The Scars of Evolution Read online

  Elaine Morgan

  The Scars of Evolution

  “Remnants of the past that don’t make sense in present terms – the useless, the odd, the peculiar, the incongruous – are signs of history.”

  Stephen Jay Gould

  Souvenir Press

  Acknowledgements

  This is the third book I have written promoting a view of human evolution hitherto regarded as heresy.

  I should like to express my sincere gratitude to Dr Marc Verhaegen. It was a paper published by him in 1987 which gave me the idea of approaching the subject from a different angle, and I have benefited greatly from his advice and co-operation during the writing of this book. (This does not necessarily imply that he agrees with all the opinions expressed in it.)

  I am especially grateful to the family of the late Leon p. La Lumiere, Jr, for allowing me to reproduce his maps of the geological history of the Danakil Alps in Ethiopia, showing how our ape ancestors could have been marooned on an island, and to Caren Meyer who helped me to locate some of the more inaccessible source materials.

  My thanks are also due to the hundreds of people who have written to me since 1972 expressing interest, offering ideas and suggestions or enclosing cuttings and references. Their letters have been a constant and invaluable source of encouragement.

  Contents

  Title Page

  Acknowledgements

  List of maps

  Introduction

  1 The Emergence of Man

  Why are we so different? – Evolutionary ladder a myth – The unanswered questions – The information explosion – Something must have happened – The wilder shores of speculation – The conservative position: ‘From the trees to the plains’ – Outflanking Natural Selection – Ignoring an axiom.

  2 Fossil-Hunters

  The bones of contention – The missing link – Keith recants – Birth of the savannah theory – The hunt moves north – Lucy and the crocodiles – Molecular biologists – The fossil gap narrows – Sometimes they are wrong.

  3 The Cost of Walking Erect

  It looks easy – Darwin’s double negative – Lucy confounds the theorists – Walking bridge into walking tower– Kinks in the spine – Stresses on the vertebrae – Disc trouble – Remodelling the muscles – Inguinal hernia – Gravity and the blood – Varicose veins – Haemorrhoids – Hypertension.

  4 Explaining Bipedalism

  Scanning the horizon – Man the hunter – Seed eaters – Locomotor analysis – The food carriers – Sex and bipedalism – The noonday ape – The proboscis monkey – Cancelling the disadvantages – Lyell and the changing planet – Continental drift – A geological hot spot – The speed of speclation – A previous aquatic ape.

  5 The Cost of a Naked Skin

  Darwin’s dilemma – Shivering on the savannah – Functions of a fur coat – What colour was Adam? – Rickets – Skin cancer – Coco Chanel and the doctors – Sebaceous glands – Acne – Dandruff.

  6 Explaining Hairlessness

  ‘Nothing to explain’ – Avoiding parasites – Sexual selection – Over-heating the hunter – The foetal ape – The vulnerable brain – Fur and sweat – The bigger, the balder – Where nakedness is at a premium – Too small to be naked? – The psychological barrier.

  7 Keeping Cool

  Panting – Sweating – Apocrine sweat glands – Milk – Cattle and horses – Conserving salt – The disappearing apocrines – Underarm odour – Finger-prints – Sweaty palms – Lie detectors – The eccrine gland mammal – heat stroke – ‘It’s the humidity’ – Heat waves and thrombosis.

  8 Sweat and Tears

  All out of step except Homo – A sweaty monkey – Water and sebum – Sea birds and salt glands – Weeping mammals – Alice and the Walrus – Psychic weeping – Darwin’s babies – Frey and the tear jerkers – A lump in the throat – Salt hunger – Eating earth – The break-through of the century.

  9 Fat

  A pathological departure? – Fat foetuses and chubby infants – Anorexics can’t conceive – Subcutaneous fat – Homo is the odd man out – ‘Slim as Nature intended’? – Wound healing – Insulation in water – Redistribution of fat – Buoyancy.

  10 Explaining the Fat Layer

  ‘Nothing to explain’ – Storing energy – Hibernation – Brown fat and white fat – A multi-stage strategy – A consequence of agriculture – ‘For sexual attraction’ – Menopause – Middle-age spread – Fat and oestrogen – Obese rats – The Gothenburg experiment – Anorexia.

  11 Breathing

  A foolproof system – Again the odd man out – The descended larynx – Smell – Processing the air – Breathing disorders – Swallowing – Adam’s apple – Snoring – Sleep apnoea – Babies are different – Cot deaths – Adenoids – Earache – Researching the larynx – An ‘unfortunate side-effect’ – Diving birds and mammals – The evolution of speech.

  12 Sex in Transition

  The loss of oestrus – Concealed ovulation – What happened to libido? – Explaining loss of oestrus – ‘Permanently receptive’ – Pair-bonding – Natural weapons – Testes size – Towards monogamy – Pheromones – Sexual skin – Ventro-ventral copulation – Orang-utans – Rape – Social conditioning.

  13 The Aquatic Ape Theory – The Counter-Arguments

  Plank’s principle – ‘A series of unconnected coincidences’ – How to tell a real scientist – The Eureka factor – The hypothermic ape – Diving women – Need of more calories – A change of diet.

  14 Brains and Baboons

  Brain tissue is expensive – Omega–3 – All the better to think with? – Two good questions – Neotenous whales – Viability of aquatic apes – History in our genes – The baboon marker – An Asian origin of man? – The other possibility.

  References

  Index

  Copyright

  List of Maps

  Figure 1. The generally supposed relationship of the Nubian plate of the African continent to the Arabian plate during the late Miocene

  Figure 2. The configuration of the same region as displayed in Figure 1, but as it may have been at the beginning of the Pliocene

  Figure 3. The African Rift Valley showing the principal sites where hominids have been dis covered

  Figure 4. The location of the Tertiary deposits called the Red Series that may yield hominid fossils if this hypothesis is correct

  Figure 5. Cross section through northern Afar, Ethiopia, looking north-northwest.

  These maps were prepared by the late Leon P. LaLumiere, Jr, of the Naval Research Laboratory, Washington, D.C., to illustrate his theory of the location for the evolution of bipedalism. Figures 1–4 were previously published in The Aquatic Ape by Elaine Morgan (1982). Figure 5 (after Hutchinson and Engels, 1970, 1972) was previously published in GEO Magazine, 14 November, 1984.

  Introduction

  ‘What a piece of work is a man! How noble in reason!

  how infinite in faculty! in form, in moving, how

  express and admirable! in action how like an angel!

  in apprehension how like a god! the beauty of the

  world! the paragon of animals!’

  Shakespeare: Hamlet

  All general practitioners with heavy casebooks, reading Hamlet’s eulogy, must be acutely aware that there is another side to the coin.

  Since all their patients are mammals – even though of an exceptional kind – it is only to be expected that in common with the rest of the animal kingdom they may occasionally suffer from fractures and lesions, digestive disorders, birth defects, viral and bacterial infections and, in old age, impairment of functions.

  But in addition to that, there will be some in every doctor’s waiting room complaining of troub
les which are unique to our species. They are apparently due to design defects – flaws in the human blueprint – the scars of our evolution. It is as if at the birth of humanity (as at the birth of the princess in the fairy tale) good fairies clustered around the cradle bearing gifts. ‘I endow this child with a wonderful brain and the powers of reasoning and inspiration …’ ‘I bring dexterity unparalleled in any other living thing …’ ‘I bestow the power of speech …’

  But last of all came the bad fairy, and added the spiteful postscript:

  ‘I curse this child with the propensity to suffer from lower back pains, obesity, enlarged adenoids, acne, varicose veins, cot deaths, sunburn, sleep apnoea, gynaecological and sexual malfunctions, dandruff, inguinal hernia, haemorrhoids.’

  These and other things are the price we pay for being human. They came as part of the package deal.

  So what sort of deal was it? What conceivable evolutionary path left us lumbered with these unwelcome gifts as well as the shining attributes praised by Hamlet? It is a fascinating riddle, and in searching for the answer it is necessary to begin at the beginning, with the most fundamental question of all.

  1

  The Emergence of Man

  ‘The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd.’

  Bertrand Russell

  Darwin’s theory of evolution propounded an answer to one major mystery about our species, namely, why we bear such a powerful physiological resemblance to the African apes – the gorilla and the chimpanzee. He argued that it was because we and they share a common ancestor.

  This solution immediately raised a further problem. If we are so closely related to them – and everything we have learned since suggests that the relationship is even closer than Darwin supposed – then why are we not more like them? When a species splits and gives rise to three separate lineages, there is no reason to expect that species C will differ from A and B any more widely than A and B differ from one another. Yet in the case of the anthropoids this is what happened. It is not because we split off earlier: we didn’t. Evidence from molecular biology indicates that if any of the three diverged in advance of the other two, it was the gorilla.

  Darwin was well aware that he could not answer all the questions surrounding human emergence. But his supporters were confident that he was on the right lines and that it would only be a matter of time – perhaps a couple of decades – before most of the remaining problems were solved.

  One hundred and thirty-eight years have now elapsed since the publication of The Origin of Species, and scientists are no nearer to agreement on the question of why there are gorillas and chimpanzees and people, instead of merely three different species of African ape. Some people fail to see the point of the question. They would answer it by saying that we have simply ‘evolved further’ than the apes; that we have climbed a few more steps up the evolutionary ladder, while gorillas and chimpanzees have for some unknown reason lagged behind.

  The concept of the evolutionary ladder is deeply rooted in our culture. It appealed especially to the Victorians with their belief in Progress and Perfectability, and it lasted a long time.

  In the 1920s Elliot Smith, an influential British authority on human origins, lectured about ‘Man’s ceaseless struggle to achieve his destiny’, and declared that ‘for untold ages Nature was making her great experiments to achieve the transmutation of the base substance of some brutal ape into the divine form of man.’ In the 1930s another pioneer, the Scots fossil-hunter Robert Broom, asserted: ‘There was no need for further evolution after Man appeared.’

  Even today there is widespread belief that we represent a kind of pinnacle to which the evolutionary process was aspiring; that ‘more like people’ equals ‘higher up the ladder’; that Homo sapiens was in some way the object of the whole exercise, and that anywhere in the universe where the evolutionary process has gone on long enough, the emergence of an ‘intelligent life form’ akin to ourselves is a foregone conclusion, as a culminating triumph for the life force.

  But the ladder is a myth. ‘Nature’ – the evolutionary process – does not aspire to anything. It does not aspire to intelligence in its creations; it does not aspire to complexity. These qualities in living things may emerge and be intensified – as it were under duress – when conditions of life become exacting. But simple and mindless organisms persist and multiply and thrive unchanged over many millions of years while more complex and powerful species like the dinosaurs rise and fall. Sentience, mobility and intelligence, like wings or eyesight or a sense of smell, can regress in a species where they no longer conduce to survival.

  The essential point is that evolution takes place in response to things which have happened, not things which are predestined to happen. Man is no more an evolutionary pinnacle than a tree is, or a termite or an octopus. His emergence was no more inevitable than that of any other species.

  We find it easier to accept that other life-forms are fortuitous, arising as a result of special sets of circumstances. For example, in some parts of the world geological changes have left freshwater fish marooned in underground caves. If that had not happened at some time in the past, there would be no blind white cave fish. In Australia there was once a primitive mammal that burrowed in the earth like a mole. If its territory had not at some time become increasingly waterlogged, there would be no duck-billed platypus. The world would have spun on and the biosphere would have continued its permutations without them.

  The presence of people on earth is just as fortuitous. It might very easily never have come about. It takes a lot of explaining. Life on earth could well have proceeded on its way without us. In fact, nowadays Greens are tempted to say that the appearance of this improbable naked biped among the earth’s fauna was not so much an evolutionary pinnacle as an ecological disaster.

  Other people, while accepting that the presence of people on the planet requires an explanation, take it for granted that the explanation must have been discovered long ago.

  This impression is understandable. Numerous books are published on the subject, written by professional scientists and aimed at the general reader. Several highly acclaimed documentary series have been televised dealing with evolution in general and/or human evolution in particular. There are A-Level courses where the topic is covered in some detail. Very rarely in these books and programmes and curricula is there any indication that a major and crucial problem remains unsolved. Usually the evolutionary narrative progresses smoothly, confidently and seamlessly from unicellular organisms to modern man.

  There is usually a bland reference to the fact that the ancestral hominids began to stand up and walk about on their hind legs, as if it were the most natural thing in the world for a mammal to do, though no other mammal has ever done it. The question of why our bodies are hairless used to be discussed at some length, but now there is a growing tendency to avoid all mention of it. The writers have lost confidence in the answers they thought they knew thirty years ago, and naturally in addressing the layman they are not anxious to shine a spotlight on problems which have not been solved.

  This motive does not operate in the case of the academic journals. Within those precincts the writers are not concerned with papering over the cracks. Almost all of them have an entirely genuine concern with discovering the truth. They therefore respect facts, identify sources, rigorously define the borderline between what is known and what is guessed at, and gracefully admit defeat when one of their beautiful hypotheses is slain by an ugly fact. In these journals an unsolved problem is not something to be brushed under the carpet: it is regarded as a challenge and an opportunity.

  In the whole history of evolution, the emergence of man is the one episode where the unanswered questions are thickest on the ground, and the challenge is most frequently taken up. At regular intervals, hypotheses are published attempting to account for one or other puzzling feature of human anatomy. These efforts may be criticised or they may be ig
nored. In either case the hoped-for chorus of ‘Eureka!’ fails to materialise and the theorist goes back to the drawing board. After a time another hypothesis is put forward, with the same result.

  The present state of play may be summarised as follows. Four of the most outstanding mysteries about humans are: (1) why do they walk on two legs? (2) why have they lost their fur? (3) why have they developed such large brains? (4) why did they learn to speak?

  The orthodox answers to these questions are: (1) ‘We do not yet know’; (2) ‘We do not yet know’; (3) ‘We do not yet know’, and (4) ‘We do not yet know’. The list of questions could be considerably lengthened without affecting the monotony of the answers.

  Scientists do not normally sum up the situation as starkly as that, for several reasons. In the first place, they do not see it like that. They have lived long enough with the conundrums to be no longer surprised by them; they are satisfied that new data are continually being amassed and steady progress is being made. That is quite true. As in any other form of enquiry, if you can produce solid reasons for discarding a false hypothesis, that represents a significant advance. Over the last thirty years a number of seductive evolutionary scenarios have been successfully demolished.

  There is one other reason why they underestimate the extent to which they have been bogged down over this question for more than a century. That is the information explosion. Science has become ever more subdivided, and researchers have become absorbed in their own specialities.