Elephants' complete genome mapped

A team, including researchers from McMaster University in Canada and Harvard University in the US, meticulously sequenced 14 genomes from several species.

These included both living and extinct species from Asia and Africa, two American mastodons, a 120,000-year-old straight-tusked elephant, and a Columbian mammoth.

The study, published in the journal PNAS, sheds light on what scientists call a very complicated history, characterised by widespread interbreeding.

They caution, however, that the behaviour has virtually stopped among living elephants, adding to growing fears about the future of the few species that remain on Earth.

"Interbreeding may help explain why mammoths were so successful over such diverse environments and for such a long time," said Hendrik Poinar from McMaster University.

"Importantly this genomic data also tells us that biology is messy and that evolution does not happen in an organised, linear fashion," said Poinar.

"The combined analysis of genome-wide data from all these ancient elephants and mastodons has raised the curtain on elephant population history, revealing complexity that we were simply not aware of before," he said.

A detailed DNA analysis of the ancient straight-tusked elephant, for example, showed that it was a hybrid with portions of its genetic makeup stemming from an ancient African elephant, the woolly mammoth and present-day forest elephants. "This is one of the oldest high-quality genomes that currently exists for any species," said Michael Hofreiter from the University of Potsdam in Germany, who led the work on the straight-tusked elephant.