Australopithecus africanus were much like humans. They had evolved to use their hands to do intricate thing. It would have been possible for them to turn a key or hold a hammer. Coming down from the trees "caused" manipulatory advancement. The most useful attributes spread to more of their number due to longer survival and breeding capability.
While anthropologists are not sure that they used the advanced abilities, it is highly probable that they did otherwise the traits would not have become dominant. This pushes tool use way, way back to 3 million years ago.
How do scientists know that Australopithecus had complex skills? Trabeculae which is inside bones in the hands shows how hands were used. Humans, for example use the fingers and thumb region more than chimpanzees. Our friendly relations mainly use their fingers.
The supposition that tool use began millions of years ago was only theory: now it is proven. Culture must have been passed on to offspring as well. Tool use is a skill that must be taught. Humans are capable of learning all their lives. Chimpanzees can learn how to break nuts using a rock when they are young. If they watch this being done when they are adults they never learn how to do it.
✴ Science by Ty Buchanan ✴