Descent Of Man Revisited

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First Eurasians left Africa up to 130,000 years ago

April 22nd, 2014 · No Comments

First Eurasians left Africa up to 130,000 years ago
http://www.sciencedaily.com/releases/2014/04/140421164242.htm
Scientists have shown that anatomically modern humans spread from Africa to Asia and Europe in several migratory movements. The first ancestors of today’s non-African peoples probably took a southern route through the Arabian Peninsula as early as 130,000 years ago, the researchers found.

 

The Out-of-Africa model that best fits both the genetic and cranial shape data. A first migration along the Indian Ocean rim occurred as early as 130 thousand years ago (green arrow) and was followed by a second, more recent migration wave into Eurasia (red arrow).
Credit: Katerina Harvati/University of Tübingen and Senckenberg Center for Human Evolution and Palaeoenvironment

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Humans and Neandertals interbred

April 9th, 2014 · No Comments

Humans and Neandertals interbred, new method confirms
http://www.sciencedaily.com/releases/2014/04/140408111228.htm
Technical objections to the idea that Neandertals interbred with the ancestors of Eurasians have been overcome, thanks to a new genome analysis method. The technique can more confidently detect the genetic signatures of interbreeding than previous approaches and will be useful for evolutionary studies of other ancient or rare DNA samples.

A new genome analysis method
 confirms that Neandertals
interbred
 with the ancestors of Eurasians.

echnical objections to the idea that Neandertals interbred with the ancestors of Eurasians have been overcome, thanks to a genome analysis method described in the April 2014 issue of the journal Genetics. The technique can more confidently detect the genetic signatures of interbreeding than previous approaches and will be useful for evolutionary studies of other ancient or rare DNA samples.
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Bacteria Could Grow Futuristic ‘Self-Healing’ Materials

April 8th, 2014 · No Comments

Bacteria Could Grow Futuristic ‘Self-Healing’ Materials
by Katia Moskvitch posted on April 05, 2014 04:37PM GMT
Why bother to manufacture materials if you can grow them organically?

http://www.richarddawkins.net/news_articles/2014/4/5/bacteria-could-grow-futuristic-self-healing-materials#

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From athletes to couch potatoes

April 8th, 2014 · No Comments

From athletes to couch potatoes: Humans through 6,000 years of farming
http://www.sciencedaily.com/releases/2014/04/140407214904.htm
Research into the strength and shape of lower limb bones shows that, in the first 6,000 years of farming, our ancestors in Central Europe became less active as their tasks diversified and technology improved. Anthropologists show that this drop in mobility was particularly marked in men.

Early Neolithic 35-40 year old male
from Vedrovice, Czech Republic.

Human bones are remarkably plastic and respond surprisingly quickly to change. Put under stress through physical exertion — such as long-distance walking or running — they gain in strength as the fibres are added or redistributed according to where strains are highest. The ability of bone to adapt to loading is shown by analysis of the skeletons of modern athletes, whose bones show remarkably rapid adaptation to both the intensity and direction of strains.
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Why did humans replace Neanderthals? Paleo diet didn’t change, the climate did

March 17th, 2014 · No Comments

Why did humans replace Neanderthals? Paleo diet didn’t change, the climate did
http://www.sciencedaily.com/releases/2014/03/140317084643.htm
Why were Neanderthals replaced by anatomically modern humans around 40,000 years ago? One popular hypothesis states that a broader dietary spectrum of modern humans gave them a competitive advantage on Neanderthals. Geochemical analyses of fossil bones seemed to confirm this dietary difference. Indeed, higher amounts of nitrogen heavy isotopes were found in the bones of modern humans compared to those of Neanderthals. However, these studies did not look at possible isotopic variation of nitrogen isotopes in the food resource themselves. In fact, environmental factors such as aridity can increase the heavy nitrogen isotope amount in plants, leading to higher nitrogen isotopic values in herbivores and their predators even without a change of subsistence strategy.

hy were Neanderthals replaced by anatomically modern humans around 40,000 years ago? One popular hypothesis states that a broader dietary spectrum of modern humans gave them a competitive advantage on Neanderthals. Geochemical analyses of fossil bones seemed to confirm this dietary difference. Indeed, higher amounts of nitrogen heavy isotopes were found in the bones of modern humans compared to those of Neanderthals, suggesting at first that modern humans included fish in their diet while Neanderthals were focused on the meat of terrestrial large game, such as mammoth and bison.
However, these studies did not look at possible isotopic variation of nitrogen isotopes in the food resource themselves. In fact, environmental factors such as aridity can increase the heavy nitrogen isotope amount in plants, leading to higher nitrogen isotopic values in herbivores and their predators even without a change of subsistence strategy. A recent study published in Journal of Human Evolution by researchers from the University of Tübingen (Germany) and the Musée national de Préhistoire in Les Eyzies-de-Tayac (France) revealed that the nitrogen isotopic content of animal bones, both herbivores, such as reindeer, red deer, horse and bison, and carnivores such as wolves, changed dramatically at the time of first occurrence of modern humans in southwestern France.

The changes are very similar to those seen in human fossils during the same period, showing that there was not necessarily a change in diet between Neanderthals and modern humans, but rather a change in environment that was responsible for a different isotopic signature of the same food resources.

Moreover, this isotopic event coinciding in timing with the replacement of Neanderthals by modern humans may indicate that environmental changes, such as an increase of aridity, could have helped modern humans to overcome the Neanderthals.

These new results, together with recently published research showing that Neanderthals had more skills and exploited more diverse food resources than previously thought, makes the biological differences between these two types of prehistoric humans always smaller. In this context, the exact circumstances of the extinction of Neanderthals by modern humans remain unclear and they are probably more complex than just a behavioral superiority of one type of humans compared to the other.

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