Research recently published claims that Neanderthals, the ancient cousins of modern humans, were right-hand dominant just like Homo sapiens. The finding offers insights into Neanderthal brain development, including language capability.
The roundabout way the discovery was made starts with a tooth. To process an animal hide, a Neanderthal would hold one side of the hide in the mouth and stretch it out with the hands. The hide would be worked with the dominant hand, leaving scratches on the front teeth in a consistent pattern from the upper left to the bottom right.
Handedness, also called chirality and sinistrality, is often linked with language development. The two parts of the brain that control listening and speaking are in the left hemisphere. Broca’s Area is in the frontal lobe near the motor cortex that controls the mouth. In addition to speech production, Broca’s Area has been implicated in the production of syntactic structures and use of grammar.
Wernicke’s Area is in the posterior portion of the temporal lobe and is responsible for speech comprehension. Speech and handedness are both fine motor skills, and it has been hypothesized that the left hemisphere’s specialization in fine motor skills is a method of energy efficiency for the brain. However there are no clear conclusions about why humans use their left hemisphere for verbal processing.
We have all heard about right and left brain dominance and handedness: the right side of the brain controls the left side of the body and the left side controls the right. This is called lateralization. There are some unfortunate generalizations about handedness, brain dominance, and personality highlighted by pop psychology that don’t need to be repeated here. In short, the left side of the brain is where most humans process linear reasoning and language; the right side of the brain is where most humans process visual and aural information, spatial manipulation and facial perception along with artistic ability. These descriptions are unfortunately brief for a very in depth and fascinating subject.
Right-hand dominance is the latest in a growing list of evidence that Neanderthals had language. In 2008 the French archeologist Francisco D’Errico hypothesized that Neanderthals had language based on artifacts related to symbolic meaning, such as body paint, beads and other decorative materials. In addition, the only bone in the vocal tract, the hyoid, in Neanderthals and in early Homo sapiens is strikingly similar, especially in contrast to the vocal tracts of the great apes, our other cousins. Great apes have an air sac that produces a huge booming sound, but not articulation. Neanderthals and modern humans do not have an air sac. The hypothesis is that the sac diminished as survival became dependent on what was said, not how loud it was said.
Humans are the only modern primates that show a preference for right hand dominance. Between 70 – 90% of people today are right-hand dominant. The left-handed minority has been consistently 10 – 30% throughout history. When analyzed, individuals who are left handed show brain activity related to language in either the left side of the brain of both sides of the brain. Left-handed children have a statistically significant increase in language development problems, specifically phonology (sound distinction).