The Significance of an Itty Bitty Hand Bone

10 Jan
(Ward et al. 2014. Arrows indicate styloid process).

(Ward et al. 2014. Arrows indicate styloid process).


If paleoanthropological research in 2013 (see previous post) demonstrated anything, it is that ancient bones need not be very big to have big implications for our understanding of the human past. An article published in this week’s Proceedings of the National Academy Sciences illustrates how something as seemingly inconsequential as a metacarpal – and, most importantly, its styloid process, can change how we view the evolutionary development of the human hand. Unfortunately, the full text article is behind a pay wall (Knowledge should be free. Always.), but PNAS provides an abstract and summary of significance:

“A newly discovered metacarpal from Kaitio, Kenya, dates to 1.42 Mya and provides evidence for the evolution of the modern human hand more than 600,000 y earlier than previously documented. This bone displays a styloid process, which is part of a distinctively human rearrangement of the wrist associated with enhanced hand function when making and using tools. Prior to this discovery, the first evidence of this anatomy was found only in post–Homo erectus archaic humans. This new find documents its appearance much earlier in time and suggests that an increased reliance on manipulatory behaviors indicated by the archeological record early in the Pleistocene selected for the modern human hand early in the evolution of the genus Homo” (

NBC and the BBC provide nice popular summaries of the article as well. The significance of our hand morphology in allowing us to manipulate our environment really cannot be overstated – you’re probably using your hand(s) to operate a mouse, keyboard, or smart phone right now! This recently analyzed bone pushes the origins of these hands farther into the past.

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