Washington - A DNA investigation has solved the mysterious origin of Gibraltar's Barbary macaques, the only free-ranging monkeys in Europe, according to a report on Monday.

The approximately 200 macaques alive today had nearly disappeared in 1942, and Britain's then-prime minister, Winston Churchill, ordered that their numbers be replenished or risk fulfilling a folklore belief that Britain would lose Gibraltar if the macaques ever died out.

"Our project was designed as a test case for conservation genetics," said Robert Martin, lead author of the study released by the Proceedings of the National Academy of Sciences.

"The Gibraltar colony of Barbary macaques provided an ideal example of genetic isolation of a small population, which is now a regular occurrence among wild primate populations because of forest fragmentation.

"To our surprise, we found a relatively high level of genetic variability in the Gibraltar macaques. This is now explained by our conclusion that the population was founded with individuals from two genetically distinct populations in Algeria and Morocco," said Martin, a primatologist and provost of the Field Museum in Chicago.

Some scientists believe the Barbary macaques were first brought to Gibraltar by the Moors, who occupied Spain between 711 and 1492. On the other hand, it is possible that the original Gibraltar macaques were a remnant of populations that had spread throughout southern Europe during the Pliocene, up to 5,5 million years ago.

"Our findings reveal that the Algerian and Moroccan populations are genetically very distinct and that there are major genetic differences even within Algeria," said Lara Modolo, of University of Zurich's Anthropological Institute.

"Mixing of founders from Algeria and Morocco explains why the Gibraltar macaques have kept a surprisingly high level of genetic variability despite a long period of isolation.

"At the same time, the large degree of genetic difference seen between various wild populations tells us that we should be cautious about translocating animals from one area to another," added Modelo, another co-author of the study.

Gibraltar is 5,8km2 of British territory, strategically located at the mouth of the Mediterranean at the southern tip of Spain. - Sapa-AFP