South Africa West Coast

Discovery

The discovery of the Langebaan footprints was the final event in a serendipitous web of circumstance reaching 120 000 years into the past. Not the least fortuitous aspect is their exquisitely tranquil setting in the West Coast National Park. Situated on the Atlantic coast some 100 kilometres north of Cape Town, the turquoise Langebaan Lagoon, laced by azure tidal channels and flanked by lowering granite domes, is the showpiece of the Park.

In the early autumn of 1995, I was picnicking with a group of friends on the beach at Kraal Bay, on the western shores of the lagoon, enjoying the sweeping views. The sandstone cliffs flanking the bay represent ancient coastal dunes formed by sand blown from the beach. The northward sloping cross- beds, recording ancient dune surfaces, are superbly exposed (see figure).

I knew that the fossil prints of a large carnivore had been found in the cliffs at Kraal Bay in 1976. I scrambled around on the cliffs, searching for more fossilised animal footprints. My efforts were rewarded when three paw prints of a large carnivore showed clearly on a rock slab. Claw marks were faintly discernable, showing that the animal was probably a jackal, rather than a member of the cat family (cats walk with their claws retracted).

The animal had been walking down a sloping dune surface, previously drenched by rainfall - footfalls in dry, loose sand leave only blurred traces. There were prominent ridges of sand, pushed up by the paws on the down-slope side of the prints when the sand was soft.

I returned to the Park a few months later, in my capacity as a scientist with the Council for Geoscience, to begin a research project on the geological history of the western coastal platform. The spring low tide at Kraal Bay reveals sweeping expanses of ponded tidal flats, where strutting sacred ibises spear unwary crustaceans with sabre-like bills. I was studying ancient (Pleistocene) lagoonal sediments (the Velddrif Formation) patchily exposed in the floor of the present-day lagoon. I noticed a piece of quartz that had clearly been been shaped into a point by a Stone Age craftsman, protruding from the sandstone.

Holding the artefact up, my gaze fell on the low cliffs a few hundred metres away, where the wild dog had left its marks in the rock. Humans! Footprints! - at this instant I made the vital connection. I splashed across the tidal flats to the cliffs, and started a concerted, systematic search of every exposed rock surface that might conceivably bear human footprints- even the undersides of sandstone beds.

Photo right: The footprint showing the broad sole and narrower heel. There is a push-up mound on the left side of the print caused by the sloping surface of the sand dune on which 'Eve' was walking as she approached the Lagoon
I focussed on a mental image of how human prints should appear on the sandstone surfaces. The lesson learned from the animal tracks - don't look for depressions on the rock surfaces. These are common and can be formed by a variety of causes other than footfalls - but search for raised ridges of sandstone, pushed up by a foot when the sand was soft. After hours of fruitless searching, I came to a well-known locality, marked by a lone pinnacle known as the "Pulpit Rock".

I hauled myself wearily up onto a nearby large block of sandstone that had broken away from the cliff. Wiping perspiration from my eyes with my shirt-sleeve, I crouched down for a closer look at the surface. Two oval depressions in the sandstone a short stride apart with tell-tale ridges alongside each. Could it be? I knew that the quest had been virtually hopeless. Only a few sets of fossilized hominid (human-like) footprints had ever been found in the entire world.

I fell on my knees and brushed the loose sand out of the hollows. The heart-stopping instant of discovery - two beautifully preserved fossil human footprints. They could have been minutes old rather than thousands of years. Gingerly I placed my feet alongside the impressions and felt an electric link with the past! People are often curious about my feelings at the moment of discovery. Ironically, my gut reaction was not elation, but incredulity. The million -to -one throw of the dice had come good! Had I stumbled on them accidently, the event would have been more believable.

The footprints were beautifully preserved, considering the unpromising medium in which they were made - a fairly coarse sand. There were two complete footsteps and the remnants of a third, eroded since they were exposed a few years before. They formed a right-left-right track descending diagonally down the dune face towards the ancient lagoon, which was only metres away when they were made. The stride length of 0.51 metres and the length of the feet themselves (0.22 metres - size 5 by today’s standards), suggests that the dune -walker was a smallish female, about 1.6 metres tall. The feet had well developed arches, and the big toe was the longest of the toes - all features of modern humans.

The long axes of the right and left complete prints form large angles to the direction of motion (see photo). This was caused by the waddling gait that the dune-walker had adopted to negotiate a sloping and unstable sandy dune. The steepness of the slope was reduced by walking diagonally rather than directly down the dune. Prominent ridges of sand, superbly preserved (see photo), had been squeezed up on the down-slope side of each print, formed at the instant of weight transfer during the stride.

Dating

The contact of the Velddrif and Langebaan Formations at Kraal Bay is 1.4 metres amsl. This suggested that the prints dated to the Last Interglacial Period, which lasted from about 135-115 thousand years ago. An initial luminescence date of 85 000years BP funded by the Council for Geoscience seemed too young to me. Lee Berger, an anthropologist at Wits became involved in the project and obtained further funding from National Geographic. With the assistance of Stephan Woodbourne of CSIR I was able to date the entire Cenozoic sequence at the site. From sea level curves, in tandem with the laboratory dates I refined the age of the footprints to 117 000 years BP.

This age was highly significant, relating to the critical period in human evolution when anatomically modern man was emerging from archaic types. The earliest fully modern human skeletal remains were found at Klasies River Mouth on the east coast near Mossel Bay, which date from 110 000years BP. The footprint-maker would therefore likely have represented a group of the earliest anatomically modern humans. According to the ‘Out of Africa ’ theory of modern human origins, anatomically modern man evolved in Africa, subsequently dispersing to Eurasia and displacing the more primitive inhabitants such as the Neanderthals in the process. Thus the footprint-maker may have been have been ancestral to modern human populations. This is why we nicknamed her “Eve” (there is a lesser chance that the prints could be those of a male adolescent).

Dave Roberts
Council for Geoscience