Lecture 27 - Human Evolution Flashcards

1
Q

Humans (who are we?)

A

One of the few hominid species
- only homo species left

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2
Q

What are humans ancestor?

A

Hominidae (Family) 15 mya
Homininae (Subfamily) 10 mya
Hominini (Tribe) 5 mya

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3
Q

What are the three Homo species

A

Homo sapiens “Humans”

Homo denisova “Denisovans”

Homo neanderthalensis “Neanderthals”

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4
Q

Neanderthals (when, where and climate)

A

lived 700,000 - 200,000 years ago

mostly found in Europe but also Asia

Neanderthals were well adapted to colder climates (survived through 3 or 4 ice ages)

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5
Q

Neanderthals characteristics

A

Same average height as pre-industrial humans , but with larger brains

broader structures and weighed more than pre-industrial humans

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6
Q

Do Neanderthals share genes with Humans?

A

Yes, known through remains found in the same places and are dated to the same time

evidence that co-existed as Neanderthals genomes have been sequenced and there has been at least one major introgression event between humans and Neanderthals.

Main introgression event occurred around 60,000 years ago when humans migrated to Africa. this is likely the reason that non-sub-saharan Africans all have some Neanderthal DNA in their genomes

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7
Q

What is strong correlation in allele frequency plotted on a graph for two populations allele frequencies?

A

Strong correlation means that if the SNP is high in one population it is also high in the other.

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8
Q

What is likely to be seen where there is little to no divergence between populations?

A

suggests that the evolution has occurred in one population more than the other (points on the graph that stray from the strong correlation diagonal line)

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9
Q

Where did EPAS1 allele for altitude adaptation cum from?

A

it came from Denisovan introgression

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10
Q

Current selection in humans:

is there still genetic and phenotypic variation?

is there still heritable variation?

are there still fitness differences

A

YES

YES

Probably

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11
Q

What kind of species are humans, neanderthals, and Denisovans?

A

These are morphological species

some people say that they are not different species because they can produce viable offspring

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12
Q

The retention CCR5-delta 32 in some human population is a result of…

A

Antagonistic pleiotropy

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13
Q

what is antagonistic pleiotropy?

A

this is when a single gene affects more than one trait related to fitness, with allelic variants promoting the fitness of different traits

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14
Q

How did Homo sapiens spread out of Africa?

A

They left Africa around 60,000 years ago in a founder population event and spread worldwide.

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15
Q

What evidence supports Neanderthal and Denisovan interbreeding with Homo sapiens?

A

Genomic evidence shows traces of Neanderthal DNA in non-sub-Saharan Africans and Denisovan DNA in East Asians and Melanesians.

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16
Q

Why do some genes appear to have been inherited from Neanderthals?

A

They provided adaptive advantages, such as altitude adaptation in Tibetans and immune responses.

17
Q

What is an example of recent human evolution related to Homo species interbreeding?

A

Delta-32 CCR5 deletion, which provides HIV resistance, likely increased due to selection pressure.

18
Q

What is the role of modern evolution in human health traits?

A

Traits like cholesterol levels can show heritable variations associated with fitness differences, leading to ongoing evolution.

19
Q

How does genetic evidence confirm interaction between humans and Denisovans?

A

Denisovan DNA is found in specific human populations, indicating interbreeding, especially in Melanesians.

20
Q

How do we infer that Homo erectus used tools and possibly fire?

A

Archaeological evidence of tools and controlled fire use points to advanced behaviour in Homo erectus.

21
Q

What traits suggest Neanderthals were well-adapted to their environment?

A

Their short, robust builds and large brains indicate adaptation to cold climates and complex behaviour.

22
Q

What evidence supports ongoing natural selection in modern humans?

A

Genetic studies showing allele frequencies linked to traits like lactase persistence and disease resistance.