‘EVOLUTION IN FOUR DIMENSIONS’ BY EVA JABLONKA AND MARION LAMB
The concepts of survival of the fittest, competition for resources, and genes as the drivers of evolution are deeply ingrained in our psyche. The classic paradigm of evolution still leaves certain issues unexplained. The very simple bacteria have remained unchanged, despite the status of resources, for billions of years. They will likely continue to survive and thrive for billions of years, even after humans have vanished. Equally, the origin of species, or speciation, remains somewhat of a mystery in the classic theory of evolution.
However, there are many dimensions to evolution, and genes are only the first. Evolutionary biologist Richard Dawkins attributes evolution solely to genes and their “selfish” propagation. Dawkins’ theory suggests that genes possess the eerie ability to think and manipulate the body for their own purposes. It is almost a devilish gene. This is not accurate, say Eva Jablonka, and Marion Lamb in this wonderful paradigm-changing book on evolution.
This book presents a more comprehensive perspective on evolution, incorporating factors beyond just genes as the sole mechanism. The classical methods of DNA change are a) reproduction, b) sexual processes, and c) mutation. The classical paradigm of evolution is that mutations occur randomly, causing a survival advantage. However, epigenetics shows that environmental influences can also cause secondary DNA changes, which can then pass on to the next generation. Cellular and extranuclear influences on DNA content and expression form the core of the entire field of epigenetics.
Genetics, Epigenetics, Cultural, and Symbolic Factors
Epigenetic factors, which consist of numerous self-sustaining loops, along with cultural and symbolic factors, work together to modify the effects of genes, resulting in a vast variety of species. Sometimes, the inheritance of the other three factors is strictly non-genetic, bringing a Lamarckian perspective to the concept of evolution. The authors repeatedly stress that genes still have a central role, but not in the way the strict Darwinians would like us to believe.
The traditional Darwinian view, or the Neo-Darwinist view, holds that genes are the entire story of evolution. The traditional perspective — the classic ‘dogma’ — posits a linear process from genes to proteins to functions. Every protein has a corresponding gene, and every function has a corresponding protein; the reverse is not possible. The variations in species occur due to random mutations in the genes that are blind to purpose and function. They remain undirected and independent of any external factors. Blind mutations result in a variety of species. The species then attempt to adapt to their environment, with the best and fittest surviving to perpetuate themselves in the struggle for existence. In this competitive world, the strongest emerge as the victors, while the weakest face extinction. There was no possibility of reversing genetic influences.
Lamarck was a prominent contemporary of Darwin, who proposed the theory of the inheritance of acquired characteristics. Lamarck cited the classic example of giraffes developing long necks to reach food from tall trees. The Neo-Darwinists quickly discredited this and abused it to such an extent that the mere mention of Lamarck sometimes elicits accusations of anti-science or even creationism. Currently, Richard Dawkins is its most prominent voice. Interestingly, Darwin himself held some positive views regarding the inheritance of acquired characteristics, but later Neo-Darwinists forcibly removed any Lamarckian ideas from Darwin’s theory.
Are Genes Everything?
The stunning aspect of the Human Genome Project was the discovery that only 20,000 genes comprise the human DNA. It was shocking, to say the least, because scientists expected many more, in the hundreds of thousands, given the huge complexity of the human species. A grain of rice, lowly worms, and some mice turned out to have an equal or greater number of genes than the human being. Therefore, it is evident that development, evolution, heredity, and related concepts involve factors beyond genes.
The authors write that evolution involves the variation of different species, the transmission of information that leads to the perpetuation of species, and the selection of species in the fight for survival. The crucial aspect is the transmission of information, either vertically or horizontally, between species within the same generation, which drives evolution. This transmission of information occurs not in one manner but in four different ways. Genetics is the first and still the most important mechanism. However, other mechanisms include epigenetic, cultural, and symbolic factors (language development is a significant component of the last). The combination of these four factors paves the way for evolution. The authors show that the vastness of the living kingdom provides ample evidence for all these theories proposed in evolution.
Epigenetics
Epigenetics is the study of cellular and cell membrane mechanisms that influence genes to turn them on and off at the appropriate times. An undifferentiated cell mass divides into various cells. At a critical moment, the cells assume various functions and migrate to different locations, such as the liver and kidney cells. After reaching that point, they divide into identical cells. It is very difficult to explain this selective switching off and perpetuation of a single type of gene product solely based on genetics. And here the epigenetic mechanisms come forcefully into play. They enable the expression of certain genes and the suppression of others.
Only 3% of human DNA contains the genes that code for proteins; the vast majority, once deemed ‘junk,’ is hardly that. The recognition of epigenetic mechanisms as a crucial factor in controlling genes is growing. In epigenetics, the interaction between gene products and cell membranes with surrounding environmental influences determines the expression of certain genes. In contrast to the classic dogma, this approach reverses the direction of genetic changes and expression. The exciting part is that we can inherit these epigenetic mechanisms. It is known that the epigenetic mechanisms actively interact with the surrounding environment, inducing changes in DNA that manifest not only in one generation but also in subsequent ones.
Bruce Lipton simplifies and romanticises epigenetics in his book, “The Biology of Belief.” Being a book written for a general audience, it tends to simplify the science. He calls the cell membrane the Mem-Brain, the actual brain of the cell, interacting with the surrounding environment and allowing the transfer of energy and waste across the cell. It empowers the cell to operate as an autonomous energy system capable of replication and utilising DNA for this purpose. The nucleus is in fact the “gonad” of the cell because it appears to serve this purpose. Removing the nucleus does not hamper the function of the cell, which continues till its death. The removal of the cell membrane kills the cell immediately. Unfortunately, traditional biologists do not believe in or emphasise the importance of epigenetics, despite the great dimension they have added to evolution. Genetic mechanisms ultimately translate from epigenetic mechanisms.
Is It Always Competition in Evolution?
Lynn Margulis, in her book ‘Microcosmos,’ actually places mutation as only one of the mechanisms driving evolution. Mutation, despite being a slow process, can explain the evolution of human life over a vast time frame of 4 billion years. However, due to the horizontal transmission of genes from freely flowing DNA between bacteria, we can consider all bacteria in the world as a single, shared genetic pool. Therefore, organisms’ transmission and adaptation are not solely due to random and untargeted gene mutations. These horizontal transmissions in the same generation are responsible for the widespread antibiotic resistance in times of stress. Here, the mutations are targeted.
Symbiosis is another intriguing method of adaptation and evolution. Humans and other genetic pools have incorporated bacterial genes, and species have co-evolved in a spirit of cooperation rather than competition. The mitochondria in every cell for oxygen utilisation and in sperm tails serve as examples of symbiotic phenomena. We now know that the mitochondrial DNA replicates independently and has a definite bacterial origin. At some remote time in the past, the mitochondrial DNA incorporated into the cell and evolved as the present human cell.
Cultural Factors
They also play a significant role in evolution. Mothers who follow a specific diet during pregnancy or breastfeeding can significantly impact the dietary preferences of their offspring. In fact, the mother’s body excretions modify the eating preferences of the species! In these cases, it is evident that non-genetic factors play a role in the transmission of specific tastes and preferences. Studies have demonstrated that these transmissions impact variations and survival.
There are cultural factors that influence the selection and propagation of the species. Systems biology studies the system holistically, recognising emergent properties that arise from any system. In contrast to the prevalent belief in classical sciences and biology, the characteristics of the entire system surpass the sum of its components. A philosophy of science, known as reductionism, has been to study the smallest parts in minute detail in order to understand the whole. Modern scientists, such as Fritzof Capra and others, assert that this approach is impossible. We must study the system holistically. Reductionism works only to a limited extent.
Cultural factors lead to various transmissions of information, sometimes dependent on genes and sometimes independent of them. Even without any exposure to lions, a certain animal species of harbour an innate fear of their smell. This information passed from parents to offspring does not seem to arise out of genetic mechanisms alone. Many times, exposure to specific influences leads to the transmission of numerous genetic and epigenetic changes. These instances result in targeted and functional genetic changes.
Symbolic Factors (Including Language)
Finally, in higher animals like chimpanzees and humans, symbolic communication plays a key role in deciding the direction of evolution. Particularly in humans, the development of language represents a highly advanced form of symbolic communication. Language has allowed a very rapid transfer of information and is instrumental in the development of strategies to manipulate the environment using science and technology. This scheme of manipulation involves manipulating the genes themselves to steer evolution in a specific direction. So, in the final analysis, as Lynn Margulis says, DNA has evolved to manipulate and change itself!
Humans have this great idea of being the top of the evolutionary ladder, but Lynn Margulis happily takes them off the pedestal. Her book teaches us a valuable lesson in humility as we confront the ‘lowly’ bacteria, who are likely to outlive us many times over. However, the Earth may find its own Gaian mechanisms to survive human extinction.
Concluding Remarks
The genetic and epigenetic mechanisms are so complex and intricate that a manipulation cannot possibly happen on a large scale anywhere in the near future. The reverse manipulation of genes has begun, and its end is unknown. It is a complex, interacting web of factors leading to evolution. Dawkins’ idea of the selfish genes, replicators, and vehicles is too simplistic a view of evolution. Rather, the animal kingdom is rich with examples of these mechanisms, as the authors wonderfully demonstrate. The only criticism is that the descriptions sometimes exceed the comprehension of a layperson, yet these instances do not diminish the book’s brilliance. The authors have refrained from presenting their theories in a “popular” format, as challenging the standard paradigms requires a detailed and scholarly approach, which is what the authors have opted for in their book.