TUFTS of frozen woolly mammoth hair have yielded a rough draft of the dead beast鈥檚 genome. It is the most successful attempt yet at sequencing the DNA of an ancient extinct animal, and could not only offer clues to why the mammoths died out, but also mean we are one step closer to bringing them back to life.
Sequencing extinct organisms is tricky because DNA strands quickly degrade into short fragments. DNA from bacteria and fungi growing on the decomposing body can also flood in, producing an indecipherable mess of DNA.
Stephan Schuster from Pennsylvania State University in University Park and colleagues sequenced DNA from two frozen mammoths that died in Siberia between 20,000 and 60,000 years ago. They were able to do this because the hard keratin protein that makes up hair had protected the mammoth鈥檚 DNA.
Advertisement
After identifying the DNA base pairs in each fragment, the team used the genome of the mammoth鈥檚 closest living relative 鈥� the African elephant 鈥� as a guide to putting the fragments back together. It turned out that elephants and mammoths are more closely related than previously realised (Nature, ).
So far, the team have sequenced about half of the mammoth鈥檚 DNA. Further work could reveal what drove the species to extinction, says team member Webb Miller, also from Penn State. They might find that 鈥渢he [genetic] diversity between individuals was low due to inbreeding鈥�, he says, which could have contributed to their demise.
The discovery that mice can be cloned from frozen brain cells (快猫短视频, 8 November, p 12) hinted at the possibility of raising extinct animals from the dead. The draft genome 鈥渋s perhaps a little step in that direction鈥�, says bioarchaeologist Ian Barnes from Royal Holloway, University of London. But he thinks it unlikely mammoths will rise again soon: 鈥淭here are still fundamental problems in engineering an extinct organism.鈥�