Lecture 16 Flashcards

1
Q

Explain how we classified humans before evolution.

A

“homo” - defined by Carl Linnaeus.

  • people and apes in the same order.
  • based on morphological characteristics.
  • still thought species to be made by god and ‘unmutable’.
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2
Q

Explain Lamarck’s beliefs.

A

Lamarck thought that acquired characteristics can be inherited (e.g. giraffe necks).

First to suggest that humans and ape had a shared evolutionary history.

Thought that through acquired characteristics and over many generations humans became bipedal and lost the ability to climb trees.

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3
Q

Why was there such a debate about human evolution?

A

We had only found a fraction of the fossil record which we have discovered today.

Until the 1800s, no fossils found of ancient human species, only a few stone tools.

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4
Q

What was the first piece of human fossil record found? What were people’s reactions?

A

Homo Neanderthalis - first human species identified besides our own.

People were not pleased, controversial.

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5
Q

Describe Australopithecus.

A

Base of the human tree.

  • bi-pedal, ape-like.
  • small brains, but some made tools.
  • change in diet.
  • greater sexual dimorphism.

Habitat: Africa.

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6
Q

Describe homo habilis.

A

The first Homo.

  • brain is getting bigger, teeth smaller.
  • definitely made stone tools (“the handyman”).

Habitat: Africa.

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7
Q

Describe Homo erectus.

A

Most successful human species identified to date.

  • believed to be the first to leave Africa.
  • big brains, tools, hunters.
  • possibly fire, art, speech.

Habitat: Africa.

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8
Q

Describe Homo antecessor.

A

Two lineages from homo erectus that became us and other species.

  • sister species to H. Sapiens.
  • suggests an entire other lineage of human evolution.

Habitat: Western and Southern Europe.

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9
Q

Describe homo heidelbergensis.

A

Overlapped with (evolved from) h. Erectus.

Habitat: Asia, Europe, Northern Africa.

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10
Q

Describe homo neanderthalensis.

A
  • sister species to us.
  • survived many ice ages.
  • had many technologies we recognize.

habitat: Europe, Central Asia.

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11
Q

Describe Homo Florensis.

A

Nicknamed the hobbit.

  • species which lived alongside our own.
  • may have experienced insular dwarfism.
  • many primitive features: possibly directly evolved from H. Erectus, or H. Habilis.

Habitat: Flores, Indonesia.

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12
Q

Describe Denisovans.

A

A sister species to us - believed to have descended from the same common ancestor.

The only human species identified solely by DNA, no skull identified to date,

Habitat: Western and Central Asia.

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13
Q

Describe Homo sapiens.

A

Only extant species in the Homo genus.

  • skull morphology has changed distinctly over time.
  • evolved in Africa and left, current global distribution.
  • interacted with other Homo species.
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14
Q

Describe the progression of evolution.

A

It was once believed that there was a straight line of evolution - home species did not go extinct, instead they became the next species in the homo genus.

Evolution is associated with physical and technological changes that opened up new niches.

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15
Q

Explain why there are debates about focusing solely on morphological traits.

A
  1. Fossil record is very fragmented, there may be intermediates missing.
  2. Difficult to distinguish chrono species.
  3. Difficult to tell apart natural variation within species from differences separating species.
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16
Q

What is the issue with using DNA to characterize evolution?

A

Widely believed that we would never be able to analyze DNA past its half-life.

Half-life = 521 years.

17
Q

What is ancient aDNA?

A

DNA that gives the ability to sequence DNA beyond its hard-life.

Current theoretical upper limit for analysis: 1.5 million years.

18
Q

How does aDNA work?

A

PCR lets us amplify tiny samples, so it is not an issue that DNA breaks down significantly over time - we can analyze it past its half-life.

We can build ancient genomes from fragments y comparing them to modern ancestors.

19
Q

How do we expect degree of genetic diversity to differ between populations in different continents?

A

Africa: high diversity.

  • greater portion of rare alleles.
  • rare alleles are likely to be found in founder populations.

Europe: lower diversity.

  • greater proportion of deleterious mutations.
  • expected in recent founder population.

Asia: lowest diversity.