Thousands of years ago, species of humans, different from the modern ones, existed in the valley of Denisova in Russia. They mated among themselves and also produced offspring. The DNAof the fossilofatwo-centimeter long bone collected from the Denisova cave revealed that the sample was of an offspring of two different species of ancient humans, Neanderthal and Denisovan. Analysis of the DNA sample indicated that the father of the offspring was a Denisovan and mother a Neanderthal. The analysis also showed that the bone belonged to a female.
This discovery is a significant one. It gives important insight into the lives of our closest ancient human relatives. Neanderthals and Denisovans were early humans, but belonged to different species. The genes of both the archaic species are present among many people eventoday. During the ice age in Europe and Asia, Denisovans, Neanderthals and modern humans interbred. Studies made on ancient genomes led scientists to arrive at this conclusion. Finding the DNA of an actual offspring who was half Neanderthal and half Denisovan will surely strengthenthe scientific understanding about our ancestry and evolution.
The bone fragment was collected by Russian archaeologists in the Siberian cave several years back. Viviane Slon of Max Planck Institute for Evolutionary Anthropology in Germany, along with her colleagues carried out ananalysis of theDNA that they could extract from the bone. Pulverizing the sample, extracting DNA out of it,and then sequencing- was the strategy they adopted for deciphering the history of the bone piece. The characteristicfeaturesof the bone fragment suggested that it came from someone who was at least 13 yearsold and its genome matched to that oftheNeanderthal and Denisovan in a nearly equal measure. The portion of the DNA present in the mitochondria, an important compartment inside the cell, was also analyzed. The mitochondrial DNA matched with that of a Neanderthal, confirming that the mother of the offspring was a Neanderthal. The DNA in the mitochondria is inheritedonlyfrom the mother. Itis said to be the power house of a cell.
Upon deeper analysis, the research also inferred that the father of the offspring hadaNeanderthal as its ancestor, probably several hundred generations back. Moreover, the offspring’s maternal (Neanderthal) genes were found to be closely matching with the Neanderthal found in Croatia than those found in the Siberian cave. This is interestingbecause this reveals the fact that groups of Neanderthals used to migrate from western Europe to Siberia and mated with the Denisovans there. These early humans freely spread their genes to outsiders.
Neanderthals and Denisovans existed in Eurasia until 40,000 years back, with Neanderthals in the west and Denisovans in the east. These two early humans separated from each other some 90,000 years ago, but occasionally they met each other intheir paths of migrations. On suchincidences when they crossedeach others path they freely mated.
The existence of Denisovans as a related ancestor of the modern human is a comparatively new discovery. It is the Denisova cave situated in the Altai mountain of Siberia where Neanderthals, Denisovans and early humans overlapped through time. Thisapparently wasalsobethe place where the inter-species breeding happened.