Australopithecus africanus Dart 1925

Where Lived: Southern Africa (South Africa) When Lived: About 3.3 to 2.1 million years ago Au. africanus was anatomically similar to Au. afarensis, with a combination of human-like and ape-like features. Compared to Au. afarensis, Au. africanus had a rounder cranium housing a larger brain and smaller teeth, but it also had some ape-like features including relatively long arms and a strongly sloping face that juts out from underneath the braincase with a pronounced jaw. Like Au. afarensis, the pelvis, femur (upper leg), and foot bones of Au. africanus indicate that it walked bipedally, but its shoulder and hand bones indicate they were also adapted for climbing.

Height: Males: average 4 ft 6 in (138 cm); Females: average 3 ft 9 in (115 cm) Weight: Males: average 90 lbs (41 kg); Females: average 66 lb (30 kg)

Many scientists consider either this species or Au. afarensis of East Africa to represent a viable candidate for the ancestor of the genus Homo.

Year of Discovery: 1924 The Taung child, found in 1924, was the first to establish that early fossil humans occurred in Africa. After Prof. Raymond Dart described it and named the species Australopithecus africanus (meaning southern ape of Africa), it took more than 20 years for the scientific community to widely accept Australopithecus as a member of the human family tree.

The hunter or the hunted? No stone tools have been discovered in the same sediments as A. africanus fossils; however, for a long time researchers believed A. africanus was a hunter. Raymond Dart created the term ‘osteodontokeratic’ culture (osteo = bone, donto = tooth, keratic = horn) in the 1940s and 1950s because remains of this species were found alongside broken animal bones. Dart assumed these broken animal bones, teeth and horns were used by Au. africanus as weapons; however, in the 1970s and 1980s, other scientists began to recognize that predators such as lions, leopards, and hyenas were instead responsible for leaving these broken animal bones. These predators even ate Au. africanus individuals, too. Despite the carnivorous preferences of their contemporaneous predators, Au. africanus individuals had a diet similar to modern chimpanzees, which consisted of fruit, plants, nuts, seeds, roots, insects, and eggs. How do we know what they ate? Scientists can tell what Au. africanus may have eaten from looking at the remains of their teeth---tooth-size, shape, and tooth-wear can all provide diet clues. Dental microwear studies found more scratches than pits on Au. africanus teeth compared to a contemporaneous species, P. robustus. This pattern indicates that Au. africanus ate tough foods but also had a very variable diet including softer fruits and plants.

STS 14 Site: Sterkfontein, Republic of South Africa Date of discovery: 1947 Discovered by: Robert Broom and John T. Robinson Age: About 2.5 million years old Species: Australopithecus africanus Curved spine This partial skeleton consists of several thoracic and lumbar vertebrae, a pelvis, a sacrum, and pieces of a rib and a femur. The vertebrate show this species walked upright in a way very similar to modern humans. The uniquely human curve of your lower back absorbs shock when you walk. This early human's spine had the same curve. STS 5 Nickname: Mrs. Ples Site: Sterkfontein, Republic of South Africa Date of discovery: 1947 Discovered by: Robert Broom and John T. Robinson Age: Between 2.5 and 2.1 million years old Species: Australopithecus africanus Not predator, but prey STS 5, a nearly complete adult Australopithecus africanus, was an important fossil find because skeptics had previously argued that the Taung Child was actually a baby chimpanzee that would have gained its ape-like features when it got older. This fossil showed that maturity wouldn’t make A. africanus less human. The main difference between STS 5 and the Taung Child is that this fossil's face is strongly prognathic, an ape-like feature that becomes more pronounced as A. africanus individuals grow up. STS 5 was nicknamed 'Mrs. Ples' by scientist Robert Broom after initially hypothesizing that she was a middle-aged female Plesianthropus transvaalensis, which was the original name of this species---thus, ’Mrs. Ples.’ This skull now thought to have belonged to a male. Often found alongside animal bones, Australopithecus africanus was once considered a “killer ape.” Now we know that members of this early human species were sometimes eaten by predators. Living together in groups helped these early humans protect themselves. Why dynamite is not necessarily the best way to excavate human remains.... do you see the wedge-shaped portion of the forehead reconstructed here in a light color? If you follow that crack around to the rear of the skull, you’ll see why scientists are much more careful today when excavating, or digging for human remains. Mrs. Ples’ skull was actually blown into two pieces during its extraction from the breccia (a cement-like rock) because Broom used dynamite to expose the remains over backbreaking work with a pickaxe. 3-D collection link: http://humanorigins.si.edu/evidence/3d-collection/f-sts-5 Taung Child Site: Taung, Republic of South Africa Date of discovery: 1924 Discovered by: Raymond Dart (via local quarrymen) Age: About 2.8 million years old Species: Australopithecus africanus African Origins When this 3-year-old child's skull was found in 1924, it was among the first early human fossils to be found in Africa -- and the first early human fossil discovery to draw major attention to this region as a place of origin of the human family tree. Still, it took over 20 years after that before scientists accepted the importance of Africa as a major source of human evolution. The Taung Child’s fossilized anatomy represented the first time researchers saw evidence of early human upright, two-legged (bipedal) walking. The evidence was the position of the Taung Child’s foramen magnum, or the hole through which the spinal cord connects with the brain. This spinal cord hole is positioned toward the front of the Taung Child’s skull, a characteristic associated with bipedal locomotion. This bipedal adaptation allows the head to balance atop of the neck; while contrastingly, a four-legged ape has its foramen magnum positioned toward the rear of the head to keep its eyes facing forward (and not down) when it moves. How do we know how old the Taung Child was at death? The Taung Child’s first molars had only just begun to erupt through the gum and become visible as teeth, indicating that the fossilized jaw belongs to a child. Closer analysis of dental development, crown formation, and root length has estimated the child’s age at death at 3.3 years. How do we know how the Taung Child died? The Taung Child is thought have been attacked and killed by an eagle. Scientists suspect an eagle killed the Taung Child because puncture marks were found at the bottom of the 3-year-old’s eye sockets (see close-up photo below). These marks resemble those made by a modern eagle’s sharp talons and beak when they attack monkeys in Africa today. Other evidence for the eagle kill hypothesis includes the presence of eggshells at the site and an unusual mixture of animals bones found alongside the Taung Child’s skull. Most of the bones found are from small animals (including hyrax, rodents, tortoises, lizards, crabs, small antelopes, and small baboons), which is uncommon compared with animal bones at other early human sites. Many of these small animal bones also have damage resembling that made by modern birds of prey. 3-D collection link: http://humanorigins.si.edu/evidence/3d-collection/f-taung-child-cranium http://humanorigins.si.edu/evidence/3d-collection/f-taung-child-mandible

We don’t know everything about our early ancestors—but we keep learning more! Paleoanthropologists are constantly in the field, excavating new areas, using groundbreaking technology, and continually filling in some of the gaps about our understanding of human evolution. Below are some of the still unanswered questions about Au. afarensis that may be answered with future discoveries: 1. Au. africanus is currently the oldest known early human from southern Africa. Where did it come from? Was it a descendent of Au. afarensis from Eastern Africa? 2. Is Au. africanus part of the lineage that led to our own species, Homo sapiens? 3. In 1994, scientist Ron Clarke found four left early human foot bones while searching through boxes of fossils at Sterkfontein, a site in South Africa where most Au. africanus fossils come from. He dubbed this fossil "Little Foot", and has since found that it comes from a 3.3 million year old partial skeleton, most of which is still embedded in the cave sediments. When this fossil is completely excavated, it shed light on several questions about this species (if it is designated as an Au. africanus individual): How big was it? What did its post-cranial skeleton look like? How does it compare to STS 14, another partial skeleton of Au. africanus?