5 Reasons why no one is talking about the revolution going on in evolutionary science
Science is a lot like evolution; there is a monotonous trudge forward, during which marked progress is made, punctuated with occasional leaps ahead.
There are also resumptions, where old ideas are given new life in slightly altered embodiments (see convergent evolution.) For some time evidence has been amassing, which supports a dusty yet well worn theory: the Inheritance of Acquired Characteristics. Currently there is a flurry of peer-reviewed literature discussing this quiet shift in the basic paradigm of evolutionary theory. Unfortunately, no one outside of scientific circles is discussing it.
Why? Well there are really five things holding back this potentially revealing conversation.
Nothing new has been suggested. The Inheritance of Acquired Characteristics (IAC) a theory supported by French Naturalist Lamarck, but which dates back to the time of Hippocrates, supposes that characteristics acquired by individuals over the course of their lifetime may be inherited by offspring. Lamarck is best remembered by his example of IAC employing giraffes, which is repeated during every Intro Biology lecture covering evolution. Giraffes stretch their necks to reach the higher up, tastier leaves on African trees, and after generations of this, giraffes are born with very long necks. Ring a bell? Lamarck was not a contemporary of Darwin’s, but is often presented as a counterpoint to Darwin’s theory of Natural Selection.
Lamarckian evolution contends that changes are not random, but a direct response to environmental pressures. As each cell in our bodies experiences the world an indelible mark is left on its hereditary material, and the sum of differences are inherited by offspring. Natural selection purports that new traits arise within populations randomly, that may either enhance or hinder the reproductive success of individuals. Traits which improve the likelihood that individuals will successfully reproduce, have a greater chance of being passed on, ergo those traits are selected for by environmental conditions. Traits that hinder survival and reproduction may disappear over time as individuals die before reproducing or sire offspring that are ill equipped. As changes add up over many generations a nascent population becomes so different it is incapable of breeding with the original population, from which it split.
It is complicated. The trouble is Darwin published a companion theory to natural selection, the theory of Pangenesis, which adopts several of the principles of IAC. Pangenesis was Darwin’s mechanism of heredity, in which tiny hereditary molecules float about inside of organisms called gemmules. Neither Lamarck nor Darwin had the benefit of Mendel’s work on inheritance, his mathematical predictions of pea plant phenotypes wouldn’t be rediscovered until the 1900s. Scientists had not yet discovered the form or function of DNA. But Darwin thought that hereditary material could be acted on by an organism’s environment, and change before being inherited by offspring. He did not think that all changes were necessarily inherited, but how did Darwinian evolution become irrevocably related to random change and pitted against Lamarck’s reactionary evolution?
The identification of DNA as the material of heredity occurred after Darwin’s theory had been widely accepted, and IAC been fairly discredited. It was proven that adverse environmental conditions could produce changes to the sequences of four nucleotides, the bases that make up DNA, and thus change the expression of genes. In addition to being initiated by environmental mutagens such as radiation, mutations occur randomly over time within a population. Evolutionary theory followed this preponderance of evidence to the conclusion that random mutations arising within populations were the mechanism, through which evolution was occurring. Natural selection provides the environmental sieve through which mutations are refined, as being adaptive or not. This is how Darwinian evolution became synonymous with random and was pitted against the Inheritance of Acquired characteristics.
Darwin is still our man. Natural selection and IAC have been presented as incompatible because as Lamarck described, with the Inheritance of Acquired Characteristics individuals can drive evolution with behavior. Freud was a big fan of Lamarck’s, as was Joseph Stalin. The mischaracterization of Darwinian evolution as entirely random is a vestige of the first half of our genetic revolution. Darwin and Lamarck both believed that hereditary molecules could be changed through feedback mechanisms over the course of an individual’s lifetime, and that those changes could be inherited.
Discover magazine recently covered research conducted by pioneers of Epigenetics, one of the fields driving science’s swing back, and toward a progressive evolutionary theory. Heritable traits are conveyed through DNA by at least two mechanisms, mutations of the nucleotide sequence and genes being turned “on” or “off.” Epigenetics is the branch of genetics examining chemical modifications of DNA that don’t involve mutation, but which do effect gene expression. Research in this field has demonstrated how epigenetic changes occur, that they are heritable, and that they have evolutionary consequences. Epigenetics has allowed us to see real-time evolutionary feedback mechanisms at work. Scientists have not yet elucidated why some changes are inherited while others are not, but research in this field is well funded as it has far reaching medical import.
Behavioral epigenetics has provided exciting evidence that the experiences of an individual’s lifetime produce epigenetic changes, which may be handed down to offspring. Traumas and triumphs can imprint upon our genes and change their expression not only in us, but also in our children and grandchildren. Genetic technology has leapt forward in recent decades, and made it possible for evolutionary theory to take a step back. While Darwin didn’t expound upon individual determinism as a force driving evolution, his theories did not actually exclude that possibility. Historically there are many more people involved in shaping evolutionary theory than just Darwin, but his ideas have not yet been invalidated.
Science follows the evidence, but resists making big changes at any faster rate than a snail’s pace, and rightly so. For trust to be fostered among non-scientists there should be a careful and patient examination of data. Conclusions should not be hastily reached. But this discussion must be initiated within the general public, or science will fail to propagate the one universal human compulsion that has kept this discussion going for thousands of years, curiosity.
We still have to argue the validity of evolution (the most widely proven theorem in the history of science) with a sub sect of the population that refuses to value evidence. This argument isn’t philosophical or religious; it is instead a quarrel over the most basic definition of the word “education.” While some of our population considers the word “educate” to mean indoctrinate, some of us believe it means to inform. Information is knowledge concerning facts, not the agreed upon dogma of one philosophical belief which is valued over another. With this quandary over definitions, there hasn’t been time for a thorough and comprehensive discussion of the finer points of evolutionary theory.
This stigma makes for fickle news and fecund debates, but where there is a will apparently there is also a way. If individual determinism can drive evolution, we become what we do, then we may become a people who value rational dialogue based on verifiable proof as long as we continue to insist on parlay.