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Darwin’s limitations (03/2006)
The major features of evolution are pre-determined and not only the result of random or accidental processes, two leading European scientists propose in a paper published in the Journal of Theoretical Biology .
Professor Robert Williams of the University of Oxford and Professor Fraústo da Silva of the Instituto Superior Tecnico of Lisbon, challenge the Darwinist idea that the overall course of evolution random and purposeless, and that the appearance of organisms with increasing complexity (including man) is ‘sheer luck’.
In a polemic argument likely to fuel the controversy of Intelligent Design – the idea of a hidden hand behind life as supported by Creationists - Williams, an Oxford Emeritus Professor of Inorganic Chemistry, and Fraústo da Silva, Professor of Analytic Chemistry, propose that evolution is directly influenced by the changes in the chemical environment. This theory snubs the Creationists’ major criticism of Darwin by explaining how evolution follows a trail of increasing complexity without relying on the existence of a ‘supernatural’ entity.
In an argument contributing to the ongoing debate about the origins of life, the two scientists claim that the path of evolution was scientifically unavoidable
Williams and Fraústo da Silva also affirm that the chemical organisation associated with life had to exist before the emergence of the genetic code: the genetic code was not the origin of life, but the written instructions of something that already existed. The code is necessary for reproductive life but it had to follow the changes of the environment.
This order of events disagrees with Darwinists that believe living machines began as passive receptacles for genes while providing protection against external aggression.
The two scientists write “chemicals exposed on Earth will also be driven towards such a steady state of optimal energy retention and maybe it was progress towards this state which forced life to start and then for evolution to proceed as it has done in a general inevitable way.”
Fraústo da Silva, Professor of Analytic Chemistry at the Instituto Superior Tecnico of Lisbon, Portugal, was the Founding Chancellor of the New University of Lisbon, and a former Portuguese Education Minister.
Williams is a Fellow of Britain’s Royal Society, which bestowed the same honour on Charles Darwin in 1839. He is now Emeritus Professor of Inorganic Chemistry at the University of Oxford, a Fellow at Wadham College, Oxford, and formerly Napier Research Professor of the Royal Society.
Was the overall course of evolution chemically constrained and so inevitable, or a random process?
Darwinists propose that the evolution of species came about through random mutations producing variations and natural selection excluding the less successful ones. To the Darwinists, although natural selection itself is not a random process (since a policy of ‘survival of the fitness’ introduces a selective elements into the process), evolution as a whole, is a purposeless process without a defined course. This, however, cannot explain the observed tendency to increasingly complex organisms over time, including man. According to Darwinists this was nothing more than a product of chance.
Williams and Fraústo da Silva challenge that idea and ask why would organisms expend energy in becoming more complex when primitive life forms, such as bacteria, were so successful? They propose a simple answer: they could do nothing else if they wanted to survive.
The two scientists, who have co-operated for more than 20 years, argue that the Darwinist theory is not sufficient to explain evolution. Williams’ and Fraústo da Silva’s hypothesis tries to ‘extend’ Darwinism, by explaining the reasoning behind the changes observed in life’s complexity over time (starting with very basic life forms such as bacteria and ending millions of years later with highly complex organisms such as mammals).
They explain how the appearance of increasing complexity in the process of evolution was result of environment influences on living organisms and their need to survive, and therefore inevitable.
The essential difference between Darwin’s, and Williams’ and Fraústo da Silva’s theories is their approach to the study of evolution.
Darwinists started studying evolution by following changes in the physical properties and activity of the organisms; once genes were discovered they observed molecular changes.
Williams and Fraústo da Silva, on the other hand, argue that evolution cannot be studied in isolation from the changes that occur in the environment. They believe that living organisms and their environment constantly interact and so affect each other’s evolution.
And to them, crucial to the development of life during the past 4.5 million years must have been the chemical environmental change in which hydrogen was initially predominant (that is a ‘reducing environment’), which was followed by a predominance of oxygen (an ‘oxidising environment’).
Williams and Fraústo da Silva consider that energy was the basic driving force behind of all evolution. Energy from the sun increased earth’s temperature and was the responsible for the alterations in the chemical environment. Evolution followed a path towards an optimal energy retention state.
In their paper, Williams and Fraústo da Silva also give especial attention to energy sources available to living organisms: how these changed with time and how this influenced life. Again, the major modifications occurred through the chemical environment. Chemical changes in the atmosphere and the sea led to changes in the availability of different chemicals elements that could be used as energy sources. Evolution, in order to make the optimal use of these resources, followed.
The evolution of the environment
Williams and Fraústo da Silva argue that the changes from a reducing to an oxidising environment must have started with the separation of water into hydrogen and oxygen in a reaction catalysed by the sun’s energy. When separated, these two elements would bind to different molecules creating an environment composed of a mixture of reduced - that is bound to hydrogen - and oxidised elements.
Organic molecules - those associated with life - would bind preferentially to hydrogen and so be found in a so-called ’reduced state’ (of higher stability in water). In time, some reduced organic molecules were trapped in small isolated structures or ‘vesicles’. Because organic molecules continued to bind hydrogen from water, releasing oxygen to the environment, the differences between the two compartments (inside and outside the vesicles) increased.
Williams and Fraústo da Silva explain how there had to be exchange of material between these newly separated vesicles and their surroundings, and eventually a relatively stable equilibrium must have been achieved: Lipids, nucleotides (the basic “bricks” of DNA and RNA), sugars and proteins appeared, probably by chance, in the vesicles. Later, DNA (or RNA) also emerges what allowed these vesicles to replicate and self-perpetuate.
This was probably the beginning of life as we know it, and the separation between reduced and oxidised elements (inside and outside vesicles) was the key for its emergence according to Williams’ and Fraústo da Silva’s theory.
These new life forms were the first prokaryotes (simple cells with no organised nucleus or cytoplasmic 2 compartments).
It is the transfer of energy from the sun to earth’s chemicals, changing their reduced/oxidised state, that initiates the process that culminates in the appearance of life.
To Williams and Fraústo da Silva the appearance of genetic code was important because it allowed the successful chemical organisation of the emergent vesicles to replicate and be conserved. Only after this stable organisation was achieved, did the code emerge and persist; vesicles capable of replication must have been the most successful in evolutionary terms, they argue.
But, contrary to Darwinist theory, the two scientists think that it was the environment which gave the ‘impulse’ to the creation of the chemistry that is now associated to the life. The genetic code was not the beginning of everything as Darwinists claim but most probably the written instructions of something already in existence.
In fact, Darwinists believe that the chemical organisation appeared to protect the genetic material and so emerged later in the sequence of events.
Williams and Fraústo da Silva continue:
To maintain stability in water, chemicals inside the vesicles, had to be kept in a reduced state so hydrogen was constantly captured from water and oxygen released to the environment. This increasing availability of oxygen led to the oxidation of several chemical elements making their use difficult by cells that require them ‘reduced’.
Probably by then, water becomes the cell’s source of energy due to both its high capacity to reduce molecules, and its abundance. But the use of water and the new oxidised elements within the cell would compromise the cell’s chemistry and damage its reduced elements such as DNA.
Overcoming this problem, a new type of more complex organisms appeared with separated compartments within the cytoplasm. These allow the presence of ’dangerous’ molecules inside the cell without coming into contact with the cytoplasm 2. These molecules now could also be used, not only as source of matter but also of energy. Evolution of a communication system was now necessary between the genetic code and these new compartments or this more complex organisation would not be sustainable. Again, the new oxidised elements from the environment were perfect for this function.
These were the eukaryotes (more complex organisms where the genetic material is contained in the nucleus and subcellular structures carry out particular functions)
It was the need of deal with the increasingly oxidising environment that forced organisms to evolve in order to survive.
So what initially was a problem, the high oxidation of the medium, eventually lead to advantages: a more efficient usage of the environment, a new (and more efficient) source of energy. Evolution’s path leads to a full exploitation of space and environmental resources.
The two scientists also explain, using environmental changes and their effect on life, the emergence of increasingly complex organisms such as plants and animals.
In plants, a more complex organisation allows a better use of land and light.
In animals, not able to synthesise their own energy, their complex body organisation allows a more effective search for food and the use of the environment for protection. Larger bodies appeared with organs in communication with each other and under the control of a nervous system (that eventually evolved to a brain).
However, highly complex organisms need high quantities of energy for their maintenance. This diminishes the amount of energy available for reproduction and survival. In order to overcome this problem, cooperation between different species emerged. Cooperation, by creating “division” of jobs between the species involved, allows reduction of complexity and subsequent increase in survival potential. This is especially true among complex eukaryotes.
The future of evolution
To Williams and Fraústo da Silva the drive behind evolution was the energy transfer from the Sun to the Earth and its chemical elements. These elements will be driven towards a state of optimum energy retention and it is the resulting alteration in the chemical environment that will force evolution. The key to the appearance of life is, as shown, the initial separation between reduced and oxidised chemicals. Next, as the chemical environment progresses, life had to evolve in order to survive and this resulted in an extensive use of the environmental space and resources. The process was balanced and slow until man appeared.
Humans have a developed brain and learned how to manipulate the environment to improve what is considered ‘quality of life’. For immediate satisfaction we have created new chemical elements changing the chemical milieu, often irreversibly. Communication systems, new sources of energy - many times based on new chemicals - emerged. Chemical resources and space approach exhaustion.
And the equilibrium of the open (energetic) system where we live is fragile. To Williams and Fraústo da Silva this is the last stage of chemical evolution. Now the question is how will these chemical changes affect the future of evolution. And this has to be taken in account if we want to survive.
Williams’ and Fraústo da Silva’s theory tries to explain the past as well as predicting a possible future.
In an interview this week, Professor Williams refers to geochemical data supporting his theory. These data show that certain elements, such as sulphur, appeared initially in a chemical form not associated with biological processes, and only later started to be use by living organisms. This shows that it has appeared before life and so are not result of the genetic code.
Williams also mentions the fact that some of the cell chemistry involves the use of elements, which are ‘dangerous’ to organic molecules, such as DNA or RNA. So systems to protect these two molecules are needed before the genetic code (DNA or RNA) can appear. This means that the chemical structure had to be functioning before the code appeared.
Calcium is one such example. It needs to be continuously expelled from the cell otherwise it will damage organic molecules. Interestingly, during evolution, this initial disadvantage was later transformed into a gain by using calcium as a messenger between the cell and the outside environment. This is a good example of how evolution follows a path which maximises resources. An initial problem is adapted to become a gain.
Williams and Fraústo da Silva do not dispute the foundation of Darwinism, which theorises that variations in species appeared by random processes or mutations, or that the less successful ones are eliminated by natural selection. Because they do not deal with species but only with life’s major organisation.
They argue, however, that the overall direction of evolution was limited by the changes in the surrounding chemical environment, and so the evolutionary path was inevitable and predictable. The fact that the genetic code is not thought to have appeared before much of the chemistry associated with life further supports their hypothesis. An important prediction by Fraústo da Silva and Williams’ theory is that man’s manipulation of the chemical environment, for example by creating new elements, will no doubt influence the future of evolution. For the better or the worse.
Journal of Theoretical Biology (2003) vol 220, p323-343
2 cytoplasm - living part of a cell, excluding the membrane and the nucleus
Ends/CA/5 March 2003.
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In collaboration with the Observatório da Ciência e do Ensino Superior (OCES)
Financed by the Fundação para a Ciência e Tecnologia (FCT) |
