For a long time, scientists have thought that the common ancestor of humans and chimps would be a chimp-like creature. Comparisons between humans, chimps, and the other apes led to this conclusion as humans seemed to be the least similar and chimps appeared to share many traits with our relatives like gorillas. Recent work in paleontology, behavioral biology, and molecular biology has suggested that this assumption may be incorrect. Studies of the chimp genome have shown that chimps appear to have more genes that have been influenced by natural selection than humans do, suggesting more changes from our common ancestor. Researchers looking at animal behavior also made a family tree of traits belonging to apes and monkeys and found that our common ancestor likely had a lifestyle pattern different from both humans and chimps today. Finally, studies on the Ardipithecus ramidus fossil unearthed in 2009 have revealed more potential differences. The specimen is one of the closest ever found to the chimp-human split, and researchers believe it may have walked on tree branches on all fours like a monkey rather than hung from them like apes. This conclusion however is still controversial, but when combined with the other studies mentioned here, does point out that chimps have not stayed the same since their split with humans. Rather, they evolved and changed just as humans did.