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Evolution and Human Origins. Common Ancestors. Closeness of relationship is reflected by greater DNA sequence similarity i.e. the closer 2 species are in relation to each other, the more DNA sequences they will share Similar sequences are likely to have arisen from a common ancestor.
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Common Ancestors • Closeness of relationship is reflected by greater DNA sequence similarity • i.e. the closer 2 species are in relation to each other, the more DNA sequences they will share • Similar sequences are likely to have arisen from a common ancestor
Evolutionary Tree • Evolution is NOT a linear morphing of one organism into another! • Each branching point represents divergence from a common ancestor • Does NOT happen overnight
Hominoids vs. Hominins • Hominoid • Animals ancestral to apes and humans • Hominins • Animals ancestral to humans only
Molecular Evolution • Field of study that compares genomes, DNA or protein sequences, and chromosome banding patterns • Sequences that are similar in many species are said to be “highly conserved”
What Makes Us Human? • Spoken language • Abstract reasoning • Highly opposable thumb • Large frontal lobes (brain) • Also, we have a lot less body hair • Keratin gene found in apes is silenced by a nonsense mutation in humans • Natural selection may have favored the loss of bidy hair as a way to help cooling or prevent lice
mtDNA and the Y Chromosome • Allow us to track migration of humanity • mtDNA is only from mom • Y chromosome is only from dad
Eugenics • Control of individual human reproductive choices to achieve a societal goal • Ex: US Antimiscegenation Laws • 1930-1967 • Banned marriage between people of different races • Ex: Sterilization of the “feebleminded” • Ex: The Holocaust