The great secret of Australopithecus: what happened 3 million years ago.

Scientists have concluded that the famous Lucy and her fellow australopithecines began using tools over 3 million years ago. This is indicated by an analysis of the hand muscles of australopithecines, as reported by LiveScience.

The new study provides further evidence that tool use started long before our species – Homo sapiens – appeared on Earth.

"While we cannot say definitively that early humans made stone tools, the results show that their hands were often used in ways closely associated with tool manipulation," says co-author of the study, Fotios Alexandros Karakostis from the University of Tübingen in Germany.

As part of their research, the scientists examined the muscle attachment sites on the hand bones of three australopithecine species, comparing them to the hands of monkeys and humans. It is noted that australopithecines represent a midpoint in human evolution from ancient apes.

The team focused on the entheses of the hands – the areas where tendons attach muscles to bones. When muscles and joints are used frequently, these areas begin to adapt, leading to characteristic bone changes.

"By studying these sites, we can reconstruct how muscles and ligaments were engaged throughout life, providing a clearer picture of hominin behavior," emphasizes the researcher.

The researchers examined the entheses on the hands of three australopithecine species and found that all of them were capable of manipulating objects. Notably, one of the latest hominins, Australopithecus sediba (1.95–1.78 million years ago), had hands that were more human-like than the two older species, A. africanus (3.7–3.4 million years ago) and A. afarensis (3.7–3 million years ago).

While monkeys can grasp and manipulate objects, the dexterity of their hands is often limited by their anatomy. In contrast, Homo sapiens possess two key traits that enhance the dexterity of our hands.

The first dorsal interosseous muscle is located in the palm between the thumb and index finger, allowing us to grasp objects delicately.

"This unique functionality provided early hominins with the dexterity necessary for effective manipulation of objects, including tools, paving the way for both technological and cultural progress," says the first author of the study, Jana Kuntze, a paleoanthropologist from the University of Tübingen.

The pinky finger also plays a crucial role in human-like grasping. Even early hominins, such as A. afarensis and A. sediba, utilized their pinky for everyday tasks like tool use and food preparation.

"The evolution of the thumb and pinky was critical for the evolution of hominins in general, laying the foundation for the hand dexterity that humans now possess," adds Kuntze.

The question of how dexterous australopithecine hands were is directly linked to which species first crafted and began using tools.

"The study shows that the species Australopithecus afarensis, to which Lucy belonged, frequently performed human-like grasping movements, suggesting skilled manipulation of objects in their hands," the researchers concluded.

As a reminder, the ancestor of humans, "Lucy," who is nearly 4 million years old, was capable of walking upright. Recent research utilizing advanced 3D modeling of muscles has shed new light on our ancient ancestor known as "Lucy," a member of the species Australopithecus afarensis. Lucy lived around 3.2 million years ago.