Exam 4 - Chapter 20

Question 1

What is one of the profound implications of human evolution made in The Origin of Species?

Answer 1

humans are descended from more basal lineages and ultimately non-human taxa altogether

Question 2

What are the realities of human evolution?

Answer 2

• we are eukaryotes
• we are animals
• we are tetrapods
• we are amniotes
• we are mammals
• we are primates

Question 3

What do the realities of human evolution not tell us about?

Answer 3

• the supernatural
• a creator
• morality
• our value as individuals or communities

Question 4

What taxa to humans belong to?

Answer 4

Catarrhini, the primate taxon that includes the old world monkeys

Question 5

What species are included in the great apes?

Answer 5

• orangutans, gorillas, chimpanzees, bonobos, and humans

Question 6

What are the synapomorphies that humans share with apes?

Answer 6

• large brains
• absence of a tail
• more erect posutre
• greater flexibility of the hips and ankles
• increased flexibility of the wrist and thumb
• changes in the structure and use of the arm and shoulder

Question 7

Who did a molecular analysis to prove that humans belong to the same clade as the African great apes?

Answer 7

Sarich and Wilson, looked at human serum albumin (blood serum), which resulted in a polytony

Question 8

Humans and chimpanzees are more closely related to each other than what?

Answer 8

than either is to gorillas

Question 9

How are conflicting implications of molecular analyses reconciled?

Answer 9

with independent lineage sorting

Question 10

What is independent lineage sorting?

Answer 10

the gene tree estimated from sequence data may differ from the true species tree, occurs when some alleles are sorted out from the common ancestor into different species (ex: the common ancestor may have allele 1,2 and 3, but the descendants may only get allele 2 or 1)

Question 11

What are some of the anatomical similarities between modern humans and apes?

Answer 11

• opposable thumbs and flat nails
• large brains
• binocular vision (depth perception)
• have all of the same bones, but proportion differs

Question 12

What can the difference between bone structure in the lower limbs of humans and apes be explained by?

Answer 12

bipedalism, walking upright

Question 13

What may have bipedal running evolved from?

Answer 13

persistence hunting, the pursuit of faster prey until they exhaust

Question 14

How long ago did the old world monkeys diverge from the apes?

Answer 14

23.3 MYA

Question 15

How long ago did the lineage of apes that would become humans and chimpanzees diverge?

Answer 15

6.4 (+ or - 1.5) MYA

Question 16

How long ago did the human and chimpanzee lineage split?

Answer 16

5.4 (+ or - 1.1) MYA

Question 17

So then, what happened after the human chimp split?

Answer 17

reticulate evolution, the origination of a lineage through the partial merging of two ancestor lineages (hybridization)

Question 18

Hominins

Answer 18

includes humans and ancient relatives

Question 19

Sahelanthropus tchadensis

Answer 19

• appear from the back as chimpanzees due to small braincase
• appear from the front as australophithecus
• could be closely related to the last common ancestor of humans and chimps
• proves that hominins were in Africa about 7 MYA

Question 20

Australopithecus

Answer 20

• appear after Sahelanthropus tchadensis
• some species likely have derived into Homo
• appear in AFrica about 4 MYA

Question 20

What species is debated to be more closely related to humans or chimpanzees?

Answer 20

Ardipithecus ramidus

Question 21

Which species proved that walking upright predates humans? What other similarities does this species have with humans?

Answer 21

• Australopithecus
• similar pelvis and legs

Question 22

What genus did Australopithecus give rise to?

Answer 22

Homo

Question 23

What was the evolution of the Homo skull driven by?

Answer 23

• increased brain size, mainly in the frontal lobe
• shifting dietary patterns

Question 24

What were some of the trends in early Homo?

Answer 24

- reduction of brow ridges - loss of body hair - fire use (to keep warm, and for cooking)

Question 25

Does fire use predate homosapiens?

Answer 25

Yes, by the Homo erectus

Question 26

When were the oldest known tools in Ethiopia?

Answer 26

2.5-2.6 MYA

Question 27

What is a recent adaptation in the bones of the hand, and what does it do?

Answer 27

- third metacarpal styloid process - enables the hand to lock the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand - not seen in chimps or gorillas

Question 28

When did Homo expand from African into Eurasia?

Answer 28

between 1.8 MYA - 800 KYA

Question 29

What three lineages did Homo erectus diverge into?

Answer 29

- neanderthals (Europe and Middle East) - denisovans (Asia) - anatomical modern humans (Africa)

Question 30

How does the Anatomically Modern Human (AMH) differ from previous Homo?

Answer 30

- larger frontal lobe - more lightly built, early Homo were much more heavy boned

Question 31

AMH left Africa in how many waves? Explain both.

Answer 31

1st: may have went extint or retreated 2nd: 66-77 k years ago, reached Australia and Europe

Question 32

After migrating from Africa, AMD hybridized with:

Answer 32

mainly neanderthals, but evidence shows that some hybridization occurred with Denisovans as well

Question 33

Hybridization created more genetic variations for _________ to act on.

Answer 33

selection

Question 34

Behavioral modernity, what was also occurring at this time?

Answer 34

complex symbolic thought and expressions of cultural creativity, about 50K years ago - hybridization between Hominids

Question 35

Is skin pigmentation a poor classifier of race? How so?

Answer 35

- yes - skin pigmentation is more so the result of environmental selection, rather than similarities between lineages (Dark skin is advantageous in strong solar environments to protect against UV damage, but is selected against in weaker solar environments so that the organism can absorb more vitamin D)