Neanderthals, forerunners to modern humans, buried their dead, an international team of archaeologists has concluded after a 13-year study of remains discovered in southwestern France, according to a December 16, 2013 news release, "Neanderthals buried their dead, new research concludes." You can check out online since December 16, 2013, the abstract of the study, "Evidence supporting an intentional Neanderthal burial at La Chapelle-aux-Saints."
Their findings, which appear in the journal Proceedings of the National Academy of Sciences confirm that burials took place in western Europe prior to the arrival of modern humans. The idea of burial shows compassion, empathy, and dignity for another being. The discovery is about closing the behavioral distance between them and us.
"This discovery not only confirms the existence of Neanderthal burials in Western Europe, but also reveals a relatively sophisticated cognitive capacity to produce them," explains William Rendu, in the news release. Rendu is the study's lead author and a researcher at the Center for International Research in the Humanities and Social Sciences (CIRHUS) in New York City. CIRHUS is a collaborative arrangement between France's National Center for Scientific Research (CNRS) and New York University.
The findings center on Neanderthal remains first discovered in 1908 at La Chapelle-aux-Saints in southwestern France. The well-preserved bones led its early 20th-century excavators to posit that the site marked a burial ground created by a predecessor to early modern humans. However, their conclusions have sparked controversy in the scientific community ever since, with skeptics maintaining that the discovery had been misinterpreted and that the burial may not have been intentional.
Beginning in 1999, Rendu and his collaborators, including researchers from the PACEA laboratory of the University of Bordeaux and Archéosphère, a private research firm, began excavating seven other caves in the area
In this excavation, which concluded in 2012, the scientists found more Neanderthal remains—two children and one adult—along with bones of bison and reindeer. While they did not find tool marks or other evidence of digging where the initial skeleton was unearthed in 1908, geological analysis of the depression in which the remains were found suggests that it was not a natural feature of the cave floor.
As part of their analysis, the study's authors also re-examined the human remains found in 1908. In contrast to the reindeer and bison remains at the site, the Neanderthal remains contained few cracks, no weathering-related smoothing, and no signs of disturbance by animals.
"The relatively pristine nature of these 50,000-year-old remains implies that they were covered soon after death, strongly supporting our conclusion that Neanderthals in this part of Europe took steps to bury their dead," observes Rendu in the news release. "While we cannot know if this practice was part of a ritual or merely pragmatic, the discovery reduces the behavioral distance between them and us."
The French ministry of Culture and Communication supported the study in part. Also, the Regional Archaeological Service of the Limousin region, France, supervised the research.
Neanderthal genome yields insights into human evolution and evidence of interbreeding
On another note, you may wish to read about another study described in the May 6, 2010 news release, "Neanderthal genome yields insights into human evolution and evidence of interbreeding." After extracting ancient DNA from the 40,000-year-old bones of Neanderthals, scientists have obtained a draft sequence of the Neanderthal genome, yielding important new insights into the evolution of modern humans.
Among the findings, published in the May 7, 2010 issue of Science, is evidence that shortly after early modern humans migrated out of Africa, some of them interbred with Neanderthals, leaving bits of Neanderthal DNA sequences scattered through the genomes of present-day non-Africans. "We can now say that, in all probability, there was gene flow from Neanderthals to modern humans," said the paper's first author, Richard E. (Ed) Green of the University of California - Santa Cruz, according to the May 6, 2010 news release, "Neanderthal genome yields insights into human evolution and evidence of interbreeding."
Green, (as of the 2010 news release) is an assistant professor of biomolecular engineering in the Baskin School of Engineering at UC Santa Cruz, began working on the Neanderthal genome as a postdoctoral researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Svante Pääbo, director of the institute's genetics department, leads the Neanderthal Genome Project, which involves an international consortium of researchers. David Reich, a population geneticist at the Broad Institute of MIT and Harvard, also played a leading role in the new study and the ongoing investigation of the Neanderthal genome.
"The Neanderthal genome sequence allows us to begin to define all those features in our genome where we differ from all other organisms on the planet, including our closest evolutionary relative, the Neanderthals," Pääbo said, according to the news release.
The researchers identified a catalog of genetic features unique to modern humans by comparing the Neanderthal, human, and chimpanzee genomes
Genes involved in cognitive development, skull structure, energy metabolism, and skin morphology and physiology are among those highlighted in the study as likely to have undergone important changes in recent human evolution. "With this paper, we are just scratching the surface," Green said in the news release. "The Neanderthal genome is a goldmine of information about recent human evolution, and it will be put to use for years to come."
Neanderthals lived in much of Europe and western Asia before dying out 30,000 years ago. They coexisted with humans in Europe for thousands of years, and fossil evidence led some scientists to speculate that interbreeding may have occurred there. But the Neanderthal DNA signal shows up not only in the genomes of Europeans, but also in people from East Asia and Papua New Guinea, where Neanderthals never lived.
"The scenario is not what most people had envisioned," Green said, according to the news release. "We found the genetic signal of Neanderthals in all the non-African genomes, meaning that the admixture occurred early on, probably in the Middle East, and is shared with all descendants of the early humans who migrated out of Africa."
The study did not address the functional significance of the finding that between 1 and 4 percent of the genomes of non-Africans is derived from Neanderthals. But Green said there is no evidence that anything genetically important came over from Neanderthals. "The signal is sparsely distributed across the genome, just a 'bread crumbs' clue of what happened in the past," he said. "If there was something that conferred a fitness advantage, we probably would have found it already by comparing human genomes."
The draft sequence of the Neanderthal genome is composed of more than 3 billion nucleotides--the "letters" of the genetic code (A, C, T, and G) that are strung together in DNA
The sequence was derived from DNA extracted from three Neanderthal bones found in the Vindiga Cave in Croatia; smaller amounts of sequence data were also obtained from three bones from other sites. Two of the Vindiga bones could be dated by carbon-dating of collagen and were found to be about 38,000 and 44,000 years old. Deriving a genome sequence--representing the genetic code on all of an organism's chromosomes--from such ancient DNA is a remarkable technological feat. The Neanderthal bones were not well preserved, and more than 95 percent of the DNA extracted from them came from bacteria and other organisms that had colonized the bone. The DNA itself was degraded into small fragments and had been chemically modified in many places.
The researchers had to develop special methods to extract the Neanderthal DNA and ensure that it was not contaminated with human DNA. They used new sequencing technology to obtain sequence data directly from the extracted DNA without amplifying it first. Although genome scientists like to sequence a genome at least four or five times to ensure accuracy, most of the Neanderthal genome has been covered only one to two times so far.
The draft Neanderthal sequence is probably riddled with errors, Green said, but having the human and chimpanzee genomes for comparison makes it extremely useful despite its limitations. Places where humans differ from chimps, while Neanderthals still have the ancestral chimp sequence, may represent uniquely human genetic traits. Such comparisons enabled the researchers to catalog the genetic changes that have become fixed or have risen to high frequency in modern humans during the past few hundred thousand years.
"It sheds light on a critical time in human evolution since we diverged from Neanderthals," Green said in the news release. "What adaptive changes occurred in the past 300,000 years as we were becoming fully modern humans? That's what I find most exciting. Right now we are still in the realm of identifying candidates for further study."
The ancestral lineages of humans and chimpanzees are thought to have diverged about 5 or 6 million years ago. By analyzing the Neanderthal genome and genomes of present-day humans, Green and his colleagues estimated that the ancestral populations of Neanderthals and modern humans separated between 270,000 and 440,000 years ago
The evidence for more recent gene flow between Neanderthals and humans came from an analysis showing that Neanderthals are more closely related to some present-day humans than to others. The researchers looked at places where the DNA sequence is known to vary among individuals by a single "letter." Comparing different individuals with Neanderthals, they asked how frequently the Neanderthal sequence matches that of different humans.
The frequency of Neanderthal matches would be the same for all human populations if gene flow between Neanderthals and humans stopped before human populations began to develop genetic differences. But that's not what the study found. Looking at a diverse set of modern humans--including individuals from Southern Africa, West Africa, Papua New Guinea, China, and Western Europe--the researchers found that the frequency of Neanderthal matches is higher for non-Africans than for Africans.
According to Green, even a very small number of instances of interbreeding could account for these results
. The researchers estimated that the gene flow from Neanderthals to humans occurred between 50,000 and 80,000 years ago. The best explanation is that the admixture occurred when early humans left Africa and encountered Neanderthals for the first time. "How these peoples would have interacted culturally is not something we can speculate on in any meaningful way. But knowing there was gene flow is important, and it is fascinating to think about how that may have happened," Green said in the news release.
The researchers were not able to rule out one possible alternative explanation for their findings. In that scenario, the signal they detected could represent an ancient genetic substructure that existed within Africa, such that the ancestral population of present-day non-Africans was more closely related to Neanderthals than was the ancestral population of present-day Africans. "We think that's not the case, but we can't rule it out," Green said.
The researchers expect many new findings to emerge from ongoing investigations of the Neanderthal genome and other ancient genetic sequences. Pääbo's group recently found evidence of a previously unknown type of hominid after analyzing DNA extracted from what they had thought was a Neanderthal finger bone found in Siberia. Green is also taking part in that continuing investigation.
The Neanderthal genome sequence has been posted on the UCSC Genome Browser (genome.ucsc.edu), which contains a large collection of genomes and provides a convenient framework for genome comparisons and tools for genome analysis
The Science paper on the Neanderthal genome involved 56 coauthors from 22 different institutions. An accompanying paper by the same team, with Hernán Burbano of the Max Planck Institute as first author, describes a particular method used to investigate the genome. Support for the project includes funding from the Max Planck Society of Germany, the Ministry of Science and Innovation (MICINN) of Spain, and the National Human Genome Research Institute of the U.S. National Institutes of Health. However in 2012, researchers found another type of individual and named the person Denisovan, a type of cousin of Neanderthal, but different, an individual with brown hair, brown eyes, and brown skin. Check out the August 30, 2012 news release, "Scientists sequence the genome of Neandertal relatives, the Denisovans." And time will tell whether there are even more cousins with different patterns of DNA or appearances who lived 40,000 years ago and earlier.
A 2012 report describes the complete sequence of the Denisovan genome, shedding light on the relationships between these archaic humans, who were closely related to Neandertals, and modern humans. The results were published online by the journal Science, in the August 30, 2012 edition of ScienceExpress. Science is the flagship journal of AAAS, the nonprofit science society.
Fossil evidence of the Denisovans is scanty; the existence of this group only came to light in 2010 when DNA from a piece of a finger bone and two molars that were excavated at Denisova Cave in the Altai Mountains of southern Siberia was studied
Because they had only a tiny sample of material from the finger bone, Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and his research team developed a treatment that unzipped the DNA so that each of its two strands can be used to generate molecules for sequencing. This method allowed the team to generate an extremely thorough genome sequence (30X), similar in quality to what researchers can obtain for the modern human genome.
The researchers compared the Denisovan genome with those of several modern humans from around the world. The Denisovans share more genes with populations from the islands of southeastern Asia, including Melanesia and Australian Aborigines, than with populations elsewhere in Asia. Analysis of the Denisovan genome further illuminates the relationships of Neandertals with individuals from East Asia, South America and Europe.
The study reports several other findings. For example, the researchers generated a list of recent changes in the human genome that occurred after the split from the Denisovans, for example, changes unique to modern humans.
This list will help scientists understand what sets modern humans apart from Denisovans and Neanderthals. They also show that the Denisovan individual whose genome was sequenced carried genetic variants that in present-day humans are associated with dark skin, brown hair and brown eyes, and that the genetic diversity of the Denisovans themselves was extremely low. Given the Denisovans' wide geographic range over time, it is likely that their population was initially quite small but grew quickly, without time for genetic diversity to increase. If further research shows that the Neanderthal population size changed over time in a similar way, that may suggest that a single population expanding out of Africa gave rise to both the Denisovans and Neandertals, the study authors say.
By 2013, scientists described how Denisovans remains showed up not only where they were first found in the Altai mountains area of Siberia, but also in Spain around the same time that Neanderthals lived in Western Europe. When Homo Sapiens arrived in Europe, they may have encountered not only Neanderthals but also their cousins, Denisovans, and who knows how many other types of prehistoric individuals? Check out the news releases, "Oldest hominin DNA sequenced. "
You might also enjoy the following: "Scientists sequence the genome of Neandertal relatives, the Denisovans." Also, you may wish to see the news release, "Mysterious ancient human crossed Wallace's Line." Or see, "Genome of extinct Siberian human sheds new light on modern human origins" and "Genome of extinct Siberian cave-dweller linked to modern-day humans." There were many variations on a theme.