Are humans evolving faster?

[Ikutiera]

Are humans evolving faster? Findings suggest we are becoming more different, not alike

Researchers discovered genetic evidence that human evolution is speeding up – and has not halted or proceeded at a constant rate, as had been thought – indicating that humans on different continents are becoming increasingly different.

Are humans evolving faster? Findings suggest we are becoming more different, not alike

[Monolith]

“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.”

Interesting and logical at the same time, having that one species, if split, will evolve in different directions.

[Vincent]

Originally Posted by Monolith

Interesting and logical at the same time, having that one species, if split, will evolve in different directions.

Of course it's logical, but don't you think that 'man' him self does not have any impact on the whole direction of his evolution? Immigration, race mixing... Where ever nature would lead us, we are heading towards just one goal. A single race, with an artificial culture. Sad but true.

[Agrippa]

Crucial is the proof that since the Neolithicum evolutionary change increased rather than decreased, and that regionally and indvidually different. Overall, especially since the medieval times, Europe's biological niveau decreased while the numbers increased, which can be attributed to contraselective, dysgenic trends.

Without selection no population keeps a niveau but get broader and broader variation with more minus- or at least less positive variants and genetically inherited traits. This is very important from the Eugenic perspective as well as if looking at racial developments, since in the past, especially egalitarians often argued that the limited time doesnt allow significant genetic and racial changes in human populations, so that all humans are basically equal with just minor changes since the split or that in Europe racial changes couldnt take place in the respective time frame - which is wrong either.

Today we evolve in a negative direction, which leads us to the Eugenic-debate:
The Coevolution of Parochial Altruism and War - Aspects of Group Selection

Future evolution of human appearance

My argumentation in favour of an Eugenic policy

The racially progressive tendencies in sapiens:
Racially progressive tendencies in Homo sapiens

This also negates "the must" of long racial continuities, and speaks for faster racial changes. Of course this news are not that new at all, but its one piece after another making up the whole pictures of faster human evolution (for bigger mammals - relative).

[Agrippa]

Dienekes dealt with the subject too now and mentions interesting aspects in his comment:

Dienekes\' Anthropology Blog: Hawks et al. paper on accelerated recent human evolution

Originally Posted by Dienekes

The paper has a simple but powerful idea: that really useful mutations are more likely to occur in large populations than in small ones: mutations are random accidents that happen in bodies; the more bodies you have, the more likely it is you'll get a really neat one.
All populations have the capacity to evolve by shifting around the frequencies of the different alleles in their gene pools. But, the kinds of alleles that evolution can work with are not the same. Large populations have a greater repertoire of alleles to work with.
But, some species with really huge numbers don't really evolve that fast. This is because they have already reached an adaptive plateau; they are already well-suited to their environments and don't face large selection pressures.
New challenging environments + growing population = accelerated human evolution.

Abstract from the paper:

Recent acceleration of human adaptive evolution
John Hawks, Eric T. Wang, Gregory Cochran, Henry C. Harpending, and Robert K. Moyzis
Genomic surveys in humans identify a large amount of recent positive selection. Using the 3.9-million HapMap SNP dataset, we found that selection has accelerated greatly during the last 40,000 years. We tested the null hypothesis that the observed age distribution of recent positively selected linkage blocks is consistent with a constant rate of adaptive substitution during human evolution. We show that a constant rate high enough to explain the number of recently selected variants would predict (i) site heterozygosity at least 10-fold lower than is observed in humans, (ii) a strong relationship of heterozygosity and local recombination rate, which is not observed in humans, (iii) an implausibly high number of adaptive substitutions between humans and chimpanzees, and (iv) nearly 100 times the observed number of high-frequency linkage disequilibrium blocks. Larger populations generate more new selected mutations, and we show the consistency of the observed data with the historical pattern of human population growth. We consider human demographic growth to be linked with past changes in human cultures and ecologies. Both processes have contributed to the extraordinarily rapid recent genetic evolution of our species.

Dienekes\' Anthropology Blog: Hawks et al. paper on accelerated recent human evolution

[Kernunnos]

See also this confirmation: europeans evolve faster than africans

from Scientific American




News - December 10, 2007
Culture Speeds Up Human Evolution

Analysis of common patterns of genetic variation reveals that humans have been evolving faster in recent history

By David Biello



Homo sapiens sapiens has spread across the globe and increased vastly in numbers over the past 50,000 years or so—from an estimated five million in 9000 B.C. to roughly 6.5 billion today. More people means more opportunity for mutations to creep into the basic human genome and new research confirms that in the past 10,000 years a host of changes to everything from digestion to bones has been taking place.
"We found very many human genes undergoing selection," says anthropologist Gregory Cochran of the University of Utah, a member of the team that analyzed the 3.9 million DNA sequences* showing the most variation. "Most are very recent, so much so that the rate of human evolution over the past few thousand years is far greater than it has been over the past few million years."
"We believe that this can be explained by an increase in the strength of selection as people became agriculturalists—a major ecological change—and a vast increase in the number of favorable mutations as agriculture led to increased population size," he adds.
Roughly 10,000 years ago, humanity made the transition from living off the land to actively raising crops and domesticated animals. Because this concentrated populations, diseases such as malaria, smallpox and tuberculosis, among others, became more virulent. At the same time, the new agriculturally based diet offered its own challenges—including iron deficiency from lack of meat, cavities and, ultimately, shorter stature due to poor nutrition, says anthropologist John Hawks of the University of Wisconsin–Madison, another team member.
"Their bodies and teeth shrank. Their brains shrank, too," he adds. "But they started to get new alleles [alternative gene forms] that helped them digest the food more efficiently. New protective alleles allowed a fraction of people to survive the dread illnesses better."
By looking for wide swaths of genetic material that vary little from individual to individual within these sections of great variation, the researchers identified regions that both originated recently and conferred some kind of advantage (because they became common rapidly). For example, the gene known as LCT gave adults the ability to digest milk and G6PD offered some protection against the malaria caused by Plasmodium falciparum parasite.
"Ten thousand years ago, no one on planet Earth had blue eyes," Hawks notes, because that gene—OCA2—had not yet developed. "We are different from people who lived only 400 generations ago in ways that are very obvious; that you can see with your eyes."
Comparing the amount of genetic differentiation between humans and our closest relatives, chimpanzees, suggests that the pace of change has accelerated to 10 to 100 times the average long-term rate, the researchers write in Proceedings of the National Academy of Sciences USA.
Not all populations show the same evolutionary speed. For example, Africans show a slightly lower mutation rate. "Africans haven't had to adapt to a fundamentally new climate," because modern humanity evolved where they live, Cochran says. "Europeans and East Asians, living in environments very different from those of their African ancestors and early adopters of agriculture, were more maladapted, less fitted to their environments."
And this speedy pace of evolution will not slow until every possible beneficial mutation starts to happen—the maximum rate of adaptation. This has already begun to occur in such areas as skin color in which different sets of genes are responsible for the paler shades of Europeans and East Asians, according to the researchers.
The finding raises many questions. Among them: "the medical applications of this kind of knowledge [as well as] exactly what most of the selected changes do and what drove their selection," Cochran says.
But the history of humanity is beginning to be read out from our genes, thanks to a detailed knowledge of the thousands of them that have evolved recently. "We're going to be classifying these by functional categories and looking for matches between genetic changes and historic and archaeological changes in diet, skeletal form, disease and many other things," Hawks says. "We think we will be able to find some of the genetic changes that drove human population growth and migrations—the broad causes of human history."
*This article wrongly characterized the HapMap genotype dataset used for this analysis as "genes" rather than "DNA sequences."