In early human ancestor, growing up came late for males

Dr. Lockwood and his colleagues compared the size and shape of several P. robustus specimens. The one on the far left is the most well-preserved female specimen. The next one is one of the largest young adult males. The two on the right are older adult males.

If Paranthropus robustus -- a human ancestor that lived about 2 million years ago -- had gone to school dances, it would have been pretty awkward. New research shows that the males of this species matured much later in life than females.

These findings could help researchers understand how these early human ancestors lived and socialized together.

Charles Lockwood of University College London and his colleagues made this discovery about P. robustus by analyzing a variety of skulls.

They looked at how worn down the teeth were to determine how long the individuals had been alive. And, the researchers measured the size and shape of the skull to determine how mature the individuals had been, and also to figure out whether they were male or female

The results indicate that P. robustus males developed more slowly than females. This is also true for some living primates, such as gorillas.

In gorilla populations, individual mature males, the large “silverbacks,” live with a group of females, mating with them and protecting them. P. robustus may have lived like this too, according to Dr. Lockwood and his colleagues.

The study appears in the 30 November issue of the journal Science.

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