Question

Until recently, there were two competing theories about the origin of our species- "modern Homo sapiens". The first (single African origin) is that all modern humans descended from a recent ancestor in Africa, less than 200,000 years ago, and that our ancestors replaced the archaic human species they found in their migrations, including Neanderthals and Denisovans. (In the last few years evidence from nuclear genomes of fossil humans has indicated that there was limited interbreeding between the ancestors of modern humans and Neanderthals and Denisovans, contributing an average of 2% to the genome of humans today). The competing theory, now disfavored, was "multiregionalism". It held that modern humans evolved separately from Homo erectus between one and two million years ago, and different Homo erectus lineages on different continents separately evolved to modern human "races." According to the multiregional theory, modern Europeans would have evolved from European Neanderthals, Asians from an Asian archaic species, and Africans from an African archaic species. The mitochondrial evolutionary tree we generated from DNA sequence in class supports only one of these two theories. (You may have to look at it again).

,0.01 -Chimp -M4 -Z6 A20 TA19 M20 TA4 1A11 75 A6 Z2 Z1 Cro-Magnon -M7 Early M14 jM19 1211 T1A13 -M17 _A22 TA21 1A15 A12 -A18 LA5 -A17 FAZ A10 M8 -A9 UZ7 LA2 FM9 IM3 -M21 -M15 -28 A16 -M2 -Z9 Cro-Magnon2_25_000 -M5 -Z4 Denny -N5 -N2 from -N1_from - N4 IN3_from -Denisovan

a) Which theory does it support, and why? Answer as specifically as possible, keeping in mind the predictions of the two theories.

b) What is the relevance of this debate to the question of whether races are biologically real or not? Discuss

Answer 1

a) Keeping the two predictions in mind, the given figure supports the theory of Multiregionalism .

• the given figure starts from chimpanzees and the lineage breaks up into many parts showing cromagnon and its divisions and denisovan and its divisions.
• according to the Multiregionalism, all modern ancestors originated from their ancestors and broke up into many human races, as depicted in the figure.
• also, it says that our ancestors replaced the neandethrals and denisovans, which is shown by the different divisions depicted in the chart.

b) the two theories and the debate of the origin of human races and its relevance to whether races are biologically real or not can be depicted as given below:

• Biological races: genetically distinct population of individuals within the same species.
• as we observe in the given debate that humans are said to be dividing into various kinds in their evolutionary tree, given in the two theories, we may be able to arrive at the conclusion that biological races do exist due to this division.
• specifically, in the Multiregionalism ​​​​​​ theory, it clearly states the occurance of multiple human races.