"It's an arid badlands desert area now," Ward said. "There's not much vegetation to cover up fossils — there's cobble and rock everywhere, and we try and find fossils by going out and looking under all that cobble and rock on the surface."
The hand-bone fossil is about 1.42 million years old. The researchers suspect it belonged to the extinct human species Homo erectus, the earliest undisputed predecessor of modern humans.
"Back then, this area was an open woodland area much more lush than today, probably with some trees and some areas of grassland," Ward said. "The fossil was found near a winding river, which often deposits things like fossils."
By revealing the early human lineage had a modern handlike anatomy, the fossil "suggests this feature may have a pre-adaptation that helped set the stage for all the technology that came later," Ward said.
Intriguingly, "at this time, in addition to early members of Homo, there were some late-surviving members of Australopithecus still around — close relatives of humans that don't seem to have this adaptation," Ward said. "This raises the question of how important our hands were in the success of our lineage and the extinction of their lineage (Australopithecus)."
The researchers now want to find older hand bones "to see when this feature evolved," Ward said. "We want to get closer to 2 million years ago to find out when this transition to modern hand anatomy took place."
Ward and her colleagues detailed their findings online Dec. 16 in the journal Proceedings of the National Academy of Sciences.
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