30.01.2009

A paleogenetical study determines the blood group of Neanderthal man

The study, published in BMC Evolutionary Biology  as directed by Carles Lalueza-Fox in collaboration with Jaume Bertranpetit, researchers at the Barcelona Institute of Evolutionary Biology (UPF-CSIC), among other scientists of the El Sidron Project (Asturias). This is the first gene recovered in Neanderthals and may be associated with their resistance to certain diseases .

The research has highlighted that the  blood group of two male Neanderthals who lived over 43,000 years ago on the El Sidrón site belonged to group 0

Studying the evolution of the blood groups in fossil species is most helpful to understand which have been the selective forces that have modelled the evolution of the hominids. Determining at what moment and circumstances of the evolutive history of human beings the genetic variations that determine the different blood groups emerged could be helpful to determine its  relationship with certain pathogenic agents of the past.

In their cell membrane, red blood corpuscles, as well as other epithelial cells, have molecules which act as antigens, that is, molecules capable of provoking an immunologic reaction. The human species has three variants of the ABO genetic System, which determine four different blood groups: A, B, AB and 0.

Belonging to group 0 means that membrane antigens are missing and this is associated with a greater resistance to certain diseases such as severe malaria, because some pathogens use these antigens as points of recognition of the cell they want to infect.

Since a few years ago, we have known the gene involved in the ABO blood group. This gene, also known as ABO, is localized in chromosome 9 and codifies for an enzyme responsible for the synthesis of N-acetyl galactosamine sugar (in individuals of A group) or of galactose (in those of group B) in the membrane of red blood corpuscles. Most of the people who are in blood group 0 belong to this blood group because of a mutation in  position 261 of chromosome nine that interrupts the synthesis of this enzyme.

Researchers have recovered fragments of the ABO gene in two Neanderthals of el Sidron and have discovered that they had the same mutation observed in 0 blood group in humans today. The fact that at least some Neanderthals belonged to group 0, could mean that they were adapted to a certain pathogen with which they would have made contact during their long staying in Eurasia. For the time being, these possible pathogens are unknown but are not necessarily the same that influence the present human population.

So, the results of this research show that the mutation that defines group 0 is shared by Neanderthals and modern humans. That means that it must have been inherited from the common ancestor of the two species that lived more than half a million years ago.

A rigorous, pollution-free protocol of clean extraction

The procedure known as "clean extraction protocol" is a unique methodology and marks a before and after in archaeo-paleontological excavation methods. Among other reasons, this is why El Sidron is part of the prestigious " Neanderthal Genome" project directed by Svante Pääbo of the Max Planck Institute of Evolutionary Biology (Leipzig, Germany)

Thanks to the protocol developed at El Sidrón, it has been possible to obtain anclean extraction of fossil bones, that is to say, completely free of all kinds of  contamination with modern DNA. Contamination with modern human DNA (the DNA of researchers and archaeologists, for example) is one of the main problems that limit the reliability of studies of ancient DNA.

The El Sidrón archaeological site (Borines, Asturias) is being excavated under the direction of Javier Fortea and Marc de la Rasilla co-directs the fieldwork, both from the University of Oviedo. So far nearly 1500 human osseous remains have been recovered, from at least nine different Neanderthal individuals studied under the direction of Antonio Rosas, of the CSIC.

The Paleonthological study has been directed by Carles Lalueza-Fox, of the Barcelona Institute of Evolutionary Biology (UPF-CSIC). The project is subsidised by the Principate of Asturias Culture Department.

Reference works:

Lalueza-Fox C, Gigli, E., de la Rasilla, M., Fortea, J. Rosas, A., Bertranpetit, J. and Krause, J. (2008), "Genetic characterization of the ABO blood group in Neanderthals", BMC Evolutionary Biology, Dec 24;8(1):342.