In this video, we'll be exploring the theory that left and right handedness evolved in ancient humans. We'll discuss the evidence and argument for this theory and explore the implications it has for human evolution.

From the time most children first start picking up and using objects, they tend to favor one hand over the other. And, in a majority of humans, the right side is dominant: around 85 percent of the modern human population on Earth is right handed. This trend is borne out by another line of evidence: skeletal asymmetry. As you (or anyone—even a Neanderthal) use muscles in your body, and as those muscles grow stronger, the parts of the skeleton to which those muscles attach also grows in order to provide more robust anchor points for the increased muscle mass. After death, the skeleton can reveal which parts of the body were stronger, and thus used more intensively, than others.

Furthermore, New research suggests right handedness in humans goes back at least 1.8 million years. The controversial Homo habiliss, who lived in what is now Tanzania some 1.8 million years ago appears to also have favored his or her right hand, according to new research published in the Journal of Human Evolution. Until this study, the earliest evidence of right handedness appeared in Neanderthals and their earlier relatives from about 430,000 years ago, But how can researchers figure out from just bones if an individual was right or left-hand dominant, or if they were handed at all?