Archaeological records - paintings, drawings and carvings of humans engaged in activities involving the use of hands - indicate that humans have been predominantly right-handed for more than 5,000 years. In ancient Egyptian artwork, for example, the right hand is depicted as the dominant one in about 90 percent of the examples. Fracture or wear patterns on tools also indicate that a majority of ancient people were right-handed. Cro-Magnon cave paintings some 27,000 years old commonly show ...

Archaeological records - paintings, drawings and carvings of humans engaged in activities involving the use of hands - indicate that humans have been predominantly right-handed for more than 5,000 years. In ancient Egyptian artwork, for example, the right hand is depicted as the dominant one in about 90 percent of the examples. Fracture or wear patterns on tools also indicate that a majority of ancient people were right-handed. Cro-Magnon cave paintings some 27,000 years old commonly show outlines of human hands made by placing one hand against the cave wall and applying paint with the other. Children today make similar outlines of their hands with crayons on paper. With few exceptions, left hands of CroMagnons are displayed on cave walls, indicating that the paintings were usually done by right-handers.

Anthropological evidence pushes the record of handedness in early human ancestors back to at least 1.4 million years ago. One important line of evidence comes from flaking patterns of stone cores used in tool making: implements flaked with a clockwise motion (indicating a right-handed toolmaker) can be distinguished from those flaked with a counter-clockwise rotation (indicating a left-handed toolmaker).

Even scratches found on fossil human teeth offer clues. Ancient humans are thought to have cut meat into strips by holding it between their teeth and slicing it with stone knives, as do the present-day Inuit. Occasionally the knives slip and leave scratches on the users' teeth. Scratches made with a left-to-right stroke direction (by right-handers) are more common than scratches in the opposite direction (made by lefthanders).

Still other evidence comes from cranial morphology: scientists think that physical differences between the right and left sides of the interior of the skull indicate subtle physical differences between the two sides of the brain. The variation between the hemispheres corresponds to which side of the body is used to perform specific activities. Such studies, as well as studies of tool use, indicate that right- or leftsided dominance is not exclusive to modern Homo sapiens. Population of Neanderthals, such as Homo erectus and Homo Habilis, seem to have been predominantly right-handed, as we are.

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