Richard Potts surveys assortment of Early Stone Age handaxes discovered in the Olorgesailie Basin, Kenya. Photo: Human Origins Program, Smithsonian
Unpredictable climate and natural disasters like earthquakes may have spurred early humans to create innovative tools and ways to communicate earlier than previously thought, according to 3 studies published Thursday in Science.
What they found: Evidence that around 320,000 years ago — near the start of the Middle Stone Age (MSA) and tens of thousands of years earlier than previous evidence has shown — early humans in East Africa may have created projectile hunting tools, developed ways to communicate using colors for mapping or identification purposes, and traveled longer distances to trade, hunt or obtain valuable materials.
"It's not just humans changing but really the entire ecosystem. It's a picture that's bigger than just the human ancestors themselves."— Smithsonian's Richard Potts, who spearheaded the studies
The big picture: Potts and his colleagues published three studies — on environmental dynamics, transition chronology, and stone transport and pigment use. Potts says the studies represent what likely happened in and near Kenya's Olorgesailie basin, where he's studied for 34 years.
Yonatan Sahle from Tubingen University told The Atlantic that different parts of Africa may have had varied timing when MSA first appeared, how much it overlapped with the older Acheulean tech, and whether it occurred together with Homo Sapiens fossils.
Why it matters:
"This is surely a landmark study. The work at Olorgesailie is most welcome as plaeoanthropologists have very little information about the habitats and behaviors at 320,000 years ago, a critical time period in human evolution... the rigorous work at Olorgesailie fills a a gap in our knowledge about environments and human behaviors at this critical time. It is very rare to have well-dated stone tools in association with animal remains and environmental information."— Michael Petraglia, from the Max Planck Institute for the Science of Human History, Germany, who was not part of the studies
Environmental triggers: The scientists believe dramatic changes in the environment like periods of intense rain or drought, earthquakes, and altered animal communities pushed early humans to travel greater distances for food, find new super-sharp obsidian rocks to use for tools and pigments to use for communication, and locate other communities of early humans with whom to trade.
"[T]he behavioral hallmarks of the MSA they observe — refined tool manufacture, wider mobility and foraging, pigment use, implied social networks — occurred during a time of enhanced environmental variability. As with modern hunter gatherer populations, these are anticipated behavioral and cultural responses to greater environmental variability and food insecurity."— Columbia University's Peter de Menocal, who was not part of the study
Innovative tools and weapons: Prior to this time period, early humans had been using rudimentary hand axes and cleavers to hunt animals and as weapons.
- The teams discovered large amounts of non-native obsidian rock in the basin. The obsidian, which is extremely sharp when fractured, was traced back to their origin at locations up to 55 miles away through very rugged terrain.
- Prior to this, 99% of their rocks were obtained within 5 km — this is a "radical change," Potts says.
- What it means: "The transfer of obsidian from long distances is essentially the first evidence of trade," Potts says.
- The smaller shapes and modification at the base suggests the pointed tips were hafted to wood or bone — essentially the original projective weapon.
"What can you say — the world hasn't been the same since [the discovery of projective weapons]," Potts says.
Pigments: The teams found red, green and black pigments used in various locations. "Pigments are evidence of symbolic communication," Potts says. It can be used to stain the hair or skin to show if you are "friend or foe." It could also be used to mark the best way to get somewhere on a map — or warn people off a particular territory.
"The possible production of red pigments is especially exciting, as this may imply that the humans at Olorgesailie were cognitively advanced. This is some of the best, and earliest evidence for pigment use in the archaeological record, reaffirming that at the outset, Homo sapiens was a symbolic species," Petraglia says.
What's next: Research is lacking for a chronological gap — the time period between 500,000 years ago and 320,000 years ago. Potts says his team is currently working to discover more about that period.