Evolutionary theory is based on a number of crucial assumptions. One of the most important of these assumptions is that biological organisms are infinitely plastic – they can accumulate an endless number of mutations and be gradually transformed into different organisms. After all, if an ancient one-celled organism eventually begot creatures that possess brains, gills, wings, immune systems, antlers, capillaries and countless other features, the process must have involved millions of mutations that stretched organisms beyond recognition.
Nobody denies that there is some flexibility within life forms. Breeders exploit this biological malleability to enhance desirable features – more colourful crests in pigeons or tennis-ball-sized peaches. But this is a far cry from the flexibility that is required to allow an organism to accumulate mutations to the point where new organs and body plans emerge. That level of plasticity is indispensable to evolutionary theory. The co-discoverer of Natural Selection, Alfred Russel Wallace, called his 1858 essay “On the Tendency of Varieties to Depart Indefinitely from the Original Type”. The operative word here is indefinitely.
But infinite plasticity is an assumption – there is no evidence that biological organisms can change beyond very narrow limits. One of the architects of Neo-Darwinism, Theodosius Dobzhansky, emphasised the differences between micro-evolution (the small, intra-species events that are observed in nature and in breeding programs) and macro-evolution (the emergence of new organs and body plans). As I wrote in Genesis and Genes,
In 1937, Dobzhansky noted that there was no hard evidence to connect small-scale changes within existing species (which he called microevolution) to the origin of new species and fundamentally-new structures (an eye or a wing where there hadn’t been one before) and body plans that are recorded in the fossil record (which he called macroevolution).
Dobzhansky clearly acknowledged that it is nothing but an assumption and a working hypothesis that the accumulation of micro-evolutionary changes can account for macro-evolution.
For centuries, breeders have tried to push the limits of biological variability, with little success. Norman Macbeth, in his book Darwin Retried, quotes Luther Burbank (1849-1926), who was called “the most competent breeder of all time”. Burbank worked in Santa Rosa, California in the early decades of the 20th century, and his work was funded by Andrew Carnegie. Burbank wrote that,
I am willing to admit that it is hopeless to try to get a plum the size of a small pea or one as big as a grapefruit. I have daisies on my farms little larger than my fingernail and some that measure six inches across, but I have none as big as a sunflower and never expect to have. I have roses that bloom pretty steadily for six months in the year, but I have none that will bloom twelve, and I will not have. In short, there are limits to the development possible…
The biologist Julian Huxley (grandson of Darwin’s Bulldog, Thomas Huxley) made much the same point as Burbank:
In spite of intensive and long-continued efforts, breeders have failed to give the world blue roses and black tulips. A bluish purple and a deep bronze in the tulip are the limits reached. True blue and jet black have proved impossible.
Huxley attributed this limit to a “lack of modificational plasticity” – variation can only go so far.
Thomas Hunt Morgan (1866-1945) was one of the founders of genetics, and received a Nobel Prize for his work. Working in the famous Fly Room that he established at Columbia University, Morgan used artificial selection to try to increase the number of bristles in fruit flies. He found that the bristle number reached a maximum and could not be increased further, no matter how much selection pressure was applied.
In The Natural Limits of Biological Change, Lane P. Lester and Raymond G. Bohlin quoted the noted French biologist Pierre Grassé (1895-1985):
What is the use of their [E. Coli] unceasing mutations if they do not change? In sum, the mutations of bacteria and viruses are merely hereditary fluctuations around a mean position; a swing to the right, a swing to the left, but no final evolutionary effect.
In Genesis and Genes, I mentioned Lynn Margulis (1938-2011) a number of times. A world-famous biologist, she was elected to the United States National Academy of Sciences in 1983 and inducted into the World Academy of Art and Science, the Russian Academy of Natural Sciences, and the American Academy of Arts and Sciences between 1995 and 1998. She was the recipient of the William Procter Prize for Scientific Achievement (1999) and was awarded the National Medal of Science by President Bill Clinton in that same year. Margulis was an evolutionist, but she rejected Neo-Darwinism partly because of her perception that the standard picture of new species being formed as a result of the accumulation of mutations was false. In an interview in Discover Magazine, she said:
… neo-Darwinists say that new species emerge when mutations occur and modify an organism. I was taught over and over again that the accumulation of random mutations led to evolutionary change – led to new species. I believed it until I looked for evidence.
Margulis makes the point that Neo-Darwinism requires that biological organisms be infinitely-plastic – just pile mutation upon mutation and you’ll eventually get a new species. She explains why this is unrealistic:
This is the issue I have with neo-Darwinists: they teach that what is generating novelty is the accumulation of random mutations in DNA, in a direction set by natural selection. If you want bigger eggs, you keep selecting the hens that are laying the biggest eggs, and you get bigger and bigger eggs. But you also get hens with defective feathers and wobbly legs. Natural selection eliminates and maybe maintains, but it doesn’t create.
Dr. Lee Spetner echoes this observation:
Degrading side effects have also been noted in insects that have become resistant to insecticides. M. W. Rowland from the Rothamsted Experimental Station in Hertforshire, England has reported that mosquitoes that have become resistant to dieldrin are less active and slower to respond to stimuli than are other insects. Their resistance to the insecticide is thus bought at the price of a more sluggish nervous system…
In grain, selection for high protein content has been found to result in less starch per seed and less grain per planting. Dairy cattle bred for high milk production turn out to be less fertile than normal cattle.
This effect – that every “advantageous” genetic trait is bought at the expense of some other trait, a case of stuffing your right pocket with notes taken from your left pocket – is recognised by world-famous scientists whose fealty to the evolutionary paradigm is uncontested. Thus, E.O. Wilson writes that,
Artificial selection has always been a tradeoff between the genetic creation of traits desired by human beings and an unintended but inevitable genetic weakness in the face of natural enemies.
And Ernst Mayr wrote that,
The most frequent correlated response of one-sided selection is a drop in general fitness. This plagues virtually every breeding experiment.
As I wrote in Genesis and Genes:
Whether it is the finches’ beaks, or minuscule growth in the length of frogs’ feet, or slight colouration variations between moths, or minor changes to the genomes of bacteria, or elephant tusk size as measured by the Uganda Game Department between 1925 and 1958, or the change in head size of a Mediterranean lizard, Podarcis sicula, between 1971 and 2008 as registered by a Belgian team studying the lizard population on a pair of little islands off the Croatian coast, the claims far outstrip the evidence.
Finally, here is what the delightful David Berlinksi had to say on the subject, as quoted in Genesis and Genes,
Changes in wing color and the development of drug resistance are intraspecies events. The speckled moth, after all, does not develop antlers or acquire webbed feet, and bacteria remain bacteria, even when drug-resistant… the grand evolutionary progressions, such as the transformation of a fish into a man, are examples of macro-evolution. They remain out of reach, accessible only at the end of an inferential trail.
Informed consumers of science are aware that the grand evolutionary story is crucially dependent on the alleged ability of biological organisms to change without limit. The oft-repeated claim about overwhelming evidence heard in the context of evolution is indeed true, but not in the way it is usually intended. There is overwhelming evidence – from the field, the farm and the laboratory – for the fact that living creatures cannot change beyond narrow limits.
The post Birds and Micro-Evolution:
The post An Interview with Lynn Margulis:
The post More on Margulis:
 Norman Macbeth, Darwin Retried, Dell Publishing, 1973, page 36. I came across the quotations from this book in an essay by Tom Bethell on the website Evolution News and Views. See http://www.evolutionnews.org/2012/04/natural_limits058791.html.
Retrieved 15th April 2013.
 Julian Huxley, Evolution: The Modern Synthesis, London, Allen and Unwin, 1943, page 519.
 “American zoologist and geneticist, famous for his experimental research with the fruit fly (Drosophila) by which he established the chromosome theory of heredity. He showed that genes are linked in a series on chromosomes and are responsible for identifiable, hereditary traits. Morgan’s work played a key role in establishing the field of genetics. He received the Nobel Prize for Physiology or Medicine in 1933.”
Morgan, Thomas Hunt. (2009). Encyclopædia Britannica. Encyclopædia Britannica 2009 Ultimate Reference Suite. Chicago: Encyclopædia Britannica.
 Pierre Grassé, Evolution of Living Organisms, 1977, quoted in Lane P. Lester and Raymond G. Bohlin, The Natural Limits of Biological Change, Zondervan Publishing, 1984, page 149.
 The interview can be read online:
Retrieved 25th February 2013.
 Lee Spetner, Not By Chance!, The Judaica Press, 1997, pages 144-148.
 Rowland, M.W. (1987). Fitness of Insecticide Resistance, Nature, volume 327, page 194.
 Brock, R.D. (1980). Mutagenesis and Crop Production, in Carlson, P.S., The Biology of Crop Productivity, New York: Academic Press, pages 383-409.
 Hermas, S.A. (1987). Genetic relationships and additive genetic variation of productive and reproductive traits in Guernsey dairy cattle, Journal of Dairy Science, volume 70, pages 1252-1257.
 Wilson, E.O. (1992). The Diversity of Life, Cambridge, Harvard University Press.
 Ernst Mayr, Populations, Species, and Evolution, Harvard University Press, 1970, page 163.
 The last two examples come from Richard Dawkins’ book The Greatest Show on Earth: The Evidence for Evolution. The chapter containing the discussion of the elephant tusks and the lizards’ heads is bombastically entitled [Evolution] Before Our Very Eyes.