NEW YORK (AP) - Scientists have reached farther back than ever into the
ancestry of humans to recover and analyze DNA, using a bone found in Spain
that’s estimated to be 400,000 years old. So far, the achievement has
provided more questions than answers about our ancient forerunners.
The feat surpasses the previous age record of about 100,000 years for
genetic material recovered from members of the human evolutionary line.
Older DNA has been mapped from animals.
Experts said the work shows that new techniques for working with ancient DNA
may lead to more discoveries about human origins.
Results were presented online Wednesday in the journal Nature by Matthias
Meyer and colleagues at the Max Planck Institute for Evolutionary
Anthropology in Leipzig, Germany, with co-authors in Spain and China.
They retrieved the DNA from a thighbone found in a cave in northern Spain.
It is among thousands of fossils from at least 28 individuals to be
recovered from a chamber called the “Pit of the Bones.” The remains are
typically classified as Homo heidelbergensis, but not everybody agrees.
The age of the bones has been hard to determine. A rough estimate from
analyzing the DNA is around 400,000 years, which supports what Meyer said is
the current view of the anthropologists excavating the site. Todd Disotell,
an anthropology professor at New York University, said geological techniques
suggest the remains are older than 300,000 years but it’s not clear by how
much. By comparison, modern humans arose only about 200,000 years ago.
The researchers mapped almost the complete collection of so-called
mitochondrial DNA. While the DNA most people know about is found in the
nucleus of a cell, mitochondrial DNA lies outside the nucleus. It is passed
only from mother to child.
Researchers used the DNA to construct possible evolutionary family trees
that include the Spanish individuals and two groups that showed up much
later: Neanderthals and an evolutionary cousin of Neanderthals called
Denisovans. They assumed the DNA would show similarities to Neanderthal DNA,
since the Spanish fossils have anatomical features reminiscent of
But surprisingly, the DNA instead showed a closer relationship to Denisovans,
who lived in Siberia and apparently elsewhere in Asia, far from the Spanish
cave. Scientists are uncertain of explain that, Meyer said.
The picture should get clearer if scientists can recover the other kind of
DNA, found in the nucleus, from the Spanish bones, he said. Nucleus DNA
would give more comprehensive information about evolutionary relationships
between species, perhaps telling a story much different from the
mitochondrial DNA evidence, Meyer said. Nucleus DNA is harder to recover,
but Meyer said he’s optimistic that some small fraction might be
He also noted that the cave has acted as “the perfect fridge” to preserve
the DNA for eons, and said it will be hard to find comparable situations
Experts in ancient DNA called the new paper exciting because it showed
scientists can recover older DNA than many had thought outside the deep
freeze of permafrost areas. Much of human evolution happened in warmer
“We had been operating for a while under the assumption that the oldest DNA
we’re going to get is about 100,000 years,” said Disotell. Now, “we might
take a shot at some older samples that we just never would have bothered
with in the past.”
In warm places like Africa, where DNA does not preserve well, even getting
genetic material that is just tens of thousands of years old would be an
advance, said David Reich of Harvard Medical School.