New 3D fossil scans reveal when humans started walking on two feet
A study published in the American Journal of Primatology has provided new insights into the emergence of bipedalism in human ancestors. Using advanced 3D scanning techniques, researchers analyzed fossil bones to investigate how early hominids moved, focusing on the transition from arboreal locomotion to upright walking. The research was led by Professor Josep M. Potau from the Department of Human Anatomy and Embryology of the University of Barcelona and Neus Ciurana from Gimbernat University School. Collaborators included a team from the University of Valladolid.
Innovative 3D analysis techniques
The study examined muscle insertion sites in the ulna bone, a major component of the elbow joint, to determine locomotor types in extinct and living primates. The findings suggested that species such as Australopithecus and Paranthropus combined upright walking with arboreal movements, similar to modern bonobos (Pan paniscus).
The methodology involved in creating detailed 3D models of the ulna of modern primates, humans and fossilized hominids, according to sources. Researchers measured the insertion zones of two crucial muscles: the brachialis, which helps flex the elbow, and the triceps brachii, which is responsible for elbow extension.
The study found that arboreal species such as orangutans showed greater brachialis insertion area, while terrestrial species such as gorillas showed greater development in the triceps brachii region. This comparison helped identify locomotion patterns in extinct species.
In a statement, Potau explained that this muscle ratio allowed researchers to compare extinct species such as Australopithecus sediba and Paranthropus boisei with modern bonobos. These fossil species showed features associated with both bipedal and arboreal movements, indicating that they were transitional forms.
Absence of adaptations for the behavior of tree dwellers
In contrast, fossil species of the genus Homo, such as Homo ergaster, Homo neanderthalensis, and archaic Homo sapiens, showed muscle insertion ratios similar to those of modern humans. These findings indicate the absence of adaptations for arboreal behavior in these species, highlighting their commitment to bipedalism.
The study provides a basis for future research into the evolution of locomotion. As stated in several publications, similar methods could be applied to other anatomical areas to deepen the understanding of human evolutionary history.
