Chimpanzees live only in the rainforests and forests of Africa. Orangutans live only in the jungles of Indonesia. But humans live everywhere. Our species has spread across frozen tundra, settled on mountaintops, and called other extreme environments home.
Scientists have historically considered this adaptability to be one of the hallmarks of modern humans and a sign of how evolved our brains have become. But new research suggests that perhaps we're not that special.
Researchers have discovered that one million years ago, an extinct species of human relative known as Homo erectus thrived in harsh desert regions that were off limits before the emergence of Homo sapiens. I discovered it.
“This is a major shift in the story of adaptability, extending beyond Homo sapiens to its earliest origins,” said Julio Mercader, an archaeologist at the University of Calgary and author of the study published Thursday in Communication Earth. This will be extended to include relatives of And the environment.
Fossils of our early ancestors, collected over decades, seemed to confirm the special adaptability of our species. Our ancestors, known as hominins, separated from other great apes in Africa about 6 million years ago and lived in open woodlands for millions of years. They did not appear to live in extreme environments.
Dr. Mercader and his colleagues took a closer look at the East African environments that have produced some of the richest troves of human fossils. They chose a site in northern Tanzania called Engazi Nanyor, where paleoanthropologists had previously discovered Homo erectus fossils.
Homo erectus is thought to have evolved in Africa about 2 million years ago. They were the first animals to reach the height of modern humans and had long, slender legs for running. Their brains were larger than those of early humans, but only about two-thirds the size of ours.
At one point, Homo erectus expanded from Africa and reached Indonesia, but became extinct about 100,000 years ago. Many researchers believe that they may have given rise to our own species over the past few hundred thousand years, and then disappeared there as well.
Dr. Durkin and his colleagues set out to determine exactly what kind of environment Homo erectus lived in Engazi Nanyor one million years ago. They observed fossilized pollen grains, analyzed the chemistry of the rocks, and looked for other clues about the landscape.
“These studies are a huge amount of work,” said Elke Zeller, a climate scientist at the University of Arizona who was not involved in the project.
Researchers determined that for hundreds of thousands of years, Engadzi Nanyor was a pleasant open forest area. However, about a million years ago, the climate became drier and the trees disappeared. The landscape changed to Mojave-like desert scrubland. It was an extremely dry place that was uninhabitable for early humans.
“This data brings us to a crucial question: How was Homo erectus able to survive and even thrive under such difficult conditions?” Dr. Mercader said.
Instead of fleeing, the hominins figured out how to survive in their changing homeland. “Their greatest asset was their ability to adapt,” Dr. Mercader says.
For example, they changed the way they searched for and cleaned up animal carcasses. Hominids discovered ponds and streams that appeared after storms. They weren't just drinking water from a fleeting watering hole. They also hunted the animals that appeared there and slaughtered their carcasses by the thousands.
Hominins also adapted by upgrading their tools. They took more care when chipping away the flakes from the stone to give it a sharper edge. They preferred materials from specific locations rather than just picking up stones from anywhere. Once they had made the tools, they carried them with them.
“They may have had a strategy where they basically said, 'Here's a good tool,' and we've got to bring it and be ready if we find food,” said geologist at the University of Manitoba. said Paul Durkin, who was also involved in the study.
Dr. Durkin and his colleagues discovered that Engadzi Nanyor lies at the southern end of a vast belt of desert scrub that stretches from Africa across much of the Middle East and into Asia. The adaptability shown by Homo erectus at Engadzi Nanyor may have helped it spread to other continents.
Dr. Zeller and his colleagues took a different approach to studying humans. The goal is to create a large-scale climate model in order to elucidate the conditions that prevailed during the course of human evolution. Their model, as well as new research, suggests that Homo erectus may have thrived in environments once thought to be too harsh for species other than our own.
Studies like the one Dr. Zeller and Ngazi Nanyor's team are conducting “are all starting to tell the same story,” she says. “We definitely need to look back further to understand our ability to adapt.”
