Evolving

Peter Wood

A team of nine European, South African, and Australian scientists have succeeded in dating two crucial episodes in the emergence of human culture. Their work is reported in the current issue of Science (subscription required for full article).

Professor Zenobia Jacobs of the GeoQuEST Reasearch Centre, School of Earth and Environmental Sciences, at the University of Wollogong in New South Wales and her collaborators did a seemingly simple thing. They dated nine of the 26 known sites in South Africa associated with two stone tool technologies, known by their type sites as Still Bay and Howieson Poort. It’s been known for a while that the Still Bay and Howieson Poort sites are important because they contain some of the earliest evidence of symbolic behavior. These engraved ostrich shells and manufactured shell beads, as well as inventing innovative stone tools and making what archaeologists call “composite weapons.” 

But because different archaeologists worked on different sites and dated their findings using different techniques and different labs, there has been considerable uncertainty as to exactly when the Still Bay and Howieson Poort peoples lived and what their relationship was. Jacobs and her colleagues gathered material from all the sites and used a single technique in a single lab. The result is a startlingly clear and consistent picture of two sudden bursts of creativity, at about 72,000 years ago and 65,000 years ago. The Still Bay culture seems to have lasted less than a thousand years and was followed by gap of over 6,000 years before the Howieson Poort culture took off.   Howieson Poort seems to have lasted about 5,000 years—not a bad run, if you consider Egyptian civilization lasted about 3,000 years.  

Jacobs and her colleagues don’t speak of a “dark age” and a “renaissance,” but the terms might be appropriate. These may well be the first flickering flames of human culture. What makes Jacobs’ dates particularly exciting is that they correspond extremely well with another event in pre-history that has emerged from the study of genetics. We know that about 70,000 years ago, our species nearly died out. We went through a “genetic bottleneck” that reduced humanity to 15,000 or fewer. The most plausible explanation on offer (introduced by Stanley Ambrose in 1998) is that the eruption of a supervolcano at Lake Toba on Sumatra triggered a massive global cooling and ice age. 

The importance of genetic bottlenecks in evolution is that they cordon off the surviving population, eliminating a great deal of variation and setting in place a “founder’s effect.” One aspect of that founder’s effect in humans is the estimated date of the common male ancestor of all living humans, attested by our Y-chromosome. This fellow lived about 60,000 years ago, and now there appears a good chance that he wore Howieson Poort beads and hunted with Howieson Poort hafted bone points. 

The researchers on South African sites draw the inference that “these bursts of innovative behavior cannot be explained by environmental factors alone.” Then what? They stop short of saying there was a genetic substrate to these developments, but they note their dates do indeed coincide with the genetic bottleneck and bring the story right up to the point when modern humans migrated out of Africa to colonize Europe and Asia. 

These discoveries and conjectures are intrinsically interesting, as they provide detail that only a few decades ago seemed beyond any imaginable reach of research. We know more and more about the deep past of our kind, and the more we find out, the more certain we are that human commonality is the more profound existential truth. Every variation we know in human appearance and human culture has arisen in the blink of time since those South African survivors of a Sumatra volcano started scratching designs on ostrich eggs. The endless injunction in schools and colleges to “celebrate diversity” is a call to ignore our profound commonality in favor of superficial difference. The newer injunction to “celebrate sustainability” likewise misses our most important legacy, which consists of invention and creativity, especially when faced with difficulty.             

The team of geologists, archaeologists, and geographers who gave us this new and more precise dating of Still Bay and Howieson Poort also exemplify a welcome trend in scholarship: the attempt to systematically reanalyze the mountains of data that have accumulated in many fields in search of patterns that were invisible to the original researchers. “Meta” studies have become a major pursuit in medicine and pharmacology and are beginning to spread into other disciplines. Archaeology is particularly ripe for this kind of work. All over the world, museums house artifacts excavated according to old protocols (and sometimes no protocols), dated, sorted, and arranged by hundreds of idiosyncratic methods. The Still Bay and Howieson Poort researchers show one way to illuminate these remnants.

NAS articles, of course, always have an ulterior purpose. On election eve, I commended the reading of world history. Election day requires still stronger medicine. It seems an appropriate time to consider how much was actually accomplished during the previous Stone Age.

  • Share

Most Commented

September 16, 2019

Slavery Did Not Make America Rich

'King Cotton' isn't King

September 18, 2019

Most Read

January 03, 2011

May 26, 2010