Thursday, February 12, 2009

Human Evolution.


There is a new book out The 10,000 Year Explosion: How Civilization Accelerated Human Evolution which explains that human evolution accelerated in the last 10000 years and did not stand still they many believe it did. This view ties in with other articles written in recent years.
We used a new genomic technology to show that humans are evolving rapidly, and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago," says research team leader Henry Harpending, a distinguished professor of anthropology at the University of Utah.

"Human races are evolving away from each other," Harpending says. "Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity." He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, "and there has not been much flow of genes between the regions since then.

Read the full article
Researchers discovered genetic evidence that human evolution is speeding up.


I have taken these extracts from two articles.Evidence is gradually accumulating that there are really different races and that we are not as alike as some would have us believe. They do not hide the fact that populations have evolved separately. The way I see it is that there are really two races. Those in Africa and those that left. Once modern humans left Africa there was little gene flow back into Africa.



The world map shows thespread of IQ across the world with the lowest in Africa and the highest in China, Japan and Korea. Don't be upset that the Chinese have the highest IQ.


65 dark red 70 med red 75 light red 80 orange 85 yellow 90 light blue 95 med blue 100 dark blue 105 purple N/A




The emphasis in the following quotes is mine.
We aren't the same as people even 1,000 or 2,000 years ago," he says, which may explain, for example, part of the difference between Viking invaders and their peaceful Swedish descendants. "The dogma has been these are cultural fluctuations, but almost any Temperament trait you look at is under strong genetic influence."


"Human races are evolving away from each other," Harpending says. "Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity." He says that is happening because humans dispersed from Africa to other regions 40,000 years ago, "and there has not been much flow of genes between the regions since then.

The increase in human population from millions to billions in the last 10,000 years accelerated the rate of evolution because "we were in new environments to which we needed to adapt," Harpending adds. "And with a larger population, more mutations occurred."

Next, the researchers examined the history of human population size on each continent. They found that mutation patterns seen in the genome data were consistent with the hypothesis that evolution is faster in larger populations.

Ten thousand years ago Eurasia had a much larger population than Africa,hence a more rapid evolution rate.From the full article, "some 2500 years ago
the population of Subsaharan Africa was likely fewer than 7 million
people, compared to European, West Asian, East Asian, and South
Asian populations approaching or in excess of 30 million each"

But Harpending believes the speedup in human evolution "is a temporary state of affairs because of our new environments since the dispersal of modern humans 40,000 years ago and especially since the invention of agriculture 12,000 years ago. That changed our diet and changed our social systems. If you suddenly take hunter-gatherers and give them a diet of corn, they frequently get diabetes. We're still adapting to that. Several new genes we see spreading through the population are involved with helping us prosper with high-carbohydrate diet

The second reason for the accelerated evolution was that the expanding human populations in Africa and Eurasia were encountering climates and diseases to which they had to adapt genetically. The extra mutations in their growing populations allowed them to do so.

(From Nicholas Wade's review)
Dr. Moyzis said it was widely assumed that once people developed culture, they protected themselves from the environment and from the forces of natural selection. But people also had to adapt to the environments that their culture created, and the new analysis shows that evolution continued even faster than before.

So the environmentalists are right but not for the reasons they think.The environment can bring about genetic change both good and bad.
Harpending says genetic differences among different human populations "cannot be used to justify discrimination. Rights in the Constitution aren't predicated on utter equality. People have rights and should have opportunities whatever their group."


See the full paper here if you have the inclination

For links to many more blogs about this article see Gene Expression
From an older blog of mine I found this;
Some humans left Africa, about 4000 in number. They entered a new environment which was different. They had passed through a genetic bottle neck and would be severely challenged and had to adapt. And as they headed for colder climes their skin colour had to become lighter in order to obtain the necessary Vitamin D. They had a change in a gene that allowed adults to process milk by being lactose tolerant which enabled them to take advantage of pasturing cattle. But these are side issues. The big changes came at 37000 years ago and then later, 5800 years ago. These new mutations spread throughout the population and eventually spread throughout Asia and the Americas but not to Africa except to North Africa. They were needed for civilization to flourish, the invention of the wheel and cities and towns, agriculture, industry and the written language. None of these were found in Africa before the white man and Arabs returned. This is why the black man does not have the ability to govern
himself. They have great confidence but no ability in this direction.All talk talk and no action. So read on to see where I got all this from.
Sharon Bagley writes that "a curious thing about early Homo species is that they looked quite human early on. 'By 600,000 years ago everyone had a big brain, and by 200,000 years ago people in Africa looked like modern humans,' says archeologist Richard Klein of Stanford. 'But there was no representational art, no figurines, no jewelry until 50,000 years ago. Some kind of cognitive advance was required, probably in language or working memory. But since size hardly changed, the brain change that produced behaviorally modern humans must have been in structure.'
The source of such structural changes must come, like every aspect of our physiology, from genes. Combing the genome for genes that emerged just when language, art, culture and other products of higher intelligence did, researchers have found three with the right timing"


But then something else happened. Some of these intelligent modern humans started to leave Africa in search of greener pastures.
These pilgrims were strikingly few. From the amount of variation in Y chromosomes today, population geneticists infer how many individuals were in this "founder" population. The best estimate: 2,000 men. Assuming an equal number of women, only 4,000 brave souls ventured forth from Africa. We are their descendants.


It was from these individuals that very modern humans spread throughout Europe, Asia and the Americas but first there were other changes in their brain structure that occurred after leaving Africa.
Another gene with interesting timing is microcephalin, which affects brain size. It carries a time stamp of 37,000 years ago, again when symbolic thinking was taking hold in our most recent ancestors. The third, called ASPM and also involved in brain size, clocks in at 5,800 years. That was just before people established the first cities in the Near East and is well after Homo sapiens attained their modern form. It therefore suggests that we are still evolving.


Before leaving Africa there was further evolution in brain developnment through a mutation.
The first, called FOXP2, plays a role in human speech and language, but it must do something else in other species, because the decidedly nonverbal mouse has a version of it. Using the standard molecular-clock tactic, Svante Paabo and colleagues at the Max Planck Institute estimate that the human version of FOXP2 appeared less than 200,000 years ago—about when anatomically modern humans stepped onto the world stage—and maybe as recently as 50,000.

But to repeat

If so, then it is only humans as modern as those in the last diaspora out of Africa who developed advanced, spoken language. Another gene with interesting timing is microcephalin, which affects brain size. It carries a time stamp of 37,000 years ago, again when symbolic thinking was taking hold in our most recent ancestors. The third, called ASPM and also involved in brain size, clocks in at 5,800 years. That was just before people established the first cities in the Near East and is well after Homo sapiens attained their modern form.



The fossils have not finished speaking, of course. These countless postcards from the past surely still lie en-cased in the rocks of the Old World. But now, as ancient DNA and gray matter give up their secrets, they are adding life to the age-old quest to understand where humankind came from and how we got here.


To sum up then
Pretty impressive growth rates, for sure. That figure of 4,000 refers to the hominids who left Africa for Eurasia (not that they knew they'd entered a new continent, of course); others like them remained in Africa and became ancestors of people living there today. The point was to contrast the old view of how modern humans arose to the current one: it had been thought that Homo erectus populations gave rise to H. sapiens multiple times across Eurasia, producing modern populations there. But genetic evidence says that erectus (like neanderthals) died out and left no descendants. That means that we're all the children of early modern humans, from whom those 4,000 emigrants were drawn.Sharon Bagley.


They would not have returned to Africa to spread the new mutations. It would have been just too difficult and there were already Africans occupying the land, whereas when they spread throughout Europe and Asia it was empty of modern humans.

1 Comments:

Anonymous Anonymous said...

A great article and it shows exactly how different we all are.

One point of contention is that the article refers to the "out of Africa" theory as if it was a fact.

It is a theory only and recently scientific research has surfaced that totally disproves the out of africa theory. The OfA theory hinges on the fact that Algeripithecus was considered to be a human ancestor. It has been proved that this is not the case......thus no out of Africa theory.
http://news.nationalgeographic.com/
news/pf/74602818.html

Then additionally to that is that they have found human skulls that are just as old as the oldest ones found in Africa.
http://www.independent.co.uk/news/
science/a-skull-that-rewrites-the-
history-of-man-1783861.html

Fact is that when the latest scientific discoveries are taken into account, then the theory of multi-regionalism blows the out of africa theory away.

November 19, 2009 at 10:13 PM  

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