Share:
Evolution theories, meanings and examples
Nature accompanies our thinking. Naturopaths often equate nature with gentle or romanticize them as a counterpoint to alienation or the side effects of "unnatural" methods of medical treatment. This often lacks the basic knowledge about natural relationships, especially about how the evolution of life forms works. Instead, some "nature healers" use prescientific ideas that attempted to explain the events of life before the Darwinian Revolution.
Jablonka and Lamb criticize the synthetic evolutionary theory, the standard of evolutionary science. They consider it necessary to expand them. Molecular, developmental and behavioral biology today show that inheritance also takes place outside of genes and DNA.
contents
- Presentation of the authors
- A tough scientific piece
- popular science
- How does inheritance work??
- Not just the genes?
- Three more dimensions of inheritance
- Synthesis between genetic and non-genetic inheritance
- Darwin's idea of inheritance
- Darwin's concept is possible even without genes
- Modern synthesis
- Richard Dawkins and Stephen Jay Gould
- Mutations of individual genes irrelevant
- Can an inheritance system be replaced??
- Social questions
- New perspectives
- Medical consequences
Presentation of the authors
"One should see everything as simple as possible - but also not simpler," so quote Eva Jablonka and Marion J. Lamb Albert Einstein and give with her work "Evolution in four dimensions. How genetics, epigenetics, behavior and symbols shape the history of life "is an example of this claim. They give a new impulse about the heredity of living things, without on the one hand slipping away in scientific jargon, not understanding the outsider and without on the other hand shortening in such a way that the information gets wrong.
In their book "Evolution in Four Dimensions: How Genetics, Epigenetics, Behavior and Symbols Shape the History of Life", Eva Jablonka and Marion J. Lamb describe an extended and differentiated theory of evolution. (Image: hecke71 / fotolia.com) Eva Jablonka, born in Poland in 1952, works as a biologist, evolutionary theoretician and geneticist in Israel and researches non-genetic inheritance of animal behaviors as a professor at the Cohn Institute for the History of Science and Theory of Science at the University of Tel Aviv. Marion J. Lamb taught at the University of London Birkbeck College and has been researching epigenetic inheritance with Eva Jablonka for several decades.
The English-language original is already 12 years old and is now available in Hirzel-Verlag in German translation.
A tough scientific piece
The evolutionary sciences are meanwhile exceedingly complex, and the history of evolution theory has been controversial since Darwin. In addition, biology is constantly gathering new insights into the way genes work.
The American biologists Jablonka and Lamb focus on a "developmental and system-oriented approach to inheritance and revolution" and are concerned with concepts that include developmentally-induced hereditary epigenetic changes as the origin of new variants, which pure geneticists deny.
"Evolution in four dimensions" deals with a hard scientific hunk. However, this is of great importance for medicine: the knowledge of how heredity works has an immediate effect on assessing genetic dispositions to diseases and using the logical methods to treat them.
In order to convey the matter comprehensibly, each chapter ends with a fictive dialogue in which the authors answer the critical questions of an Advoctus Diaboli.
popular science
"Evolution in four dimensions" is explicitly aimed at biological laymen. The first part in particular may therefore bore academically trained biologists, since the authors describe Darwin, Lamarck and Weismann's ideas in detail and repeat what they have written. But for the layman to understand what it is all about, these repetitions are understandable in the literal sense.
They may even be necessary, because the second part deals with an extended concept of evolution, which involves the transmission of information such as behavior, symbols, writing and language. Without explaining comprehensively what inheritance made possible by Darwin, Lamarck, Weismann, in modern synthesis, in molecular biology, by Richard Dawkins and Stephen Jay Gould, non-specialist readers will find it hard to understand what the authors of the book are Criticize fixation on the gene as a carrier of heredity.
According to Lamb and Jablonka, man controls his evolution through language and culture, which became at least as important as genetic selection.
The authors point out that inheritance is not just about genes. (Image: Sashkin / fotolia.com) How does inheritance work??
The book is about heredity, and the authors focus on four theses:
1) Biological inheritance includes more than just genes
2) Some hereditary variations do not arise by chance.
3) Some forms of acquired information are hereditary.
4) The change of species is not only the result of selection but also of learning.
This contradicts the traditional Darwinian view that adaptation is always the result of natural selection of random genetic variants. Their theses are based on experimental and empirical findings, which, according to Jablonka and Lamb, make a new concept of inheritance necessary.
Not just the genes?
Not only genes controlled heredity, but heredity has, according to the authors, three further dimensions: Molecular biology has shown that body cells transmit information to daughter cells through epigenetic distribution. Animals would pass on information through specific behaviors, that is, have another inheritance system - social learning. With the symbol-based inheritance, humans even had a third inheritance system, for example through language and writing. Thus language would have played a crucial role in human evolution.
Not only genetic, but also epigenetic processes, behavior, and symbolic inheritance bring forth additional variants, among which natural evolution selects. Environmental skills also played a key role in evolutionary processes. Instead of just seeing the genes as the originator of inheritance, the authors therefore choose a four-dimensional perspective, as the book title announces.
The first part of this extensive work deals with the genetic system. Its first chapter outlines the theory of Charles Darwin and shows why its development in the 20th century focused on the genes. Chapter 2 shows how molecular biology broke this focus and Chapter 3 discusses that not all mutations are the result of random events.
Three more dimensions of inheritance
The second part deals with the three further dimensions of heredity, first the epigenetic systems of inheritance such as architectural memory, ie the inheritance of structures or the memory of chromosomes and the transmission of epigenetic variations to the offspring.
This is followed in Chapter 5 by behavioral inheritance systems such as the sharing of information through social learning, inheritance through the transmission of behavioral substances or inheritance through non-imitative social learning such as opening milk bottles, learning by imitating, for example, singing whales and learning through traditions and cumulative evolution.
Inheritance through the transmission of behavior-influencing substances: The later dietary preferences in infants are already influenced by breast milk. (Image: stanislav_uvarov / fotolia.com) The sixth chapter deals with symbol systems of inheritance. These include symbolically mediated communication as an inheritance system, cultural evolution and symbolic communication, the "egoistic meme", evolutionary psychology, the reading and writing module, and ultimately the transition from evolution to history.
Synthesis between genetic and non-genetic inheritance
In the third part, the authors put the parts together again to the big picture. In Chapter 7, they shed light on the interactions between genes and epigenetic systems of inheritance. How do epigenetic systems influence the generation of genetic variability? How do genomic imprints and gene selection affect you? What does genetic assimilation mean??
Chapter 8 outlines genes and behavior as well as genes and language. These include genes, learning and instincts as well as cultural niche construction. The authors deal with the question: what is language ?, and explain how language changed the genes.
Chapter 9 is called "Lamarck's Mechanisms: The Evolution of the 'Justified Conjecture." Here, Jablonka and Lamb show the origin and genetics of interpretive mutations such as the origin of epigenetic systems of inheritance. It also deals with structural inheritance, RNA interference and the origins of tradition in animals. The authors examine: Under what conditions does the evolution of communication through symbols occur??
Darwin's idea of inheritance
So it's a complex matter that the two biologists try to explain as understandably as possible. First of all, they show that there is no such thing as an "indisputable, scientifically accepted theory of evolution, which every biologist equally understands". But they do not support the pseudo-science of Intelligent Design, which puts the Christian belief in creation into modern phrases, but rather show the complexity of theories within evolutionary science.
They ask: Can natural selection alone explain any form of evolutionary change? Where are the origin of, how are all these hereditary variants, under which the selection should select?
Darwin himself, according to the authors, did not provide a sufficient answer to these questions. The crucial laws of life were, according to him, duplication (reproduction), heredity, the differences between the individuals and the struggle for existence.
Darwin's concept is possible even without genes
This Darwinian concept criticizes the authors as extremely general; it says nothing about the processes of heredity and duplication, "nothing about how hereditary variation arises, nor about the nature of the entity, which is to change by natural entity over time." It would be possible, Jablonka and Lamb To be a consistent Darwinist without following Mendel's laws, mutating genes and DNA codes.
From the authors' point of view, Darwin's theory of evolution is very general and says, among other things, nothing about how hereditary variation arises. (Image: zinkevych / fotolia.com) Darwin, according to the authors, suspected hereditary variability by direct environmental effects on the organism but also an indirect mechanism through "use and disuse of organs".
Darwin was therefore in the notion that acquired properties can be inherited, not far from Lamarck, and "virtually all biologists at the beginning of the 19th century" shared this view. Darwin and his followers would have realized that a viable inheritance theory was missing.
Only the neo-Darwinist Weismann rejected since the 1880s, according to the authors, the inheritance of acquired properties. Unlike Darwin, he excluded an evolutionary effect of the use or disuse of organs. The sexual processes caused the hereditary differences between the individuals, so Weismann.
Modern synthesis
In the 1930s, a modern synthesis of Darwinian and Weismann ideas came about. This was based on the following conditions:
1) Inheritance occurs through the transmission of germ cell genes
2) Hereditary variations are the result of random combinations of alleles produced during various sexual processes.
3) Selection takes place between individuals.
Within evolutionary biology, these theses were contradictory. So many biologists have criticized that inheritance is more than the transmission of nuclear genes from one generation to another. Also, the egg cell would have a significant importance in the development of artifacts.
Molecular neo-Darwinism since the 1950s finally focused on the DNA of which Darwin knew nothing. However, molecular genetic studies have shown that populations have significantly more hereditary variability than previously thought. Biochemical findings in the 1960s showed that chance had a significant impact on how natural populations developed.
Richard Dawkins and Stephen Jay Gould
Richard Dawkins finally stated that the body of an individual is a vehicle, not a replicator. Individual adjustments, according to Dawkins, have no effect on heredity.
The American paleontologist Stephen Jay Gould sharply criticized Dawkins. He said that any gene-centered view of evolution must necessarily be misleading. Because always individuals, groups or species survived - not the genes. Instead, according to Gould, one has to consider earth-historical events as well as coincidences that influenced the genetic variants in populations - natural selection is only one of many factors in the world of living beings.
This controversy lasted until Gould's death in 2002. The polemics with which the two camps argued concealed, according to the authors, that Gould and Dawkins agreed on heredity in two ways: first, both of them considered genes to be the only essential inheritance units in living beings (other than humans) secondly, acquired properties as not hereditary.
Epigenetic research is concerned with hereditary changes in genome function that are not based on a change in the DNA sequence. (Image: Dan Race / fotolia.com) Mutations of individual genes irrelevant
According to the authors, individual mutations are statistically selection-neutral, only in interaction with other genes and under certain environmental conditions increases the likelihood of producing offspring - the environmental conditions and interactions with genes are different, however, the same mutation can be detrimental. Evolutionary change as a result of individual mutations is thus untenable. Units of evolutionary change are rather networks rather than individual genes.
Can an inheritance system be replaced??
In Chapter III of the first part, Jablonka and Lamb discuss that the genetic inheritance system can not be replaced by other forms of inheritance, although this is theoretically possible. The various epigenetic inheritance systems have in common that they transfer information from cell to cell.
Epigenetically inherited expressly does not necessarily mean "good". Cancer cells, for example, proliferated and spread throughout the tissue, harming the organism. On the other hand, an epigenetic variant would have to bring benefits on the whole organic level in order to spread in a population.
Also valid for epigenetic inheritance. "In a multicellular organism, every type of variability is often limited - each variant must first and foremost pass through the bottleneck of development before it becomes a viable organism."
Social questions
Lamb and Jablonka write: "Since many biologists emphasize the genetic aspect in human behavior, laymen often conclude that general behaviors (especially reprehensible ones) are" genetic ", thus" natural "and (...) inevitable. This is nonsense (… )."
On the other hand, humans have a story, could plan their future and create common imaginary worlds. Genes, on the other hand, have neither responsibility nor explanatory power. Sociobiologists sometimes run "scientific" soft pornography and might thus satisfy the desire for simple causal thinking - without significant empirical evidence.
Genes as "connection to our distant past" have something that touches us in an irrational-mystical way; The evolutionary history of many human sociobiologists is moving in this strange combination of romanticism and science.
New perspectives
The authors state: "What we call" a plant "or" an animal "is in fact an integrated community of species that live together, evolve together and evolve together." Systems biology today is from an idea to mainstream within the community Become biology. Their primary focus would be on the networks of the cell. Whether their approach is a decisive change of perspective in evolutionary thinking, perhaps science historians of the future would decide.
Medical consequences
If, as the authors assume, individual experiences have an effect on the offspring, that is, if genetic and non-genetic heredity interact, this has consequences, as Jablonka and Lamb explain with examples. They describe how, in northern Sweden, a grandfather's access to food in his childhood influenced the mortality risk of his grandchildren, and grandmother's food supply the mortality of granddaughters.
An English study from the 1990s has shown that the sons of early smokers are at higher risk of becoming obese as adults.
In both men and women, therefore, extra-genetic factors influence their offspring. Any long-term learned behavior would have an epigenetic effect on heredity.
They quote Lawrence Parson: "The brain is a cultural artifact, it not only constructs, but it also reflects culture."
Jablonka and Lamb suggest that individual experiences have an impact on offspring. For example, they report a case from Sweden where a grandfather's food supply in his childhood impacted the mortality risk of his grandchildren. (Image: A_Lein / fotolia.com) For the treatment of diseases that have a genetic component, the approach of Lamb and Jablonka means: There is not one gene that decides whether a disease breaks out or not, and the average increased risk of such a genetic disposition says nothing about the individual case.
A treatment that makes sense for one person can even be harmful for another person affected by this genetic feature - it does not depend on the individual gene, but on networks of different genes, which in turn interact with extra-genetic factors.
The authors discuss biologists who deal with fundamental questions of evolutionary science, not as medical women.
However, their emphasis on epigenetic structures and the rejection of "gene determinism" raises crucial questions for diseases with a strong genetic component, from autism and Alzheimer's to some types of cancer to schizophrenia: social and cultural experiences in the family influence the " genetic disposition ". Only when genetic, epigenetic and symbolic-cultural aspects are taken into account can these diseases be prevented.
If you are interested in naturopathy and would like to find out what nature, genes, DNA or heredity are, this book is recommended as a basis and read more fluently than other standard works on evolutionary science. (Dr. Utz Anhalt)
Evolution in four dimensions
How genetics, epigenetics, behavior and symbols shape the history of life
by Eva Jablonka and Marion J. Lamb
Hirzel Verlag 2017
566 pages, 42,00 EUR
ISBN 978-3-7776-2626-0