Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
The Origin of Adaptation
Living organisms exhibit a striking property: their parts and their behavior are adapted to ensure the survival and the reproduction of their entire body. Not only the parts: the behavior too. Animals are born knowing what to do to survive.
Adaptation is a fact, not an opinion. How it came to be is an opinion, not yet a fact.
According to Jean-Baptiste Lamarck, the French botanist of the 19th century who had already claimed in 1802 that animal species are not immutable, acquired characters are inherited: each generation passes on to the following generation what it has learned about adapting to the environment. So far, evidence is against Lamarck: genes do affect proteins, but proteins cannot affect genes. It is a one-way process, from genes to bodies. Once they have been created, bodies cannot change their genes. No matter how much they learn, bodies cannot store it in their genes and pass it on to future generations.
The evidence against Lamarckism is overwhelming. Every generation has to re-learn what previous generations learned. After thousands of years of civilization, children are still born unable to write and to count. Worse: after millions of years, we are still born unable to walk and to speak. According to Lamarck, humans should have already manufactured genes about walking upright and speaking.
We have not found any evidence that a body can purposely alter its own DNA or the DNA it will pass to the offspring. DNA changes only because of random errors in copying. The DNA of a species is manufactured over millions of years by natural selection: the errors that survive become permanent instructions for future generations. But each individual is stuck with the DNA it receives at birth.
Even if he was wrong about the specific mechanism for evolution, Lamarck had powerful insights in the way Nature works on a large scale. In particular, he argued that all of Nature reflects a few general organizing principles. Foremost among them is the effect of use and disuse of organs: muscles atrophy if they are not exercised and bones grow stronger at points where muscles are attached and produce tension.
What Darwin proposed was not "the" theory of evolution (which had already been proposed by many thinkers, including Lamarck himself), but a particular mechanism for evolution: the differential rate of reproduction, under pressure from the environment, of different sorts of individuals within a population; i.e., the differential survival and reproductive success of units of different adaptive efficiency. The key point of Darwin’s theory is that variation and selection are dual aspects of the same problem. Lamarck proposed instead a transformational (rather than variational) mechanism.
Later, Darwin's theory of evolution by selection of that variation was indirectly supported by Mendel's mechanism for the inheritance of variation.
However, the US psychologist James-Mark Baldwin discovered what is now known as the "Baldwin effect" ("A New Factor in Evolution”, 1896): the ability of individuals to learn can guide the evolutionary process, i.e. the ability to learn can affect evolution. Baldwin was interested in the long-term evolutionary effects of environmental changes. For example, organisms that move to a new ecological niche indirectly subject their descendants to selection pressures which are different from the ones experienced by their ancestors; i.e., the selection pressures that generated their own generation are different from the ones that will generate future generations. It is therefore possible that future generations will evolve because of the change in selection pressure due to the new environmental conditions. The ancestors had to “learn” how to behave in the new environment, whereas the descendents will behave by instinct in that same environment. Thus learned behaviors may become instinctive behavior in subsequent generations, without requiring Lamarck’s inheritance. He proved that evolution under those effects is more rapid than in a situation of no change.
In 1958 the Austrian physicist Erwin Schroedinger said something similar: behavior can indirectly alter genetic code, by enabling organisms to survive and reproduce where non-intelligent organisms would simply die.
The British geneticist Conrad Waddington (“Genetic Assimilation Of An Acquired Character”, 1953) discovered “genetic assimilation”, the process of differential selection by which an individual’s response to an environmental stimulus can eventually become a fixed behavior in the species even in the absence of stimulus. Waddington also pointed out that the behavior of a living being changes the environment, and therefore helps to create the selection pressure that will influence its own evolution. Both phenomena point to the importance of the behavior of the organism for its own evolution in a sort of Lamarckian fashion.
Likewise, the German zoologist Ernst Mayr argued that any change in behavior by a population (for example, the acquisition of a new habit due to a move to a new ecological niche) has an effect on the selection pressures that will operate on that population.
Back to the beginning of the chapter "The Evolution of Life: Of Designers and Design" | Back to the index of all chapters