ate (often preserved, highly adapted)

Question 19

Eye orbits

Answer 19

skeletal cavities where eyes are

Question 20

Eyes -Importance?

Answer 20

tell us size, shape and position of eyes from fossil animals

Question 21

What are the advantages and disadvantages of more forward-facing eyes?

Answer 21

• Better for precise tasks, three-dimensional visualization

- Not as good for looking around, being alert

Question 22

What are the advantages and disadvantages of larger eyes?

Answer 22

• Better for night vision

- More costly? Harder to protect?

Question 23

In species where there is more variation in male success, we expect:

Answer 23

More sexual dimorphism

More competition between males for females

Question 24

Gorilla Dimorphism and sexual strategies

Answer 24

live in male-centered groups (one adult male, several adult females)

Question 25

Chimp Dimorphism and sexual strategies

Answer 25

live in large, well-mixed groups with lots of interactions between males
and females

Question 26

Which species, gorillas/chimps, should have more sexual dimorphism overall?

Answer 26

Gorillas. Males are huge and strong and compete for females by displaying and fighting. A dominant male has exclusive access to a group of females

Question 27

Which species, gorillas/chimps, should have larger male genitals?

Answer 27

Chimpanzees have much larger genitals.

Gorillas don’t use genitals as part of sexual competition

Question 28

Hominins

Characterized by….

Answer 28

refer to people and our upright ancestors
–Walking upright
– Specific changes in chewing design: teeth, jaws and skull

Question 29

Modern humans

Characterized by…

Answer 29

• small face and teeth

* Less robust skeletal structure

Question 30

How did upright posture and upright walking evolve?

Theories

Answer 30

–Adaptation to walking on the ground instead of swinging through trees
– Adaptation for keeping cool
– Adaptation for harvesting food
– Adaptation for carrying food

Question 31

complex foraging

Answer 31

rely on many types of food, including types of food that are difficult to get or process

Question 32

What adaptations likely favored complex foraging?

Answer 32

Clever hands, upright walking

Question 33

What further adaptations might complex foraging have favored?

Answer 33

–Big brains
– co-operation, including male-female co-operation
– Social behaviour

Question 34

Complex foraging may have promoted

co-operation between:

Answer 34

• between females and males, since primate child care is not well suited to a hunting life style
• between people with different skills, since they might have access to food at different times
• among hunters, since hunting success is highly variable
• in teaching and learning

Question 35

Complex foraging and thinking

Answer 35

Complex foraging favors large brains that can learn a lot

• It also favors a long learning period and communication

Question 36

Why do human children develop so slowly?

Answer 36

Presumably related to elaborate sociality

-interested in how long it took our ancestors to mature: clues available in dental enamle/molar development