Erik Trinkaus, Department of Anthropology of Washington University, St. Louis, Missouri, and Shang Hong, of the Institute of Vertebrate Paleontology and Paleoanthropology in the Chinese Academy of Sciences, Beijing, China, studied a 40,000-year-old skeleton found in Tianyuan Cave near Zhoukoudian, China.
What was unique about this skeleton was that the small toe bones were still intact, something that is not usually found.
They also studied other foot bones from ancient Native Americans, Puebloan and Alaskan Inuit skeletons, a 27,500-year-old Russian skeleton with middle toe bones still present, and Neanderthal and early human skeletons.
Shoes were known to have been worn about 12,000 years ago. Some of them consisted of string attached to the feet, what scientists call rope sandals. Others were no more than protection for the feet to insulate them and to cover them from the cold.
These early forms of shoes did not change how humans walked when compared to going barefoot. Rugged shoes, however, reduced the need for the toes to grip and balance, and they became weaker and less flexible, especially the lesser toes, all of the toes except the big toe.
Scientists can study the bones in the feet because they change over time depending on whether people wear shoes or go barefoot. Walking barefoot causes the middle toes to curl into the ground in order to balance oneself and to provide better traction.
However, wearing shoes makes the big toe work harder. It is the one that primarily is used for pushing off while walking and to provide more traction and balance.
For the new study by Trinkaus and Hong, they looked at the middle toe bones that change during an individual's lifetime if the person wears shoes.
The two scientists examined early modern humans (Homo sapiens) and Neanderthals (Homo neanderthalensis). Neanderthals and early humans living in Middle Palaeolithic times (from about 100,000 to 40,000 years ago) had thicker and stronger lesser toes, while people living in Upper Palaeolithis times (about 26,000 years to 10,000 years ago) had lesser toes that were not as thick and strong.
Their findings are published in the online version of the Journal of Archaeological Science. The title of the article is “Anatomical evidence for the antiquity of human footwear”.
Their abstract states, “Trinkaus … provided a comparative biomechanical analysis of the proximal pedal phalanges of western Eurasian Middle Paleolithic and Middle Upper Paleolithic humans, in the context of those of variably shod recent humans. The anatomical evidence indicated that supportive footwear was rare in the Middle Paleolithic but became frequent by the Middle Upper Paleolithic. Based on that analysis, additional data are provided for the Middle Upper Paleolithic ( 27,500 cal BP) Sunghir 1 and the earlier ( 40,000 cal BP) Tianyuan 1 modern humans. Both specimens exhibit relatively gracile middle proximal phalanges in the context of otherwise robust lower limbs. The former specimen reinforces the association of footwear with pedal phalangeal gracility in the Middle Upper Paleolithic. Tianyuan 1 indicates a greater antiquity for the habitual use of footwear than previously inferred, predating the emergence of the Middle Upper Paleolithic."