Exam 4 - Chapter 20 Flashcards
What is one of the profound implications of human evolution made in The Origin of Species?
humans are descended from more basal lineages and ultimately non-human taxa altogether
What are the realities of human evolution?
- we are eukaryotes
- we are animals
- we are tetrapods
- we are amniotes
- we are mammals
- we are primates
What do the realities of human evolution not tell us about?
- the supernatural
- a creator
- morality
- our value as individuals or communities
What taxa to humans belong to?
Catarrhini, the primate taxon that includes the old world monkeys
What species are included in the great apes?
- orangutans, gorillas, chimpanzees, bonobos, and humans
What are the synapomorphies that humans share with apes?
- 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
Who did a molecular analysis to prove that humans belong to the same clade as the African great apes?
Sarich and Wilson, looked at human serum albumin (blood serum), which resulted in a polytony
Humans and chimpanzees are more closely related to each other than what?
than either is to gorillas
How are conflicting implications of molecular analyses reconciled?
with independent lineage sorting
What is independent lineage sorting?
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)
What are some of the anatomical similarities between modern humans and apes?
- opposable thumbs and flat nails
- large brains
- binocular vision (depth perception)
- have all of the same bones, but proportion differs
What can the difference between bone structure in the lower limbs of humans and apes be explained by?
bipedalism, walking upright
What may have bipedal running evolved from?
persistence hunting, the pursuit of faster prey until they exhaust
How long ago did the old world monkeys diverge from the apes?
23.3 MYA
How long ago did the lineage of apes that would become humans and chimpanzees diverge?
6.4 (+ or - 1.5) MYA
How long ago did the human and chimpanzee lineage split?
5.4 (+ or - 1.1) MYA
So then, what happened after the human chimp split?
reticulate evolution, the origination of a lineage through the partial merging of two ancestor lineages (hybridization)
Hominins
includes humans and ancient relatives
Sahelanthropus tchadensis
- 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
Australopithecus
- appear after Sahelanthropus tchadensis
- some species likely have derived into Homo
- appear in AFrica about 4 MYA
What species is debated to be more closely related to humans or chimpanzees?
Ardipithecus ramidus
Which species proved that walking upright predates humans? What other similarities does this species have with humans?
- Australopithecus
- similar pelvis and legs
What genus did Australopithecus give rise to?
Homo
What was the evolution of the Homo skull driven by?
- increased brain size, mainly in the frontal lobe
- shifting dietary patterns
What were some of the trends in early Homo?
- reduction of brow ridges
- loss of body hair
- fire use (to keep warm, and for cooking)
Does fire use predate homosapiens?
Yes, by the Homo erectus
When were the oldest known tools in Ethiopia?
2.5-2.6 MYA
What is a recent adaptation in the bones of the hand, and what does it do?
- 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
When did Homo expand from African into Eurasia?
between 1.8 MYA - 800 KYA
What three lineages did Homo erectus diverge into?
- neanderthals (Europe and Middle East)
- denisovans (Asia)
- anatomical modern humans (Africa)
How does the Anatomically Modern Human (AMH) differ from previous Homo?
- larger frontal lobe
- more lightly built, early Homo were much more heavy boned
AMH left Africa in how many waves? Explain both.
1st: may have went extint or retreated
2nd: 66-77 k years ago, reached Australia and Europe
After migrating from Africa, AMD hybridized with:
mainly neanderthals, but evidence shows that some hybridization occurred with Denisovans as well
Hybridization created more genetic variations for _________ to act on.
selection
Behavioral modernity, what was also occurring at this time?
complex symbolic thought and expressions of cultural creativity, about 50K years ago
- hybridization between Hominids
Is skin pigmentation a poor classifier of race? How so?
- 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)
