VOA慢速英语--新发现的骨骼显示古人类的基因组合

Newly Discovered Bones Show Genetic 1 Mix of Ancient Human Relatives

Scientists say they have discovered the remains 2 of an ancient female whose mother was a Neanderthal and whose father was Denisovan.

Neanderthals and Denisovans are early human species that have been extinct for thousands of years. The discovery marks the first time scientists have found the remains of a child created by these two kinds of early humans.

The researchers found the 90,000-year-old pieces of bone in southern Siberia. The team published their findings in the journal Nature on Wednesday.

Why the discovery is important

Neanderthals lived in Europe and Asia. Remains of Denisovans are known only from the cave where the bone was found. Both groups disappeared by about 40,000 years ago.

Past genetic studies have shown evidence of sexual relations between the two groups, as well as with our own species, Homo sapiens. The unions show in the genetic structure, or DNA 3, of today’s people. But the new study is the first to identify a first-generation child with Neanderthal and Denisovan parents.

Svante Paabo is one of the lead researchers of the study. He is a geneticist at the Max Planck Institute for Evolutionary 4 Anthropology 5 in Leipzig, Germany. Paabo said he was surprised the bones were found. Both Neanderthal and Denisovan remains are rarely discovered anywhere in the world. So finding an actual child of the two groups seemed like unusually good luck, Paabo said.

The discovery is also interesting because the two groups were more different from each other than any two present-day human groups.

“The fact that we stumbled across this makes you wonder if the mixing wasn’t quite frequent,” said Paabo,

Other opinions

Ron Pinhasi is a physical anthropologist 6 at the University of Vienna who was not involved in the study. He noted 7 that the discovery does not answer how often Neanderthals and Denisovans mated. If they mated often, he said, the DNA of Neanderthals and Denisovans would not show such major differences.

Anders Eriksson is an evolutionary population geneticist at King’s College London who was not involved in the study either. He suggested that the DNA could be looked at in several different ways.

“I think they convincingly showed that genetically 8 this individual falls halfway 9 between the Neanderthal and Denisovan fossils found in the same cave,” said Eriksson. “But I’m less convinced that it is necessarily a first-generation offspring of a … Neanderthal and Denisovan.”

The fossil could instead have come from a population with nearly an equal mix of Neanderthal and Denisovan relatives, he observed. And it will take studies of more fossils to find this out.

What else can we learn?

The authors of this week’s report said the small pieces of bone likely came from the arm or leg of a female who was at least 13 years old at the time of death. They call her “Denisova 11.”

The researchers compared her DNA with other ancient DNA. They learned that the genes 10 from her mother were more closely related to Neanderthals who lived later in Europe than other Neanderthal remains from the cave.

This finding suggests that Neanderthals moved westward 11 over time.

Svante Paabo said the latest discovery suggests that the now-extinct ancient relatives of humans were not killed off by warfare 12, as many experts believe. Instead, it supports a theory that our ancient relatives combined with modern humans through sexual relationships.

I’m Pete Musto.

Words in This Story

species – n. a group of animals or plants that are similar and can produce young animals or plants

extinct – adj. no longer existing

journal – n. a magazine that reports on things of special interest to a particular group of people

cave – n. a large hole that was formed by natural processes in the side of a cliff or hill or under the ground

union(s) – n. an act of joining two or more things together

stumble(d) across – p.v. to discover something accidently

quite – adv. to a very noticeable degree or extent

frequent – adj. happening often

mate(d) – v. o have sexual activity in order to produce young

convincingly – adv. done in a way that causes someone to believe that something is true or certain

fossil(s) – n. something, such as a leaf, skeleton, or footprint, that is from a plant or animal which lived in ancient times and that you can see in some rocks

offspring – n. a person's child

author(s) – n. a person who has written something