Bottom line is it's very difficult to know. A few small changes could make a huge difference, particularly if said changes affect the architecture of the prefro

Bottom line is it's very difficult to know. A few small changes could make a huge difference, particularly if said changes affect the architecture of the prefrontal cortex. Another possibility would be that these humans were about as mentally capable as we are in terms of reasoning and planning, but didn't have language abilities like we do. All of our technology builds on prior technology, which we learn about using language. If your parents can't effectively teach you about their tool use...