1.4 million-year-old fossil human hand bone closes human evolution gap
The styloid process helps the hand bone lock into the wrist bones, allowing for greater amounts of pressure to be applied to the wrist and hand from a grasping thumb and fingers. Ward and her colleagues note that a lack of the styloid process created challenges for apes and earlier humans when they attempted to make and use tools. This lack of a styloid process may have increased the chances of having arthritis earlier, Ward said.
|The styloid process allows the hand to lock into the wrist bones, giving humans the ability to apply greater amounts of pressure to the hand. This allows humans to make and use tools [Credit: University of Missouri]|
"The styloid process reflects an increased dexterity that allowed early human species to use powerful yet precise grips when manipulating objects. This was something that their predecessors couldn't do as well due to the lack of this styloid process and its associated anatomy," Ward said. "With this discovery, we are closing the gap on the evolutionary history of the human hand. This may not be the first appearance of the modern human hand, but we believe that it is close to the origin, given that we do not see this anatomy in any human fossils older than 1.8 million years. Our specialized, dexterous hands have been with us for most of the evolutionary history of our genus, Homo. They are -- and have been for almost 1.5 million years -- fundamental to our survival."
The study was published in the Proceedings of the National Academy of Sciences this week. Members of Ward's team who helped discover and analyze the bone include: Matthew Tocheri, National Museum of Natural History in the Smithsonian Institution; J. Michael Plavcan, University of Arkansas; Francis Brown, University of Utah; and Fredrick Manthi, National Museums of Kenya.
Author:Jerett Rion | Source: University of Missouri-Columbia [December 16, 2013]