The human hand is different from that ofchimpanzees. Chimpanzee fingers are curved with narrow tips, while human fingers are straight with broad tips. Chimpanzees have short thumbs, while human thumbs are larger and stouter. The hand structure of chimpanzees is designed for a power grip that is important in climbing and grasping tree limbs. While both have hands that are capable of grasping and holding things, only humans have opposable thumbs. In his book Thumbs,Toes, and Tears and Other Traits that Make Us Human, Chip Walter explains:
“What is different is that we can effortlessly swing our thumbs across the palms of our hands to meet our small and ring fingers, the fourth and fifth digits. Nothing like this exists elsewhere in nature. It’s called the ulnar opposition.”
This makes possible the precision grip which is a key element in our ability to make and use a variety of tools. In their book The Dawn of Human Culture, Richard Klein with Blake Edgar write:
“The human hand promotes a precision grip that is well suited for opening a jar, writing with a pencil, or flaking stone.”
With regard to fingers, Chip Walter reports:
“The fingers of our hands actually have no muscles. They operate by remote control, like marionettes. A web of tendons, anchored in the palm, midforearm, and as far north as the shoulder are the strings that make your digits dance.”
Writing about the human hand, Desmond Morris, in his book The Naked Woman: A Study of the Female Body, says:
“Freed from the task of locomotion, both on the ground and in the trees, the design of the hands could for the first time become solely manipulatory. This was one of the most important steps in the whole evolution of our species.”
In his book The Gap: The Science of What Separates Us from Other Animals, Thomas Suddendorf writes:
“A human hand is capable of power and precision grip that allow effective clubbing and throwing.”
The hand set the stage for tool-making and tool-using and with tools, humans moved out of Africa and colonized the rest of the world.
With regard to the evolution of the hand, Mary Marzke, in her report on the hand in the Handbook of Human Symbolic Evolution, writes:
“The concurrent appearance, in the earliest fossil hominids, of morphological features in both the hand and the locomotor apparatus that are essential to the distinctively human facility in tool-use is consistent in the divergence of hominids from the pongid line.”
With regard to time period in which human ancestors evolved the human hand, Chip Walter writes:
“Based on the garbled messages the fossil record has so far provided, science’s best guess is that they reached something like their current, thumb-opposable state a little more than two million years ago.”
With regard to genetics, the evolution of the human hand is associated with the HAR2 gene which drives gene activity in the wrist and thumb during fetal development. Katherine Pollard, in her chapter in Becoming Human: Our Past, Present and Future, writes:
“This finding is particularly provocative because it could underpin morphological changes in the human hand that permitted the dexterity needed to manufacture and use complex tools.”
The ability of the human hand to tie a bow and screw in a light bulb are just a few of the tasks that modern engineers are attempting to replicate in robots. According to a display on robotics at the Oregon Museum of Science and Industry in Portland:
“Our hands are complex. It requires sophisticated engineering to create a robot hand that looks like and works as well as a human hand.”
Human Origins
Human Origins is a series which looks at topics relating to human evolution. More from this series:
Human Origins: Bipedalism
Human Origins: Sexual Selection
Ancient Africa: Australopithecus
Ancient Africa: Homo Naledi
Early Homo Sapiens: A Brief Overview of DNA
Ancient Humans: A Short Overview of Homo Ergaster