Early humans in East Africa developed complex cultural and technological behaviors tens of thousands of years earlier than previously thought, a new research has suggested.
Anthropologists at the Smithsonian's National Museum of Natural History say humans began trading with distant groups, used color pigments and manufactured sophisticated tools around 320,000 years ago, some 100,000 years earlier than previous evidence has shown in eastern Africa.
The new evidence comes from Olorgesailie Basin in southern Kenya – a 64sq km area where early humans are known to have lived for at least 1.2 million years.
There is also evidence to suggest that climate change and other abnormal environmental events, such as earthquakes, in the area triggered technological and socio-economic innovation among our ancestors who lived there.
"This change to a very sophisticated set of behaviors that involved greater mental abilities and more complex social lives may have been the leading edge that distinguished our lineage from other early humans," said Rick Potts, head of the Smithsonian's Human Origins program.
The research is detailed in three papers in Science.
In order to produce a comprehensive picture of the evolution of early humans in East Africa, scientists analyzed sediments in the Olorgesailie area to map its climate history.
They found that the region alternated between dry and wet conditions and recorded evidence of earthquakes and volcanic activity around half a million years ago.
Scientists found signs of a dramatic change in human behavior following this period of environmental instability, with tool-making transitioning from crude stone hand axes to sharper and more precise tools made from volcanic glass called obsidian.
Evidence suggests that the humans who lived during this time traded with groups as far as 25km to 90km away to obtain the obsidian needed to make their tools.
This has led the research team to conclude that environmental pressures forced early humans to alter technology and social structures to improve activities such as food gathering.
"You have this package of behaviours – not just new ways of making stone tools, but evidence of social networks and the potential for symbolic use of colour – that are emerging right at the cusp... of us becoming Homo sapiens," Potts added.