Early modern humans inherited an 'immune gene' from Neanderthals that greatly improved our immune systems, scientists say.
A research group at Bonn University and international collaborators discovered a novel receptor, which allows the immune system of modern humans to recognise dangerous invaders, and subsequently elicits an immune response.
The blueprint for this advantageous structure was in addition identified in the genome of Neanderthals, hinting at its origin. The receptor provided these early humans with immunity against local diseases.
The presence of this receptor in Europeans but its absence in early men suggests that it was inherited from Neanderthals, scientists say.
The human immune system breaks down the invaders proteins into peptides and subsequently scans a proportion of the peptides for their amino acid sequences.
Up until now, a total of three different peptide receptors of more than 1000 different manifestations were known, which in humans can read the telltale letter combinations.
"This variety is needed so that the immune system can rate the entire spectrum of pathogens relevant for humans," said Dr Norbert Koch from the Institute for Genetics, Department of Immunobiology at Bonn.
A fourth receptor, or another "spy", has now been found by an international team of scientists from the University of Dusseldorf, the Technical University of Munich, Jacobs University Bremen and Cambridge University.
This receptor, which is abbreviated as "HLA-DRaDPb", consists of the combination of subunits of already known receptors.
Scientists compared the gene sequence, which encodes the discovered receptor, with data bases and determined that an estimated two-thirds of Europeans carry this important structure.
Koch himself carries the blueprint for this "spy", as one of his students found out by sequencing his DNA.
Scientists were nonetheless surprised to learn that the gene sequence required for this receptor is rare in people in southern Africa, the region known as the cradle of mankind.
Scientists examined whether Neanderthals as an example of early men had the key gene sequence which contains the blueprint for the receptor.
"The identified Neanderthal gene sequence is almost identical with that of modern humans," said Koch.
The study was published in the Journal of Biological Chemistry.
