Scientists have found living organisms trapped in crystals that could be 50,000 years old.

The organisms were found in a hot, but beautiful cave system in Naica, Mexico. These ancient life forms can be seen only with a microscope. They are dormant, with all biological activity suspended inside the solid crystals.

Penelope Boston leads the Astrobiology Institute at NASA, the space agency of the United States. She says the ancient microbes were able to exist by eating minerals such as iron and manganese.
潘尼洛普·波士顿(Penelope Boston)领导着美国宇航局的天体生物研究所。她说,这种古老的微生物通过吃铁和猛之类的矿物质存活。

She spoke about the discovery recently at a meeting of the American Association for the Advancement of Science. If the findings are confirmed, they will show how microbes can survive in extreme conditions.

Researchers have been studying the microbes for nine years. But they have not reported their discovery in a scientific publication, and other scientists have yet to confirm the findings.

Penelope Boston plans to do more genetic tests on the microbes, which she revived both in the laboratory and in the Mexican caves.

40 strains of microbes, viruses

Forty different kinds of microbes and some viruses were found in the underground area. The genetic structures of these organisms are 10 percent different from those of their nearest relatives. Boston says that means their closest relative is about as genetically different as humans are from mushrooms growing in the forest.

The caves in Naica are 800 kilometers deep. They were once used for mining lead and zinc. Before the miners began working in the caves, the area was isolated from the surface and the outside world.

Some of the caves are as big as the large religious centers built during Europe's Middle Ages. There are crystals covering the walls. The caves are so hot that scientists must wear special clothing to keep cool. The clothing keeps the crystals safe from human germs or other damage.

Boston said the researchers could only work for about 20 minutes at a time before they had to go to a room that was 38 degrees Celsius to cool down.

No surprise in extreme life

NASA officials would not let Boston share her findings with scientific experts before last week's announcement. So scientists could not say much about the findings. But Norine Noonan, a biologist with the University of South Florida, said she believed them.
美国宇航局官员在上周公告前不愿意让波士顿同科学专家分享她的研究结果。所以科学家对该研究结果说不上来什么。但是南佛罗里达大学的生物学家诺琳·诺南(Norine Noonan)称她信任他们。

"Why are we surprised?" Noonan asked. "As a biologist, I would say life on Earth is extremely tough and extremely versatile."

The microbes are not the oldest life forms on Earth. Several years ago, scientists published studies about microbes that may be 500,000 years old and still alive. Boston says those microbes were trapped in ice and salt, not rock or crystal.

Other experts were asked to estimate the age of the Naica microbes. To do this, they looked at where the microbes were in the crystals and how fast those crystals grow.

Boston is also studying microbes commonly found inside caves in other countries, such as Ukraine and the United States. These microbes eat copper sulfate and appear to be impossible to kill. Boston said they show how difficult life on Earth can be.

I'm Jonathan Evans.