Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Catastrophes of global extent, which accompanied or were followed by mass extinction of species, could have been caused in history by the impacts of cosmic bodies, asteroids or comets. The impact of a sufficiently large body leads to mechanical and thermal destruction of an extensive territory and, in many cases, to the massive transport of dust particles into the atmosphere, causing prolonged changes in the light and temperature regime all over the planet. For example, the impact of a large meteorite causes destructive pressure waves, enormous tsunami, forest fires and subsequent acid rain or darkness as a result of dust and soot that destroy extensive ecosystems far away from the actual site of impact. It is not clear whether these phenomena lead to global warming or global cooling; it probably depends on whether cooling occurs as a consequence of shading of the surface of the Earth or warming as a result of the greenhouse effect. Study of impact craters on the Earth and Moon has confirmed that impacts of sufficiently large bodies on the surface of the Earth occur sufficiently frequently for this phenomenon alone to explain most of the mass extinctions distinguished in the paleontological record. It can be estimated that, approximately once every 400 thousand years, a body falls to the surface of the Earth and forms a crater at the site of impact with a diameter of 20 km and, once every 50 million years, a body falls forming a crater with a diameter of 100 km. If the frequency of formation of the individual size categories of craters is compared with the intervals between mass extinctions of a certain intensity (Fig. XXII.4), it follows that the impact of a body forming a crater with a diameter of 24 km should cause the extinction of approximately 5 % of species once every million years and the impact of a body forming a crater with a diameter of 60 km should cause the extinction of approximately 50 % of species once every 88 million years (Raup 1992). These figures follow from a certain unrealistic overestimation of the assumption that all the mass extinctions are the result of the impact of cosmic bodies. Nonetheless, it seems quite realistic, either from the aspect of the frequency of impacts of cosmic bodies and also from the viewpoint of their probable effect on biodiversity (Jetsu & Pelt 2000; Sepkoski 1989).
At the present time, most impact craters are under the surface of the sea and the craters that are located on the continents have been destroyed to a major degree by erosion. Nonetheless, a number of craters have been discovered whose age corresponds very well with the dating of a mass extinction. The Manson crater in Iowa is an example. This crater has a diameter of 32 km and is 65 million years old, the same age as the mass extinction that occurred at the end of the Mesozoic and beginning of the Tertiary. The Chicxulub crater, which is of the same age, has a diameter of approximately 300 km and is buried in the Yucatan Peninsula on the coast of Mexico (Sharpton & Marin 1997; Schuraytz et al. 1996). Possibly more than 50% of species became extinct at the end of the Mesozoic and beginning of the Tertiary, and this extinction apparently affected all types of ecosystems over the whole surface of the Earth (Raup 1994). Almost all of the big five extinctions and a great many less extensive mass extinctions are now related to an impact crater of the corresponding age.
            In addition to impact craters, there are also further indications of the connection between mass extinction and the impact of a cosmic body. The most convincing of them is the occurrence of the iridium anomaly, i.e. the occurrence of layers with iridium concentrations that are elevated by more than an order of magnitude; this element occurs in only trace amounts on the Earth, while it is far more frequent in some cosmic bodies. The best known iridium anomaly was described in 1980 by the Nobel-prize winner L. W. Alvarez and his coworkers at the boundary between the Mesozoic and Tertiary (the KT-boundary) (Alvarez et al. 1980) It is interesting that this team was originally looking for evidence for the hypothesis that mass extinctions do not, in actual fact, exist and that the discontinuities in the compositions of the fauna and flora between some layers are a result of the fact that sediments were not deposited for a long time at the particular site. Only a minimum of iridium remained in the surface rocks of the Earth after cooling of the planet so that practically all of this element found in sediments is derived from meteorites or comets. Alvarez assumed that, even at times when no classical sediments were deposited, iridium was nonetheless constantly deposited so that the iridium concentration would have to be elevated in the layers of sediments that were deposited abnormally slowly. However, the measured increase in the iridium content at the boundary between the Mesozoic and Tertiary was 2-3 orders of magnitude and was thus so great that it could not be explained by gradual constant accumulation of this element. The period for which classical sediments were lacking would have to have been too long. The only reasonable explanation of the iridium anomaly seems to be a sudden, short-term increase in the amount of iridium that fell over the entire surface of the Earth during its collision with a cosmic body, most probably the core of a comet, approximately 65 million years ago.
Over time, it was found that the iridium anomaly and other geological indications for the impact of a cosmic body (chock minerals, microtektites) also accompany some other periods of mass extinction, for example the anomaly in the Frasnian period in the Devonian, the Callovian in the Jurassic, the Cenomanian in the Cretaceous and two anomalies in the Tertiary (Rampino & Haggerty 1996; Rampino, Haggerty, & Pagano 1997). Some of these indications can be found in layers of the same age even at very distant locations, while other similar anomalies tend to have a local character.   

Behavior-controlling mechanisms have appeared during evolution to enable organisms to react adaptively to the widening spectrum of stimuli coming from their surroundings. An inborn fixed pattern of behavior is the simplest mechanism. Some inborn fixed patters of behavior activate autonomously during the individual’s ontogeny  -and life cycle, independent of the environment. They are activated without any external stimulus and their form and starting point are programmed genetically. In many cases, the neural system is not required for their coordination. This kind of behavior often occurs in plants, where it is accompanied or mediated by growth; it most probably also controls the embryogenesis of most organisms.

see superinfection and virulence

see Spontaneous mutations

– see Virulence

see Cultural evolution

see Memes origin of new

see Selection kin

An obvious requirement in defining taxa within a certain phylogenetic line is that taxa at the same level must not overlap and that certain species cannot be assigned to two various taxa at the same level. The only exception consists in species or phylogenetic lines that were formed, not by splitting of lines, but rather by fusion of species belonging to two different taxa. In this case, the relevant species and its descendants can be included in both the taxa from which the relevant parent species were derived and thus the taxon in which it finally ends up is only a matter of convention. Of course, it is more practical and more common to separate the descendants of such a fusion into a new taxon. 
The entire system of overlapping taxa defined in the given phylogenetic line on the basis of the achieved level of anagenesis must also be created so as to reflect a certain hypothesis on classification of traits as homologies and homoplasies. In this respect, the system should be internally consistent. It is inadmissible to define a taxon so that its existence simultaneously necessarily requires the assumption that another taxon within the studied line is defined on the basis of homoplasy and is thus polyphyletic (Fig. XXV.7). Once again, it is necessary to bear in mind that all the taxa are, in actual fact, only our abstractions defined on the basis of subjective decisions. As individual taxa differ in their phenotypes, not in one, but mostly in a number of traits and, simultaneously, anageneses of the individual traits very frequently occurs independently and at various speeds, it need not necessarily be possible to create an internally consistent system of taxa based on the distribution of specific traits for existing species in a particular phylogenetic line. However, even this does not reduce the general requirements that the created system be unequivocal and not contain polyphyletic taxa. Our hypothesis about the classification of traits as homoplasies and homologies, on which the particular system is based, must, however, not contain any a priori inner contradictions.
Cladists generally hold the opinion that there is no difference between a polyphyletic and paraphyletic taxon that would be apparent directly from the topology of the cladogenesis scheme. This opinion has a certain realistic basis, as it holds that a paraphyletic taxon is a taxon defined on the basis of shared plesiomorphy, while a polyphyletic taxon is a taxon defined on the basis of shared homoplasy, where cladogenesis schemes do not, by definition, contain the relevant information related to anagenesis (otherwise they would be phylograms). In fact, however, it is possible to recognize the presence of polyphyletic taxa defined within a certain system even without knowledge of anagenesis and the distribution of the individual forms of the traits. In the absence of information on the distribution of the individual forms of the traits in modern species and their evolutionary ancestors, it is not possible to determine, on the basis of knowledge of cladogenesis, which of the defined taxa is paraphyletic and which polyphyletic; however, it is possible to determine that at least some of the defined taxa are polyphyletic and thus that the system as a whole is created incorrectly from the viewpoint of evolutionary systematics (see Fig. XXV.7c).

The driving force for evolution need not always be only selection following from intraspecies competition for the greatest resistance to pressures from the external environment and the best utilization of the resources that this external environment provides. In evolution, selection following from intraspecies competition can even lead to the formation of adaptations, structures and patterns of behavior that permit the organism to obtain advantages at the expense of the other members of the particular biological species and population and, simultaneously, of course, adaptations that allow individuals to prevent similar efforts on the part of the other members of the population. Thus, a constant evolutionary battle occurs amongst the members of a single species, in which individuals utilize various strategies which are intended to allow them to gain a certain advantage at the expense of the rest.

            Some of the aspects of this evolutionary game can best be illustrated on the example of intraspecies competition in animals that most frequently have a rather familiar and therefore easily understandable form of competition of various patterns of behavior. However, similar evolutionary games also take place between plants and viruses; however, there they take the form of competition in the creation of various morphological or biochemical structures rather than various patterns of behavior.

            In the following text, we will be concerned with the progress of such evolutionary games only on examples of competition of various patterns of behavior in animals. However, such an approach has certain drawbacks. If people compete together (for example play chess, football or shoot ballistic rockets at one another), they consciously choose a strategy, mostly from a number of strategic alternatives. Simultaneously, they usually know the goal that they want to achieve and also know the probable effects of the chosen strategy on their competitors and teammates. It cannot be excluded that a similar view into the rules and progress of the battle is also valid to a certain degree amongst some animals (see XVII.3.1). However, it is rather improbable and, especially, uninteresting from an evolutionary standpoint. In evolution, traits, here patterns of behavior, are of importance if they are determined genetically and are thus heritable. Thus, if we state that a female must try to force a male to invest the greatest possible amount of energy into building a nest in the precopulation phase of reproduction, then we are using our anthropomorphic terminology. If we wanted to avoid this at any cost, we would have to say: “Only those females will remain permanently in the population that carry a gene or genes that directly or frequently indirectly affect their behavior in a manner such that  they will reproduced with those males that have, in their genome, a gene or genes that directly or frequently indirectly affect their behavior in a manner such that, in the precopulation phase, they will invest great efforts in the construction of a nest.”

            If we compare the length and comprehensibility of the two sentences, the comparison will most certainly favor the anthropomorphic terminology. However, the use of this terminology is simultaneously somewhat misleading; in the absence of appropriate emphasis to the contrary, it could create the impression in the reader that the strategy is chosen by individuals in the same way as in people, i.e. on the basis of free choice. It must again be emphasized that, whatever the terminology or strategy being discussed in evolutionary biology, the individual organisms do not choose voluntarily or consciously, that they simply behave as dictated directly or indirectly by their genes. Most individuals do not use a certain strategy because it will probably be successful. Rather, because this certain strategy has already been successful, the population contains a predominance of individuals that use it.

            Here, it should be recalled that it makes no sense to attempt to evaluate the evolutionary strategy of organisms from ethical viewpoints or, to the contrary, look for justification for some form of human behavior in the evolutionary laws of intraspecies competition. The laws of ethics do not make any sense amongst animals; in human society, they should, to the contrary, be preferred over biological laws in all cases.

            In gonochorists, the individuals within the species have been differentiated into males and females. The two sexes differ in a number of traits and each has its specific role in the biology of the species. As a consequence of this division of roles, the strategies that the members of one or the other sex can use to gain an advantage at the expense of the other members of the particular species also differ. We can best understand the concept that the members of one sex can attempt to gain an advantage at the expense of members of the other sex. And this is actually frequently the case. However, it should always be recalled that a similar and usually much more intense battle for gaining advantages at the expense of another individual also occurs constantly amongst the members of the same sex.

            The course and evolutionary consequences of intersexual and intrasexual competition, similar to the course and consequences of the competition of any alternative game strategies can be estimated using the mathematical discipline, game theory (see IV.5.1 and XVI.5). For example, game theory can be used to determine the optimum strategy for males and females and the results of intersexual competition. We can also determine what is evolutionarily stable strategy (ESS) in the given case (see IV.5.1). The optimum strategy and evolutionarily stable strategy need not be identical. In more complicated games, where there is a predefined role of the competitors and teammates, the optimum game strategy can be considered to be the strategy that brings the teammates the greatest advantage at the expense of the competitors, for example the maximum average reproduction success of males at the expense of females. In contrast, evolutionarily stable strategy is strategy that, when it predominates in the population, permits gaining the maximum advantage at the expense of teammates, here members of the same sex, following any other (minority) game strategy.

            The following text will be concerned primarily with competition between members of different sexes, intersexual competition. The best known manifestations of competition between members of the same sex, intrasexual competition for sex partners, i.e. sexual selection, will be discussed in a separate chapter (XV).

see Selection intraspecific and  interspecific

The theory of aging based on interspecific competition seems to be the least probable at the present time (Nusbaum 1996). According to this theory, it is advantageous for a species if its members age and die and make room for new individuals of the particular species. In this way, the population can gradually evolve to adapt to changing living conditions. A basic drawback of this theory is that it does not take into account the simultaneous opposite action of individual selection. It could be advantageous for a species as a whole if faster and better adaptation of the gene pool of the population to external conditions is facilitated through programmed death of individuals. However, it is advantageous for the individual member of the population if he ages as slowly as possible and lives as long as possible and consequently leaves the greatest number of progeny. Any mutation that causes slowing of ageing in its carrier will increase his individual fitness and will thus have a tendency to increase its frequency in the population and finally become fixed, without regard as to whether its fixation reduces the chance of long-term survival of the entire species.

see Intra-individual competition

see Selection intraspecific and  interspecific

A number of “missing” intermediate links exhibiting the traits of two distinct extant taxa have already been found. However, an even greater number never existed at all and thus there is no point in being surprised by their absence in the paleontological record (Fig. XXVII.2). In a great many cases, the common ancestor of the two taxa lacked all the traits that are characteristic for modern members of these taxa, so that the link between the taxa cannot be recognized on the basis of its phenotype. The relevant characteristic traits developed in each taxon only gradually over an extremely long period of time.
            The situation encountered in the search for links between the individual related species, e.g. within a single genus, is somewhat different and far more interesting. The absence of transition phenotype forms between the parent and daughter species is very remarkable in a great many species of organisms. This fact is reflected in the paleontological record in that a certain species has the same phenotype throughout its existence and then, suddenly and apparently with no transitory forms, a species with a different phenotype emerges next to it and then accompanies the original species in the paleontological record, or replaces it. The new species then also does not change throughout its existence. This situation is described by the theory of punctuated equilibriums (see XXVI.5.1). The punctuated character of the evolution of species is frequently contrasted with the apparently generally anticipated character following from Darwin’s theory of evolution.
To begin with, it is necessary to explain what the paleontologist means by suddenly replace. This generally occurs in a time period of the order of tens of thousands of years which, from the viewpoint of the duration of the existence of a species (several million years) is a short period of time, but is sufficiently long for the formation of a new species by Darwinian mechanisms. It should further be pointed out what is the usual population mechanism of the formation of a new species according to current evolutionary concepts. This involves the mechanism of allopatric speciation, i.e. speciation that occurs in a geographic area away from contact with the original species. In fact, this very frequently involves peripatric speciation, i.e. the formation of a new species in a small, separate population. A great many such populations are formed during the existence of a species; however, they mostly last only a short time and, after some time, disappear or merge with the original population. The probability that gradual phenotype changes will occur in one of these small split-off populations is, for a great many reasons, substantially greater than the probability that it will occur in the large parent population (XXI.3.1). Simultaneously, there is negligible chance of encountering such a population in the paleontological record. Thus, the sudden appearance of a new species in the paleontological record is thus actually a result of the invasion of an already existing species into a new territory and not of its instantaneous emergence at the particular location. The relative lack of paleontological records for the slow development of one species from another species is thus a quite logical consequence of the character of long-known evolutionary processes and certainly does not constitute an argument against the validity of the modern the theory of evolution.

According to the opinion promulgated by some opponents of the theory of evolution, scientific facts should be taught at schools and not unverified theories.
            To begin with, it should be pointed out that this opinion is not generally held. A non-negligible part of the public thinks that, rather than teaching actual facts, schools should teach students how to discover these facts and how to deal with them. Acquainting pupils and students with unverified theories is very useful for acquiring and developing these skills and may even be essential. In actual fact, this book refers to some more “exotic” theories and hypotheses for just this reason.
Secondarily, this objection is proof of the person’s lack of knowledge or failure to understand the basic principles of general scientific methodology. Every theory or hypothesis actually represents a model of a certain phenomenon (process) and thus our idea of why and how a certain phenomenon occurs. The only way to verify whether our model is the correct one is to verify the truth of all the consequences following from the potential validity of our model. Consequences following from the model can have the nature of a statement with a general quantifier (It holds for all X that Y, for example, “All organisms on the Earth use a universal genetic code”) or a statement with an existential quantifier (There exists at least one X for which it holds that Y, for example “An animal exists that is capable of obtaining all the necessary organic carbon by photosynthesis."). Empirically, i.e., for example experimentally, it is possible to confirm the validity of statements with an existential quantifier by actually finding some X for which it holds that Y. However, these statements cannot be empirically proven to be untrue as we can never be sure that we have examined all possible X. In contrast, statements with a general quantifier can only be shown to be untrue empirically in that we find at least one X for which Y is not true; however, the validity of a statement with a general quantifier can never be confirmed, because once again we can never be sure that we have examined all X. However, the meta-statement mentioned at the beginning of this section, “All the consequences following from the potential validity of our model are true.” has the nature of a statement with a general quantifier and thus, in the optimum case, we can overturn it but never prove it.
The philosopher Karl Raimund Popper (1902–1994) was apparently the first to quite convincingly demonstrate that it is not possible to prove, i.e. verify, any scientific theory. It is only possible to attempt to overturn it, i.e. falsify it. If a theory is capable of resisting sufficiently intense attempts to overturn it for a sufficient length of time, it can be considered to be relatively verified and thus conditionally valid. However, no theory can be considered to be definitively confirmed; it is always necessary to bear in mind the possibility that even the best-confirmed theory may be erroneous. The requirement that only scientific facts be taught and never unverified theories is thus not practicable unless, of course, we don’t want to limit ourselves to teaching some parts of mathematics.

As shown by sir K. Popper, it is not possible to prove any scientific theory. Thus, the difference between a scientific and unscientific theory cannot be its provability. However, the difference lies in the fact that, for an unscientific theory, there is not even a theoretical possibility of overturning it. If someone is of the opinion that all species of creatures were created by an omnipotent God, he might well be right; nonetheless, his theory of the formation of life will not be scientific as it is not possible to in any way disprove it. If God is truly omnipotent, then He could foist any arbitrary results on us in our experiments and observations. In contrast, an enormous number of specific consequences follow from the theory of evolution and these can be gradually tested empirically. If these consequences were to be shown not to be valid, we would have to reject the theory of evolution. For example, if paleontologists were to demonstrably find a Paleozoic fossil of a mammal or if molecular biologists were to discover that there is usually no agreement amongst the phylogenetic trees created on the basis of various genes, i.e. that each gene would have its own unique evolutionary history, we would have to reject the theory of evolution in its present form. Thus the theory of evolution cannot be proven, in more or less the same way that any other scientific theory cannot be proven. However, it can very easily be shown to be false, and thus it rightly belongs amongst fully sound scientific theories.

The second law of thermodynamic is valid only for the organization of isolated systems. In open systems, i.e. systems that exchange energy and mass with their surroundings, the degree of organization can both decrease and increase (Prigogine & Stengersová 2001). Energy from the Sun constantly impacts on the Earth and, on the other hand, thermal energy is constantly irradiated back into the surroundings. This means that the overall degree of organization of the Sun-Earth system decreases, while the degree of organization of the Earth increases at the expense of the rest of the solar system. Similarly, the individual living organisms have an increasing level of organization at the expense of the organization of the substances that they consume.