Were Neanderthals and Humans connected at some time in the past? This question is still up for debate, but recently the complete mitochondrial genome of a 38,000-year-old Neanderthal has been sequenced.
At the Max-Planck Institute for Evolutionary Anthropology in Germany scientists have reconstructed the genome sequence. They sequenced the Neanderthal mitochondria—powerhouses of the cell with their own DNA including 13 protein-coding genes—nearly 35 times over. This coverage allowed them to sort out those differences between the Neanderthal and human genomes resulting from damage to the degraded DNA extracted from ancient bone versus true evolutionary changes.
This new sequence and its analysis confirms that the mitochondria of Neanderthals falls outside the variation found in humans today and it provides no evidence of integration between the two lineages although it remains a possibility. It also shows that the last common ancestor of Neanderthals and humans lived about 660,000 years ago, give or take 140,000 years.
The new sequence revealed that the Neanderthals have fewer evolutionary changes overall, but a greater number that alter the amino acid building blocks of proteins. This means that the Neanderthals had a smaller population size than humans do, which makes natural selection less effective in removing mutations.
That notion is consistent with arguments made by other scientists based upon the geological record. Anthropologists argue there were a few thousand Neanderthals that roamed over Europe 40,000 years ago. That smaller population might have been the result of the smaller size of Europe compared to Africa. Another geological issue was that the Neanderthals also would have had to deal with repeated glaciations.
Showing posts with label Neanderthal. Show all posts
Showing posts with label Neanderthal. Show all posts
Saturday, December 13, 2008
Monday, April 28, 2008
Last Common Ancestor Of Neanderthals And Humans
Finding: Fossil Found In Europe, 1.2 Million Years Old
That's 500,000 years older than the previous oldest known humanlike fossils from the area. The new find bolsters the view that Homo reached Europe not long after leaving Africa almost 2 million years ago.
It seems probable that the first European population came from the region of the Near East, the true crossroads between Africa and Eurasia, and that it was related to the first demographic expansion out of Africa.
The researchers tentatively classified the new fossil as an earlier example Homo antecessor (Pioneer Man), the species represented by the previous oldest fossils and thought to be the last common ancestor of Neanderthals and modern humans.
That's 500,000 years older than the previous oldest known humanlike fossils from the area. The new find bolsters the view that Homo reached Europe not long after leaving Africa almost 2 million years ago.
It seems probable that the first European population came from the region of the Near East, the true crossroads between Africa and Eurasia, and that it was related to the first demographic expansion out of Africa.
The researchers tentatively classified the new fossil as an earlier example Homo antecessor (Pioneer Man), the species represented by the previous oldest fossils and thought to be the last common ancestor of Neanderthals and modern humans.
Monday, January 21, 2008
Bones From French Cave Show Neanderthals, Cro-Magnon Hunted Same Prey
Finding: A 50,000-year record of mammals consumed by early humans in southwestern France indicates there was no major difference in the prey hunted by Neanderthal and Cro-Magnon.
Research findings counter the idea proposed by some scientists that Cro-Magnon, who were physically similar to modern man, supplanted Neanderthals because they were more skilled hunters as a result of some evolutionary physical or mental advantage.
The new study suggests Cro-Magnon were not superior in getting food from the landscape. Archeoligists could detect no difference in diet, the animals they were hunting and the way they were hunting across this period of time, aside from those caused by climate change.
The takeover by Cro-Magnon does not seem to be related to hunting capability. There is no significant difference in large mammal use from Neanderthals to Cro-Magnon in this part of the world. The idea that Neanderthals were big, dumb brutes is hard for some people to drop. Cro-Magnon created the first cave art, but late Neanderthals made body ornaments, so the depth of cognitive difference between the two just is not clear.
Bears, Caves, and Cro-magnon
The study also resurrects a nearly 50-year-old theory first proposed by Finnish paleontologist Björn Kurtén that modern humans played a role in the extinction of giant cave bears in Europe. Cro-Magnon may have been the original "apartment hunters" and displaced the bears by competing with them for the same caves the animals used for winter den sites.
The cave has a rich, dated archaeological sequence that extends from about 65,000 to about 12,000 years ago, spanning the time when Neanderthals flourished and died off and when Cro-Magnon moved into the region. Neanderthals disappeared from southwestern France around 35,000 years ago, although they survived longer in southern Spain and central Europe.
The researchers were most interested in the transition from the Middle to Upper Paleolithic, or Middle to Late Stone Age.
Neanderthals occupied Grotte XVI as far back as 65,000 years ago, perhaps longer. Between 40,000 and 35,000 years ago, people began making stone tools in France, including at Grotte XVI, that were more like those later fashioned by Cro-Magnon. However, human remains found with these tools at several sites, were Neanderthal, not Cro-Magnon. Similar tools but no human remains from this time period were found in Grotte XVI and people assumed to be Cro-Magnon did not occupy the cave until about 30,000 years ago.
The researchers examined more than 7,200 bones and teeth from large hoofed mammals that had been recovered from the cave. The animals – ungulates such as reindeer, red deer, roe deer, horses and chamois were the most common prey – were the mainstay of humans in this part of the world, according to Grayson.
He and Delpech found a remarkable dietary similarity over time. Throughout the 50,000-year record, each bone and tooth assemblage, regardless of the time period or the size of the sample involved, contained eight or nine species of ungulates, indicating that Neanderthals and Cro-Magnon both hunted a wide variety of game.
The only difference the researchers found was in the relative abundance of species, particularly reindeer, uncovered at the various levels in Grotte XVI. At the oldest dated level in the cave, reindeer remains accounted for 26 percent of the total. Red deer were the most common prey at this time, accounting for nearly 34 percent of the bones and teeth. However, as summer temperatures began to drop in Southwestern France, the reindeer numbers increased and became the prey of choice. By around 30,000 years ago, when Cro-Magnon moved into the region, reindeer accounted for 52 percent of the bones and teeth. And by around 12,500 years ago, during the last ice age, reindeer remains accounted for 94 percent of bones and teeth found in Grotte XVI.
Grayson and Delpech also looked at the cut marks left on bones to analyze how humans were butchering their food. They found little difference except, surprisingly, at the uppermost level, which corresponds to the last ice age.
It is possible that because it was so cold, people were hard up for food. The bones were very heavily butchered, which might be a sign of food stress. However, if this had occurred earlier during Neanderthal times, people would have said this is a sure sign that Neanderthals did not have the fine hand-eye coordination to do fine butchering.
In examining the Grotte XVI record, the researchers also found a sharp drop in the number of cave bears from Neanderthal to Cro-Magnon times.
Cave bears and humans may have been competing for the same living space and this may have led to their extinction. He added that it is not clear if the decline and eventual extinction of the bears was driven by an increase in the number of humans or increased human residence times in caves, or both.
If we can understand the extinction of any animal from the past, such as the cave bear, it gives us a piece of evidence showing the importance of habitat to animals. The cave bear is one of the icons of the late Pleistocene Epoch, similar to the saber tooth cats and mammoths in North America. If further study supports the argument, we finally may be in a position to confirm a human role in the extinction of a large Pleistocene mammal on a Northern Hemisphere continent.
Research findings counter the idea proposed by some scientists that Cro-Magnon, who were physically similar to modern man, supplanted Neanderthals because they were more skilled hunters as a result of some evolutionary physical or mental advantage.
The new study suggests Cro-Magnon were not superior in getting food from the landscape. Archeoligists could detect no difference in diet, the animals they were hunting and the way they were hunting across this period of time, aside from those caused by climate change.
The takeover by Cro-Magnon does not seem to be related to hunting capability. There is no significant difference in large mammal use from Neanderthals to Cro-Magnon in this part of the world. The idea that Neanderthals were big, dumb brutes is hard for some people to drop. Cro-Magnon created the first cave art, but late Neanderthals made body ornaments, so the depth of cognitive difference between the two just is not clear.
Bears, Caves, and Cro-magnon
The study also resurrects a nearly 50-year-old theory first proposed by Finnish paleontologist Björn Kurtén that modern humans played a role in the extinction of giant cave bears in Europe. Cro-Magnon may have been the original "apartment hunters" and displaced the bears by competing with them for the same caves the animals used for winter den sites.
The cave has a rich, dated archaeological sequence that extends from about 65,000 to about 12,000 years ago, spanning the time when Neanderthals flourished and died off and when Cro-Magnon moved into the region. Neanderthals disappeared from southwestern France around 35,000 years ago, although they survived longer in southern Spain and central Europe.
The researchers were most interested in the transition from the Middle to Upper Paleolithic, or Middle to Late Stone Age.
Neanderthals occupied Grotte XVI as far back as 65,000 years ago, perhaps longer. Between 40,000 and 35,000 years ago, people began making stone tools in France, including at Grotte XVI, that were more like those later fashioned by Cro-Magnon. However, human remains found with these tools at several sites, were Neanderthal, not Cro-Magnon. Similar tools but no human remains from this time period were found in Grotte XVI and people assumed to be Cro-Magnon did not occupy the cave until about 30,000 years ago.
The researchers examined more than 7,200 bones and teeth from large hoofed mammals that had been recovered from the cave. The animals – ungulates such as reindeer, red deer, roe deer, horses and chamois were the most common prey – were the mainstay of humans in this part of the world, according to Grayson.
He and Delpech found a remarkable dietary similarity over time. Throughout the 50,000-year record, each bone and tooth assemblage, regardless of the time period or the size of the sample involved, contained eight or nine species of ungulates, indicating that Neanderthals and Cro-Magnon both hunted a wide variety of game.
The only difference the researchers found was in the relative abundance of species, particularly reindeer, uncovered at the various levels in Grotte XVI. At the oldest dated level in the cave, reindeer remains accounted for 26 percent of the total. Red deer were the most common prey at this time, accounting for nearly 34 percent of the bones and teeth. However, as summer temperatures began to drop in Southwestern France, the reindeer numbers increased and became the prey of choice. By around 30,000 years ago, when Cro-Magnon moved into the region, reindeer accounted for 52 percent of the bones and teeth. And by around 12,500 years ago, during the last ice age, reindeer remains accounted for 94 percent of bones and teeth found in Grotte XVI.
Grayson and Delpech also looked at the cut marks left on bones to analyze how humans were butchering their food. They found little difference except, surprisingly, at the uppermost level, which corresponds to the last ice age.
It is possible that because it was so cold, people were hard up for food. The bones were very heavily butchered, which might be a sign of food stress. However, if this had occurred earlier during Neanderthal times, people would have said this is a sure sign that Neanderthals did not have the fine hand-eye coordination to do fine butchering.
In examining the Grotte XVI record, the researchers also found a sharp drop in the number of cave bears from Neanderthal to Cro-Magnon times.
Cave bears and humans may have been competing for the same living space and this may have led to their extinction. He added that it is not clear if the decline and eventual extinction of the bears was driven by an increase in the number of humans or increased human residence times in caves, or both.
If we can understand the extinction of any animal from the past, such as the cave bear, it gives us a piece of evidence showing the importance of habitat to animals. The cave bear is one of the icons of the late Pleistocene Epoch, similar to the saber tooth cats and mammoths in North America. If further study supports the argument, we finally may be in a position to confirm a human role in the extinction of a large Pleistocene mammal on a Northern Hemisphere continent.
Friday, October 26, 2007
Map of Neanderthal Geography
Neanderthals have been at the centre of many of the most intense debates in palaeoanthropology ever since the discovery of their bones spawned the field 150 years ago. A popular caricature portrays them as beetle-browed brutes, but this is far from the truth. Neanderthals were sophisticated stone-tool makers and made razor-sharp knives out of flint. They made fires when and where they wanted, and seem to have made a living by hunting large mammals such as bison and deer. Neanderthals also buried their dead, which, fortunately for researchers, increases the odds of the bones being preserved.
Bones and artefacts leave a whole range of questions wide open, though. How exactly are Neanderthals related to us? Did our ancestors interbreed with them, and if so, do modern Eurasians still carry a little Neanderthal DNA?
Just how "human" were they? There's only one way to be sure: By sequencing their entire genome we can begin to learn more about their biology. What's more, if we can answer the genetic questions we might solve the biggest mystery of all: why did Neanderthals die out while modern humans went on to conquer the globe?
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