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This is a story of the quest to understand evolution. During the last three centuries, with increasing knowledge, research has led us from Lamarck, with his theory of the Inheritance of Acquired Characteristic, to Darwin's breakthrough with his understanding of Natural Selection. Then Weismann put a spoke in progress through his ideas of Neo-Darwinism. Now in the present day,  epigenetics has led to a possible new paradigm with the idea of environmentally induced epigenetic variation.

https://en.wikipedia.org/wiki/File:Lamarck_Compared_to_Darwin,_Baldwin,_Waddington.svg

Waddington's genetic assimilation compared to Lamarckism, Darwinian evolution, and the Baldwin effect. All the theories offer explanations of how organisms respond to a changed environment with adaptive inherited change.

Jean-Baptiste Lamarck – Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck

God, environment change, species change

Jean-Baptiste Lamarck was not the first European to explain the unfolding of lifeforms with his  Theory of Inheritance of Acquired Characteristics, first presented in 1802.[1]

For centuries before Lamarck, it was thought that species were created by God and were immutable. These were the Creationists, such as those Christians who believed the world was created in seven periods of time, often stated as 'days'. Occasionally God might wipe them all out and start over again – such believers were known as Catastrophists. In the 18th century were the 'Transformistes' who believed that species do in fact change, but their voice was not clearly heard before Lamarck's ground breaking book Philosophie Zologique, 1809 which influenced much of the Western world for half a century. [2]

Lamarck believed that God changed the environment and in response lifeforms changed and passed on that change to future generations. Key to the 'species 'transformation' Lamarck described lifeforms feeling the 'need' to change because of their changed conditions of life. Lamarck was dealt a cruel blow after his death, for in the eulogy at his funeral his term 'need' – 'le besoin' in French – was changed into wish or will (le desire), so species appeared to change as they wished or willed to change... As a result of this Lamarck became a laughing stock.

However, his theories come alive again in light of new knowledge conveyed by current unfolding discoveries into epigenetics (epi  = ‘on the gene’). What became ‘registered’ on the gene was any slight change caused by a changed environment, by means of ‘alleles’ – tiny changed segments of DNA on a chromosome. This can be seen as ‘environmentally induced modification’. However, as it was reversible, it wasn’t considered important. This was a mistake, as later understandings of epigenetics became apparent.

Concentrating on Lamarck and those who came later, let it be said that he was a man of huge importance. Although usurped by Wallace and Darwin 50 years later, he influenced half the world for 50 years.

Darwin's Conditions

Darwin's publication of The Origin of Species by means of Natural selection: or the Preservation of Favoured Races in the Struggle for Life [3]  contradicted Lamarck. In fact he was overtly curt about Lamarck, referring to his "erroneous grounds of opinion".

Darwin's suggested mechanism for his thesis reversed Lamarck's ideas by suggesting lifeforms changed by means of 'natural selection', powered by periods of environmental change, then as a last thought “The Creator” was thrown in, at the end of 'Origin of Species' as a pacifier for the religious majority of those days..."There is a grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one: and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved."

Darwin’s natural selection contained a major role for the environment which he termed ‘conditions of life’, or ‘conditions of existence’ which powered the change, which was then sorted by ‘selection’, thus ‘natural selection’.

Darwin knew his theory of natural selection was similar to Lamarck's so he tried to pretend it wasn't. In the Origin he contradicts himself by saying first that natural selection was the most important "but not the only force" driving evolution. Then at the end of chapter 6 by saying that 'conditions' were in fact driving selection and had been acting for such long periods of time, that they, the conditions, were the most important factor. This not only confused readers, but also made it easy for his ideas to be misinterpreted, which is what happened after his death.

Darwin's explanation of how environmental change caused variation was placed conspicuously at the end of chapter 6 "Difficulties of the Theory" – in all six editions from 1859 to 1872... as below.

“It is generally acknowledged that all organic beings have been formed on two great laws – Unity of Type, and the Conditions of Existence. By unity of type is meant that fundamental agreement in structure, which we see in organic beings of the same class and which is quite independent of their habits of life. On my theory, unity of type is explained by unity of descent. The expression of conditions of existence, so often insisted on by the illustrious Cuvier, is fully embraced by the principle of natural selection. For natural selection acts by either now adapting the varying parts of  each being to its organic and inorganic conditions of life; or by having adapted them during long-past periods of time: the adaptations being aided in some cases by use and disuse, being slightly affected by the external conditions of life, and being in all cases subjected to the several laws of growth. Hence, in fact, the law of the Conditions of Existence is the higher law; as it includes, through the inheritance of former adaptations, that of Unity of Type.”

By understanding Darwin's mechanism we can clearly see that he rated the power of the environment way over that of natural selection itself: that selection worked as a result of the infinite power of all environmental pressures of life’s conditions of existence: of light and dark, humidity, atmospheric pressures, temperature, physics and chemistry, thus food and nutrition.

Clearly "Survival of the Fittest" was a misquote and a misunderstanding from philosopher Herbert Spencer... when Darwin wrote that those species which thrived were "best fitted to" the physics and chemistry of their environment. The meaning of the former is of course entirely different to the latter.

The Lamarckian Experiments

During the 18th century, ‘environmentally-induced-modifications’ were commonly accepted. Gardeners, horticulturalists, farmers and stockbreeders knew different environmental conditions produced varying results, in both plants and animals. But researchers in those times were looking for fixed types of change that would reproduce and stay true for generations, as happened in mutations. As environmentally-induced-modifications frequently reverted to previous forms – if the environment itself reverted, researchers were thrown off the scent as to their importance. Only through the increasing understanding of epigenetics in the early 21^st century was this recognized – just 150 years ago this year!

It’s hard to remember that in the early part of the 20^th century huge leaps of discovery had occurred. We entered that century even without knowledge of genes! Darwinism itself was going through its ‘Eclipse’ [5] having to wait until the discovery of higher mathematics and population genetics to be rescued in the 1930s as ‘The Modern Synthesis’.  Likewise, proteins weren’t understood until well into the 1910s; the vitamins in the 19’teens and 20s and the essential fatty acids weren’t discovered until the 1930s.

August Weismann

In the late 19^th century August Weismann,  an admirer of Darwin, who was said to have been “more Darwinian than Darwin”  took over Darwin’s mantle after his death in 1882 and Weismann’s creation of ‘Neo-Darwinism’, whereby apart from the gene-pool of the entire environment, he removed Darwin’s “conditions” from the equation, so Weismann’s mechanism had “competition for nourishment” in the germline as his driving force –  every bit as much a fantasy as anything Lamarck had been accused of, or Darwin’s “pangenes” (1868) (which turned out to be an astonishingly accurate piece of guesswork, but had to wait those 150 years to be proved correct by the completion  of the human genome map and the unfolding understanding epigenetics by 2011/3).

For within only very few years he published two highly influential papers which were to steer evolution theory for the next century and a half… sadly in an erroneous direction.

Both of these two papers are highly contentious in the light of today’s understanding of genetics and epigenetics.

Weismann’s Barrier

One of these papers concerned what became known as “Weismann’s Barrier” [4]. This is the principle that hereditary information moves only from genes to body cells; never in reverse. Tighter terminology would say hereditary information moves only from germ line cells to somatic cells, so germline feedback is impossible. It is this that is disproved by the unfolding of new knowledge of epigenetics, as seen in The Handbook of Epigenetics; The New Molecular and Medical Genetics.[6]

C H Waddington, was a British developmental biologist, palaeontologist, geneticist, embryologist and philosopher. He coined the term epigenetics in the early 1940s, being amongst the first to recognize the effects of environmental pressures on genes. The importance of his contribution to the evolutionary debate possibly has yet to be fully realized.[7]

In the above publication, Handbook of Epigenetics, Simon H House describes epigenetics as “the process of a gene being switched off (silenced), or conversely being switched on (activated) by removal of the methyl group. Such changes reversibly modify the development of the organism without changing the basic gene-sequence. Although the change is reversible, it can be passed on to subsequent generations.

"Epigenetic change can affect a cell's genome (genetic material) any time in the lifecycle, though the earlier in life the more potential. Reproduction involves major epigenetic changes in the genome of the developing oocyte (fertilized egg) and the genome from the sperm on fertilization. These changes allow some fine-tuning of the new organism to parental environment, yet can also give rise to problems. The grandmother is 'reading' the environment for her grandchild – and to a lesser extent the grandfather too”.

House explains how “epigenetics is more than a fascinating and fast burgeoning field of biological research: it is of vital consequence to the human race, as we have come into arguably the worst crises in new forms of disease the human race has encountered.[7] These include the ‘non-communicable’ diseases related to the metabolic syndrome. Obesity, diabetes, cardiovascular and mental health disorders are increasingly recognized as connected with epigenetic changes of early origin.”

As we have already discussed above, Darwin’s concept of natural selection had what he termed “conditions of existence” or “conditions of life”, meaning the effects of the environment, a term he used  over 100 times in the Origin. He explained that the environment was what was powering natural selection. The ‘selection’ part came in after any change had been instigated and simply sorted out those species which would prosper and those which would not, by whether they were best or least ‘well-fitted’ to whatever change there was in the environment, and which particular ‘phase’ of their evolution, whether there was ‘struggle’, competition or plenty.

To show this we can do no better than to see what we (Crawford & Marsh) wrote in 1989 in ‘The Driving Force, Food, Evolution and the Future’ showing how each epoch of evolution throughout recorded time can be seen as having Five Phases.[8]

Phase 1

1. The first ‘push’ comes from the conditions. At any given time a certain set of conditions exists in terms of the richness of chemicals or nutrients available, their concentrations and diversity, the climate, its temperature, humidity range of variation and so on. These stimulating conditions make possible the existence of certain types of organism, certain living systems’ which then appear responsive to the conditions and radiate. This is stimulation by richness;
2. Continued stimulation. The conditions are at first likely to be consistent in their stimulation, with nutritional abundance encouraging the new organisms to multiply and their numbers to rise;
3. The space/numbers game. As their numbers rise, space and resources come to be shared more thinly. During this phase Darwinian pressure exerts itself. Those species that develop even slightly advantageous adaptions have the edge on their competitors and are more likely to survive. Once this has happened the system settles down, but as there is little change in the environmental chemistry there is a period of apparent stability. Only coordinated change is possible within the framework of the original conditions;
4. Environmental change. At first the rise in numbers has a barely detectable effect on the environment, but eventually it accelerates to the point where the environment cannot keep pace. It is unable to replenish its resources as fast as they are used up. The upward surge in numbers and the downward plunge of resources leads to a crisis. The living systems have changed the chemistry of their environment beyond renewal, and by now their struggle for survival has become violent but futile. The fate of the dominant species is sealed;
5. Renewed environmental push The conditions are now appropriate to living systems of a different sort, and with the disappearance of the old species the way is open for them to develop. (In this context Food equals all the impact energies.) This phase, the fifth, is therefore the first phase of the new epoch for the new systems. The cycle has begun again.

Weisman’s 2nd Contentious Paper

Weismann’s 2nd contentious paper “The all-sufficiency of natural selection” was published in the Contemporary Review in reply to an article by the aforementioned Herbert Spencer in 1893. This paper describes Weismann’s description of his fatuous experiment cutting tails off 9 generations of mice and watching subsequent generations grow tails. Quite how Weismann got away with this no-one will  ever know, bearing mind that lambs and puppy tails had been docked for centuries yet lambs and puppies continued to be born with tails. Someone suggested that Weismann need look no further than his own foreskin… as for centuries male babies, despite circumcision, are all born with foreskins – in many cultures.[9]

This so-called scientific experiment was supposed to disprove that Darwin’s ‘conditions of life’ had any role to play within natural selection.  Weismann, poor fellow, went blind in later life turning to theory from experimental work, and formulated his theory of ‘germinal selection’ according to which variation was “directed by competition for nourishment among ‘character-units’ of the germ-plasm” (genes had still not yet been discovered) (Weismann, germinal selection 1894).[10]

For how much longer are we expected to believe these 19^th and early 20^th century fantasies?  Possibly some answers may lie with those whose thinking is still enchained by the ancient beliefs in the Right of Might?

Darwin on the Power of Misrepresentation

“Great is the power of steady misrepresentation – but the history of science shows how, fortunately, this power does not endure long.”

– Charles Darwin Origin of Species, all editions

Darwin was so unimpressed with how he was being misrepresented, that at the end of his ‘introduction’  of the Origin he stated...

“I have now recapitulated the facts and considerations which have thoroughly convinced me that species have been modified, during a long course of descent…

“But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position – namely, at the close of the Introduction – the following words: ‘I am convinced that natural selection has been the main but not the exclusive means of modification.’ This has been of no avail. Great is the power of steady misrepresentation; but the history of science shows that fortunately this power does not long endure.”

Unified Evolution Theory

Michael Skinner and Eric Nilsonn clarify the situation masterfully in their 2021 paper in Environmental Epigenetics…  (A paradigm shift which I predicted 15 years ago.)[11]

“The direct action of the environment to alter phenotype that is heritable is a neo-Lamarckian concept that can facilitate neo-Darwinian (i.e. Modern Synthesis) evolution. The integration of genetics, epigenetics, Darwinian theory, Lamarckian concepts, environment, and epigenetic inheritance provides a paradigm shift in evolution theory. The role of environmental-induced epigenetic transgenerational inheritance in evolution is presented to describe a more unified theory of evolutionary biology.”[12]

This ultimately means that all men, women, children and those yet to be born, totally depend on our 'conditions of life'... our conditions of existence for all our needs: from the air we breathe to the water we drink and the food we eat, etc. We must learn the folly of 'survival of the fittest', and realise it is the survival of those 'best fitted' to our bountiful environment which will survive. We abuse our environment at our peril!

References

1. Lamarck J. Recherches sur l’organisation des corps vivans. Paris: Chez L’auteur, Maillard,  1802. [Google Scholar])
2. Lamarck; J. Philosophie Zologique, Musée d'Histoire Naturelle (Jardin des Plantes). 1809.
3. Darwin, C. "The Origin of Species by means of Natural selection: or the Preservation of Favoured Races in the Struggle for Life", 1859.
4. Weismann, A Translation: Germ-Plasm, a theory of Heredity 1893.
5. Bowler, P J; The Eclipse of Darwinism: Anti-Darwinian Theories in the Decades around 1900. The Johns Hopkins University Press. London. ISBN 0-8018-2932-1. 1983.
6. House. S H; in ‘The Handbook of Epigenetics: The New Molecular and Medical Genetics’, Ed: Trygve Tollefsbol. 1^st edition Academic Press (Elsivier), Burlington & San Diego, USA, ISBN: 978-0-12-375709-8. 2011.
7. Waddington, C. H. www.Britannica.com
8. Crawford M A & Marsh, D E: In ‘The Driving Force, Food, Evolution and the Future’. Willian Heinemann. London. ISBN 0-434-14832-6. Harper & Row, New York. ISBN 0-06-039069-7. 1989
9. Weismann, August. "The All-Sufficiency of Natural Selection." The Contemporary Review, 1866-1900; London 64 (September 1893): 309-38.
10. Weismann, A: On Germinal Selection as a Source of Definite Variation (1896), August (ISBN: 9781164835585)
11. Marsh, D E: The Origins of Diversity: Darwin’s Conditions & Epigenetic Variations. Nutrition and Health Volume: 19 issue: 1-2, page(s): 103-132 Issue published: July 1, 2007) https://journals.sagepub.com/doi/10.1177/026010600701900213
12. Skinner, M K, and Nilsonn, E E; The role of environmentally induced epigenetic transgenerational inheritance in evolutionary biology: Unified Evolution Theory. Environ Epigenet. 2021; 7(1): dvab012. Published online Oct 30 2021. . https://doi.org/10.1093/eep/dvab012 PUBMED CENTRAL; NIH National Library of Medicine. National Centre for Biotechnology Information.