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The Cradle of Life

In some parts of the United States there are cities that are proud to boast that their history dates back to the first settlers who came across the ocean with Christopher Columbus centuries ago. Cities in other areas of the world can boast of histories that reach back for thousands of years. While both of those numbers are quite impressive, the city of Johannesburg, South Africa has roots that run even deeper into history. The earliest settlers to the Johannesburg area took up residence some three million years ago. Just about 40 km (25 miles) west of Johannesburg, amid some scattered trees and rocky outcroppings, lies a 47,000 hectare (180 sq. miles) valley that is known as the Cradle of Humankind; also called the Cradle of Life. The area is home to a series of limestone caves and that relatively small plot of land changed the way in which scientists viewed the evolution of mankind.

Charles Darwin first speculated that Africa was most probably where man began to evolve because our two closest relatives (gorillas and chimpanzees) lived there. He also mentioned however, that a large species of European ape that existed millions of years ago, meaning that our ancestors would have had plenty of time to migrate to the Dark Continent. His conclusion was that it would be “useless to speculate on the subject.”

By the early part of the 20th century however, scientists believed that they knew the truth; the evolution of humans took place in Asia or Europe. By that time, there had been Neanderthals discovered in Europe, Homo Erectus (Java Man) had been found in Indonesia, and Piltdown Man had been uncovered in England. That Piltdown Man was in fact a hoax wasn’t discovered until later. While the beings that had been discovered were very primitive, the resemblance to modern man was clear. The discovery of a fossil in South Africa in 1924 however, challenged the theory that man evolved in Eurasia and forever changed the way in which human evolution was studied.

Raymond Dart was an anatomist from Australia who was employed by Johannesburg’s University of Witwatersrand. He had a keen interest in fossils and in 1924 two boxes of rocks were delivered to his home. They had been blasted out of a limestone quarry in the vicinity of a town called Taung. Much to his wife’s dismay (he was dressed to attend a wedding), Dart began examining the contents of the boxes immediately. What he found inside surpassed his wildest dreams; a perfectly fossilized mold in the shape of a brain. That fact alone might not have been noteworthy, but the folds on the surface of this brain implicated that it had belonged to some form of human; perhaps one of our ancient ancestors.

Dart was beside himself and went to the site for himself. Digging further, Dart discovered another rock into which the brain fit perfectly. After months spent carefully chipping away at the rock, Dart finally freed the corresponding face, as well as the lower jaw. The discovery happened on December 23rd and in a book written later he commented that “I doubt if there was any parent prouder of his offspring on that Christmas of 1924.”

Every paleoanthropologist dreams of such a discovery and from the teeth, it was deduced that the skull was that of a child (thought now to be 3 or 4 years old). There were other features that confirmed Dart’s suspicions that this was indeed a human ancestor. Though in many ways the skull looked apish, it lacked the pronounced muzzle seen in gorillas and chimps. There was also the matter of the placement of the foramen magnum (the hole where the spinal cord leaves the skull). In animals that move about on four legs, such as gorillas or chimps, the hole is located toward the rear of the skull. The formen magnum in this particular skull suggested that this being traveled on two legs in an upright posture.

Dart’s findings were reported in 1925. He stated in the journal Nature that he had discovered a race of extinct apes that were intermediate between known living anthropoids and modern man. He named his race of beings Australopithecus africanus and it wasn’t well-received by may field experts. One of the fault that many experts found was that no one knew what an adult specimen of Australopithecus africanus would look like. They also argued that this fossil too closely resembled an ape to fit in with their views of human evolution and dismissed his findings as just another species of ape.

One scientist however, stood behind Dart’s findings. Robert Broom, a paleontologist, decided to investigate the caves and found numerous fossilized adult specimens of Dart’s “ape men” during the 30’s and 40’s. These specimens looked very similar to the “Taung Child”, as Dart’s discovery came to be called. In addition to this, the late 40’s and early 50’s saw the Piltdown Man uncovered as a hoax. This event prompted even the most hardened critics to accept the fact that australopithecines definitely belonged to the human family. This, in turn, forced them to accept the fact that Africa, not Europe or Asia, was indeed the birthplace of humanity, or as it is sometimes called, the Cradle of Life.

Not all of Dart’s theories have survived under scrutiny however. Later discoveries of australopithecines in South Africa by Dart brought to his attention that they were generally found along with animal parts; specifically, horns, jaws, and teeth, of hoofed animals. He thought this indicated a horn, bone, and tooth culture, in which these broken pieces were used for tools, hunting, and warfare. It was later realized that these bones had been accumulated by predatory hunters such as the big cats. Holes in the skull of the Taung Child actually revealed that it had been preyed upon by an eagle which had dropped a portion of its meal in the cave entrance where it was found.

Dart’s story reminds us that human evolution is a story that is still unfolding and you never know what’s around the next turn. Today the Cradle of Humankind (or Cradle of Life) is a World Heritage Site and discoveries are still being made there. A joint venture of the National Geographic Society and the University of Witwatersrand in 2013 led to the discovery of 1,200 specimens of a still unidentified hominin species. With many caves still unexplored, new and unexpected plot twists in the story of human evolution are sure to emerge.

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