AFRICAN ORIGINS OF MAN
January 21, 2001
The Y chromosome is one of the two chromosomes that determine sex in many animals, including humans, and it carries mostly male- specific genes.
Genetic polymorphisms are individual functional variations of specific genes or genetic markers that occur in a population with a significant frequency, e.g., more than 1%. Mitochondrial DNA (sometimes denoted as mtDNA), found in the mitochondria of all eukaryotes, is believed to evolve in parallel with nuclear DNA, but since sperm lose their mitochondria, it is inherited only in the maternal lineage in animals.
Until now, it has been mitochondrial DNA that has been greatly exploited in studies of the evolution of humans.
At a recent symposium on human evolution (Cold Spring Harbor Laboratory, NY US), a consensus was apparently reached that current studies of human Y chromosome polymorphisms indicate that the major human migrations that occurred had their source in Africa, and that a small number of present African populations, the Ethiopians, Sudanese, and south African Khoisans, possess markers that have been conserved since that time. The data are considered to confirm the recent mitochondrial DNA studies which also indicate Africa as the source of human migrations. Some paleoanthropologists are calling the Y chromosome results an "unquestionable major breakthrough".
(Science 31 Oct 97) (Science-Week 21 Nov 97)
http://www.scienceweek.com/
NET HUNTERS / Y CHROM. EVIDENCE / NEANDERTHAL DNA
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