In the Amazon rainforest of Venezuela, Yanomami hunter-gatherers exist on cassava, palm hearts and wild bananas. They also hunt frogs and monkeys using techniques that would have been familiar to their ancestors 11，000 years ago. The extraordinary continuity of their culture,and the fact that some of the groups have had little contact with outsiders,led biologists to wonder whether the Yanomami might reveal what the human digestive system looked like before industrialization supplied the world with processed foods and antibiotics.
  In 2019，researchers at the Icahn School of Medicine had a chance to find the answer in a previously unknown Yanomami village. Health workers collected feces（排泄物） from about 30 villagers. When the researchers cultured and analyzed microbes（微生物） from the feces in their laboratory,they discovered whole categories of bacteria that were absent from the guts（肠道） of people from industrialized countries. Even more strikingly, they found the microbial population in the average Westerner to be about half as diverse as the community inside these hunter-gatherers. The researchers realized that the microbes might have implications beyond basic science. People's microbial communities are believed to play a role in disorders like obesity, diabetes and Alzheimer's, which shorten lives and overburden health care systems. These disorders don't trouble these preindustrial hunter-gatherers, however. Therefore, researchers want to learn which microbes protect them and figure out how to reintroduce them in modern societies. It has the potential to affect health more profoundly than the discovery of the fabled Fountain of Youth.
But the opportunity might be more fleeting than youth itself. "The world is becoming urban so fast." says microbiologist Maria Gloria,co-author of the study that reveals the Yanomami microbiome（微生物群）. "Our lifestyles are killing microbial diversity." Although nobody has yet determined exactly what the Yanomami mystery bugs are doing and how they improve an individual's health,she believes that scientists need to collect and preserve as many microbes as possible for future breakthroughs. "We cannot afford to wait," she says, "or we'll have lost the high diversity of the human microbiome of traditional peoples before we understand how to use the microbiome to improve health."



What did the researchers find out in 2019？ ______

A. The hunter-gatherers had a different digestive system.
B. Microbial communities were to blame for many disorders.
C. People from industrialized countries had less diverse microbes.
D. Some categories of bacteria did not exist in the villagers' guts.

How did the researchers make their discovery？ ______

A. By collecting health data.
B. By conducting experiments.
C. By interviewing the villagers.
D. By recording the Yanomami's daily life.

What does the author mean by "the opportunity might be more fleeting than youth itself"？ ______

A. The opportunity seems more precious than youth.
B. The opportunity enables people to stay young forever.
C. The opportunity is of great significance to modern society.
D. The opportunity disappears so quickly that we cannot afford to miss it.

What can be inferred from the passage？ ______

A. We are close to solving the mystery of Yanomami microbiome.
B. Processed foods and antibiotics have changed human digestive system.
C. Treating diseases by introducing beneficial bacteria has been made possible.
D. The discovery of those microbes will help cure many life-threatening diseases.