A sudden increase in stone tool complexity in the fossil record suggests a sudden increase in human knowledge around 600,000 years ago, and helps explain how modern humans and our ancestors became particularly capable of adapting to new environments.
This potentially dates “to the divergence of Neanderthals and modern humans and could represent a derived feature shared by both lineages,” explain anthropologists Jonathan Page of the University of Missouri and Charles Perrow of Arizona State University, who report the discovery in a new paper.
The researchers analyzed stone tool-making techniques spanning 3.3 million years of human evolution, ranking 62 stone tool-making procedures in order of complexity for tools found at 57 sites.
The oldest artefacts were from Africa, but ancient tools from Eurasia, Greenland, Sahul, Oceania and the Americas were also included in the analysis.
Page and Perrault found that up until 1.8 million years ago, stone tool production sequences ranged in length from two to four procedural units. Over the next 1.2 million years, stone tools increased in complexity, reaching up to seven procedural units.
But it wasn’t until about 600,000 years ago that our ancestors took this to a whole new level.
At this point, tool complexity may have required up to 18 step units. Such major technological advances, Page and Perrault suggest, depended on knowledge passed down from previous generations – a cumulative culture. In subsequent generations, the complexity of stone points continued to increase rapidly.
“Cumulative culture is the accumulation of modifications, innovations, and improvements over generations through social learning,” Page and Perrow define in their paper.
“Generations of refinement, correction, and lucky errors can produce techniques and know-how far beyond what any single simple human could invent on his own in his lifetime. When a child inherits the culture of her parents’ generations, she inherits the results of thousands of years of lucky errors and experimentation.”
Accumulated culture benefits people in many ways, increasing the likelihood of solving problems through generations of trial and error, much like evolution by random mutation and natural selection. It also allows individuals to use and advance technology without fully understanding every aspect of its development, paving the way for the knowledge pool to constantly increase and adapt.
As this collective knowledge and associated behaviors grew, genes that influence learning may have also been selected for.
“The products of this coevolutionary process of genes and culture could include increases in relative brain size, long life histories, and other important traits that underlie human uniqueness,” Page and Perreault explain.
While the team’s find provides solid evidence of a culture built up during the early Middle Pleistocene, Page and Perreault note that this kind of cultural intelligence may have emerged much earlier in human evolutionary history, and in a form that is not so easily preserved.
“Early humans may have relied on accumulated culture to develop complex social, foraging and technological behaviors that are not visible archaeologically,” the researchers wrote.
Regardless of the precise technology or timing, reliance on accumulated culture may have provided a powerful selective force that shaped many of our unique human characteristics.
This research was published in PNAS.
