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Evolution + Mammalian Biology (EMB) > Human Evolution - The Homo Genus > Flashcards

Human Evolution - The Homo Genus Flashcards

1
Q

Fossil Basics - Trace Fossils (Ichnology)

A
  • Footprints
  • Coprolites, tracks, trails, nests
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2
Q

Fossil Basics - Periminerilsation + Petrification

A
  • Chemical process
  • Minerals replaced
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3
Q

Taphonomy

A
  • How an animal becomes fossilised and what processes mean it will/won’t
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4
Q

Why are some bones more commo than others?

A
  • Teeth is very common due to very solid material that survives trampling and wethering
  • Smaller bones are less likely to be fossilised as they can be crushed
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5
Q

Why are fossils not found everywhere?

A
  • Human fossils aren’t everywhere due to habitat e.g. rainforests
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6
Q

Stratigraphy

A
  • How layers of the earth is formed/what they are made of
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7
Q

Dating

A

top layer = new, bottom = older?
- not as straightforward as some things sink/ humans bury things in holes / in caves, there is a lack of banding due to flooding etc.

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8
Q

How do you determine a species? - Splitters

A

Different species unless there is a convincing reason to unite the

  • Variation = new species
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9
Q

How do you determine a species? - Lumpers

A

Same species unless there is a convincing reason to divide them

  • Intra-species variation normal e.g. age, sex, disease, genetic variation
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10
Q

Interbreeding

A
  • Different + related species can interbreed
  • Often infertile but not always (takes 2 million years of separation from a common ancestor)
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11
Q

Hybrid zones

A

10% of primate species engage in cross-species hybridization

  • can result in a new species
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12
Q

Fossil remains are limited

A
  • Complete skeletons are incredibly rare + can be difficult to identify
  • Usually find a mix of fragmentary bones + teeth
  • Often impossible to link cranial + post cranial elements
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13
Q

Original definition of Homo genus (compared to previous genus)

A
  • Small, modern teeth compared to ancestors’ large teeth in homo fossil record
  • Bipedal
  • Tool use - thought this meant intelligence so they are more human
  • Brain size
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14
Q

Small teeth not exclusive to Homo genus

A
  • Found before homo species
  • Older species (Australopithecus sediba (MH2)) had smaller teeth than homo genus
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15
Q

Being bipedal not exclusive to Homo genus

A
  • Upright posture/ bipedality goes back 7 million years with Sahelanthropus tchadensis
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16
Q

Tool use not exclusive to Homo genus

A
  • Use of tools predated Homo genus (~2.8 Mya)
  • ~3.3 Mya ‘Lomekwian’ : Kenyanpithecus platyops
  • ~3.4 Mya cut marks on bones: Australopithecus afarensis
17
Q

Bigger brains not exclusive to Homo genus

A
  • Homo habilis = 500cm^3 on low end while Paranthropus robustus = 550cm^3
  • There was a trend towards bigger brain vol over times
  • However, variations with ranges overlapping between ancestors of another genus + more modern homonids
18
Q

Is our definition of Homo wrong & why all these problems with the Homo genus?

A
  • Homo habilis was found with old definition of homo genus but with a small brain
  • Debate if it counts as a homonids e.g. they used tools a lot, small teeth, but more like the species before than species later
19
Q

Genetics + interbreeding : H. sapiens

A

Interbred with:
- Denisovans (Melanesians & Aboriginal Australians)
- H. neanderthalensis (Eurasians + Africans)
- Also with unknown archaic European pop. + African pop. (in areas with lack of fossil record e.g. West Africa)

20
Q

Genetics + interbreeding : H. neanderthalensis & Denisovans

A

Interbred thousands of years ago:
- Female remains from around 90 kya found to have a N mother + D father

21
Q

Link between climate + evolution of homonids

A
  • Large climatic fluctuations when homo genus evolved

If climate is variable/ severe, you might:
- Die out
- Move to a new area
- Adapt to diff. conditions

Hominin variability = environmental variability

22
Q

Homo mass migration out of Africa however…

A
  • Absence of evidence is not evidence of absence
  • Lack of fossils in regions doesn’t mean there are no homonids
23
Q

Did Homo habilis leave Africa? - Theories

A
  • Inefficient energetics as they were shorter = shorter strides so more energy not as efficient at moving
  • Challenging Northern African habitat - dry + desert condition
  • Were scavengers - didn’t actively hunt

However, no evidence that they left Africa

24
Q

Were Homo erectus the first global species?

A

Originally considered all individuals:
- Energetically efficient, tall, bipeds
- Had increased brain size

  • Known to be morphologically variable
  • Behaviourally more capable/adaptable since they’re active hunters - can make tools to problem solve
  • Makes it easier to eat while migrating not relying on finding food
25
Q

Violence between modern humans and neanderthals

A
  • Evidence of interspecies aggression from bone injuries
  • But, highly unlikely this caused Neanderthal extinction
  • Neanderthals also had tools + were the main species at the time
    ==> really unlikely to be extinct by violence
26
Q

Pathogens from modern humans to Neanderthals?

A
  • Happened when modern humans made it to Eurasia
  • Neanderthals had no defense as it was new to them
    => Modern humans did also pick up things from Neanderthals
  • Tapeworms, TB, stomach ulcers + types of herpes may have weakened the Neanderthal pop.
  • No evidence that this alone killed Ns off
27
Q

Did climate change, small populations and competition kill of Neanderthals?

A
  • Neanderthals were well adapted to cold
    => but climate got colder around time they died out
  • Could move south for warmer cond. but humans were migrating out of the south
    => had similar niches so more competition
  • Lived in small populations so less flow of genetics and less genetic diversity (inbreeding could happen) unlike homo sapiens
28
Q

Did interbreeding kill off Neanderthals?

A
  • DNA indicates this happened
  • However, may have not died out but the species joined with homo sapiens
  • 40,000 years ago, 6-9% of human genome came from N

Evolution + Mammalian Biology (EMB) (10 decks)

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