"THE SEVEN DAUGHTERS OF EVE" by Bryan Sykes, Corgi edition 2002 (ISBN 0 552 14876 8)
Professor Bryan Sykes asserts that by studying mitochondrial DNA samples he has found that 95% of Europeans are descended directly from seven women. He has even given names to these women who lived from 10 to 45 thousand years ago. Back in 1991 the body of a man was found high in the Italian Alps. Scientific tests soon proved that the man had not died recently but between 5,000 and 5,300 years ago. Nevertheless the body was preserved well enough for DNA samples to be taken and when comparisons were made with samples taken from living persons an exact match was found in an Irish woman now living in Dorset, England. In other words the woman now living and the man who died 5,000 years ago were related.
The importance of DNA (or deoxyribonucleic acid), as the substance through which our genetic inheritance is transmitted, only became known in 1953. This was when two Cambridge scientists, James D. Watson and Francis Crick worked out the molecular structure of the substance.
Whilst the genes that determine what we look like, whether we have blue or brown eyes for instance, are part of the chromosomes that reside in the nucleus of the cells that make up our bodies, there is also some DNA in the mitochondria, which are found in the cell but outside the nucleus.
Well before the use of DNA, some researchers had tried to study the relationship between various races by comparing blood types. This initially pointed to some strange relationships but as more ways of typing blood were found a clearer picture emerged. In fact it allowed scientists like Luigi Cavalli-Sforza to construct what looks like a family tree for the human species and gives a good idea of the genetic distances between various populations.
Sykes, however is not happy with these evolutionary trees as they are sometimes called. One reason is probably that it looks similar to a racial classification. He also claims that these diagrams give the impression that populations (eg Italians and English) diverged from some common ancestors, never to intermix again. Our common sense tells us that members of these two nationalities have, and do inter-marry; we dont need Sykes to tell us. The genetic distance between Italians and English is shown as fairly limited on the diagrams because, on average, there is not much difference between them as say compared to the differences between the population of Japan and that of Ethiopia. And while there may, or may not, have been an ancient proto-Italian/English population, the average Italian is more likely to have a relatively recent common ancestor with the average Englishman than a Japanese or Zulu.
Sykes presents us with a different diagram, this one based on mitochondrial DNA and in his opinion giving us a real evolutionary tree. This one he claims is based on individuals and not populations. If two people have very similar mitochondrial DNA then they are more closely related "with respect to this gene" than people with different mitochondrial DNA. As for the 30 to 35 thousand other genes? Sykes fails to mention these. He goes out of the way to point out that in some cases his diagram shows a closer relationship between an individual European and an African than between another four Africans shown on the diagram. A diagram based on any other gene would no doubt show a completely different relationship but Sykes fails to point this out.
Of more relevance to our understanding of how modern humans evolved is the fact that the mitochondrial DNA changes over time due to random mutations. By relating these changes to time, Sykes claims that the root of the evolutionary tree dates to 150,000 years. In other words at that time there was a living female who is a direct ancestor of all humanity.
Sykes describes some of the characteristics of mitochondrial DNA. This comes in very small amounts compared to the DNA in the cell nucleus. All individuals inherit their mitochondrial DNA from their mother. The small amount of mitochondria in sperm is jettisoned whereas that in the human egg cell is passed onto the next generation. Hence the mitochondrial DNA tells us about our maternal but not our paternal ancestry. Nevertheless scientists favour the mitochondrial DNA as mutations occur more often, especially in a small section called the control region, hence creating enough variety to tell us about developments over time.
Some of Sykes early research was with Polynesians and the mystery of their origins. Did they originate in Asia or did they come from South America as proposed by Thor Heyerdahal?
Sykes collected a number of samples of DNA from all over the pacific and the evidence indicated that Polynesians are predominantly of Asian origin. There is sequence found among a small proportion of Polynesians which points to a connection with native New Guineans, apparently due to some admixture in the past. There were also two samples, which match with sequences from Chile. This and the cultivation of sweet potatoes (a native of South America) would suggest that Polynesians visited South America but did not settle there.
Sykes then turned his attention to the origins of Europeans. It appears that humans, or pre-humans, lived in England half a million years ago. There is little evidence of these left but in 1993 bones of a very ancient human were found. These were given the name of Boxgrove Man but they do not appear to be a direct ancestor of modern humans. Neanderthals, who were still living in Europe 28,000 years ago, have been suggested as contributing to the makeup of modern humans. Because there have been a fair few Neanderthal remains uncovered it was possible to extract DNA for comparison. Nevertheless Sykes has been unable to find any modern European with any Neanderthal DNA.
Another theory of the origins of Europeans posit that the ancient hunter gatherers such as Cro-Magnon man were pretty well displaced about 10,000 years ago by early farmers who originated in the Middle East. The evidence presented by Sykes however indicates that this Middle Eastern component only contributes 17 to 20% of the ancestry of modern Europeans.
More evidence of the ancestry of Europeans was obtained with the collection of DNA from Cheddar Man. The remains of this man were found in a cave in the Cheddar Gorge in Britain and subsequently found to have lived in 9,000 years ago, about 3,000 years before farming was introduced to Britain. Testing found an almost identical match with the DNA of an adult male, a teacher, living in the area and two exact matches with two of his pupils. Further testing revealed another adult with an identical DNA match. It was obvious then that at least part of the modern English population is descended from people who lived there during the Palaeolithic age.
While Sykes used mitochondrial DNA, which tells us about ancestry along the maternal line, other researchers have used the Y chromosome, which is carried down the paternal line. Would the results be the same? Broadly they were and confirmed that the ancestry of modern Europeans was about 80% from the inhabitants of Palaeolithic Europe and at most 20% from Neolithic settlers from the Middle East.
Sykes reconstructions had identified seven major genetic clusters among Europeans. Within these clusters the DNA sequences were identical, or at least very similar. By averaging the number of mutations within these clusters it was possible to estimate when the founder sequence arose. In other words they could estimate how far back in time the "clan mother" lived. Sykes has given names to these women and has produced a map showing where he believes they lived.
Sykes has given a chapter to each clan founder, describing how and where they lived. Much of this is of course hypothetical.
The oldest founder is Ursula, born 45,000 years ago and said to be ancestor of 11% of modern Europeans. She came from an area in, or near Greece and may have been among the first modern humans to colonise Europe.
Twenty thousand years later another clan was founded with Xenia who came from east of the Don River. Her descendants make up 6% of Europeans, and surprisingly, 1% of American Indians. Somehow some of her descendants migrated to North America during the Palaeolithic. Five thousand years later another clan began with Helena. She came from an area which now forms part of France. Her clan seems particularly fecund and her DNA is found in 47% of modern Europeans.
Seventeen thousand years ago, during the last Great Ice Age, two more clans began. Velda was born in northern Iberia and her descendants make up 5% of modern Europeans, especially in Western Europe and northern Scandinavia. At the same time another clan began in northern Italy with a woman given the name of Tara and her descendants make up 9% of Europeans, being particularly numerous in the west of Britain and in Ireland. In northeast Italy, another clan founder, Katrina was born 15,000 years ago. Her descendants comprise 6% of modern Europeans, especially around the Mediterranean.
The last clan, that of Jasmine, began, not in Europe but near the Euphrates River in the Middle East. It is believed this clan developed agriculture and introduced it to Europe. The descendants of Jasmine now make up 17% of Europeans and are most common where prehistoric farmers first became established.
All of these women had mothers of course and received DNA from them. The common maternal ancestor of all humanity is, according to Sykes, a woman who lived in Africa 150,000 years ago. She of course was not the only female alive at the time and the others would have passed their DNA onto their children. Nevertheless the mitochondrial DNA of only one woman has survived until modern times.
This brings us to the out of Africa theory which asserts that all modern humans are descended from a small group that evolved in that continent. To back up this assertion Sykes points out that although Africa has only 13% of the worlds population it has 40% of the maternal clans, in fact 13 of the 33 clans he has identified. One of these clans is ancestral to all those native to areas outside of Africa, including the seven European clans.
What about the 5% of Europeans who do not match the DNA of the seven clans? Two fishermen living off the west coast of Scotland had unusual DNA sequences which were traced back to Siberia and South America. In fact as American Indians are largely of Siberian descent both men probably had a common ancestor. Sykes claims that stories like this "make nonsense of any biological basis for racial classifications". He also claims that "we are all a complete mixture; yet at the same time, we are all related".
Obviously all humans, being of the same species, are related to some extent. By the same token we are more closely related to chimpanzees and gorillas (according to DNA analysis) than are orangutans or other anthropoids. Does this mean we should head for the zoo and try to find our soulmates in the gorilla cage?
The evidence as presented by Sykes is that 95% of Europeans are descended from seven women, all of whom lived in or near Europe tens of millennia ago. This and the fact that their DNA is rare or non-existent in most non-Europeans would indicate that the mixing of peoples has been fairly limited. One hardly needs DNA to differentiate between the average white man and a Negro, Polynesian or South American Indian. To the extent that there is evidence of race mixing this begs the question how can races mix if, as Sykes seems to be claiming, race does not exist?
How much does the DNA of the mitochondria really tell us about an individual? An individual receives pretty much the same amount of nuclear DNA from each of their four grandparents. The further back we go the more ancestors we have, all contributing to our genetic make up. If we could trace back thousands of years we could no doubt discover millions of direct ancestors (albeit allowing for some inbreeding). On the other hand there must be millions, in many cases hundreds of millions, of the present day population which carry identical, or very similar mitochondrial DNA. Sykes rails against the results gained by Cavalli-Sforza and the emphasis on what he considers subjective "populations" rather than individuals. Yet two individuals can have identical mitochondrial DNA but look very different due to having very different genes in the nucleus of their cells. Alternatively two individuals can have similar genetic make up overall but have very different mitochondrial DNA. Like it or not Sykes discoveries would seem to tell us more about populations races if you like than it tells us about individuals.
The book is interesting to read and is recommended for anyone wanting to know themselves or humanity at large. Nevertheless we could have done without Sykes politically correct incantations on race.
"THE MADNESS of ADAM AND EVE: How Schizophrenia Shaped Humanity" by David Horrobin, Corgi edition 2002 (ISBN 0 552 99930X)
Horrobin asserts that insanity, or more particularly schizophrenia, has played a crucial part in the cultural development of mankind. Schizophrenia, a serious psychiatric disorder, affects around 1% of the population. It can have a serious and debilitating effect and schizophrenics who have not been treated for the problem can be involved in weird, bizarre and occasionally violent behaviour. How then can it be advantageous to the human race?
The physiology of modern man is different, but not too different, to his ancestors who lived hundreds of thousands of years ago. A Neanderthal, cleaned up and dressed in modern clothes would not look too far out of place in our society. Not only did he look much like us he appears to have had a larger brain. Nevertheless cultural and technological development until the advent of modern man (Homo sapiens) was terribly slow. It appears that it was not simply the size of the brain but something about its structure that enabled us to develop a complex culture. These changes to brain structure may have, in some cases, also been involved in a tendency to schizophrenia.
Twin studies with schizophrenics indicate a genetic determinant for the disorder. If one member of a set of identical twins is schizophrenic then in 40 to 50% of cases the other twin is schizophrenic as well. This occurs even when the twins are separated at birth. It was also found than when a schizophrenic woman had children, one in ten of them inherited the disorder. The evidence points to a genetic predisposition for schizophrenics but other factors must also be important as evidenced by the less than 100% concordance found in twin studies.
It is the case that some very creative persons had psychotic episodes. Unfortunately until the invention of anti-psychotic drugs many sufferers had their lives destroyed. This is despite the fact that many had been high achievers at school.
It has been found that a disproportionate number of close relatives of schizophrenics are highly creative, highly imaginative and highly successful. They are more likely to have an interest and ability in music, to lead interesting lives and many make enormous contributions in intellectual, political and commercial fields. Unfortunately a few are sociopathic and criminal. Studies of the families of some famous persons revealed that Albert Einstein had a schizophrenic son and Bertrand Russell had a number of schizophrenic relatives. A lot of creative persons have exhibited odd behaviour, but not to the point of psychoses, and are referred to as schizotypal. It appears that the genes that predispose a person to schizophrenia also contribute to creativity and achievement. It stands to reason that any eugenics program which eliminated schizophrenia could actually slow down human progress.
What of other mental disorders? It has been claimed that 30 to 60% of creative writers suffer at some time from bipolar (manic-depressive) disorder. Einstein, Edison, Disney and Churchill are a few of the high achievers believed to be dyslexic.
There is more criminality, paranoia and psychopathy in the families of schizophrenics. Schizophrenics are themselves only slightly more likely to commit crimes than most non-schizophrenics but when they do resort to violence it can be in really bizarre ways.
Horrobin contends that the schizophrenia that affected people thousands of years ago was less severe than that which occurs in modern societies. For that matter it could have been much less prevalent or severe in any pre-industrial or less-developed nation. Its believed that a rise in saturated fat in our diet that came about with industrial society worsened the condition. Those in less developed societies had a diet richer in essential fatty acids, which is said to attenuate the impact of the biochemical changes which lead to schizophrenia.
It would appear then that a change in diet should reduce the severity of mental problems and this in fact appears to be the case. Patients with schizophrenia and bipolar disorder expressed a substantial improvement where omega-3 fatty acids were added their diet. In a prison experiment volunteers were given capsules of multivitamins, omega-6 and omega-3. This resulted in a 30% drop in violence in general and a 50% reduction among those with a violent prison record.
It seems that not only psychotics but many other troubled souls could be assisted by an improvement in diet. As for those with psychoses, the diet regime seems a much cheaper alternative than drugs and eliminates the side effects of drug treatment.
As for Horrobins contention that our cultural evolution rested largely on the appearance of the genes that cause psychoses? He admits that there is much more to be learned especially from studies of the human and chimpanzee genomes. Much of the evidence he discusses is highly technical and confusing for the average reader. His ideas however give us a different slant on how we humans came to be as we are today.