From swinging to swiping: a short history of arms and hands
In that rough-and-tumble of time and change we call evolution, we in the human-line lost some features and gained others, most noted is our upright posture and big brain. Less celebrated is the fact that as a result of our standing upright on two legs, we got a loose, liberated set of forelimbs and hands. With time these freed upper limbs were to perform functions never seen before in the animal-dom.
By comparison our common ancestor, uncannily similar to the present-day chimpanzee, used her long arms primarily for transport; scampering, climbing and swinging to get from A to B. As with other primates, there were some stick-gathering, stick-digging, stick-throwing and grooming activities in the repertoire of these forelimbs, but mostly arms were for moving forwards.
Our ancestor used her arms primarily for transport;
scampering, climbing and swinging to get from A to B
Once our line had made the revolutionary transition to standing on her hind legs, about 5 million years ago, everything changed. Standing upright gave the feet and legs exclusivity on transport, and freed the shoulder girdle, [shortened] arms and hands, allowing us humans to dedicate ourselves to the tasks of doing and making. From that point on, along the hominid line, we 'go' with our feet and 'do' with our hands.
we 'go' with our feet and 'do' with our hands
The age of doing and making
It may not sound extraordinary to you, but we humans have thumbs that can touch the tips of our other fingers. We are the only living creatures on earth that can do this. TRY IT. It's called thumb opposition and it allows us to grip and manipulate objects and materials with precision and dexterity.
When we as a species perfected manipulation we started to make tools and artifacts that made functioning easier and enriched our experience of living. Our forefathers and mothers mastered the making of fire and carved sharp objects. The rest, as they say, is history.
From wheels and pots, to ploughs, hooks, arrows, needles and forks, the use of these technologies lessened the demand on the human body. These tools gave us agriculture, engineering, construction, storage, transport, industry and so much more that changed the nature of human life. Concurrently our hands fashioned tools and instruments that gave extra dimensions to our experience and perception of living and formed what we call culture, from the use of chisels, quills and brushes to pipes, drums and lyres and so much more. For thousands of years the human brain has imagined, calculated and invented and the arms and hands performed according to these instructions. The arms and hands went from being the primary technology to being the activator of tools. But activating still demanded a lot of physical and specifically arm-hand effort.
Once the arms and hands were the main tools of the human body, but after humans started developing technologies the arms and hands became the 'assistants', operating these devices
The sweep and freedom of the arms
The arms and hands are the extension of the shoulders, which are the loosest joints of the human body [so loose that it has sets of strong muscles and ligaments to stop it from dislocating]. The shoulder is part of the shoulder girdle, made up of two more bones which slide smoothly round the curve of the rib cage, and have only a very minor attachment to it at the collar bone in front.
The very loose contact of the arm in the shoulder joint and in turn the shoulder-
girdle on the rib cage allows for an
enormous range of arm movement.
courtesy © Kenhub (www.kenhub.com); Illustration: Y. Koh
Kenhub - recommended anatomy-study course
Together with the arms, the whole upper limb is a bit like a summer jacket thrown lightly over the sturdy central rib-cage. Due to the very light attachment to the rib-cage, these loose long appendages, our arms, have an extensive range of movement; the arms move easily in every plane, stretching and reaching around in front of the body, extending out to the sides, up above the head and behind the back. And the articulations at the elbows, wrists and fingers allow for the arms to bend and turn and twist in a variety of extra directions. In all, the arms and hands have a very big repertoire of mobility; movement that can be precise and purposeful, and also expansive, graceful and far reaching. In order to maintain this extensive mobility it is essential to incorporate on-going functional arm and hand movements into our everyday lives.
the upper limb is like a summer jacket thrown lightly over the more solid rib-cage. Strong sets of muscles and ligaments hold the girdle in place and, in effect, prevent the limb from 'falling off'.
This was how we managed our lives and arms until very recently; sweeping and scrubbing, slicing, stirring, wringing, chopping and a doing a host of other everyday activities that demanded different forms of arm-hand effort and mobility. But over the last few decades a culture has developed that encourages us to avoid making even the most moderate of efforts. Technologies are being developed and perfected that are sitting us down, shoulders locked and elbows tucked tightly into our sides, demanding only minimal movement of the hands, if at all.
the goal we are seduced into aspiring to, is to make as little manual effort as possible.
Technologies are being developed that are inviting us to sit down, shoulders locked and elbows tucked tightly into our sides
Take for example floor-sweeping; the vacuum cleaner replaced the broom and now there is a robotic floor cleaner operated by remote hand control. Even the minimal physical activity of writing has now been replaced by finger-tip tapping and thumb swiping. Correspondingly a hefty price is being paid by technologically-privileged people, in the form of neck pain, headaches, eye-strain, shoulder discomfort and immobility, 'tennis' elbow, wrist and finger ailments and pains, to name just a few of the effects on arms and hands that move very little. Never has the adage 'if you don't use it you'll lose it' been more apt.
How functional and active are your arms and hands?
What proportion of your day do you find yourself with your elbows tucked into your sides?
Which tasks do you still do manually? Tooth brushing..................
Tip of the post
Choose one everyday task that you usually do using a device powered by fuel/electricity and do it manually, using your own muscle energy and joint power.