ANTH Final: PART1 - Modern Humans and Archaic Hominins

Ancient DNA (aDNA)

Genetic material obtained from the remains of organisms that lived in the past, such as bones, teeth, or preserved tissues.

Challenges of working with aDNA

Degradation of DNA over time and contamination from modern DNA during excavation or lab work.

Denisovans

A group of archaic humans closely related to Neanderthals, identified primarily through DNA analysis of fossils found in Denisova Cave.

Evidence of Denisovans' existence

Known from ancient DNA extracted from fossil remains revealing a unique genetic lineage.

Relationship of Denisovans to Neanderthals and Homo sapiens

Denisovans and Neanderthals were sister groups splitting from a common ancestor after diverging from Homo sapiens, with all three interbreeding.

Regions inhabited by Denisovans

Parts of Asia, including Siberia and possibly Southeast Asia, with genetic legacy strongest in Melanesia, Papua New Guinea, Aboriginal Australians, and some Southeast Asians.

Introgression

The incorporation of genes from one population into another through interbreeding.

Neanderthal DNA in African populations

Originally believed absent, recent research found low levels of Neanderthal DNA in Africans due to back-migration from Eurasia.

Origins of Neanderthal DNA in Africans

Likely introduced through non-African humans who interbred with Neanderthals and migrated back.

Selection against Neanderthal or Denisovan variants

Evidence shows that many of these genetic variants were selected against due to being harmful or incompatible with Homo sapiens.

Positive selection of archaic variants

Some archaic genetic variants were beneficial and favored, such as those involving immunity, skin pigmentation, and adaptations to environmental conditions.

Role of disease in genetic selection

Archaic genes that enhanced immunity to new pathogens would have provided survival advantages.

Genes dealing with high altitude

An example is the EPAS1 gene variant found in Tibetans, believed to be inherited from Denisovans.

Habitat of Neanderthals

Lived across Europe and parts of western and central Asia, from Spain to Siberia.

Possible encounters between Neanderthals and Denisovans

Likely encountered each other in Central and Eastern Asia, particularly in the Altai region.

Encounters between Neanderthals and Homo sapiens

Likely occurred in the Middle East and Europe after modern humans migrated out of Africa leading to interbreeding.

Phylogenetic analysis and African origin of Homo sapiens

Mitochondrial DNA shows greatest diversity in African populations, supporting the hypothesis of an African origin.