The first fossil hominins were discovered at the beginning of the 20th century in South Africa, just over half a century after the publication of Darwin’s milestone work The Origin of Species (published in 1859) set the foundation for evolutionary theory based on natural selection. Since that time, the human ancestral lineage has constantly been broadened by new fossil discoveries that are progressively adding to the (still very fragmentary) picture of the long and complex family tree from which we have emerged to become the last remaining representative of the hominin line on the planet.
Among this ever-widening range of primate ancestors, the Paranthropus genus is of particular interest. Presently documented from the African continent, at least three distinct species of Paranthropus are known to have existed for a combined period of some 1.5 million years. To put this into perspective, consider that our own species (Homo sapiens) emerged—also in Africa—only some 300,000 years ago.
The Paranthropus were robust bipedal hominins with distinct cranial features that are believed to have supported a vegetarian diet. Their wide and flat skulls display pronounced crests and arches to buttress the heavy facial musculature required for chewing abrasive foods like plants, hard nuts, tubers, and seeds, which likely formed an important part of their dietary staple. Their powerful and protruding jaws were equipped with massive teeth in thick enamel that would have been effective for masticating fibrous plant matter and tubers. A distinctive salient sagittal crest traversing the midline area along the top of the skull maintained the heavy musculature attached to flaring cheekbones.
While the three best-known species of Paranthropus share these cranial features, studies of dental microwear patterns observed on their teeth suggest that there may have been interspecific dietary differences and that their diet may have been more diverse and eco-dependent than previously thought.
The first South African Paranthropus specimen was identified in 1938 by Robert Broom, who provided the genus designation “Paranthropus” to signify “beside Man” and the species’ name “robustus,” in reference to their outstandingly robust features. This species is documented in South African sites from around 1.8 to 1.2 million years ago.
The second species is the East African Paranthropus called P. boisei, which is known from sites in Ethiopia, Kenya, Tanzania, and Malawi, dating between 2.3 and 1.2 million years ago. The holotype specimen is a skull unearthed by Mary Leakey at Olduvai Gorge, Tanzania, in 1959. It was initially named Zinjanthropus boisei, with the genus name meaning “East African Human,” and the species’ name was coined in honor of Charles Boise, who funded the Leakey family’s excavations. This discovery was, at the time, the most primitive hominin ancestor ever to be discovered in East Africa.
Then there is “The Black Skull,” a magnificent specimen some 2.5 million years old, found by Alan Walker and Richard Leakey in 1985 at West Turkana in Kenya, near the border with Ethiopia. As a student just starting out in archeology, I remember being completely mesmerized by this well-preserved specimen, whose striking dark color was the result of the magnesium absorbed from the soil it was buried in during the fossilization process.
This skull is attributed to the third Paranthropus species, called P. aethiopicus, first described in the late 1960s by French paleoanthropologists (Camille Arambourg and Yves Coppens) after they observed fragmentary remains they found in the Lake Turkana-Omo River region. While the phylogenetic relationship between these three species remains to be clearly elucidated, some believe that this species might have been ancestral to the South and East African Paranthropus.
Female Paranthropus were smaller than males (sexual dimorphism), weighing in at around 35 and 50 kilograms, respectively, for a height of less than a meter and a half. Despite their voluminous skulls, the Paranthropus had relatively small brains, close to the size of a chimpanzee’s and less than a third of the size of that of a modern human’s.
The great longevity of the Paranthropus group not only means that they were a successful genus but that they also coexisted with various other hominin forms that were thriving in South Africa and East Africa between 2.7 and 1.2 million years ago. In fact, they might have rubbed shoulders with at least two species of gracile Australopithecines and, even more surprisingly, multiple representatives of our own genus, including H. erectus, H. ergaster, H. rudolfensis, and H. habilis. Their prolonged existence means that they even coincided with the first “out of Africa” hominins, known presently as H. georgicus and perhaps a second, yet unnamed species.
Not only that, these small-brained robust Paranthropus likely made stone tools: a practice that has long been considered the defining attribute of our own genus. This somewhat arrogant bias is underscored by the naming of the first member of the genus Homo, H. habilis, meaning “handyman.” While the possibility that Paranthropuses were toolmakers was raised as early as the 1970s, after specimens were found in proximity to primitive stone tools at Olduvai Gorge, and was also advanced by scientists working in South Africa, the prospect has not gained popularity, nor has it been widely disseminated in scholarly venues.
However, combined with the fact that succeeding discoveries now demonstrate that Oldowan technologies actually predate the emergence of Homo, more and more evidence of Paranthropus fossils in probable—or indisputable—geostratigraphic relationship with stone and even bone tools is now apparent.
As new technologies transforming archeology continue to accelerate discoveries in the field of human evolution, it is becoming clear that humanity’s course through time has been one of complex interrelated species with varying degrees of competence in inventing technological solutions to address survival-related challenges. Over time, this uniquely human adaptive strategy would revolutionize the hominization process and change the face of the planet.
This article was produced by Human Bridges.
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