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Dinesh

Dinesh club

Posted: 19 Sep 2023

Taken: 19 Sep 2023

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Mitochondrial DNA

Mitochondrial DNA
False-colour transmission electron micrograph of Mitochondrial DNA


www.youtube.com/watch?v=uFAQcL5wacM

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 Dinesh
Dinesh club
Prior to the recovery of Neanderthal DNA the biggest single impact of genetic data on research of modern human evolution came in 1987, with the publication of a study of mtDNA variation in modern humans. . . . .

The distribution of ancestors suggested that the single common ancestor must have lived in Africa, and the number of mutations which had accumulated from the time of the common ancestor suggest that this evolutionary process had taken about 200,000 years. This then, was the birth of the famous ‘mitrocondrial Eve’ or lucy mother, since the common mitochondrial ancestor must have been a female. These results seemed to provide strong support for the ‘Out of Africa’ model of modern human origins, because the research suggested that a relatively recent expansion from Africa had occurred, replacing any ani=cient populations living elsewhere, and their mtDNA lineage.
7 months ago.
 Dinesh
Dinesh club
In contrast to ll other genes, mitochondrial DNA (a collection of genes outside the cell nucleus) is inherited only through our mothers, and the Y chromosome is inherited only by men. These two sets of gender-linked genes are passed on unchanged from generation to generation, with no shuffling, and can therefore be traced right back to our ancestors, to the first mammals, and even beyond to worms and worse. We can thus construct two family gene trees, one of our fathers and one for our mothers. As a result, in any population, of whatever size, we can trace any two individuals through one of these two gene trees back to a most recent shared ancestor on the tree. Such an ancestor may have lived 200, 5,000 or 150,000 years ago, but all ancestors can be assigned a place on the newly constructed Adam-and-Eve genetic trees. These are real family trees of modern human gene lines, with real branches, each branch on each tree can be dated (although the accuracy of such dating still leaves much to be desired) ~ xix (Preface)

The idea that we somehow grew a big brain first, then decided what it was for, is a negation of Darwinian principles. Any new kind of behaviour always precedes the physical adaptation that evolves to exploit that behaviour. Well before the start of the Pleistocene ice epoch there must already have been some aspect of our behaviour -- something to do with the way we faced the climatic challenge, perhaps -- that gave large, energy-expensive brains survival value. The problem of finding food in an increasingly dry environment must have taxed our ancestors' resourcefulness. Larger brains clearly helped them in some way. That behaviour must still be with us today, because over subsequent major glaciations during the past 2.5 million years, new human species with larger brains and more skill appeared in Africa. As the climate briefly warmed after each glacial maximum, the Sahara would become green for a few thousand years and the new human species would venture out to try their luck in Eurasia. Bu 1 million years ago, brain volumes of various human species living both within and outside Africa had increased from 400 to 1,000 cm (power of 3) and even into the modern size range. In other words, human brains had grown to three-quarters of their modern size long before we came on the scene. ~ Page 9

THE REAL EVE
7 months ago. Edited 7 months ago.
 TOZ
TOZ club
Very very interesting read Dinesh.
Best TOZ
7 months ago.
 Roger (Grisly)
Roger (Grisly) club
Fascinating, thank you for posting Dinesh !
7 months ago.

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