I’ve often been asked, given my reputation as a sceptic, why I don’t challenge the scientific case for evolution and against creation. If I look hard enough, they tell me, I’ll find the theory of evolution to be full of holes. Well, I did, and I don’t.
I have a reputation for scepticism about scientific findings. I do not believe that just because something appears in a peer-reviewed journal, it is a proven fact. I do not believe that only scientists are permitted to challenge other scientists, and then only if they’re scientists of the same kind. I do not believe that “scientific consensus” is evidence, even when it exists. I am highly suspicious of scientists who become activists for this or that political policy.
I believe systemic bias can occur in the sciences, for various reasons. The beliefs and objectives of research funders, both private and public, can influence research outcomes. The largest of those funders is usually the government. Government has enormous vested interests, in terms of political ideology, public policy, economic protectionism and outright cronyism, yet politicians often hold the power of the purse over scientists. There has been an outcry over Donald Trump’s influence over the scientific and regulatory community, but don’t believe that his predecessors, or governments in other countries, have any less influence over research priorities and funding, or are any less willing to use it.
For professional scientists, there is pressure to fall in line with the convictions of senior academics, either to obtain qualifications or gain career advancement. This tends to stifle original or dissident thought. As the philosopher Thomas Kuhn observed, “normal science” is bound within paradigms, and does not seek novelties of facts or theory. “Novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation,” he wrote.
Anomalous discoveries are usually met with resistance and attempts to explain it within existing paradigms. They rarely lead to paradigm shifts. This is not entirely a bad thing, since, as Kuhn writes: “By ensuring that the paradigm will not be too easily surrendered, resistance guarantees that scientists will not be lightly distracted and that the anomalies that lead to paradigm change will penetrate existing knowledge to the core.”
Scientists are themselves subject to motivated reasoning to reduce cognitive dissonance between their research findings and their emotional convictions, spiritual beliefs, or political views. Such biases can be strong. Scientists are only human, after all.
So whether the bias is personal, professional, or political, there is no reason to believe science to be immune from human frailty. Science is not a thing. “That’s science!” is not a argument. Science does not preclude error. It doesn’t confer perfect understanding upon us. It isn’t some deity, to which we ought to bow in unquestioning faith.
Science is a process; a method that attempts to systematically improve our understanding through a process of testing hypotheses against real-world observation. It can be, and on several occasions has been, thoroughly undermined by bias or ideology.
Perhaps the most infamous case of science being influenced by ideology was the adoption of Lysenkoism during Stalin’s totalitarian reign. The early 20th century’s synthesis of Charles Darwin’s theory of evolution by natural selection with Gregor Mendel’s theory of genetic inheritance was considered too closely associated with the “dog-eat-dog” world of capitalism, and was declared to be “bourgeois pseudoscience”.
Soviet agrobiologist Trofim Lysenko rejected both genetics and natural selection in favour of the theory advanced by Jean-Baptiste Lamarck, which says evolution occurs by inheritance of characteristics acquired during an organism’s lifetime. For example, people who exercise much would pass strong muscles to their children, and plants which have their leaves plucked will produce leafless offspring. Lamarckism also held that organisms were driven to evolve towards greater complexity, so the adaptation that drives evolution is goal-oriented.
In 1928, Lysenko proposed to apply these theories to improve Soviet agriculture, which was in crisis after the forced collectivisation of farms. Lysenko’s programmes initially appeared to enjoyed a modicum of success, and earned wholehearted approval from Joseph Stalin. The apparent success, however, can largely be attributed to the rapid industrialisation of the Soviet Union, which brought modern equipment and fertilisers to farms. The rest was due to his improvement of plants by modifying them or exposing seeds to different environments. These had only short-lived results, however, since the acquired characteristics he produced were not inherited by the next generation, contrary to Lamarckian theory.
By 1948 Lysenkoism had been declared “the only correct theory” by the Lenin Academy of Agricultural Sciences. Scientists who disagreed were brought in line by public denunciation, dismissal, expulsion from the Communist Party, imprisonment in the Gulags, and even execution. Thousands of scientists were lost to Soviet biology and agriculture, and a great deal of perfectly good but politically incorrect research was suppressed. The doctrine of Lysenkoism survived more than 35 years. It did not fall until after a series of crop failures and famines, which cost Lysenko his position in 1965.
“Science cannot long remain unfettered in a social system which seeks to exercise control over the whole spiritual and intellectual life of a nation,” wrote Charles A. Leone in a paper on Lysenko versus Mendel, in 1952. “The correctness of a scientific theory can never be adjudged by its readiness to give the answers desired by political leadership.”
By contrast, the success of Darwinian evolution and Mendelian genetics in the bourgeois capitalist world was undeniable. Norman Borlaug was the West’s answer to Lysenko. He applied Mendelian genetics to produce and test tens of thousands of varieties of wheat. Best-selling books – written by the likes of William and Paul Paddock, Paul Ehrlich, and future Obama science czar John Holdren – were predicting mass starvation because of population growth. Instead, Borlaug ushered in what would become known as the Green Revolution in the 1960s. His wheat would eventually account for a quarter of the world’s calorie intake, and earn Borlaug a Nobel Peace Prize in 1970.
Mendelian genetics and selection resulted in similar crop and livestock improvements across agriculture, enabling a rapidly growing world population not only to feed itself, but to eat better consistently over time.
Now let’s consider some of the objections to evolution, advanced mostly by proponents of “intelligent design” (which is one way of saying “God did it”) and “creationism” (which is another way of saying “God did it”).
It is said complex organisms, or organs, could not possibly evolve by chance. But they don’t. Many random mutations occur from one generation to the next, most of which do not become traits. Selection of those that do, however, is based on very real, non-random events, such as how useful those variations are or how geographically isolated sub-populations become. The “natural selection” part of evolution is not at all a random process.
The eye is often cited as an example of an organ that must have been created fully formed, since it wouldn’t work without most of its constituent parts. Darwin himself singled out the eye as an organ that seems too complex to have evolved by natural selection. However, his view was that different stages of eye development, from the first photoreceptors to fully formed eyes in mammals, would have conferred some advantage to its possessor, which makes the evolutionary development of eyes plausible.
That he was correct has been borne out by later research, and we now know the very gene that is responsible for eye development in both insects and vertebrates. It is probable that the eye, in some form or another, evolved independently dozens of times. Octopus eyes, for example, are very similar to those of vertebrates, but show some peculiar differences: how the retina connects to the optic nerve, the lack of a cornea, and a lens that focuses by movement, rather than changing shape. Unlike vertebrate eyes, which developed as outgrowths of the brain, octopus eyes developed from an infolding pocket in the body surface. They are a great example of parallel evolution, or even convergent evolution.
Detractors of the theory of evolution sometimes accept evolution within species (micro-evolution) but say there aren’t any “transitional fossils” which would show that animals could evolve from one species, genus, family, order, class or phylum into another (macro-evolution). The nature of the fossil record, which is sparse, and in which transitional forms couldn’t have occupied much time, makes the discovery of transitional fossils unlikely. Despite this, many examples have been found.
Tiktaalik roseae is a fossil of a fish that developed traits of four-legged land animals, or tetrapods. Its is dated to a few million years before the first known tetrapod, which suggests that it is one of the much-caricatured fish that crept out of the water and started walking on land. Other fossils, occurring before and after Tiktaalik in the transition, show different features in the evolution of tetrapods from fish, include Eusthenopteron, Panderichthys, Ventastega, Acanthostega, Ichthyostega, and Pederpes.
Evolving in the opposite direction, whales are descended from four-legged land-dwelling mammals. Many transitional forms exist, such as Pakicetidae, Ambulocetidae, Remingtonocetidae, the aptly named Protocetidae, and Basilosauridae.
The animal for which we probably have the most transitional fossils is the horse, which evolved (along with rhinos and tapirs) from a common ancestor, a dog-sized creature that lived in forests.
Darwinian evolution predicted that transitional fossils must exist, and he said himself that their absence would undermine his theory. The first major transitional fossil to be discovered was Archaeopteryx, in 1861. It shows how modern birds descended from reptilian dinosaurs. Other transitional “proto-birds”, even older than Archaeopteryx, have since been found, such as Anchiornis, Xiaotingia, and Aurornis. Later transitional forms are also known, such as Confusiusornis, Sinornis, Vorona, and Icthyornis.
A flatfish is a weird, asymmetric animal, with both eyes on one side of its head. A fossil that shows the transition, having one eye near the top of the head, is Amphistium.
Perhaps the earliest known chordate is the Haikouella, which resembles a vertebrate, but lacks some of their key characteristics. This makes it a probable transitional fossil.
In the plant kingdom, a well-known transitional fossil is the Runcaria, which shows the evolution of seeds, and predates the earliest seed plants by about 20-million years.
An early candidate for the so-called “missing link” between the apes and humans turned out to be an infamous hoax concocted in 1908, known as the Piltdown Man. Subsequently, however, many examples of “missing links” have been discovered, perhaps the most prominent being Lucy, or Australopithecus afarensis. Other examples are Adripithecus ramidus, which had a brain the size of a chimpanzee’s, but could walk upright and had an opposable toe, and Homo habilis, whose brain was 50% larger and who used tools. Many early hominids are extinct but are clearly related to human ancestors, which shows natural selection at work.
They’ll say nobody has ever seen a new species evolve. The most common delineation between species is that different species cannot interbreed. The best experiment with speciation in the laboratory was conducted almost 30 years ago, by William Rice and George Salt, who separated fruit flies with different preferences, and found that after 35 generations, the separated populations stopped interbreeding. Since then, more research has been conducted into how speciation occurs. One notable discovery is that periods between species transition can be very long, but if and when a transition happens, it can be very quick. This explains the relative paucity of transitional forms in the fossil record.
Another argument used against evolution is that some parts of Darwinian theory have been overturned, and some problems in evolutionary theory remain unsolved. Or that “evolution is just a theory”. This argument could be used to make a case against any scientific theory whatsoever. The theory of gravity is no longer how Newton first described it, and questions remain about how exactly gravity works. But in the words of Tim Minchin (if you haven’t seen Storm, you must), the uncertainties about gravity ought not to influence your decision to leave your apartment by the front door, or by the window on the second floor.
It is true that certain of Darwin’s beliefs have been disproven. Darwin did not understand genetic inheritance at all. His belief that all evolution occurs gradually is wrong. Mechanisms exist for sudden evolutionary jumps, including one-step speciation. The Darwinian notion of a “tree of life”, with all species descended from a single ancestor, remains conceptually useful on a macro level. However, bacteria are able to exchange genes with each other, which makes nonsense of the notion of an evolutionary hierarchy. It has become clear that the Darwinian idea that all evolutionary traits are adaptive, enhancing reproductive success, is not true. Many heritable traits have nothing to do with the “survival of the fittest”. Darwin also shared the belief that there is some sort of biological progress towards a goal or ideal state, or, in his words, a “progress to perfection”. This is now also known to be false.
Modern evolutionary biology draws from numerous scientific fields, including new study areas such as molecular biology, microbiology and genomics. Much of the new research has corrected or supplanted older ideas, whether they are Darwinian, or part of the “modern synthesis” of the 20th century. There isn’t yet a single, over-arching new synthesis of evolutionist thought (although there are candidates), but this does not undermine evolution at all. If there were holes in it, what we’re seeing now is how they’re being filled. These advances are a sign that scientists are developing a better understanding of the mechanisms of evolution and how it shaped our modern world, not that they are rejecting evolution as a theory.
Some anti-evolutionists argue that the Second Law of Thermodynamics says that entropy (commonly thought of as disorder) can only increase, which makes the spontaneous evolution of complex cells and structures such as proteins impossible. This is a misreading of the law, however. It says that total entropy cannot decrease in a closed system. If that meant no organisation can ever arise, then we would also not see the formation of crystals or other non-living structures. The Earth is not a closed system. It constantly receives energy from the sun. Organisms on Earth can increase their complexity simply by using this energy, without reducing the total entropy in the solar system. No breach of the laws of thermodynamics is necessary to explain evolution.
Finally, they might say that evolution cannot explain the origins of life. This is true. And that’s because it doesn’t try to do so. No matter how life first arose on Earth, evolution explains its development since then. There are numerous ideas in biochemistry about how the first amino acids, proteins and other building blocks of cellular life may have originated. But just because we do not know the right answer does not mean we can simply make up any story that might explain it. There are infinitely many hypothetical causes for observed effects. Determining which is true is the ongoing task of science. Claiming that one of them is true without sufficient evidence is unscientific.
As we’ve seen, just because Darwin did not perfectly explain evolution does not mean that Lamarck was right. In the same way, the imperfections of Darwinian theory do not justify the acceptance of any other extravagant hypothesis, even one that explains observed consequences. Like all science, evolutionary biology progresses by means of hypotheses are tested against real-world observation in repeatable experiments. The better our ability to observe the real world, the better the science becomes.
The great achievements of genetics and evolutionary biology to date suggest that its incompleteness is not a reason to reject it, but a reason to be optimistic that it is on the right track. Just like ideology should not interfere with scientific progress, as it did in the Soviet Union and arguably still does in many areas today, trying to fit scientific conclusions to religious beliefs is inadvisable, and ultimately futile.
Darwin was technically wrong on many aspects of evolution. It required Mendel’s genetics to explain the mechanism by which evolution works, for example. But his theory, more than 150 years old, was a great step towards a better understanding of the biological world. Today’s evolutionary biology is merely a better description of evolution. And it will get better still, in future. That’s science! DM
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