Tuesday, 28 December 2004 05:00
Author: Maciej Giertych
THE ARROW POINTS DOWN:
THE ROLE OF INFORMATION IN BIOLOGY
By
Dr. Maciej Giertych
Life is more than just chemistry and physics. It also includes information. Information is part of biological reality. We can study it from the point of view of molecular biochemistry but also in terms of mathematical relations, logic and transformation.
Comparison with Computers
There is some analogy with computers. A computer has a shape, dimensions, a chemical composition, physical parameters etc. All of this we refer to as hardware. But there is also software, currently much more expensive than hardware. We have the programs, the databases, the files, the calculation sheets etc. Without the software, a computer is a pile of junk. With the software in place it does not change its shape, weight, or the chemistry of physical parameters, but it becomes functional.
Working with computers we have learned certain facts about the role of information in dealing with almost anything. We know that a program can become spoiled on its own through faults in the discs that carry the program. We know that we can spoil a program by mistake. We know that it will never correct itself. By accident it will not become better or more useful. After an accidental change the number of functions a program has will not increase. We know also that an error can protect a word or file from being erased when deletion is commanded. A computer program has an intended plan, a purpose meant for it by the programmer. There is an intelligent input.
Breeders
Similarly a breeder has a plan, a purpose, and a direction for the intended improvement. However, a breeder does not create new information. He only selects among the information available in nature and strives for such a combination of it so as to direct the breeding program towards the desired improvement.
Natural reproductive processes maintain biodiversity through recombination. Natural selection acts on existing forms. It reduces the number of forms by eliminating genotypes that are not adapted in the given environmental conditions. It does not create anything new. Breeders replace natural selection with their own, favoring what meets human needs.
Physicists
In the physics of micro- and macro-cosmos there are doubts about the probabilistic model of explaining reality. There is a school of thinking that favors an information model. They speak of the Unitary Information Field Approach (UIFA) assuming that somewhere there is information that is being realized in the functioning of the cosmos. They envy biologists that have found their Information Field in the genetic code. It needs to be pointed out that we have known where this information is located only since mid 20th century. When the theory of evolution was proposed, and during the time its role in dominating biological thinking developed the most, we had no idea that information for the realization of biological systems existed and was specifically located in a particular place within a living cell.
Fate of Information
Now let us look at what happens to the information accumulated in the genetic code during the functioning of biological systems, or when man manipulates these systems. In Table 1, some of these biological functions and human activities are listed, segregated into those that reduce information, mix information and increase information.
Table 1. Fate of information in living systems.
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INFORMATION
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Reduction Recombination Growth
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Isolation Panmixy
Inbreeding, self-pollination Hybridization, introgression
Transformations, engineering
Genetic drift Meiosis, crossing-over
Selection Heterozygocity protects recessives
Adaptation Migration
Domestication Protection of gene resources
Improvement Care for biodiversity
Breeding Increasing heterozygocity
Race formation Going wild, mongrelization
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Deleterious mutations Positive mutations
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Reduction of Information
Isolation of a biological population will lead to a reduction of genetic information. Inbreeding is the consequence of isolating a population. Sexual reproduction occurs between relatives and, in extreme cases, we see self-pollination. This always leads to accidental loss of some information. This loss of some genes is referred to as genetic drift. (This can be compared to the accidental reduction in the number of surnames in a small group of colonists who are left without new arrivals for several generations. Such a phenomenon was known to have occurred on several Caribbean Islands during the 18th and 19th centuries). A gene once lost is lost forever. It does not reconstitute itself. It can only reappear if it is reintroduced.
Selection acts much faster. Forms that are not adapted to a given environment will perish together with their genes responsible for the lack of adaptation. As a result a population develops that is adapted to the specific conditions of the place, adapted in the sense that it is deprived of the genotypes that are unable to live in this environment. The gene pool is reduced relative to the one it was derived from. One can observe some vegetation on industrial spills. Many seed fall there, but only a few survive. The population that develops there may be adapted to the spill, e.g., a high level of heavy metals, but it is genetically much poorer than the population of seed that fell on the spill.
Based on this adaptation mechanism, much work has been done by breeders leading to the domestication of plants and animals. The domesticated plants and animals are genetically poorer that the wild organisms they were derived from. When we speak of genetic improvement we mean "improvement" from the human point of view. The yield of sugar from sugar beets is increased or the yield of milk from a cow. But this is always at the expense of some other functions, and results in the "improved" varieties becoming less able to live in natural conditions, becoming dependent on man. The more improved the varieties, the more dependent on humans they are and the poorer they are in genetic diversity.
Breeding, as well as natural adaptation, leads to the formation of races. Races are genetically poorer than populations they were derived from. All races of dogs can be bred from wild wolves, but it is not possible to breed a St. Bernard from a terrier.
It is of course well known that mutations can destroy genes. Since mutagenic agents (radiation, chemicals) bombard us all the time, the number of damaged, and therefore defective genes in any population increases. We speak of an increase in the genetic load. When such defective genes meet in a homozygote, the defect shows, and natural selection eliminates the genotype with the defect.
Reshuffling of Information
Population genetics recognizes recombination of genes as the primary source of variation in nature. It is universally accepted that panmixy occurs in nature. Panmixy is the random meeting of gametes in the process of sexual reproduction. Each gamete (pollen grain, sperm, ovule, egg cell) has its own genetic identity, and therefore, when two combine, a new entity arises.
In extreme cases we have hybridization, the meeting of gametes from different species. When the hybrid is viable and fertile with one of the parental species we get introgression, the entering of genes of one species into the population of another.
Transformation is the transfer of genes from one population to another by some other method than through sexual reproduction. A parasite may introduce its genes into the genome of the host to use its metabolism for its own purposes. A sawfly will cause a willow leaf to produce a gall that is useless for the willow but is a home for the sawfly. The genetics of the willow was modified. Its metabolic potential was utilized according to genetic information from a foreign entity. Now we do the same in genetic engineering. We transfer genes from a fish to a tomato. We produce modified organisms referred to as transgenic. We mix genes from organisms that do not hybridize in nature.
In sexual reproduction we observe a mechanism for the mixing of genetic information at the reduction division. During meiosis the information inherited from the father and the mother is reshuffled. During pachytene, crossing over of chromatid parts occurs. During anaphase, homologous chromosomes separate and, together with the parts exchanged during crossing over, they travel to the opposite poles. In the process the chromosomes (or their parts) originating from father and mother get mixed so that each resultant haploid gamete is genetically different.
If a haploid gamete contains a gene that is not adapted to a particular environment or in some way defective, this will cause difficulties to the gametophyte, resulting in it being impoverished or simply perishing. In this way defective or nonadapted genes get lost. However after fertilization, in a diploid zygote and the resultant sporophyte, the non-adapted or defective gene can survive, thanks to the presence of a functional homologous one from the fertilization partner. This is referred to as dominance of some genes over recessive ones. The net result is heterozygocity or genetic biodiversity in the population. This is a natural mechanism for the protection of genes useless in a given environment, but possibly useful in another, in which some descendant will happen to live. Unfortunately this is also a mechanism that protects defective genes, the genetic load, as it is called.
Gene mixing results also from plant and animal migration. Each species constantly places some of its progeny beyond its current range of occurrence. Man also frequently transfers populations beyond their natural ranges. The new arrivals, whether naturally or artificially introduced, if they find it possible to interbreed with the local populations, become a source of an increase in the genetic biodiversity. As new territories are being colonized by a species, sometimes separate waves of colonization from different refugia meet, and then recombination between them occurs, giving a rich genetic diversity of the population.
Seeing the genetic resources of our planet decline, man has made efforts to protect them. We now often speak about the protection, or even promotion, of biodiversity. It needs to be stressed that breeding and gene pool protection have opposite effects on genetic information. However, in breeding work it is possible to deliberately increase heterozygocity to assure greater stability of the improved population. Highly bred pure lines are especially hybridized to achieve heterozygocity. The breeding population is often deliberately kept diversified to counteract the loss of genes accompanying selection.
Highly bred and improved plants and animals need human protection. Usually they need special environmental conditions that only man can supply (fertilizers, fodder, antibiotics, pesticides, herbicides etc.). But not only that. They require human protection from outbreeding. They have to be kept isolated. Once the isolation is discontinued, we get mongrels; selected varieties go wild.
Increase of Information
There is only one mechanism that is credited with increasing genetic information. It is mutagenesis. It is assumed that once in a while a mutation occurs that is positive, in the sense that it increases the survival potential of the individual, and of the population derived from it. A positive mutation is the only possible source of new information. The whole theory of evolution hinges on the existence of positive mutations. But do we have good examples of them?
Darwinian Evolution
Darwin observed variation within species (beaks of finches). He observed adaptation to various environments and diversification of isolated populations (now referred to as genetic drift). What he observed was the consequence of recombination and of reduction of genetic information. Yet his conclusion was Evolution, a natural process giving growth of information.
Darwin observed variation within species (beaks of finches). He observed adaptation to various environments and diversification of isolated populations (now referred to as genetic drift). What he observed was the consequence of recombination and of reduction of genetic information. Yet his conclusion was Evolution, a natural process giving growth of information.
His conclusion was wrong! Adaptation, often referred to as microevolution, is not an example of a small step in macroevolution. It is a process in the opposite direction!
In school textbooks the world over we find the example of the peppered moth Biston betularia that sits on the bark of birch trees. It was found to change its color to black when, in industrial areas, the bark of birches was soot covered. When the industrial soot was cleaned up, the peppered moth returned to its whitish gray color. This is an example of adaptation, reversible adaptation, since there was a breeding link with wild populations living outside the polluted area. Natural selection, birds feeding on the moths, leaves only those that are least seen when sitting on the birch bark. Genes for the dark color are present in the wild population and dominate it when environmental conditions demand it. The dark colored race has no new genetic information. It has only a portion of the information present in the wild genetic pool. In fact, only proportions of black and gray moths change. These are differences in numbers, not in kind.
[Editor's note: The peppered moth (Biston Betularia) experiment has been discredited in recent times, but evolutionists have not given up. See for example thisarticle from Answers in Genesis.]
It must be stressed that the formation of races is not an example of a small step in evolution.
Lessons from Breeding
Breeding work has taught us several important things.
First of all, we now know that there is a limit to the possibility of breeding in any particular direction. The information content of a gene pool is finite. In breeding we can use what is available, and no more.
Secondly, we know that our improved varieties need isolation to maintain their improvement. Without the isolation they will go wild, interbreed with the wild varieties, and thereby lose their identity.
Thirdly, we know that highly bred and improved varieties are biologically weaker than the wild varieties.
We have painfully learned that wild varieties are absolutely necessary for breeding work. We must have the rich pool of genes in the wild conditions to be able to select from, and incorporate into, our bred varieties, as new demands on the breeding program are articulated.
To summarize, we must learn how to manage the resources of genetic information available to us in nature, because they are finite and can be irretrievably lost.
Mutations
Now a word is needed about mutations, the only potential source of new genetic information. We have been studying mutations for over 70 years and some definitive conclusions are permissible.
First of all we observe a general decline of interest in mutagenesis as a breeding method. Most laboratories all over the world are closing their mutagenic programs. Some useful varieties have been obtained through mutagenesis, but few and far between, and they are only useful from the human point of view. Some dwarf forms were obtained, useful as root stocks for grafting or for rock gardens. Some very sensitive plants were obtained that were good for monitoring pollution. A seedless variety of oranges was produced. There are many ornamental varieties of flowers that have been deprived of certain natural pigments by mutagenesis. In each case, however, the plant obtained is biologically poorer, and usually weaker than its unmutated progenitor. It is deprived of something that, in natural conditions, is useful.
We know of many mutations that are deleterious. We are afraid of them. We try to protect the wild gene pool and ourselves from various mutagenic agents. We discourage nuclear tests, redundant X-rays, asbestos, etc. If a mutagenic environment favors positive mutations it is deluged by a multitude of destructive, negative mutations.
We know of the existence of mutations that are biologically neutral. These are changes, either in the non-coding part of the genome or in the genetic code, but not affecting the functionality of the protein they code for. We refer to these variants as alleles. When copying a text we can make mistakes. If the mistakes do not alter the meaning of the text, we can refer to them as neutral. As long as the meaning is preserved, the changes are tolerated, but usually they are also considered a nuisance. Also in the genome, the information change - when neutral - is tolerated, but if it only slightly reduces functionality of the protein it codes for, then there will be selection against it. However, when the meaning is changed, when functionality is significantly altered, we can speak of a change, either negative or positive.
Positive mutations are more a postulate that an observation. Usually races of organisms resistant to man-made chemicals (herbicides, fungicides, pesticides, antibiotics, etc.) that have developed only after marketing the given product, are quoted as examples of positive mutations. When dealing with such arguments it is necessary, first, to realize that the new forms are not new species. They are usually interfertile with the original population, and usually disappear when the use of the chemical is stopped. Thus they appear similar to the reversible adaptation of Biston betularia. It is quite possible that the adaptation was similarly achieved, by recombination. There are very few examples where a documented change in the genome is responsible for the newly generated resistance to a chemical.
In the known examples it can be shown that the change involves a defense of natural functionality. It is not a creation of something new but a protection of something already existing.
Defense of Functionality
There are various ways in which functionality can be defended in the natural conditions.
Natural selection is one such mechanism. By eliminating defective forms natural selection protects the population from deteriorating.
Natural selection also occurs on the level of cells. Within a tissue defective cells will be eliminated and prevented from multiplying.
There are various mechanisms for correcting defects. Healing of wounds is one such mechanism. There are others, also on the genomic level. Defective nucleotide sequences can sometimes be corrected. Just as computer programs can have some back-up information allowing corrections, so do biological systems.
Finally biological systems have a method of identifying and neutralizing an invading foreign factor. On an individual level this is referred to as immunity. An invading protein is recognized and antibodies are custom made to neutralize it. This immunological adaptation can also occur on a population level. An organism that adapts its biology to the combating of the foreign chemical, multiplies and replaces the whole population that fell under the heavy selection pressure of the chemical. This has been particularly demonstrated for chemicals that were custom made to destruct a single vital protein in a specific organism. These chemicals are developed to attach themselves to a specific sector of the protein, with a specific sequence of amino acids. A mutation that is neutral (not affecting the functionality of the protein it codes for) but which alters the sequence of amino acids defining attachability of the chemical, can be considered positive from the organism's point of view. It frustrates the effectiveness of the chemical as a killing agent. But it is positive only because it protects existing functions, and not because it provides new functions or organs.
This in no way helps to support the theory of evolution.
Information and Time
There are two visions of the Universe. Relating those visions to information and time we can say that one vision starts with total chaos at the beginning of time (Big Bang) and sees gradual accumulation of information through evolution of particles, molecules, compounds, organic compounds, through life all the way to man and on towards an ever improving and, increasing in information content, glorious future. The other vision starts with a glorious, plentiful beginning, and then sees gradual corruption, extinction of species, deterioration of genes, dissipation of energy and movement towards an inevitable end of the visible reality. This is available to our senses and our scientific cognition for only a small sector of the time postulated in these visions.
The big question is: In the time available to us, do we see an increase of information, or its decline? As I see it, all scientific evidence points to a decline!
