Sequenced the oldest human DNA from a femur ... - The Mundo.es

Just two grams

-1.95 – Bone have been sufficient for a DNA oldest known hominid. It may seem a small amount, but a fossil femur drilling nearly 400,000 years old until two grams of material from which to extract DNA is a risky bet. This time it went well. Researchers at the Max Planck Institute for Evolutionary Anthropology (Germany) and Atapuerca just published in the journal Nature one of those rare works that promise to revolutionize a field of science in the next Year: the oldest DNA sequence that has ever earned a hominid

.

the finding has come from fossil remains found in the Sima de los Huesos Atapuerca Burgos, which puts Spain in the thick of the evolutionary study of human’s closest relatives global scale. “The conditions of conservation of Sima Bones are really extraordinary,” explained Matthias Meyer WORLD, a researcher at the Max Planck Institute for Evolutionary Anthropology and first author of the research. “It will be difficult, and perhaps impossible, to find elsewhere in the world where the remains of very ancient hominids have been preserved in such constant humidity and low temperature,” says Meyer.

All researchers involved in the research coincide in pointing to the Pit of Bones as the real world palaeogenetics jewel. And it is not easy in a place like Spain, with a temperate climate. Anyone would have thought it would be simpler to have found traces of genetic material well conserved in other icy places, as in the permafrost of Siberia.

src=”http://estaticos02.elmundo.es/assets/multimedia/imagenes/2013/12/04/13861845411611_189x0.jpg”

‘d have to have the entire genome to know what the hominid species

belongs

“Amazing” Conditions for storage

gap is a vertical shaft 13 meters deep, located 30 meters under the surface more than 500 meters from the nearest entrance of the cave-limestone-karst in the found. The humidity is always constant and very close to saturation, ie the maximum amount of water vapor that can contain a cubic meter of air or 100% humidity-and temperature more than half a million years without leaving the 10.6 º C.

“Wish I had depths of 40 bones throughout the world, the conditions are amazing, and the amount of fossil tide that is there really … We tend to figure that has been extracted 1% of what there is, and it seems much, “says José María Bermúdez de Castro, co-director of Atapuerca and one of the authors. Despite the small percentage of material from Atapuerca , the Burgos field is the most important in the world for this type of hominid fossils point.

However, the excellent preservation of the fossil material from the Sima de los Huesos not prevent DNA of about half a million years old be highly fragmented in very small chains . “In the Atapuerca fossils, almost all fragments of genetic material are broken into pieces less than 50 pairs,” explains Meyer. It is useful to put this in comparison to the size of a human genome to get a real idea of ??how enormous the challenge for researchers to reconstruct a sequence can provide some information on the species or the evolution of the ancestors human . The complete human gene sequence has about 3,200 million base pairs, and the fragments with which it has worked the science team for this work are less than 50 base pairs, and many of them under 30.

A “hybrid”

species

is why, for now, only obtained mitochondrial DNA, which contains a small human cell organelle responsible for respiration at the cellular level, called mitochondria . This genetic material, as found in the cell nucleus [ whose genetic information is 50% and 50% dad mom ] but in the cytoplasm (I contributed in the formation of the embryo by the mother’s egg) , is transmitted in all cases the mother.

smaller size of such nuclear DNA compared makes easier the work of reconstruction of the genome. But also allows comparison with other mitochondrial genetic material obtained from other species , or at least more recent fossils, such as Neanderthals or Denisovans, a species of the Homo genus identified in Siberia almost exclusively by DNA traces.

In fact, one of the conclusions are even-more-main hypothesis of the study is about the origin of the hominid from the Sima de los Huesos, which has not yet been classified in any of the hominid species known to date. “If you never would have found Denisovans now convinced that this is a kind of close to Neanderthals,” explains Bermudez de Castro. However, the comparative analysis situated mitochondrial DNA found closer to that of Neanderthals Denisovans , while morphological traits, physical appearance, is much more similar to Neanderthals.

The big question is how could get mitochondrial DNA from Denisovans an individual much more like the Neanderthals? The study brings three possible scenarios, but the Spanish team leans more by one. denisovana hybridization between a mother and a father Neanderthal that led to hominid found in the Sima de los Huesos de Burgos.

“This is an unexpected result for us,” says Bermudez de Castro. “But human evolution in Eurasia is very complex. There are crosses and hybrids that have not been taken into account. It’s a story of a million years and a lot has happened, “he concludes.

Researchers have deciphered part of their DNA, but to clarify what species it is or what has been their evolutionary history in more detail, it is necessary to take a huge leap to technical and scientific achieve genome Full , nuclear DNA.

“We would need at least one sequence of the nuclear genetic material to determine its position vigorously in the human evolutionary tree,” says Meyer. For the Spanish team that signed the article, led by co-directors of the Atapuerca Juan Luis Arsuaga, Bermúdez de Castro and Eudald Carbonell, with whom this newspaper has been unable to speak because he is incommunicado in Eritrea-an excavation of the entire genome can accommodate many of the largest responses. “That is out of our reach now. But we are at the beginning of a great scientific project with Juan Luis Arsuaga team to complete the puzzle together. is an exciting time and we are all dedicated body and soul , so who knows what the future may hold us … “Meyer says.