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A team of British and French researchers have discovered that the thumbs of Neanderthals (who who lived in Eurasia until going extinct roughly 40,000 years ago) were better adapted for holding tools in what is known as power "squeeze" grips (in the same way that we hold a hammer -- between the fingers and the palm with the thumb directing force) and found grips requiring more precision (like holding objects between the tip of the finger and thumb in the way we hold a pen) more difficult.
Using 3D analysis, Ameline Bardo, a Biological Anthropologist and Primatologist at the University of Kent's School of Anthropology and Conservation's Skeletal Biology Research Centre, and her colleagues mapped the joints between the bones responsible for movement of the thumb (known as the trapeziometacarpal complex) of the remains of five Neanderthals and compared them to those from both early modern humans and recent modern adults.
While it has been known that their fingers were considerably more chunky than ours it appears that their thumbs stuck out from the hand at a much wider angle.
"The joint at the base of the thumb of the Neanderthal fossils is flatter with a smaller contact surface between the bones, which is better suited to an extended thumb positioned alongside the side of the hand," Bardo explained in an e-mail. "By contrast, human thumbs have joint surfaces that are generally larger and more curved, "which is an advantage when gripping objects between the pads of the finger and thumb, a precision grip,"
Bardo noted that "If you were to shake a Neanderthal hand you would notice this difference. There would be confusion over where to place the thumb, and for a thumb fight I think you would win in terms of speed and movement!"
The researchers noted that Neanderthals would still have been capable of precision hand postures, but would have found this more challenging than modern humans, according to the authors.
The entire paper, The implications of thumb movements for Neanderthal and modern human manipulation can be seen at the hyperlink provided. Here is the abstract from it.
Using 3D analysis, Ameline Bardo, a Biological Anthropologist and Primatologist at the University of Kent's School of Anthropology and Conservation's Skeletal Biology Research Centre, and her colleagues mapped the joints between the bones responsible for movement of the thumb (known as the trapeziometacarpal complex) of the remains of five Neanderthals and compared them to those from both early modern humans and recent modern adults.
While it has been known that their fingers were considerably more chunky than ours it appears that their thumbs stuck out from the hand at a much wider angle.
"The joint at the base of the thumb of the Neanderthal fossils is flatter with a smaller contact surface between the bones, which is better suited to an extended thumb positioned alongside the side of the hand," Bardo explained in an e-mail. "By contrast, human thumbs have joint surfaces that are generally larger and more curved, "which is an advantage when gripping objects between the pads of the finger and thumb, a precision grip,"
Bardo noted that "If you were to shake a Neanderthal hand you would notice this difference. There would be confusion over where to place the thumb, and for a thumb fight I think you would win in terms of speed and movement!"
The researchers noted that Neanderthals would still have been capable of precision hand postures, but would have found this more challenging than modern humans, according to the authors.
The entire paper, The implications of thumb movements for Neanderthal and modern human manipulation can be seen at the hyperlink provided. Here is the abstract from it.
Much research has debated the technological abilities of Neanderthals relative to those of early modern humans, with a particular focus on subtle differences in thumb morphology and how this may reflect differences in manipulative behaviors in these two species. Here, we provide a novel perspective on this debate through a 3D geometric morphometric analysis of shape covariation between the trapezial and proximal first metacarpal articular surfaces of Neanderthals (Homo neanderthalensis) in comparison to early and recent humans (Homo sapiens). Results show a distinct pattern of shape covariation in Neanderthals, consistent with more extended and adducted thumb postures that may reflect habitual use of grips commonly used for hafted tools. Both Neanderthals and recent humans demonstrate high intraspecific variation in shape covariation. This intraspecific variation is likely the result of genetic and/or developmental differences, but may also reflect, in part, differing functional requirements imposed by the use of varied tool-kits. These results underscore the importance of holistic joint shape analysis for understanding the functional capabilities and evolution of the modern human thumb.
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