Evolution and Human Origins Common Ancestors Closeness of

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

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

mt. DNA and the Y Chromosome § Allow us to track migration of humanity § mt. DNA 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