GUARDIAN NEWS SERVICE

By Ian Sample, science correspondent

Scientists have unravelled the genetic makeup of the woolly mammoth by analysing hairs plucked from carcasses recovered from the Siberian permafrost.

The feat was hailed as a milestone in genetic science on Wednesday and represents the first time an extinct animal has had its genome sequenced.

The first draft of the genetic code shows mammoths split into two groups about two million years ago. One group became extinct about 45,000 years ago, while the other is thought to have lived on to as recently as 10,000 years ago.

"It has now become feasible to sequence a complete extinct animal, which is quite amazing," said Stephan Schuster, who led the research at Penn State University.

The achievement is an indication of the rapid progress in genetics. In 2003, the 13-year effort to read the human genome was completed at a cost of $2.6bn. The mammoth genome was read at one laboratory in less than a year and cost just over $1m.

Schuster's team gathered hair samples from 18 woolly mammoths and pieced together 3.3bn pairs of letters that make up about 70% of the animal's genetic code, the journal Nature reported.

By comparing the mammoth's DNA with that of the African elephant, the scientists identified sections of genetic code that may explain how the beasts adapted to harsh Arctic conditions. All elephants originated in Africa, but split into different species around 6.5 million years ago. One group migrated to tropical Asia, while the mammoth headed for temperate Europe and eventually the Arctic.

Schuster said genetic diversity was very low in the two groups of mammoths. That may explain why the animals suddenly became extinct after enduring successive ice ages. The changing climate could have depletedtheir populations, leaving them vulnerable to disease and hunting whenhumans arrived in their regions about 23,000 years ago.

Analysis of the mammoth genome reveals it differs from the African elephant by only 0.6%. That is about half the difference between humans and chimpanzees, which split from a common ancestor at around the same time.

The greater genetic gulf between humans and chimps suggests primates haveevolved faster, probably because apes have historically been preyed on morethan mammoths.

"It's an absolute first to have a genome sequence of an extinct animal,that's really a milestone," said Michael Hofreiter at the Max PlanckInstitute for Evolutionary Anthropology in Leipzig, Germany.

Ultimately, scientists want to compare the genomes of mammoths that lived at different times to see how the species evolved. "Within the next decade, that is what people will go for. It's what evolutionary biologists