The Repercussions of Aquatic Ape Theory (Written in 2006)
A recently-repeated two-part programme on Radio 4 attempted to resurrect the Aquatic Ape Theory of human evolution by adding new evidence to the already impressive evidence used by Elaine Morgan in her many books on the subject. What was not mentioned, and has never to my knowledge been mentioned in respect of this theory, is that it is essentially Lamarckian, which may account for the neo-Darwinian scientific establishment’s resistance to it. (Similarly, a recent BBC2 Horizon on epigenetics never mentioned Lamarckian inheritance by name, even though that was what it was about). According to neo-Darwinism, the fact that we, uniquely amongst the apes, have many features that appear to be adaptions to an aquatic life does not mean that our ancestors had one; those features suit us just as well to a terrestrial life. In order for Aquatic Ape Theory to be totally convincing, you need to be a Lamarckist. For the benefit of those who may not know them, I must explain the origins and characteristics of Lamarckism and neo-Darwinism.
Though Darwinists and neo-Darwinists have seldom acknowledged it, there were plenty of evolutionists before Darwin, including such celebrities as Kant and Goethe. The views of most 18th century evolutionists can be most easily summarised with reference to the most prominent of their number, Jean-Baptiste Lamarck. In the simplest terms, what Lamarck believed was that every living organism was the product of the accumulated responses that all its ancestors had made to the environments they had inhabited. In order that environmental effects could be cumulative, the central tenet of Lamarckism was the inheritance of acquired characteristics, which means that offspring can build on the achievements of their ancestors. In other words, the changes that occur to an organism during its lifetime, as a result of behaviour, diet, climate or illness, could (though not necessarily would) be transmitted to any subsequent offspring. All pre-Darwinian evolutionists took it as read that acquired characteristics were inheritable in some degree.
The relatively new idea that Darwin and Wallace became famous for introducing into evolution theory was the issue of Natural Selection, whereby every living organism owes its existence to the fact that all its ancestors were lucky enough to have inheritable characteristics which suited them to the environments they inhabited. Those fortuitous characteristics prevented all those ancestors from being culled by cruel nature before they managed to reproduce and pass on those characteristics to some of their offspring. But Natural Selection is, in itself, only the guiding system of evolution; it says that, given that there self-evidently is variation between and within species, the organisms which leave descendants tend to be the ones whose inheritable variations favour their survival over their competitors. The hidden assumption behind Natural Selection, especially amongst neo-Darwinists, is that the source of variation is random. Though Darwin did make occasional references to the concept of spontaneous variation, he had very little to say about the cause of variation, which is where one must look for the source of evolutionary change. Consequently, it is a supreme irony that one of the most famous books of all time, “The Origin of Species”, is notable for the fact that it has almost nothing to say about the origin of species.
In the mid-19th century, there was no natural conflict between Darwinism and Lamarckism, since one concentrated on the guiding system of evolution and the other concerned itself with the source of inheritable variations; consequently, it was possible to regard Darwinism as a complimentary development of Lamarckism, which is exactly what the famous German evolutionist, Ernst Haeckel, did. As it happened, throughout his life as a renowned evolutionist, Darwin also accepted that one of the sources of variation was the inheritance of acquired characteristics. In modern-day terms, Darwin was a Lamarckist. What this shows is that, in order to be a believer in Lamarckian inheritance, you do not need to believe it is the only factor in evolution; nor do you need to deny the importance of Natural Selection, either in its literal or Darwinian sense. However, neo-Darwinists have always been keen to create a conflict between Darwinism and Lamarckism by presenting them as exclusive alternatives.
Following Darwin’s death in 1882, a German professor of zoology, August Weismann, claimed that the germ-plasm took a continuous line of descent from grandparents to grandchildren without being affected by the parents in between. In other words, the contents of sperm and eggs are unaffected by their possessors. As a consequence of this, Weismann claimed that the inheritance of acquired characteristics was impossible. Lots of Darwinists believed him, and Darwinism became censored in respect of the inheritance of acquired characteristics. This resulted in a major row in evolutionary circles in which everyone was forced to consider themselves to be either Weismannists or Lamarckists.
In the 20th century, following the rediscovery of Mendel’s famous 1865 paper on heredity and lots of research into the contents of cell nuclei, it gradually became apparent that the material of biological inheritance, in the form of chromosomes, could not be affected by environmental influences in any responsive way. Effectively, Weismann and Mendel were both proved right within the context of the simple materialist paradigm that has pervaded almost all science. Therefore, the inheritance of acquired characteristics became official heresy in biological circles (except briefly in the USSR) and Lamarckism became banished to the realms of vitalist philosophy. The marriage between censored Darwinism and Mendelism became known as neo-Darwinism.
During that period, a Danish botanist called Wilhelm Friedrich Johannsen had coined the term ‘gene’ as the material unit of biological inheritance, which caused the word ‘genetic’ to mean both ‘inherited’ and ‘contained in the genes’. That always suited the neo-Darwinian scientific establishment, which had come to regard genes as the sole determinants of inheritable characteristics. Consequently, the perennial Nature v. Nurture debate became translated as Genes v. Environment. In Lamarckian terms, nature is just inherited nurture, being the accumulated effects of past environments; so the real issue is not what genes an organism is born with but how its ancestors used those genes.
Throughout the entire evolution debate of the past two centuries, there has never been a shred of philosophically-rigorous evidence against the inheritance of acquired characteristics, and the empirical evidence has always been in favour of it. There are mountains of circumstantial evidence from nature which can be explained much more easily by Lamarckism than by neo-Darwinism. There have been numerous experiments done which have demonstrated the apparent inheritance of acquired characteristics, including those by Edouard Brown-Sequard and Karl Semper in the 19th century, and those of Paul Kammerer and Conrad Waddington in the 20th century. Recently, the phenomenon of second-generation Thalidomide symptoms can only be explained by reference to non-genetic inheritance, and some behind-the-scenes scientists have been reporting new evidence of Lamarckian inheritance.
Yet neo-Darwinists have always denied all that evidence, describing Lamarckism as discredited and its adherents as ridiculous, simply because they cannot reconcile it with their belief that genes must be the sole determinants of inheritable characteristics. The reality is that genes are only known to be the coded determinants of an organism’s chemical – and hence medical – abilities; no satisfactory mechanism has ever been offered to as to how the ability to do certain chemical processes could also determine morphological and behavioural characteristics. That is pure supposition.
In recent years, the issue of gene expression has come very much to the fore, and it is in this field that the most doubts have been expressed, even by some scientists, about the orthodox neo-Darwinian view. Although we are learning a lot about all the material intermediaries involved in gene expression, ultimately we still don't have the faintest clue as to what causes the chain of events that lead to any particular gene being expressed. There is invariably an environmental trigger, but whether that can be increased or decreased in its efficacy over time and generations is not clear. What is clear is that chromosomes are not as invulnerable to change as was previously thought and that some of those changes are transmissible to future generations. So now, at long last, some scientists are beginning to realise and acknowledge that genes are not the determinants that neo-Darwinism has always supposed them to be. If genes are not the sole determinants, then, whatever other factors determine inheritable characteristics, they are undoubtedly not constrained by the limitations of Mendelism.
With regard to Aquatic Ape Theory, the neo-Darwinian view is that new inheritable characteristics are caused by random changes to, and mixings of, genes. Our aquatic features would have been randomly caused, and either favoured by Natural Selection (if our ancestors had an aquatic existence) or retained merely because they never did us any harm. With Lamarckian inheritance, those features were both caused by our ancestors living at least a semi-aquatic existence and retained by Natural Selection because they were useful then and they don’t do any harm now. The most impressive new piece of evidence for our aquatic origins concerns our dependence on Omega-3 fatty acids and iodine for the development of our large, complex brains. These chemicals would not be readily available to a terrestrial ape, but would be abundant in a seafood diet. However, diet is an environmental effect which would need to be cumulative in order to cause any evolutionary change. Both the anthropologist, Leslie Aiello, who featured in the Radio 4 programme, and the science populariser, Robert Winston, have repeatedly asserted, in books and TV programmes, that the reason our ancestors developed big brains was because their diets became richer; they don’t acknowledge (and probably don’t realise) that their assertion is flat Lamarckism (unless of course they are claiming our ancestors’ brains could have gone from small to big in one generation). Similarly, many prominent evolutionists who are critical of neo-Darwinism for down-playing the role of the environment do not acknowledge that, in order for nurture to have played any direct part in evolution (as opposed to individual development), its effects have to be cumulative, which means that acquired characteristics must be transmitted through generations.
If such transmission happens at all, then the mechanism exists, so its effect upon evolution could have been enormous. In my opinion it is in the mechanism by which acquired characteristics become transmitted that the key to evolution lies. Rupert Sheldrake’s hypothesis, which I fully support, is that the answer lies in some as-yet-undetectable communication system. The difference between this view and classic Lamarckism is that characteristics are not inherited exclusively from parents but are received, in descending degree, from one’s close relatives, one’s race, one’s species, one’s genus and ultimately from the whole of the living world. Whatever the answer turns out to be, evolution theory is not going to advance until it goes back to the end of the 19th century and re-accepts the transmission of acquired characteristics as an empirical reality that needs to be accommodated. Acceptance of Aquatic Ape Theory is just one of its consequences.