Extremophiles are animals that live in challenging environments such as the vents from undersea volcanos or beneath the arctic ice. Humans, being hairless, warm blooded and not very picky about our diets, tend to try to avoid extreme environments. However, according to researchers, there may have been an exception about 12,000 years ago in Peru.

At that time the Earth was in the final days of an ice age. Even today, the Peruvian Andes are cold with average annual temperatures of between 32 and 64 degrees Fahrenheit, depending on the location. At 4500 meters above sea level (masl) there would have been other problems beyond cold. At that elevation the air is thin, with a low oxygen content and solar radiation is high.

Nevertheless, according to Kurt Rademaker, a University of Maine visiting assistant professor in anthropology and his colleagues that was the environment that these early South Americans lived in, just 2000 years after the earliest known human inhabitants arrived in the Americas.

“Study of human adaptation to extreme environments is important in understanding our cultural and genetic capacity for survival,” said Rademaker, a University of Maine visiting assistant professor in anthropology, writing in the journal Science.

The researchers located a rock shelter, with views of wetland and grassland habitats as well as about 260 tools. The tools are made from locally available obsidian, andesite and jasper and, according to the team, consistent with hunting and butchering tools of the time. The site also contained plant remains and the bones of vicuña and guanaco camelids and the taruca deer.

The evidence found, such as stream-polished tools, suggests that the high-altitude dwellers regularly visited lower elevations and may have spent the coldest parts of the year elsewhere.

Based on the discovery, scientists are now asking whether life at high altitudes required genetic adaptations. The existence of the site, however, suggests to some that the Andean environment may have had some moderate zones and that the physiological capabilities for Pleistocene humans was greater than imagined.

“The Pucuncho Basin sites suggest that Pleistocene humans lived successfully at extreme high altitude, initiating organismal selection, developmental functional adaptations and lasting biogeographic expansion in the Andes. As new studies identify potential genetic signatures of high-altitude adaptation in modern Andean populations, comparative genomic, physiologic and archaeological research will be needed to understand when and how these adaptations evolved,” said the researchers in a statement.