Gene data place home of 'Eve' in Africa.A study of random genetic changes in one type of human DNA DNA: see nucleic acid.
or deoxyribonucleic acid
One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. supports and expands a controversial 1987 DNA investigation that placed the origin of anatomically modern humans in Africa approximately 200,000 years ago. Although both studies indicate that modern Homo sapiens Homo sapiens
(Latin; “wise man”)
Species to which all modern human beings belong. The oldest known fossil remains date to c. 120,000 years ago—or much earlier (c. spread from Africa to other regions and replaced the descendants DESCENDANTS. Those who have issued from an individual, and include his children, grandchildren, and their children to the remotest degree. Ambl. 327 2 Bro. C. C. 30; Id. 230 3 Bro. C. C. 367; 1 Rop. Leg. 115; 2 Bouv. n. 1956.
2. of an earlier African migration by H. erectus, some anthropologists still contend that modern humans originated closer to 1 million years ago in several parts of the world, with some genetic input from Neandertals along the way (SN: 6/8/91, p.360).
In the new work, molecular biologist Linda Vigilant of Pennsylvania State University Pennsylvania State University, main campus at University Park, State College; land-grant and state supported; coeducational; chartered 1855, opened 1859 as Farmers' High School. in University Park and her colleagues studied mitochondrial DNA Mitochondrial DNA (mtDNA) is the DNA located in organelles called mitochondria. Most other DNA present in eukaryotic organisms is found in the cell nucleus. Nuclear and mitochondrial DNA are thought to be of separate evolutionary origin, with the mtDNA being derived from the -- located outside the cell nucleus and inherited only from the mother -- obtained from 121 native Africans, 20 Papua New Guineans Politics
Native Africans possess more mitochondrial mitochondrial
pertaining to mitochondria.
a unique set of tRNAs, mRNAs, rRNAs, transcribed from mitochondrial DNA by a mitochondrial-specific RNA polymerase, that account for about 4% of the total cell RNA that mutations than the other groups, the team reports in the Sept. 27 SCIENCE. Within each human population, specific chemical sequences turn up and others do not, but U.S. blacks show close mitochondrial DNA links to native Africans, the scientists assert.
Estimates of mutation rates In genetics, the mutation rate is the chance of a mutation occurring in an organism or gene in each generation (or, in the case of multicellular organisms, cell division). See Luria-Delbrück experiment. in mitochondrial DNA provoke much controversy. Some researchers doubt the existence of any such "mitochondrial clock." But Vigilant and her co-workers argue that their analysis, based on a mutation rate derived from a comparison of mitochondrial DNA from humans and chimpanzees, indicates that the ancestral mother or mothers of modern H. sapiens sa·pi·ens
Of, relating to, or characteristic of Homo sapiens.
[Latin sapi lived in Africa between 166,000 and 249,000 years ago.
They made this calculation with two key pieces of information: a new reckoning that the chemical sequence of the rapidly evolving mitochondrial DNA in humans differs from that in chimps by nearly 70 percent, and a previous estimate that the chimp and human mitochondrial lineages split between 4 million and 6 million years ago.
The researchers note that even if the chimp-human split occurred 9 million years ago, as some scientists argue, human mitochondrial origins would extend back only about 373,000 years.
Such age estimates remain preliminary, they add. Possible differences in the mitochondrial mutation rates of humans and chimps may throw off the timing of the proposed mitochondrial clock.
Still, they conclude that the new data provide the strongest support yet for assigning a relatively young evolutionary age to the anthropological "Eve" -- our common mitochondrial DNA ancestor in Africa.