WASHINGTON — Some of humans’ tree-swinging, pre-human ancestors may have been a bit more like modern humans than previously thought, thanks to a tiny section of their thumbs.
One key attribute that separates humans from other animals is the opposable thumb, and the way parts of the thumb are structured to allow for a strong yet precise grip that fostered advanced use of tools.
Scientists have determined that a couple of million years ago one pre-human ancestor had the same human-defining precision grip, even though researchers think of the creature as little more than an upright walking ape, according to a study published Thursday in the journal Science. That supports earlier evidence that the small-brained Australopithecus africanus fashioned early tools.
“It forces us to revisit how we think [the entire pre-human genus] made a living,” said study lead author Matthew Skinner of the University of Kent in the United Kingdom. “It could be evidence of our greater reliance on tools.”
This is the oldest evidence of pre-humans using hands to manipulate items, said Brian Richmond, human-origins curator at the American Museum of Natural History in New York. He wasn’t part of the study but praised it as important.
This species, not technically part of the Homo family, roamed South Africa between 2 million and 3 million years ago. A similar pre-human species of hominids, typified by the famed Lucy fossil, lived in East Africa.
“These are some very primitive creatures overall,” Richmond 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.”