Scientists have long recognized the close evolutionary relationship between humans, chimpanzees, and gorillas based on their common anatomy, raising some serious questions: How are humans related to other primates, and how exactly did the first human move? Some answers will be given by the research of a professor at Texas A&M University.
Thomas Cody Prang, assistant professor of anthropology, and his colleagues examined the 4.4 million-year-old skeletal remains of an Ardi hominid (Ardipithecus ramidus, Ardipithecus) found in Ethiopia. One of Ardi’s hands is exceptionally well preserved.
Researchers compared the shape of Ardi’s hand with hundreds of other hand specimens representing recent humans, great apes, and dry-nosed primates to compare the type of locomotor behavior used in the earliest hominins (fossil human relatives).
The results of the study, published in Science Advances, provide clues to how the first humans began to walk upright and perform movements similar to those we are used to today.
“Bone shape reflects adaptation to certain habits or lifestyles, such as the movement of primates. By establishing links between bone shape and the behavior of living forms, we can draw inferences about the behavior of extinct species such as the ardiptecs, ”explains study author Thomas Cody Prang.
In addition, scientists have found evidence of a large evolutionary “leap” between Ardi’s hand and the hands of all later hominins, including the species Lucy (Australopithecus). This “leap” came at a critical juncture when the hominins evolved to adapt to a more human form of upright walking. Examination of the skeleton has provided scientists with the earliest evidence of hominin stone tool making and use.
The fact that Ardi represents an earlier phase in human evolutionary history is important because it potentially sheds light on the species of ancestors from which humans and chimpanzees descended.
The new research supports the classic idea, pioneered by Charles Darwin in 1871, when he had no fossils or understanding of genetics, that the use of hands and upper limbs for manipulation appeared in early human relatives in connection with upright walking. Scientists suggest that the evolution of human hands and feet was probably interconnected in ancient humans.
Major changes in the anatomy of Ardi’s hand and all later hominins occurred approximately between 4.4 and 3.3 million years ago. This coincides with the earliest evidence for the loss of the grasping big toe in human evolution.
Among other things, the study as a whole confirms Darwin’s theory of the origin of man from apes.