But aren't we inherently aggressive and warlike?
If you were to ask a scientist why only the human, among all the primates, has a hand with a finger – thumb opposition chances are the answer would be about tool wielding.
The scientist would explain that this finger-thumb opposition permits humans a wide range of holding from gentle (holding a butterfly) to hard (grasping a lever). Further more, s/he might tell you about Homo habilis who lived just over 2 million years ago and was the first of the Homo species to emerge. Habilis became known as ‘handy man’ because stone tools were found with the fossils which were discovered by Lois and Mary Leakey in East Africa. Its brain, at about 650 cc, was bigger that the earlier bi-pedal primate, Australopithecus, and scientists thought this is what allowed habilis to use tools. But what they are forgetting is that this finger- thumb opposition existed a long time before Homo habilis. It had existed for close to 3 million years and now you can learn the story of how this human hand evolved and tell it to your little ones..
We call our very oldest ancestors by the name of Australopithecus which means Southern Ape. These primates were bi-pedal and upright, however our hip joints are more evolved so compared to us Australopithecus would still seem quite ape-like in its movements. Importantly their brains were a little larger than those of the old world apes and monkeys. Probably they were about the size of a modern chimpanzee, that is about 380 – 500cc. For comparison this is much smaller than ours which is about 1350cc.
This upright, walking primate emerged about 5million years ago. There are many views about why they became bi-pedal and the most likely is that changes in climate caused a shift in land cover from forestation to the grasslands we know as savannah. While there are still trees in the savannah they bear little relation to the earlier, dense, tropical forests. Thus Australopithecus had to spend much greater periods on the ground and standing helped to watch out for predators in the grasslands and also to look out for food. Since all the Australopithecines were vegetarian their food would have been roots, fruits, seeds and nuts perhaps with some insects. It may well be also that in these times when the savannah was emerging there were still many wet-lands and it was safer and easier to walk upright through water.
Our earliest ancestor had arrived, living still as a vegetarian primate but the giant shift had emerged – this ancestor walked upright. Along with the change in posture there was another even more important change, the gradual growth in brain size. From this point onwards each species of firstly, Australopithecus and then Homo, would have a slightly larger brain than the species which came before. In evolutionary terms it was not long before the brain size of the species would begin to cause a huge problem for birth because the female birth canal had evolved for babies with small brain size. The way evolution dealt with this was to retard the development of the brain prior to birth. So today when a baby is born its brain is only one third developed and the skull is flexible.
This has huge implications and led to what biologists call neoteny. We can understand this human characteristic as an extension of childhood. Human babies are the most dependent of all the mammals and creatures on Earth and the least able to fend for themselves.
When we watch a chimpanzee with its baby we notice that it doesn’t take very long after birth for the baby to be able to grab onto its mother’s fur. The mother can then climb and move about freely thus staying with the troop as it travells searching for food and security. When we observe grassland animals we can see that they stand and are able to run within a few hours of birth. This protects them from predators which would easily take advantage of a new - born which could not run away.
When it comes to human infants then they are the most defenceless and this high dependency remains for a long time. It takes, for example, about 18 months for the human baby to complete the growth of its brain. At first the infant cannot even hold up its head and generally it takes about 6 months before there is any independent movement. Reaching the stage of becoming a toddler who can stand up independently, takes about a year. Depending on culture the human child is dependent until it reaches adolescence and in modern societies even longer. It is easy to see why biologists call this characteristic dependency neoteny or the extension of childhood. Another way to view this is to recognise that human adults are more like children than the adults of any other animal species.
When a young Australopithecine mother has a baby the first thing she realised is that the baby was incapable of holding on to her. There was no option but to carry the infant.
While we have the image of this highly dependent infant being carried by its mother it is not hard to realise that such vulnerable babies would not have lasted very long if the males of the species were violent. On the contrary within the male there were evolving protective behaviours. When this young mother sits looking at her infant she uses her hand to support its neck.
Since it takes a long time in human terms before the hunting of animals arises and thus the use of animal hides for clothing and carrying, or the use of grasses to craft primitive fabric this carrying of the infant is not a short term activity; it will continue until after the arrival of Homo habilis almost 3 million years later. Eventually habilis, erectus, neanderthalis or even early sapiens will discover how to make a baby sling which is widely used around the world to carry infants to this day.
During this very long period many evolutionary changes are happening to this bi-pedal primate. The first changes occur with the pelvis, hips and legs allowing a modern walking gait to emerge. Then around 3 million years ago there were development in the jaw and areas we use for talking for this is the time when speech arose along with the monthly periodicity of the female as distinct from the annual oestrus of the earlier apes and monkeys. (It would be an entirely separate essay to ask, ‘why did speech arise?" It is not as if we have to have it. Apes for instance have survived quite well with their signalling and sounds. Then we might further ask " why did speech arise at the same time as the female gained a monthly periodicity?")
With each new species and each new biological or skeletal adaptation the largest change, as we have already discovered, was an increase in brain size. Neoteny was becoming even more apparent and each generation of babies was carried.
Babies of course need much more than just being carried about from one feeding place to the next. They require nursing and feeding, washing, changing, carressing and stroking and all of these activities are done with the hands. Thus from the time of the early Australopithicenes the bi-pedal primate was holding and touching its infants with its hands. Gradually this constant contact led to the development of the most marvellous adaptation, the human finger-thumb opposition. Since bi-pedal primates no longer lived in trees they did not need to conserve the hand that chimpanzees and apes have to this day, a hand which is good for climbing. Over time the human hand evolved to carry and tend to all the tasks that infants need and in this way the hand developed its greatest characteristic.
The greatest characteristic of the human hand is that it can fit every surface of the body. It is a caressing hand!
Try it now for yourself. See how well your hand can support an infant’s head, curve about en elbow or flatten along a forearm. It can clasp around another hand, or put a finger into an itchy ear, massage a tight shoulder, fondle a breast, hold a finger, rub a sore spot, stroke a cheek, caress and it is famous for giving comfort. This ability has given rise in the language to the expressions ‘healing hands’.
Our human hand is therefore first and foremost a carressing hand and in evolution this was achieved long before Homo habilis started to make primitive, stone tools such as axes for chopping and sharp rocks for cleaning the flesh from animal hides. We did not evolve from violent origins but from gentle, vegetarian origins which can still be viewed in the life and ecology of the great apes. It was our species, Homo sapiens, ironically Latin for ‘wise man’, which all by itself created terror and warfare. Our hands to this day show us clearly how tender our past was, how carefully we cared for our higly dependent infants. Had we been violent then such dependant infants would never have survived. Fortunately we are not inherently violent, we are neotenic and of all the creatures on Earth it was us who gave rise to the carressing hand.