Human population genetics Flashcards
When did hominids and great apes diverge?
5-7 MYA
What % of our DNA differs from chimps?
1%, 30 million differences in total, 1 in every 9 base pairs
What are the different hominid species to evolve first?
Australopithecus anamensis ~ 3.9-4.2 MYA Australopithecus afarensis ~ 3.0-3.9MYA, “Lucy”, bipedal
Paranthropus: robust, small-brained hominid ~ 1-2 MYA
When did the gene homo evolve?
Homo erectus ~ 2.5MYA. African
Homo heidelbergensis ~ 1MYA.
Homo neanderthalensis ~ 28-250 KYA
Homo sapiens. Ethiopia. 154-160 KYA.
What is the multi regional model?
Transition from h.erectus to H.sapien took place in many places, with gene flow between the populations
What is the Out of Africa model?
Divergence occurred in Africa 200kya, the spread out
How phenotypically diverse are humans?
Not diverse in comparison to our nearest relatives
Which populations are the most diverse?
African, most diverse at most markers, supports out of Africa model - would expect higher diversity if evolved via multi regional
Why are mitochondrial and DNA used to trace evolutionary relationships?
These are non recombine molecules
What is TMRCA?
Time to most recent common ancestor
What do headline strains show about ancient human populations?
Two main lineages, one isolated for 1my, on a different host. Homo sapiens must have come into contact with them due to inbreeding or fighting, for strain to be passed over
What is the importance of agriculture?
Led to change from hunter gatherer lifestyle to settlers, drove expansion of human population size
What was the consequence of transitioning to settlers?
Increased risk of infectious disease
How do humans show adaptation to the climate?
Experienced new environments out of Africa, adaptation took place in the pigmentation of skin, Bare skin at risk from UV, stronger sunlight in Africa, so darker skin, lighter skin elsewhere, due to need to absorb Vitamin D from weaker sunlight - had a grain diet, poor in vitamin d
How do humans show adaptations to diet?
Lactase enzyme, diminishes in most populations after weaning, however continues in European populations, along with pastoralism, inherited as an autosomal domoinant Mendelian trait.
