Perché gli esseri umani sono diversi – Inglese

 Fossil documentation demonstrates that erect position had already been aquired 6 million years ago. The body was, therefore, human, starting with the feet but with arms which were longer and more robust than ours, short in stature. From around 4 millions years onwards more fossil documentation became available showing that brain volume had increased, the skull becoming larger and more rounded, with a flatter face. The head had undergone a profound recontruction in order to adapt to a body which had become erect, athough certain arcaic characteristics were maintained, in particular the prominant arches over our eyes and the protruding mouth. The teeth were like ours, demonstrating that they were omniverous while their brain must have been about as big as that of a chimpanzee (about 400 cubic cm, with respect to the1,450 of modern man) The Australopitecus afarensis (3.8 – 3 million years ago) skull volume was 450/520cc while the Austalopitecus africanus (3 -2.3 million years ago) brain was 450/600 cc, and that of Homo abilis (2.5 – 1.8 million years ago) 500/780. To these we can add the lateral branch of Australopitecus robustus and the paranthropus, various other branches and subbranches, more or less divergent from what must have been the main branch of evolution. At least until 4 million years ago, our ancestors lived in trees and not in the savanah, we can therefore dismiss the theory which explains the aquisition of erect position as a result of the need to conquer an environment characterised by open fields/meadows. Our other oldest ancestors were always found in the proximity of rivers, surrounded by forests, or else near to ancient salt water lakes (more numerous then than nowadays) in the profound depression of the Great Rift Valley. The Aquatic Theory

 

The above is based on fossil documentation. We can, however, learn from research into comparative anatomy.
According to a hypothesis formulated for the first time by Sir Alister Hardy in 1960, all the principal characteristics which differentiate the human body from that of monkeys, can be explained as an adaptation to a water existence, a process which never reached full completion. First of all, the erect position, the oldest human characteristic according to fossil documentation.
Elaine Morgan, a journalist who has elabourated the various aspects of the aquatic theory (1) suggests that a population on primates, living in a forest near to the sea, started to visit the beach in order to collect sea food, and to enter the water in order to escape from predators. Like other anthropomorhpics they were able to stand up for brief periods, and in times of need they could move away from the shore, enter the water, and being upright could venture further than the felines chasing them. In time the custom of visiting the beach and paddling/splashing in the sea became more more frequent, this new environment offered fewer dangers than the savanah, offering a readily available food source.
From here, we have the adaptation to an existence in water, with the long term effect of  “streamlining” the body to make it suitable for swimming, and allowed our distant ancestors to survive when the equatorial forests of Eurasia receded. Probably this took place with the colonialization of the marine coastlines which slowly approached Africa and penetrated into the depression of Rift vally (see the map) where we can find their remains today. During all this period, while the body was adapting more and more to a water lifestyle, during the night time they took to the trees where they constructed homes made of leaves and branches just like the primates, in this way conserving certain characteristics of tree dwelling primates. When terra ferma became a more attractive option they started to move more and more towards open spaces, without completely abandoning the forests or a watery environment.
This theory may seem bizarre, perhaps because it has not yet been studied by anthropologists working in the field of fossil research, however the anatomic evidence that supports this theory is remarkable. Sooner or later, it will be necessary to make a comparison with the reconstruction of our evolutionary history based on fossil documentation, in particular the oldest period.
The first characteristic to be explained by the aquatic theory is the erect position. Only animals which have adapted themselves to living in water have an hydrodynamic, tapering shape. If they are four legged when they return to land they remain in a horizontal position; but if their shape was originally more vertical than horizontal they take on a perfect vertical position. Penguins are one example and we have followed the same trend.
The loss of fur and the formation of a layer of fat under the skin can also be explained by the aquatic theory. Only aquatic mammals, especially in hot regions, lose their fur which would otherwise slow down their swimming speed and would require time to dry out, this fur is then substituted with a layer of fat. Normally it is these mammals which are most suited to an aquatic lifestyle. In addition, the body hair which remains, clearly visible in the foetus when it has not shed its “fur”, is distributed in a different manner with respect to all other primates, to make the body hydrodynamic. Another detail is the sensibility of our finger tips which are able to recognise objects immerged in water, an ability which the primates do not possess. Once again, man, like all aquatic animals is able to control his breathing, while with terrestrial animals breathing is involuntarily, just like the heartbeat. Another characteristic of aquatic animals is the slowing down of the heartbeat when diving into water. We also possess this quality, though to a lesser degree than seals and marine iguana. If this were not the case it would not be possible for us to stay at the bottom of a swimming pool for seven or eight minutes even for athletes like Pellizzari.
Another anatomic characteristic that can only be explained as an adaptation to swimming, is the special shape of our nose which is hydrodynamical and protects our nostrils when we swim. Only one other primate has a real nose, the proboscis monkey, a primate which used to paddle in the water and to move around with a swimming style similar to that of a dog.
In addition humans cry salt tears, this is a characteristic which they have in common only with those animals which can swallow salt water. Given that the only birds which cry are marine birds, and that only those crocodiles, snakes, lizards, turtles and mammals which live in a marine environment cry, we should not be surprised that the only primate to cry was once a marine primate.
Other anatomic modifications regard the female body, once again these modifications are the result of adaptation to an aquatic lifestyle and erect posture. Above all the shifting of the vaginal channel to a frontal position, which leads to frontal sexual intercourse. In reality it is the entire human body which is remodelled. The pelvis is transformed, becoming larger to contain the internal organs, powerful gluteal musles are needed to balance the trunk, the trunk itself becomes more flexibile taking on a “S” curve. One consequence of this transformation is the modification of the birth channel, wider first in one direction and then in the other, forcing the baby to rotate 90° in order to be born. This would have made the presence of a midwife a necessity. Breasts, which are absent in other primates, and found only in some marine mammels, can also be explained with the aquatic theory. Baby monkeys grasp their mothers’ fur to cling to the nipples which protrude from a flat chest. Once the “water” monkey lost its fur, the baby had nothing left to cling to. Two soft, protruding breasts which could be grasped by small hands would have represented the ideal solution. Finally, hair. Try and imagine our ancestor, millions of years ago, in the water with her offspring. The baby is able to float but naturally must stay near to his mother. The simplest way to remain attached is to hold on to her long hair which floats all around her, the only part of her body which remains above the water. The fact remains that women approaching the moment of child birth experience rapid hair growth.
The newborn baby has a natural affinity with the water, in favourable conditions he is able to swim before he can walk. Tiny babies can be left on the beach in contact with sea water. They will teach themselves to swim by exploring the water, bit by bit, without going too far.
To sum up, practically all the principal anatomical characteristics which differentiate us from primates can be explained as adaptation to an aquatic lifestyle and to salt water, they cannot be explained in any other way. In addition to the anatomic characteristics we can also add the adaptation to food resources which are easily found on the sea shore, from sea food to nest eggs easily killed by marine animals like the seals. From anatomical studies on the human body we can also obtain other useful data. In general, the older the anatomic characteristic, the earlier it appears in the child or feteus. This is certainly not a criteria which can provide exact dates, but it can indicate certain information. The shape of our feet, no longer prehensile and the lack of body hair are present at birth, this is an indication that these two characateristics were already formed in the distant past.
It should not surprise us, therefore that erect posture is the oldest human characteristic which emerges from fossil documentation. Fossil documentation, however, can tell us nothing about the loss of body hair/fur, but the reconstructions which we can see on TV in which our ancestors of tens of thousands of years ago appear covered with fur are completely unrealistic. The reconstruction of Neandertal man, able to produce gutteral sounds is also highly unrealistic: in children the ability to produce words appears after few months while a real language appears around the age of two.
As far as language is concerned, in general aquatic mammals articulate sounds better than terrestrial animals (think of the dolphins), due to the fact that they are the only animals which are able to control their breathing, and also because they are unable to use other forms of communication such as body language or body odours in water. An aquatic lifestyle could have represented the definitive mover towards the development of efficient vocal communication.
The aquatic theory, however, is not taken into consideration by paleo-anthropology, perhaps because it has not been possible to find evidence from fossil documentation. It is, however, not incompatible with data which is already available. The oldest humans remains are always found in the proximity of water, in the ancient salt lakes or the rivers surrounded by forests, or else in swampland at the bottom of Rift Valley.
But now, there is a finding which can only be explained by the aquatic theory, it dates back to the right period, 6 million years ago.

The Tugen Hills ancestor
Various remains of what has been called Orrorin tugenensis were found in Rift Valley in Kenya in 2001, this is rather a strange name but it means “ Tugen Hills ancestor”.
These remains include jaw fragments, finger and arm bones and certain parts of femurs. The femur is very similar in shape to a human femur, this would suggest an erect posture. However, if we consider other aspects then Orrorin was primitive, the finger and arm bones indicate a life spend climbing trees. A TAC exam shows a distribution of bone tissue in the femur that is similar to that of a chimpanzee; an indication of strain supported by the legs during locomotion (while in A. afarensis the distribution of bone tissue is typically human).
The combination of seemingly contradictory characteristics has created perplexity among anthropologists. The aquatic theory could dispel this perplexity, we are in the phase in which our ancestors are still adapting to an aquatic environment. They have aquired an erect posture, not for walking upright but for swimming. Swimming would not have required a strengthening of the bone structure, and therefore this would have remained similar to that of tree dwelling primates. At this point we can try and outline a portrait of our ancestors of 6 million years ago, when they were in a crucial stage in our evolutionary history, when almost all the anatomical characteristics which differentiate humans from primates are to be found.
These ancestors would have been about 100/120 cm tall, the females were smaller, with a certain degree of dimorphism. The body was that of a human adult in miniature, nude, dark skinned, but with several differences. The arms were longer, almost reaching the knees, and robust. The feet were already completely human, proportionately larger, with the toes apart, and perhaps webbed according to a theory of Sir Alister Hardy, (still today many of us have some toes which are joined together).
The biggest differences, however regard the head. If he were alive today he would make a strange impression on us, a seemingly human appearance combined with several rather exotic characteristics. The general appearance, starting with the stature is human, because the morphology of the body is already human, including the postion of the head (with lots of hair ) on an upright body.
But, when we stop to study the face through the straggling locks of hair we can note something that is not quite normal. The face is chubby, (due to the thick layer of fat) wide, the lips red and fleshy.
What is most notable, however is the lack of forehead and the prominence of the mouth which gives the face an appearance of a caricature. The result is not ugly, far from it, but due to the prominance of the jaw we have a striking impression when he smiles, we can see the canines, no bigger than ours, but pointed. The skin is soft and smooth the nose rather squashed and fleshy. Then we have the eyes, well protected by bushy black eybrows we can hardly see the whites of the clary.
Overall we are dealing with graceful slightly amusing beings. Good swimmers, they spend hours paddlings in the water, calling out to each other. One of them is always to be found sitting on a rock to dry himself or to rest. In the cooler hours of the morning and in the evening he is to be found in small groups along the coast looking for sea food. Now and again you can hear the sound of the oyster shells breaking. The rest of the day is spent in the trees, not far from the beach where groups of about 60 meet up to sleep.

Why are we different?
But, let us return to our original theme. Are we or are we not different? And, if it is true that we are different, what do we have in common with other animals?
Man has been taming nature for thousands of years. He is the only animal species which is able to profoundly modify the environment in which he lives. He has transformed the landspace in order to farm the land and breed animals, he has construced bridges and streets, he has created a civilization.
For these reasons human beings have always been certain of their superiority over all other living forms, they have expressed this conviction with cultural traditions. The Bible affirms that man is above all other forms of living beings, but the same conviction is expressed in all other cultures, in all eras all over the globe. In more recent times attempts have been made to understand more clearly the reasons for this superiority, and if possible to give a scientific explanation.
The characteristics which define the uniqueness, and the superiority of man, have been identified in: the upright carriage, the large brain, the capacity to construct tools, etc. But many other animals are able to make tools and manipulate utensils, albeit with less skill. Other animals have large brains and socialize well, or else a perfect erect posture, like the penguins. Others are, either faster, stronger or more aggressive or have better sight or a more keenly developed sense of smell, etc. But this does not mean that they dominate the world like us. The truth is that it is our language which makes us superior, and it is this which explains the enormous gap between ourselves, the primates and all other animals.

Language
Animals also possess some form of language, that of body language, different vocal signs and olfactory signs. But these forms of communication are limited. Adult elephants, despite being very intelligent continue to teach the younger elephants the same thing, and have done so for millions of years. They are like a computer with only a screen, no keyboard, nor other forms of input – output. Certain animals possess something more than simple body language. Some dolphins have notable vocal skills, they learn quickly to imitate the human voice, but, despite this they lack a real language. Perhaps they are not even able to use these vocal symbols to indicate real things. On the other hand a small baby is able to start making use of words with their correct meaning before he is able to pronounce them well, and at the age of two he possesses a real language with simple phrases, questions and answers. No other animal has the linguistic abilities of a two year old child. The Bonobo chimpanzees are able to learn hundred of words, pressing a button with a picture of the “thing” that corresponds to the word they hear. But, even here we are not really able to speak of a real language, the monkey is unable to sustain a dialogue, and there is no real exchange of information In any case, these chimpanzees demonstrate that they know many words, words which would, however, be expressed in nature by body language and not with vocal sounds. In fact, apart from some rare exceptions, animals generally express emotional states with sounds, sounds that they are not able to control. This then, is the first hurdle that must be overcome in order to aquire a real language, to emit sounds that symbolize things that are present or not present, and in a controlled way. This step was surely taken by our ancestors in the period of adaptation to an aquatic existence, and it was not a step that involved greater speed in movement, or the increased ability to emit sounds (chimpanzees can emit about 20 different sounds which can be regulated in infinitive ways). What was missing was the ability to emit sounds in a voluntary manner. This was achieved by controlled breathing, and by the need to communicate with others in the group when they were in the water and unable to use body language. Paleo-anthropologists have searched for anatomical modifications related to vocal ability in fossil documentation. From this research it has emerged that the first signs of vocal capacity start to appear about two million years ago with Homo ergaster, while a more mature vocality, similar to ours can be found 600,000 years ago in one Homo heidelbergensis discovered in Ethiopia. The interpretation of this data, however is not very satisfactory.

 

The prevailing opinion amoung paleo-anthropologists is that vocal abilities appeared first, perhaps by chance, and then later language developed much later. This conviction is based on the fact that cultural “production” which appears in fossil documentation dates back to tens of thousands of years ago, and this would have represented the moment in which man had the idea of abstract ideas and symbols. Before the appearance of these mental representations it would not have been possible for words to exist. Studies on Bonobo chimpanzees, however, demonstrate that the word precedes an ability to pronounce. Therefore, we should not be surprised to find this capacity in our ancestors of 6 million years ago. The same anatomical modifications begin to appear in a child of five months and this indicates the fact that vocal skills were present in the remote past. It seems possible that language preceded the anatomical modifications tied to vocalization, either stimulating evolution or accompanying it. The idea that the development of language must go hand in hand with the production of artistic/cultural objects is without any foundation, even in modern day man, the creation of such objects is connected closely with social functions. In other words, language could have evolved, first for social needs, and at a later date could have been used for art, history, science, etc. Naturally it is true that certain intellectual achievements spread rapidly in the last period of prehistory. Here, however we are not speaking about evolution; the reasons are cultural. The great advantage of possessing a language meant that man was able to develop more quickly. Culture allowed for improvements to take place which went beyond the possibilty of evolution, and this is precisely the reason for our superiority over all other living beings. No other animal possesses a language, not even at the level of a two year old child. Therefore it is impossible to carry on a dialogue with an exchange of questions and answers, it is impossible to communicate or exchange information or even the simplest of ideas. But, as far as we know such speaking animals do not exist and will never exist, because of the millions of years of evolution that separate us. Culture, liberty and responsibility

 

It is, in fact the explosion of culture and the abiltiy to accumulate and conserve knowledge, the capacity to invent new and efficient forms of communication (books, press, cinema, radio, television and internet) that marks the huge difference between us and all other animals. Language and culture means that not only are we able to improve ourselves with incredible speed with respect to the rhythm of evolution, but we are able to decide for ourselves, in other words we are free. According to materialism, freedom is merely an illusion, because our behavior is completely determined by nature and history. But this is an argument which holds good only for animals which are governed by instinct. Just as we are free from the limits of evolution we are free from the limits of instinct, our behaviour is determined by our culture which we construct day by day with our own hands.
Man is, therefore free, capable of self determination and capable of choosing between good and evil, this means that we are moral beings and responsible for our actions. The creationalists base man’s superiority on a literal interpretation of the Bible which is not supported by any scientific proof.
In reality the superiority and uniqueness of man are based on sound principles and we must turn to them if we wish to assume our responsibility towards the world of nature.—————————————————–(1) The Descent of Woman – Elaine Morgan – Souvenir Press, London