Researchers at the Institute of Evolutionary Biology (UPF-CSIC), Barcelona and of the Institute of Oncology of the University of Oviedo have contributed to unravelling the orang-utan genome, the most distant hominid from the human being with whom a common ancestor was shared over 12 million years ago.

This study is the result of the collaboration of over thirty laboratories spanning seven countries and is led by Devin Locke of Washington University (St. Louis, USA).

The Spanish contribution to this study, which features on the cover of Nature dated 27 January, was coordinated by Arcadi Navarro, professor of Genetics at Pompeu Fabra University and ICREA research professor of the Institute of Evolutionary Biology (UPF-CSIC); Tomàs Marquès-Bonet, who recently joined the Institute as head of the Genomics of Primates group thanks to the Ramón y Cajal programme, and Carlos López-Otín, professor of Biochemistry and Molecular Biology at the University of Oviedo.

97% genetic coincidence with humans

Determining the more than three thousand million base pairs that make up the orang-utan genome has now been added to the previously sequenced human and chimpanzee genomes, and provides a more precise picture of the evolutionary process that gave rise to humans.

Comparing these genomes, with a genetic overlap of over 97% between the human and the orang-utan in the sections whose comparison has been possible, shows the different evolutionary pressures which the ancestors of these species had to face and the considerable differences between the chromosomes of orang-utans and those of other hominids.

The orang-utan, an endangered species

Comparing the two species of orang-utans in existence today, the Bornean (Pongo pygmaeus) and the Sumatran (Pongo abelii) , has revealed the existence of significant changes in population between them. It has thus been established that during the last 400,000 years, the population of Sumatran orang-utans greatly expanded whereas the Bornean variety suffered a decline.

Despite this, the current number of Sumatran orang-utans is far lower than those of Borneo, basically due to factors linked to human intervention. Knowledge of their genetic differences may help with efforts to conserve the two species of orang-utans that face extinction.

New keys to understanding the evolution of some illnesses

These results provide new keys to understanding the evolution of hominids and information regarding the mechanisms of chromosomal reorganization in illnesses such as cancer.

Professor Carlos López-Otín states that "the detailed comparative study of multiple families of genes in human, chimpanzee and orang-utan genomes would indicate that in human evolution there has been significant evolutionary pressure on the immune and reproductive systems". Professor Arcadi Navarro says that "studies on the genomic organization of the orang-utan will enable obtaining valuable information concerning the mechanisms of chromosomal reorganization that take place in such diseases as cancer".

The contribution by Spanish researchers

The participation of Spanish researchers in this project is thanks to the research work carried out by Tomàs Marquès-Bonet, of the IBE (UPF-CSIC) and of the University of Washington (Seattle, USA); Rui Faria, Olga Ferran, Fleur Darré, Domènec Farré, Elodie Gazave, Meritxell Oliva and Arcadi Navarro, also of the IBE, and Víctor Quesada, Xose S. Pont, Gonzalo R. Ordóñez and Carlos López-Otín, from the University of Oviedo.

Arcadi Navarro's group has studied the organization of orang-utan chromosomes in comparison with other hominids, which has enabled reconstructing several important events in the differentiation of the various species of hominids

Tomàs Marquès-Bonet, on the other hand, has led the section of segmental duplications and structural reorganizations in comparison with other hominids

Finally, the group under Carlos López-Otín has produced a detailed study of the different families of genes frequently associated with diseases that display significant differences between humans and orang-utans

Reference works:

Devin P. Locke et al. (2011), " Comparative and demographic analysis of orang-utan genomes", Nature, vol. 469, pages 529-533, 27 January, doi:10.1038/nature09687.