New fossil discoveries in South Africa's Swartkrans Cave shed new light on the physical characteristics and lifestyle of Paranthropus robustus, a species of prehistoric human that lived about two million years ago. In a study published in The Journal of Human Evolution, it was revealed that Paranthropus robustus walked upright like modern humans, according to Discover Magazine. This finding comes from the analysis of three fossils—a femur, a tibia, and a fibula—that resolved previous limitations in understanding the species' stature, posture, and movement.
These fossils not only demonstrate bipedalism but also confirm the remarkably small size of Paranthropus robustus. "These fossils not only show that this species, comparable to modern humans, walked upright, but they also confirm that it was of extremely small body size," said Marine Cazenave, according to Archaeologie Online [https://www.archaeologie-online.de/nachrichten/erster-gelenkknochen-eines-beines-von-paranthropus-robustus-entdeckt-6218/]. The species stood at just 103 centimeters (3.4 feet) tall and weighed approximately 27 kilograms (60 pounds), making it vulnerable to the predators of its environment.
The area around Swartkrans Cave, located approximately halfway between Johannesburg and Pretoria in the region known as the Cradle of Humankind, was inhabited by dangerous predators like giant hyenas and sabertooth cats. "The estimate is that the discovered bones probably belonged to a female. Her height was only about one meter and her weight 27 kilograms at her death. These dimensions make the female Paranthropus robustus even smaller than adult individuals of other earlier human species," said Professor Travis Pickering, according to IFLScience.
Evidence of predation was found on the bones of Paranthropus robustus. Bite marks and chewing damage consistent with attacks by predators were identified. "The examination of the surface damage on the SWT1/HR-2 fossils—bite marks and other tooth impressions—that are identical to those left by leopards on the bones of their prey confirms this assumption," explained Jason Heaton from the University of Alabama in Birmingham, as reported by Archaeologie Online. Despite these dangers, Paranthropus robustus was a survivor, able to endure in situations where food quality was low.
The discovery also provides insights into the species' social structure. The Paranthropus robustus skulls and teeth come in two distinct sizes, indicating a composition of large males and small females. This size difference suggests that they likely participated in polygyny, where a single dominant male mates with multiple females. As noted by IFLScience, "When this sort of sexual dimorphism is seen among animals, it's usually associated with a dominant male mating with multiple females, while other males are excluded unless they can overthrow the king."
Fossils of Paranthropus robustus are consistently found near stone tools, which were likely used for various purposes, including slaughtering animals and digging for edible roots. However, there is ongoing debate about whether Paranthropus robustus or neighboring species like Homo ergaster were the makers of these tools. Discover Magazine reports, "Researchers have a big question: whether the tools found were made by Paranthropus robustus, by neighboring species like Homo ergaster, or by both."
The species coexisted with early Homo, specifically Homo ergaster, a direct ancestor of modern humans. This coexistence raises intriguing questions about their interactions and the sharing of resources and habitats. Much information has been revealed about the diet and social organization of Paranthropus robustus based on studies of its numerous skulls and hundreds of teeth discovered in the South African cave.
The heavy jaws and thick teeth of Paranthropus robustus, which earned it the nickname "the nutcracker man," indicate its ability to survive even during periods when food was of low quality and hard to chew. The research team behind this discovery plans to continue investigating the new fossils using CT-scan analyses to gain insights into the internal bone structures. "These analyses will provide additional insight into Paranthropus robustus' patterns of growth and development," including its walking patterns and locomotion behavior, according to Archaeologie Online. They hope these analyses will add more details to the story of how Paranthropus robustus lived, offering a deeper understanding of this ancient species.
The article was written with the assistance of a news analysis system.