One of the most basic human physical attributes, the opposable thumb was an important part of modern man's evolution and may have existed in pre-human ancestors earlier than previously thought.
According to the Associated Press, authors of a study published in the journal Science found the pre-human ancestor was probably more advanced due to their discovery. With opposable thumbs, these ancestors would have been able to use tools and operate them in a wide variety of ways.
"It forces us to revisit how we think (the entire pre-human genus) made a living," study lead author Matthew Skinner, of the University of Kent, U.K., told the AP. "It could be evidence of our greater reliance on tools."
The pre-human ancestor at the center of the study were determined to not belong to the Homo genus and lived in South Africa between two million and three million years ago. Brian Richmond, human origins curator at the American Museum of Natural History in New York, was not involved with the study, but told the AP this would be the oldest evidence of human predecessors having and using opposable thumbs.
"These are some very primitive creatures overall," he said. "Basically they would have more or less been like upright walking great apes. We wouldn't think of them as very human, but this makes them a little more human than we thought."
For their study, the researchers examined the trabecular bone in chimpanzees, apes, modern humans, Neanderthals and Australopithecus. According to Reuters, the bone was the pivotal aspect of the study because it evolves itself depending on how it is used in a lifetime. This evolution in pre-human ancestors apparently occurred some 500,000 years before the first tools showed up.
"This evidence suggests that species of Australopithecus were more human-like in their behavior than we previously thought and that we should concentrate our efforts on finding evidence for tools that they might have been using," Skinner told Reuters, "whether made out of stone, wood or bone."
