Evolution theory
Chapter 1 - Worldview
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Welcome to the Evolution theory page
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How life evolved
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Life as we know it today would be impossible without the processes described in Darwin's evolution theory.
Before Darwin, men assumed that a supernatural creator provided all kinds of life. We can hardly overestimate its revolutionary character.
However, organisms with traits that are better adapted to the circumstances can produce more offspring because those traits help them survive. Through (chance) variation and adaptation to changing external conditions, populations change because the genes of better-adapted individuals can spread more quickly in the population.
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Core of the evolution theory as constructed by Charles Darwin
The core message of the evolution theory is that all species of life on this earth have evolved slowly from a common ancestor organism thanks to the mechanism of natural selection.
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- Mutation
- somewhere in the population, ensures
- Variation
- in the relationship of individuals of the population regarding the context, creats possibilities for
- Selection
- of the most adapted individual regarding the context who is able to reproduce.
- Reproduction
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Only the third step of the evolutionary process is focused on the individual. Even in the case of selective survival, if the most adapted to the environment cannot reproduce, the new feature will only exist for a very short time in a very tiny place.
Darwin's theory is about 'the origin of species, not the origin of individuals'.
| External links |
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| Darwin Online (darwin-online.org.uk) |
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A dangerous idea
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The core idea by Darwin himself
| If under changing conditions of life organic beings present individual differences in almost every part of their structure, and this cannot be disputed; if there be, owing to their geometrical rate of increase, a severe struggle for life at some age, season or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of life, causing an infinite diversity in structure, constitution, and habits, to be advantageous to them, it would be a most extraordinary fact if no variations had ever occurred useful to each being’s own welfare, in the same manner as so many variations have occurred useful to man. But if variations useful to any organic being ever do occur, assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance, these will tend to produce offspring similarly characterised. This principle of preservation, or the survival of the fittest, I have called Natural Selection. (1) |
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We are not the centre of the world
| Both the emergence of adaptation and diversity were different aspects of one complex phenomenon, and the idea that links the two was, in his view, the principle of natural selection. (2) |
Darwin's (evolution theory) most significant contribution to thought is his rejection of essentialism. This classical doctrine holds that for every natural thing or species, there is an essence, a necessary and sufficient set of properties that make something part of that species. Instead, he showed that species are historically linked by a chain of variations that differ so tiny that there is no reason to draw a line anywhere.
| Content source | |
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| (1) | On the Origin of Species BY MEANS OF NATURAL SELECTION - By Charles Darwin, M.A., F.R.S. - Sixth London Edition, with all Additions and Corrections. |
| (2) | D. Dennett – Darwin’s Dangerous Idea |
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Key take-aways from the deep dive
- Life occurs in the form of one of two 'major systems': self-organising or complex adaptive
- Forms of self-organising: plants, animals, humans, ...
- Forms of complex adaptive: nature, culture, ...
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Deep dive
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Structures in nature and human systems
Life occurs in the form of one of two 'major systems'.
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Self-organising (dissipative) structures
| A Dissipative Structure is a thermodynamically open system operating far from thermodynamic equilibrium, that exchanges energy, matter, and information with the external environment. In this kind of systems, organization can emerge through a spontaneous self-organization process, by virtue of the exchanges with the external environment, that generates a formation of both spatial and temporal ordered structures, in which interacting constituents show long-range correlations.
The creation of spatiotemporal structures is extremely interesting because it causes macroscopic self-organisation that depends on microscopic interaction between organic and inorganic elements in the system. Order is created from an initial state of uniformity and chaos. (1) |
Complex adaptive systems
| Interactions between system constituents, that are neither isolated nor free, involve continuous reciprocal adaptation; each individual acts and reacts according to actions and reactions of the other individuals. This process, generated by competition and cooperation among the components, each pursuing its own aims, does not stop until organization that guarantees harmonious, non conflicting interactions among individuals is achieved.(1) |
| Content source | |
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| (1) | E. B. P. Tiezzi, R. M. Pulselli, N. Marchettini & E. Tiezz - Dissipative structures in nature and human systems |
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Genes
The evolutionary process
Genes are passed on from parents to offspring, combining the genetic material of two organisms during sexual reproduction and ensuring parents transmit their characteristics to their offspring.
Copying errors in transferring genes to offspring cause variation. Without these copying errors in the genetic material and offspring differing from their parents, life on earth today would still consist of the first single-celled bacteria, which multiplied through cell division and emerged in the ocean about four billion years ago.
There is no evolution without
- variation, because organisms do not change over time
- heredity, because there is no selection, and beneficial variations are not passed on to offspring
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Competition to reproduce
Evolutionary competition to reproduce takes place not so much between organisms themselves as between genes.
They 'compete' to get as many copies of themselves into the next generation of organisms as possible. Of course, they don't do that consciously. They are blind, mechanical replicators. When the organism they create and inhabit reproduces, they simply make copies of themselves.
Genes control the organisms—they determine their physical and mental properties and, therefore, their behaviour. And genes use them to get as many copies of themselves as possible into the next generation. This has significant consequences for us, the organisms.
Dangers lurk around every corner, and the competition for scarce raw materials and reproductive opportunities is challenging. Only those genes who know how to equip and control their vehicles masterfully will succeed in that competition.
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How do they accomplish this?
Remarkably, the best way to succeed is to grant the organisms they inhabit a certain degree of 'freedom'. Only then the organisms can tackle the dangers of the environment and the context.
A particularly ingenious strategy for the gene to successfully guide their vehicle through an often hostile environment and to reproduce ensures that the organism responds appropriately to threats and opportunities. The organism responds appropriately to threats through intense sensations of pain or fear. Cravings or desires drive organisms towards food or reproduction.
- When an organism's action is beneficial to its survival or reproduction, it is rewarded with 'pleasure sensations'.
- When an action is detrimental to its survival or reproduction, it is punished with 'pain sensations'.
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- Men are attracted to slim women
- Overweight and obesity affect fertility by preventing ovulation.
- Women want taller men more than men want shorter women
- Women prefer, on average, a larger height difference between themselves and their partner (i.e. males being much taller than themselves) than men do.)
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