Scientists Successfully Sequence DNA of a 400,000-Year-Old Hominin From Spain

With the help of new technologies a team of researchers has successfully sequenced the complete mitochondrial genome of a 400,000-year- old hominin from Spain.

Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have determined the mitochondrial genome sequence of a 400,000 year old hominin that was unearthed from a cave site, Sima de los Hiesos (bone pit), in Northern Spain. They revealed that the hominin was related to the extinct Neanderthals in Asia.

Till date the bone pit has yielded more than 28 skeletons belonging to the Middle Pleistocene era. The fossils have been excavated and pieced together by the Spanish paleontologist, Juan-Luis Arsuaga. The fossils are called Homo heidelbergensis and also carry traits commonly found in the Neanderthals.

"Our results show that we can now study DNA from human ancestors that are hundreds of thousands of years old. This opens prospects to study the genes of the ancestors of Neanderthals and Denisovans. It is tremendously exciting" Svante Paabo, director at the Max Planck Institute for Evolutionary Anthropology, said in a news statement.

Matthias Meyer and his team from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, came up with the new technique to sequence  extinct ancient DNA. The technique was used on a cave bear from the bone pit. They successfully carried out the sequencing and then used the same technique on two grams of bone powder from a hominin thigh bone retrieved from the cave to sequence the mtDNa. Later they compared the mtDNa with Neanderthals, Denisovans, present-day humans and apes.

Looking at the missing mutations in the sequences of the ancient DNA, the researchers estimated that Sima hominin existed some 400,000 years ago. Apart from this they have even traced a common ancestor. The researchers claim that the Sima hominin shared a common ancestor with the Denisovans that are a group of ancient archaic population from Asia and were related to Neanderthals nearly 700,000 years ago.

"The fact that the mtDNA of the Sima de los Huesos hominin shares a common ancestor with Denisovan rather than Neanderthal mtDNAs is unexpected since its skeletal remains carry Neanderthal-derived features", says Matthias Meyer.

Looking at the age of the Sima hominin and also the features that were similar to the Neanderthals, the researchers believe they might be related to both the Neanderthals and Denisovans. Else the gene could have come from another unknown group of hominins that were introduced by Denisovans in to the Sima hominin or their ancestor population.

"This unexpected result points to a complex pattern of evolution in the origin of Neanderthals and modern humans. I hope that more research will help clarify the genetic relationships of the hominins from Sima de los Huesos to Neanderthals and Denisovans" says Juan-Luis Arsuaga, director of the Center for Research on Human Evolution and Behavior.

The finding was documented in the journal Nature.