How evolution reveals the differences between humans and apes

NARRATOR: Africa - the birthplace of humankind. Here is where human history began; numerous early finds of human remains prove this. Primitive man and the great ape have common ancestry, but their paths diverged at some point in history. From that point they evolved in completely different ways. A research expedition in Malawi - finds are continually being made here that tell of primitive humans and the stages of human evolution. Professor Friedemann Schrenk found the oldest known remains of the genus homo ever discovered, a more than two-million year-old human jawbone. Teeth reveal a lot about history. Even as far back as this, humans lived differently than their relatives from the animal kingdom.

FRIEDEMANN SCHRENK: "You can see from the cavities and the depressions that primarily plants were broken down with these. So it's a special solution for breaking down these fibrous foods. While humans - we see the teeth here - used tools instead."

NARRATOR: Is the type of food consumed the key to the divergence in the evolution of humans and primates? If you can employ tools, you can get nutrition more efficiently and don't need to eat as much, or as often. Were humans able to evolve faster than apes because of their tools? The oldest tools made by hominoids are 2.6 million years old. After the hand axe came stone knives to cut up plants and meat. Early humans gradually became more and more independent of their surroundings by developing techniques that improved their survival chances. Today, however, we know that chimpanzees sometimes use tools.

DR. CHRISTOPHE BOESCH: "Two months ago a new publication from Senegal showed that chimps often use tools to hunt with as well, although using tools as weapons has been thought to be a specific trait of humans."

NARRATOR: If chimps can use tools just as we can, what is the difference? Behavioral scientists use a special experiment to study problem solving behavior of humans and chimps. A blue box rests behind a lattice, the subjects are supposed to pull it towards themselves. Both are given a tool and the director of the experiment shows them the decisive trick. Now it's time for social learning. Who will perform the task better, little Jacob, or Sandra the chimp? Jacob's ambition has been awakened, he has already got the noose, and with a bit of practice he completes the task. All the while Sandra attempts to fish with the tool. She obviously forgot the specific details. A short time later, she gives up. The psychologist does not believe this is because the child is more clever. The divisive factor is the ability to learn in a social context. For the researchers, this is the real reason for the difference between humans and apes.