Washington, November 30: An analysis of fossils from the primate species that lived in Africa about 2 to 1.2 million years ago suggests that some early human ancestors might have lived in harem societies, just like modern gorillas and orang-utans do today.

The observations of Charles Lockwood, an anthropologist at University College London, are based on the study of fossils from Paranthropus robustus.

A report appearing in the journal Science says that harem society is an arrangement that can be observed in some modern primate species, in which males mature later in life than females and become much larger than their mates.

In such cases, a single dominant male mates with and protects a large harem of females.

The report also states that P. robustus is a descendant of Australopithecus afarensis, early humans that also gave rise to the Homo genus that includes modern humans.

Lockwood and his colleagues looked at roughly three-dozen fossil skulls and teeth from P. robustus, which showed them that male members of the species matured late in life.

Based on their observations, the researchers came to the conclusion that P. robustus males competed for groups of mates much the way gorillas do today.

The report says that male gorillas and orang-utans grow significantly in adulthood and tend to become dramatically larger than females of their species.

It, however, also states that extreme size differences are not common in other primates such as chimpanzees and humans, in which harem mating behaviour is abnormal.

The P. robustus fossils, found at the Cradle of Humankind World Heritage site in South Africa, were predominantly deposited by ancient predators like leopards and hyenas.

Since the remains were mostly male, the researchers concluded that males would have become victims far more often than females.

"One reason why that's important is because there are so few females in the fossil sample, (so) it appears that they were relatively safe, " the National Geographic quoted Lockwood as saying.

"A key inference is that there were stable groups of females that would have allowed males to pursue this (harem) strategy, " he added.

Richard Potts, director of the Human Origins Program at the Smithsonian Institution's National Museum of Natural History, said: "Lockwood's study is very clever in using the fossil record to interpret the pattern of growth in males and females in P. robustus and connecting it to the pattern to male competition, which seems to parallel that of gorillas. "

He added: "It's intriguing to me that Lockwood and colleagues have come up with anatomical evidence that converges on a similar interpretation about the social lives of Paranthropus. " (ANI)