Native people in the Amazon may have been creating fertile soil for farming for thousands of years. And what they learned could offer lessons for people concerned about climate change today.

The Amazon River basin covers much of central South America, across which are archaeological sites where ancient people left their mark on the land. And patches(小块) of strangely fertile soil dot the landscape at many of these sites. It’s darker in color than surrounding soils and richer in carbon.

The industrial world has long viewed the Amazon as a vast wilderness — one that was mostly untouched before Europeans showed up. One reason for this idea was that the soil there is nutrient-poor. But a large number of ancient finds in recent decades has been turning that idea on its head. Plenty of evidence now shows that people were shaping the Amazon for thousands of years before Europeans arrived. Ancient city centers have been found in modern-day Bolivia, for instance.

To find out more, Perron, an Earth scientist at the Massachusetts Institute of Technology in Cambridge, became part of a team that reviewed interviews with Kuikuro people, who reported making dark Earth using ash, food scraps and controlled burns. They call the product eegepe.

The researchers also collected soil samples and found that there were “striking similarities” between dark Earth samples from ancient and modern sites. Both were far less acidic than the soils around them and also contained more plant-friendly nutrients.

The soil samples also revealed that on average, dark Earth holds twice as much carbon as the soil around it. Infrared(红外线的) scans in one Brazil region suggest the area holds many pockets of this dark Earth, which may store up to about 9 million tons of carbon that scientists have overlooked, Perron’s team says. That’s about as much carbon as a small, developed country emits per year.

‘Figuring out the true amount will require more data,’ says Antoinette Winkler Prins, a geographer working at Johns Hopkins University in Baltimore, Md. Still, ‘the new research could offer insights into the Amazon’s past and future.’

【小题1】What was previously believed about the Amazon River basin?

A．It was a vast wilderness untouched by humans.

B．It was a highly developed region with large cities.

C．It was an uninhabitable region with nutrient-rich soil.

D．It was a moderately fertile region occasionally farmed by natives.

【小题2】What did the researchers find about the dark Earth created by the Kuikuro people?

A．It was made using advanced agricultural techniques.

B．It was fertile and contained more carbon than surrounding soils.

C．It was highly acidic and nutrient-poor.

D．It was only found at ancient archaeological sites.

【小题3】What is the significance of the dark Earth discovered by the researchers?

A．It offers insight into ancient agricultural practices in the Amazon.

B．It is evidence of a highly advanced civilization that lived in the Amazon.

C．It can be used to grow crops in the nutrient-poor soil of the Amazon.

D．It has the potential to reduce carbon emissions from the region.

【小题4】What is the main idea of this article?

A．Ancient Amazonians created fertile soil for farming using advanced techniques.

B．The Amazon River basin was inhabited and cultivated by ancient people.

C．The discovery of dark Earth in the Amazon could have significant implications for climate change.

D．The Kuikuro people have developed sustainable farming practices.