Human behavioural origins
Our ancestors engaged in symbolic behaviour much before than thought.
Washington: The discovery of ochre in a cave at the tip of Pinnacle Point in South Africa has offered key evidence that our ancestors engaged in symbolic behaviour much before anthropologists previously believed.
In the summer of 2009, Logan Bartram and fellow University of Vermont student Kristina Bauman joined a team of archaeologists at a pivotal dig site on the coast of South Africa.
It`s the shells, ochre and tools at this site that many anthropologists today cite as the first signs of higher human cognitive power.
The work of principal investigator Curtis Marean, a professor at Arizona State University`s Institute of Human Origins, suggests that caves along the coast of South Africa were probably occupied by the small population of Homo sapiens we are directly descended from today.
Marean`s research demonstrates that the migration of hominids to the coast of Africa may have helped develop - or at least coincided with - a boost in brain function.
The ochre at the cave sites along the Indian Ocean is a sign of symbolic behaviour, whether it was used for self adornment or markings on stone.
Small blades that would have been affixed to stone or wood, instead of just held in hand, are evidence of complex tools.
And an appetite for seafood, as evidenced by burned shells in ash pits, means that these early humans were able to use tides and lunar schedules to successfully harvest shellfish as a dietary staple.
The work at these sites, which was recently featured in the three-part Nova special "Becoming Human" (in which Bartram and Bauman have cameo appearances), has extended the origin of modern cognitive abilities further back in time, to roughly 170,000 years ago.
But why did early humans move to the coasts?
Climate change and drought throughout Africa meant fewer resources on land just shy of 200,000 years ago.
The nutrition offered up by the sea was life sustaining - a point driven home for Bartram when the site director foraged for mussels at lunchtime on a rock formation just below the caves.
For a pre-med student like Bartram, the idea that higher cognitive function may have been aided by the brain-building omega-3 fatty acids that seafood provides is an intriguing one.
The southern coast of Africa is also known for amazing biodiversity and an abundance of tuberous plants, which are high in carbohydrates.
Bartram said: "You couple that with shellfish, and you``ve got a really nice nutritional package going on.
"Is it the reason we evolved, just because we had access to this nutrient? Probably not. But the ability to have that available to you and raise kids who are getting complete brain food -- there``s no way that could have hurt."
Back at UVM, Bartram is wrapping up his thesis - "Evidence for Modern Human Behavioral Origins on the Southern African Coast."
While based on his time in Africa, where he unearthed his own share of stone tools and looked out at the sea from the same cave shelters our ancestors once shared, he believes his thesis work is really about reviewing the published research.
He said: "It``s certainly a library project...There``s been so much literature published on these issues, and from this site.
"If nothing else, my thesis is helping me reaffirm the experience I had, not just for others, but for myself."