March 15 (UPI) -- Move over Silicon Valley, newly unearthed artifacts suggest early humans were innovating some 320,000 years ago.
For a million years, bulky stone axes, often called Acheulean hand axes, were the tool of choice for primitive hominins in Africa's Rift Valley. Now, researchers have found evidence that early humans adopted a new technology during the Middle Stone Age, opting for smaller, smoother and sharper blades and points.
The stone weaponry, forged by toolmakers in Kenya's Olorgesailie Basin, was made with white and green chert, stones that would have had to be acquired via trade, long-distance travel or both. Researchers also found evidence that hominins during the Middle Stone Age carved off hunks of red and black rocks, possibly to color their body and tools with -- early evidence of symbolic behavior.
"We don't know what the coloring was used on, but coloring is often taken by archeologists as the root of complex symbolic communication," Rick Potts, director of the National Museum of Natural History's Human Origins Program, said in a news release. "Just as color is used today in clothing or flags to express identity, these pigments may have helped people communicate membership in alliances and maintain ties with distant groups."
The latest discoveries were made as part of a survey of artifacts and sediments collected from Olorgesailie archaeological sites. The artifacts and sediments revealed 1.2 million years of human evolution in the Eastern Rift Valley.
The new research -- detailed in three studies published Thursday in the journal Science -- showed early humans adapted their behavior, or innovated, during a period of significant environmental change.
"These behavioral innovations may very well represent a response to rapid changes in the environment," Tyler Faith, curator of archaeology at the Natural History Museum of Utah, said in a news release. "Such a response would have helped human populations endure climatic and environmental shifts that likely contributed to the demise of many other species in the region."
Environmental change was evidenced by significant turnover in the types of animal fossils recovered from the Olorgesailie deposits. In addition to the disappearance of species, scientists also found evidence of dramatic range shifts, with species typically found elsewhere moving into the Rift Valley.
Taken together, the studies, which combined analysis of ancient artifacts with environmental data, show environmental changes have been an important part of human evolution since the beginning.