Václav Petr

originally published in
Bulletin of the Czech Geological Survey, 71(4): 351-365. Praha 1996

"But then," thought Alice, "shall I never get any older than I am now? That’ll be a comfort, one way - never to be an old woman - but then - always to have lessons to learn! Oh, I shouldn’t like that!"
(Lewis Carroll: "Alice’s Adventures in Wonderland", 1865)

Abstract: The present article treats of the nature of species extinctions which have taken place in the fossil record and, in more detail, causes of them. A hypothesis is presented that the planetary evolutionary process, including extinction events, is governed by developmental principles. Ageing is one of them. The patterns of life histories and extinctions of trilobites and dinosaurs are briefly discussed as an example of a universal rule. From an evolutionary perspective, it seems to be clear that extinctions have no single or simple cause. Regarding the mechanisms of extinctions, in general, it is concluded that species extinctions are not solely a reflection of external (extrinsic) factors (e.g., impacts, volcanism, floods, competition, etc.) but also depend on internal (intrinsic) factors (e.g., longevity of individuals, population size, body size, etc.). Many recent evolutionary palaeontologists have infused people with the need of purely catastrophic explanations, however, they have perhaps drawn us a bit too far from the real nature of extinctions. The fashionable neocatastrophism probably "threw out the baby with the bath water". Although in evolutionary theory the developmental approach to extinctions is not new, the very old typostrophic theory by Otto Schindewolf is, unfortunately, the last one. On the other hand, among modern ecologists, the developmental approach to modelling ecosystems in which complexity works against stability is common. Modern evolutionary palaeontologists are unable to explain relations between impacts and the continuous character of extinctions. But the developmental approach on a planetary scale reveals that the extinction processes in the history of the Earth do involve the puzzling phenomenon of ageing in species and higher taxa, planetary biological megarhythms, as well as the extraterrestrial influences themselves.


Some time back, I had the enervating experience of talking to a colleague who suffered from the delusion that doing science means accumulating of facts. After him, if a palaeontologist focuses his attention on finding answers to evolutionary questions, then he is not doing science but philosophy. From his point of view all the evolutionary palaeontology is not science but philosophy and, in some respect, he is right. The fundamental misunderstanding is that many scientists still think of science as an area of life in which ideologies play no role. Of course, this is not so. It is a proper aim of palaeontology to explain history of life in theoretical terms. Even the so-called "facts" of science are shaped according to theories used, while the theories themselves are shaped according to contemporary paradigms. A paradigm (KUHN 1962, 1970) is a background of commonly shared presuppositions about what constitutes a scientific question, method and answer. Similarly, both questions and answers in evolutionary palaeontology as well as in palaeontology itself are strongly shaped by the so-called evolutionary paradigm.

According to current scientific wisdom, the fossil record (and, therefore, palaeontology and evolutionary palaeontology) is very important for our understanding of the contemporary extinction process. It is especially because of the discovery that at least one or several of the large biotic extinctions were caused by impacts of huge extraterrestrial bodies. How are these facts shaped by the evolutionary paradigm?

In the first place, although more than 99% of all plant and animal species that have ever lived on the Earth are extinct (RAUP 1993), one of the basic axioms of the present evolutionary paradigm is that a species is supposed to be essentially immortal. We know that individuals and species react to life experiences in slightly different ways but one universal experience in the "life cycle" both of the individual and the species is its ending. All living things die. Death is a part of daily life of individuals, and, in the fossil record, the extinctions of species are extremely common, too. No analogy is seen in the two kinds of life endings. Modern biologists and palaeontologists are completely sure of themselves and say that individuals do age, not species. Axiomatically, death of individuals is generally seen as inevitable end of life, while extinctions of species are seen simply as an accident. Almost every scientist recognizes it as a self-evident truth. It is widely believed that the question "Why do species age?" is a wrong one to ask. Today the only accepted questions are: "Why do species become extinct?" or "Why do species survive as long as they do?".

Only death from other causes (e.g., impacts of extraterrestrial bodies, volcanic cataclysms, extermination by human activities, competition, predation, floods, refrigeration, forest fires, diseases, environmental pollution, etc.), serves as an explanation of any species extinction, never a death from the old age. In historic times, we have many examples of species becoming completely extinct thanks to human influences. So, we think that only such sorts of external causes play the game. Extinctions represent life’s response to environmental change, including the change after impacts of extraterrestrial bodies. However, whether this is due to the generally negative community opinion of species’s ageing (strongly shaped by the contemporary evolutionary paradigm) or whether species don’t age indeed, is yet to be established. Perhaps, it is the widely supported conclusion that is essentially wrong.

The change from evolutionary to developmental paradigm is not impossible because the former may rest on extremely weak pillars. Only three decades ago, biologists, palaeontologists and evolutionists were sure of themselves, too. Then, they began to fear the presence of innumerable errors in their explanations of the tempo and mode of evolution. Almost everything in the beautiful synthetic scenario proved to be wrong and still is in dispute (LEWIN 1980). There are several remarkable patterns in the fossil record posing problems.

We know that extinctions play an extremely significant role in the long history of life as well as today. In 1985, the well-known biologist Edward O. Wilson estimated that the contemporary extinction rate had increased to about 3 species a day (WILSON 1992). Thus, the present-day extinction ranks as one of the greatest mass extinctions of the Phanerozoic (MILLER 1988). The face of the Earth is constantly changing. Individual organisms die and others are born to take their place. Species become extinct and are replaced. A damaged ecosystem is slowly rebuilt. The sequence of changes on a disturbed site is known as "ecological succession". The ecological succession is similar to an individual*s development because it proceeds from a generalized, through progressively less generalized, more specialized forms, until it reaches the most possible specialized form. During the extensive speciation after a mass extinction, commonly known as "adaptive radiation", the structure of ecosystems attains its former pattern, only the species composition changes. Therefore, many evolutionary palaeontologists logically believe that extinctions of some forms enable the further (some specialists still use the term "progressive") evolution. After some marine ecologists (e.g. WATT 1987) predation and violent storms "promote and sustain diversity. Without them, a few species would dominate the community and drive out everything else." Similarly, the medieval Swiss physician Paracelsus, 1453-1541, wrote that "death and decay brings about the birth and rebirth of forms a thousand times improved".

Interestingly, most established species durations in the fossil record are less than 10 million years and for different taxonomic groups different mean durations have been estimated in many studies. There is also a mysterious smooth continuum between the so- called background and mass extinctions (RAUP 1991a, 1993). Moreover, when speciation and extinction rates are statistically expressed (per lineage per million years), the two rates are approximately the same (RAUP 1981).

At first sight, it appears inappropriate to suggest that a concept of development as well as of developmental rules on a planetary scale may be relevant in theories of biotic evolution and extinctions. Evolution is generally viewed as a relatively continuous process punctuated by mass extinctions. It seems that there is a lack of such developmental characteristics as those of equilibrium, self-organization and self-regulation in this process. On the other hand, one of the fundamental features of the biosphere is its obvious tendency to maintain certain ecological rules. An injured or disturbed biosphere clearly repairs itself. It regulates itself. It exhibits changes which can be interpreted as resulting from intrinsic attempts to return to normal conditions. This is self-evident. Surprisingly, the same words are used by WADDINGTON (1948) for the description of a general embryological development.

Every ecologist is well aware of the infinity of the particular parts of the biosphere and of the mutual penetration and connexion of them. All the parts are regulated in the best possible way. The entire range of living beings on the Earth could be regarded as constituting an individual organism, capable of manipulating the Earth’s temperatures, atmosphere composition and other characteristics of the planet to suit its overall needs (LOVELOCK 1979, 1988). The result of this approach must be a hypothesis that the planetary evolutionary processes, including processes of extinctions, are governed by developmental rules. Ageing is one of them.


The term "ageing": Although the term "ageing" (in American English "aging") is commonly used to refer to postmaturational deteriorative processes (physiological "decay") in individuals (MASORO 1992), the more appropriate term for this is "senescence". The very term "ageing" refers to any time-related process occurring in the organism (FINCH 1990). Ageing (senescence) is a progressive loss of physiological capacities that culminates in death. It begins at the time of the postmaturational life when the mortality rate of the population starts to increase exponentially with increasing age (FINCH 1990).

Steven Austad wrote: "Soon after puberty, we begin to decay physically. The signs of deterioration are subtle at first and are probably best noted in athletes, whose physical performance is monitored closely. By thirty-two, no one*s reflexes are as quick as at twenty-five. To say that by forty an athlete has lost a step is a considerable understatement. Simultaneously, endurance wanes and the frequency of injuries increases. Soon, evidence of deterioration begins to show up even in nonathletes. We all recover more slowly from infections. Kidneys, liver, and heart operate less efficiently. We require stronger and stronger aids to maintain reasonable sight and hearing. Vague aches and pains multiply..." (AUSTAD et al. 1992).

The science of ageing, gerontology, forms, at least in the United States (partly because of the obvious connexion between cancer and ageing), one of the most important medical fields, getting more and more respect (GIBBONS 1990, 1991). It is important to say that at present not only mice and rats are used in the study of ageing processes but also spiders, fruit flies, house flies, lizards, opossums, turtles, bats etc. (MORELL 1990).

Why ageing occurs? Is it a matter simply of the deterioration due to extrinsic factors or is it genetically pre-programmed? Gerontologists cannot as yet give a satisfying answer. Some authors still believe that extrinsic factors mostly influence the ageing but majority of gerontologists don’t think that such an opinion is telling us anything fundamental about ageing. Life style and environment certainly influence the rate of our ageing but it is self-evident that the ageing processes represent only another aspect of the developmental processes themselves. In fact, the extrinsic agents work only as speeding up or slowing down factors of internal (intrinsic) processes that would occur anyway. A mouse has a maximum of only a few years of life even in the best laboratory environment.

The process of ageing differs in different organisms, it differs to some degree also in different individuals but results of statistical analyses have demonstrated conclusively that the lifespan of individuals in a given species is remarkably constant. Of course, it is relatively constant (some individuals age rapidly, some slowly) because the process of ageing represents a function of physiological age, not of chronological age. The tempo of life, rather than the passage of time, influences the ageing processes. Therefore, today, no one doubts that the species´ lifespans are determined by genes (FINCH 1992). The so- called "mortality revolution" in humans causes only that the death has become something that happens in the late adulthood. For example, in the United States, the death rates are typically below 9%, and infant mortality has fallen to about 1% (PAPALIA & OLDS 1992), life expectancy is currently 71.4 for males and 78.7 for females (CAROLA, HARLEY & NOBACK 1992). Today, it seems that elderly people die as a result of a disease or an accident, not of old age itself. But scientists have speculated that if the three main causes of death in old age (i.e., heart disease, cancer, and cerebral hemorrhage) were eliminated, the life expectancy of humans would be extended only 5 to 10 years beyond the present 75. It is self-evident that the elderly people have lowered resistance to diseases and that the maximum human lifespan remains essentially unaltered.

Which was the first? "Which was the first: the chicken or the egg?" - an old and mysterious question. Which was the first: senescence (internal biological ageing) or senility (influenced externally by diseases and accidents). Really, it is difficult for researchers to figure out which comes first: whether the intrinsic, inherited genetic defect or the extrinsic agent, corrosive influence of the environment. Curiously, cell death (necrobiosis) can be controlled by hormones which are themselves produced as a consequence of cell death (SHELDRAKE 1973).

Roy Walford wrote: "In combing the steadily accumulating mass of observations about aging, one must especially search out those aspects which militate against a particular theory. The literature of biology is so large that one can find numerous observational facts which seem to support any reasonable theory, and it may seem that one has amassed a great deal of positive evidence. Some time ago in my own laboratory ... we noted that irradiation in hamsters was followed by senile amyloidosis at a younger age than expected; nevertheless, the irradiation did not affect collagen solubility. The earlier appearance of senile amyloidosis tends to confirm the idea that irradiation- induced life-shortening is true aging; the observations on collagen are against the idea. This paper has been amusingly handled in the literature. Those for whom it would be more convenient or more consistent if irradiation did truly accelerate aging have quoted observations about amyloidosis; those who tend to regard aging and irradiation-induced life-shortening as separate phenomenon have quoted the collagen measurements..." (WALFORD: 1969; p. 13).

Possibly, the question "Which was the first?" is not reasonable (see below).

Theories attempting to explain ageing: There are two major groups of theories that attempt to explain cellular ageing (see e.g., the overview in DICE 1993). The first group, the so-called error theories, considers especially the passive deterioration (accumulation of errors in cellular constituents) due to a variety of environmental factors coupled with the imperfect repair mechanisms. After the second one, the so-called program theories, ageing is active, genetically pre-programmed event.

The two above mentioned groups of theories are not mutually exclusive. It is known, for instance, that the hsp (heat shock protein) genes, a group of ubiquitous genes, are regulated by a mechanism common to bacterial as well as eukaryotic cells (GOFF, CASSON & GOLDBERG 1984, MUNRO & PELHAM 1985). ANANTHAN, GOLDBERG & VOELLMY (1986) have demonstrated that accumulation of abnormal proteins of any kind signals the activation of hsp genes. Thus, the presence of altered proteins within cells can alter gene expression, at least in this so-called "stress response" phenomenon.

Many modern gerontologists support the idea of ageing genes. For example, Samuel Goldstein (Veterans Administration Hospital in Little Rock, Arkansas, and the University of Arkansas) believes that genes are regulated differently in old cells and young cells. After him two events are involved in ageing: the turning on of genes that block cell division and the turning off of genes that normally stimulate cell growth, and he calls these combined agents "yin and yang" (GIBBONS 1990).

Why has ageing originated? Many authors treat ageing as an epiphenomenon of life, superimposed upon the "normal" developmental processes rather than a true phenomenon of developmental processes themselves. August Weismann, classic of neodarwinism (weismannism, ultraselectionism), has speculated that animal ageing was selected for and evolved to keep parents from competion with their offspring (WEISMANN 1889). Similarly, EMERSON (1960) has suggested that death from old age is a biotic adaptation. However, today, most biologists do not accept that ageing could be selected for or against in natural populations, since death (by disease, accidents, predation) occurs long before wild animals become senescent (see e.g., HAYFLICK 1987, DICE 1993; Hayflick simply postulated that organisms age because their cells age). For many authors it is difficult to imagine any evolutionary "advantage" of senescence. COMFORT (1956, 1964, 1979) and some other authors, on the other hand, believe that ageing (senescence) is under evolutionary control of natural selection. MEDAWAR (1952), however, has suggested that a Darwinian evolution of ageing has come about because of the absence of any disadvantage, not because of any positive "advantage" ("fitness") in the process of ageing (senescence). The natural selection, acting on individuals, in favour or against any gene that come to expression late in life is extremely reduced. From this clear, othodox Darwinian point of view, elimination of "bad genes" from a population is also to postpone their time of action until the late period of life. Similarly, WILLIAMS (1957, 1966) has argued that selection may favour genes that produce slight increases in fitness in youth, even if the same genes also produce markedly deleterious effects later on. Therefore, Medawar´s and Williams´s interesting speculations are sometimes called a "genetic dustbin" theory (MEDAWAR & MEDAWAR 1977). DYKHUIZEN (1974) and others have suggested that ageing (senescence) is a genetically controlled and programmed process, the advantage of which to the organism is that it stops cells which have escaped from normal control (dividing indefinitely). The consequence of natural selection for senescence thus would be a mode of tumour suppression allowing young individuals to survive to reproductive years. Thus, the same mechanisms that limit cancer growth are supposed to be responsible for cell ageing.

As noted before, however, most evolutionary biologists do not accept that ageing could be selected for or against in natural populations. Animals generally do not die from ageing (senescence) but they frequently do so from predation, diseases or starvation. The death occurs long before organisms become senescent. Therefore, the turnover of individuals is generally high that there is no room for natural selection. Some sceptics (e.g. CUTLER 1982) even suppose that it is equally possible to imagine organisms which would not age but would have the "advantage" (survival and reproduction). On the other hand, such a situation is imaginable in a world constructed during special creation or controlled by natural selection acting strictly upon individuals. But it will be a queer thing in the world governed by developmental rules on a planetary scale (see below).

Examples of the life and extinctions: trilobites and dinosaurs

Most of the metazoan groups originated in Early Cambrian time. Interestingly, there have been many changes within the groups since the Cambrian but very few new groups have appeared. One of the most common pattern in the life histories of the particular phylogenetically independent metazoan groups is the tendency to show the same general sequence of changes (McALESTER 1977), especially in the case of parallelism (similar characters developed in different lineages of common ancestry) and convergence (homeomorphism resulted from the same mode of life in unrelated phylogenetic lineages). But the same general sequence of changes is of more fundamental nature. We can use as an example two clearly unrelated and extremely different animal groups, trilobites and dinosaurs, the best-known and best-loved fossil animals, showing startling analogous patterns in their fossil record.

Patterns of diversity and disparity in trilobites: The trilobites’ rapid rise to dominance in Cambrian seas is well-known. Almost 75% of all fossil species described from Cambrian rocks are trilobites (RAUP 1981). The Cambrian trilobite groups represented very generalized forms exhibiting impressive diversity but low disparity, while their Devonian morphotypes are distinct and specialized. The trend toward species and group "discreteness" seems to be continuous in trilobites. WHITTINGTON (1966) and FOOTE (1990) have suggested that the trilobite suprageneric taxa are morphologically more distinct from each other in the Ordovician than in the Cambrian. HUGHES (1991) has also argued that there was a progressive change in species discreteness in trilobites from the early Cambrian to late Ordovician.

Keeping in mind this important sequence of patterns, it ought to be noted that the generalized forms are sometimes supposed to be "primitive" or "lower", while the specialized "advanced" or "higher". However, almost all darwinists and many other evolutionists disagree with such words as "primitive", "advanced", "higher" and "lower". Many authors have raised serious doubts about the possible role of competitive abilities of "higher" animals in evolution and extinction. Even Charles Darwin himself was well aware of the difficulties of the concept of "higher" and "lower". GHISELIN (1969) has demonstrated that Darwin made a memorandum in his copy of Robert Chambers’s well- known book "Vestiges of the Natural History of Creation," writing "Never use the word ’higher’ and ’lower’"!

Decline and extinction of trilobites: Many studies have shown that the general retreat of trilobites at the end of Devonian was not caused but only accelerated by the particular events (CHLUPÁC 1994). After the latter author, the general decline of trilobite families was stepwise, showing the demise already prior to the event-stratigraphic turning points. It is very interesting that trilobites, which had been clearly on the wane since the end of Devonian, did not survive to the very end of the Palaeozoic. Surprisingly, before the Permian-Triassic boundary event, about one half of all the invertebrate families, including trilobites, became extinct. After RAUP (1981), the extinction of once successfull groups such as trilobites is "most reasonably explained on the basis of bad genes rather than bad luck..."

Permian-Triassic extinction event: What do we know about the cause of Permian- Triassic extinction event? RENNE & BASU (1991) have suggested that the inception of the huge Siberian Traps volcanism coincided, at least partly, with the biota extinctions at the end of the Permian. After VEEVERS, CONAGHAN & SHAW (1994), the biotic crisis at the Permian-Triassic boundary, the most severe one in the history of life, followed this chain of events: an abrupt change in the heat regime at the core/mantle boundary, eruption of a mantle plume as the Siberian Traps, greenhouse warming caused by volcanic CO2, mass extinctions of the biota. It was a strong and sudden pulse of extinction (see also WANG, GELDSETZER & KROUSE 1994). After RAUP (1979), up to 96% of all marine species became extinct at this boundary, however, STANLEY & YANG (1994) have recently suggested that only 80% of marine species were eliminated. The latter authors also discovered the occurrence of two extinctions at the end of the Permian within 5 million years.

Success of the dinosaurs: Why dinosaurs became extinct at the K-T boundary is one of nature’s fascinating mysteries. In our country, the mounting public interest in dinosaurs and their fate has led to an unusual dinosaurmania during the years 1993-94. The market searched for books on dinosaurs, small dinosaurs-toys, dinosaurs-chocolates, dinosaurs on vests, etc. Finally, there was the arrival of the American Dinamation’s exhibition "The Return of the Dinosaurs" (beginning 15.6.1994, National Museum, Praha) with its computerized life-sized models, dinosaurs-robots.

Dinosaurmania aside, both dinosaurs and mammals appeared in the Upper Triassic and while mammals remained small and relatively rare, dinosaurs were large and dominant throughout the "Age of Reptiles". First known dinosaurs are reported from rocks about 228 million years old and they became dominant three million years later. The reason of their rapid rise to dominance seems to be as mysterious as the reason for their extinction about 160 million years later (SERENO 1995). Dinosaurs* 160 million-year reign on the land make them one of the most successful animal group of all times. We know that sauropods were not "dumb giants" swimming in the sea (BIRD 1944) or in the river (COOMBS 1975) but intelligent animals walking on land (LOCKLEY * RICE 1990). The latter authors clearly show that sauropods did not frequent humid swamp palaeoenvironments.

Today, palaeontologists are trying to recast dinosaurs* image. BAKKER (1989) has found that the ratio of predators to prey is very low in dinosuars, comparable to the ratios of modern mammals. He has associated the erect limbs of dinosaurs with high body temperatures and pointed to a possible endothermy in dinosaurs. Moreover, large herbivorous dinosaurs lived in groups and probably migrated to avoid food depletion at restricted sites. Some authors (e.g., PAUL 1988, CURRIE 1989, SAMPSON 1995) have reported that hadrosaurs and horned dinosaurs migrated long distances in herds on a seasonal basis. There are also many convincing dinosaur trackway evidence for their social behaviour, at least in sauropods, hadrosaurs and horned dinosaurs (e.g., GILLETTE & LOCKLEY 1989; LOCKLEY 1986, 1995).

In 1923, the first dinosaur eggs were found and attributed to Protoceratops, however, the carnivorous oviraptorids associated with eggs were probably sitting on the eggs than preying on them (CLARK 1995), partly because the eggs were carefully turned after being laid (NORELL 1995). Many types of dinosaur nests have been found all over the world and there are examples of dinosaur nesting colonies, especially those with the volcano-shaped nest of the hadrosaur genus Maiasaura (HORNER & WEISHAMPEL 1989). The fossil evidence points clearly to an interesting possibility of nest guarding and parental care, at least in some dinosaurs. Possibly, dinosaurs were helpless when born and needed to beg for food from their parents. Konstantin Mikhailov (Moscow) has described a nest site of predatory dinosaurs showing that very small herbivorous dinosaurs were killed and brought in the nest by carnivorous adults to feed their offspring (ANDERSON 1991).

In the 1970s and early 1980s, palaeontologists cited bone histology (esp. the density of capillaries and Haversian canals) as strong evidence of endothermy in dinosaurs. However, today (see e.g., CHINSAMY 1995), these structures are recognized in some recent cold-blooded reptiles as well. On the other hand, the latter author has stressed that the dinosaur bone histology is very complicated and that rapid rates of growth appear to have evolved independently several times in several groups of dinosaurs. Certainly, dinosaurs must have had very high metabolic rates at least when young. It seems, however, that they were probably neither warm-blooded nor cold-blooded but "somewhere in the middle" (ANDERSON 1991).

On the other hand, the most important features of the dinosaur life history - obvious success and progressive "perfection" and specialization of the dinosaurs is undeniable. The more generalized forms of the Triassic period were followed by more and more specialized "advanced" ones, exhibiting more and more distinct morphotypes. Each of a particular dinosaur group shows a marked trend from relatively small and unspecialized forms to the familiar impressive "end products" of Late Jurassic and especially Late Cretaceous time (McALESTER 1977).

Some authors (SLOAN et al. 1986, SLOAN & RIGBY 1986, RIGBY et al. 1987) have presented several sets of data in support of their view that there was a gradual decline of dinosaurs. They have pointed to the fact that there are six major events recorded at a particular site of the upper Hell Creek Formation, including the K-T boundary. They have also reported declining diversity of dinosaurs in a sequence of paleochannels, most of which are Palaeocene in age. The dinosaur teeth recovered from the Palaeocene of Montana are, however, by other authors supposed to be reworked (RETALLACK & LEAHY 1986, SHEEHAN & MORSE 1986, EATON, KIRKLAND & DOI 1989, LOFGREN, HOTTON & RUNKEL 1990, SHEEHAN et al. 1991) On the other hand, from many recent studies it is evident that dinosaurs really suffered a slight extinction about 10 million years before the K-T boundary event, exhibiting a real decline of genera.

C-T and K-T boundary extinction events: We know that by the end of the Cretaceous, dinosaurs and many other higher taxa that had played important role in the ecosystems died out. Why?

It ought to be stressed that there is also evidence of other important mass extinction, before the K-T boundary event, the so-called C-T (Cenomanian-Turonian) boundary event. After PAUL & MITCHELL (1994), the C-T boundary event was initiated by a very sudden drop in sea level, followed by a slower rise during which organic carbon was buried in marine sediments, resulting in *13C excursion, removal of nutrients and consequently zooplankton starvation. At the K-T boundary, reduced light levels possibly explain the negative delta13C excursion and other phenomena on land and sea (HSÜ, McKENZIE & HE 1982, PAUL & MITCHELL 1994). After the latter authors, a crisis of marine phytoplankton (reduction of primary productivity) resulted in zooplankton starvation and extinction at both the C-T and K-T boundaries, despite possible differences in the initial trigger.

Volcanic and impact hypotheses of the demise of dinosaurs: Speculations about the demise of the dinosaurs have ranged from huge volcanic eruptions (see esp. OFFICER & DRAKE 1985, COURTILLOT 1990, and the most comprehensive summary and bibliography in SUTHERLAND 1989, 1993, 1994), fires, diseases, competition, vegetation change, global cooling and refrigeration, to impacts of large extraterrestrial bodies. Many of these ideas, including the latter one, are quite old. However, the impact hypothesis was largely dismissed as improbable until the discovery of Luis Alvarez and co-workers. For references see the articles: L. W. ALVAREZ et al. (1979, 1980, 1984), GANAPATHY (1980), L. W. ALVAREZ (1987), W. ALVAREZ & MÜLLER (1984), WOLBACH, LEWIS & ANDERS (1985), W. ALVAREZ & ASARO (1990), HUT et al. (1987), CRONIN (1989), ZHAO & BADA (1989), W. ALVAREZ et al. (1992), and the book of ALBRITTON (1989). The hypothesis has been widely publicized in the mass media and became the subject of intense inquiry and debate. In 1990 Alan Hildebrand has presented evidence of a huge impact structure, the Chicxulub crater in the Yucatan Peninsula (Mexico), which is now commonly identified as the site of the K-T boundary impact (see esp. HILDEBRAND & BOYNTON 1990; KERR 1990a, b, 1991a, b; IZETT, DALRYMPLE & SNEE 1991; McKINNON 1992; SHARPTON et al. 1992; KRING & BOYNTON 1992, W. ALVAREZ, CLAEYS & KIEFFER 1995). And 65 million years later, like in a sci-fi story, people are seeking ways to identify asteroid hazards and suggest defenses, avert collisions, and protecting Earth from a cosmic catastrophe (MATTHEWS 1992, HILL 1995). Interestingly, no impact is recognized at the C-T boundary.

Angiosperm-dinosaur interaction: Some authors have suggested possible angiosperm-dinosaur interactions with global consequences. For example, with the rise of angiosperms (flowering plants), the appearance of many pollens to which dinosaurs had not previously been exposed may have produced violent allergic reactions and dinosaurs became extinct (while mammals produced lineages resistant to antigens of the new pollen).

Other authors have suggested that angiosperm foliage had been toxic for the herbivorous dinosaurs or at least that overdoses of the toxic alkaloids in the foliage could be lethal for the dinosaurs. Others have pointed to the fact that angiosperms were more efficient producers of oxygen than conifers and cycadeoids. Greater concentrations of oxygen in the tissues of dinosaurs would cause problems for their slow metabolism (for references see ALBRITTON 1989). The innumerable present studies of the contemporary "greenhouse effect" suggest a somewhat different picture of the oxygen problem. For example, Paul Olsen has argued that plants are important in diminishing the greenhouse effect and cooling of the planet. After him, herbivorous dinosaurs, the greatest plant eaters that ever lived, were possibly able to turn dense jungles into open forests and open forests into bare lands. If the Darwinian "success" of plants has a cooling effect on the climate (by removing carbon dioxide from the atmosphere), success of herbivorous animals should have the opposite influence - "greenhouse effect" (ZIMMER 1993). As mentioned above, we know that there is an abundant evidence for massive reduction of primary producers in the uppermost Creatceous seas followed by greenhouse warming. The late Cretaceous world was really warm and essentially ice free (see e.g. WORSLEY et al. 1994).

On the other hand, BAKKER (1986, 1989) has argued that angiosperms appeared in the world dominated by herbivorous dinosaurs, about 40 million years before K-T boundary. It seems to be reasonable that dinosaurs co-evolve in relation to these plants. In modern synthesis as well as in palaeobotany, plants have been simply regarded as a part of the "environment", a "factor", while herbivorous animals played generally the role of the evolutionary "responders". However, dinosaurs exhibited two to three times faster speciation rates than plants (i.e. as fast as mammals’ rates). Moreover, the flowering plants first appeared in the early Cretaceous, i.e. after the extinction of stegosaurs and brontosaurs (both groups were represented by high-feeding plant browsers) that occurred at the end of the Jurassic. It may well be more plausible the reverse scenario: that the shift from Jurassic to Cretaceous types of herbivorous dinosaurs have opened the way for flowering plants. Cretaceous herbivorous dinosaurs were concentrated on low-feeding close to the ground. Although early angiosperms were probably eaten just as severely as conifers or cycadeoids, they were able to grow and reproduce much more successfully, having their Darwinian "advantage" and survived, from this point of view, thanks to herbivorous dinosaurs.

Impaired reproductive capabilities in dinosaurs?: Because of the above mentioned greenhouse warming at the end of Cretaceous, some authors argue that such a rise of global temperatures might have had a devastating effect on the reproductive capabilities of dinosaurs. Interestingly, ERBEN, HOEFS & WEDEPOHL (1979) have reported pathologic dinosaur eggs from the Upper Cretaceous of France and Spain. Some embryos probably died of dehydration (due to abnormally thin shells), some of suffocation (due to the presence of more shells on a single egg). The authors attributed the pathologic eggs to hormonal imbalancies in the dinosaur population, leading possibly to the demise of the whole species.

Causes of mass extinctions

Mass extinctions due to refrigeration: There is certainly a striking pattern of mass extinctions through the last 600 million years. Steven Stanley, an American palaeontologist and macroevolutionist, has proposed temperature fluctuations, particularly refrigerations, as a proximal agent of extinctions, at least in the marine fossil record. After him, during the fall of planetary temperatures, the tropical organisms have no place to which to escape and become extinct (esp. STANLEY, 1987). He has really observed that at least in some parts of the fossil record there is after the extinction an extant biotic residue consisting only of species that can tolerate cool conditions.

There is, however, an important objection found in the study of Paul Markwick (formerly a graduate student at the University of Chicago; see Geotimes, March 1995, p. 8-9) who has suggested that the global cooling was not the cause of dinosaurs’ extinction because crocodiles and alligators (i.e. cold-blooded reptiles extremely sensitive to climate change) did not disappear at the K-T boundary. Moreover, we can indicate a marked continuous increase of crocodile genera many million years before and after the terminal Cretaceous event It is possible that there was no cooling at the K-T boundary at all. The evidence shows a strong fall of global temperatures followed by a marked decrease of crocodile genera about 30 million years later.

Moreover, after Anthony Hallam, the Stanley’s hypothesis is incorrect at least as a general phenomenon because of the fact that we can "see too many instances of extinctions without refrigeration and refrigeration without extinction..." (LEWIN 1984).

Regression hypothesis of mass extinctions: On the other hand, there is the marine regression hypothesis (or "species-area hypothesis") suggesting that the sea level lowstands, commonly associated with plate movements and polar glaciations, decrease the available habitats for shallow-water organisms and eliminate whole biogeographic provinces. However, the actual observations in recent seas clearly oppose this idea (LEWIN 1984, p. 384).

Red Queen Hypothesis of evolution and extinction in the fossil record: The main body of modern darwinists remains convinced that individual-level selection is the key to understanding all evolution. Some believe that there is also group-level selection which occupies only a small portion of evolution by natural selection (LEWIN 1996). It is commonly held by post-Darwin darwinists that evolution mostly occurs by adaptation to the physical environment. However, following DARWIN (1859), VAN VALEN (1973, 1977, 1983) has suggested that the success of any organism is influenced by the strategies used by other organisms around it (evolution and extinction driven by "diffuse competition") and that the biotic interactions themselves can produce responses, i.e. coevolution. He has argued that in an ecosystem, there is constantly a strong "zero-sum constraint" on the absolute Darwinian fitnesses, i.e. that there are fixed amounts of energy available to communities. That means that if species A increases its fitness, then one or more other species B lose their fitness, by the same total amount (any gain by one species is exactly offset by equal losses to others). Such "zero-sum constraint" may lead to evolutionary equilibria or to evolutionary race with accelerated changes in counteracting strategies.

VAN VALEN (1973) has called the zero-sum constraint Red Queen, after Red Queen in Lewis Carroll´s famous book "Through the Looking Glass" in which Alice meets Red Queen and learns to keep running fast enough to stay in the same place. Really, Red Queen perpetually runs yet forever remains in place.

"Well, in our country," said Alice,... "you´d generally get to somewhere else - if you ran very fast for a long time, as we´ve been doing."

"A slow sort of country!" said the Queen. "Now, here, you see, it takes all the running you can do, to keep in the same place. If you want to get somewhere else, you must run at least twice as fast as that!" (CARROLL 1872).

After VAN VALEN (1983), coevolution occurs on a very broad scale and may comprise most of evolution but only at the community level (never at the planetary level).

There has been much debate about the Red Queen and its possible influence on origins and extinctions of species. However, the evidence runs rather more against than for it. Even within the evolutionary paradigm, the latter view seems to be impossible to sustain (see e.g., RAUP 1993). Especially, Red Queen Hypothesis is unable to explain why we have a clear evidence of simultaneous demise of whole higher taxa during the large mass extinctions. Moreover, extinctions have little to do with the general level of "fitness" (RAUP 1981, 1993). In fact, as stated above, it is practically impossible to show why any survivor is "better" than the victim (see esp. the classical work of WILLIAMS 1966).

It ought to be stressed that the "idea of absolute scale for °highness° or °lowliness° is an example of essentialist metaphysics which is very common in our everyday thought, and which has profound social implications." (GHISELIN 1969). Thanks to many modern studies, the role of competition in evolution and extinction (large-scale competitive replacements by the appearance of "key adaptations") has been deeply and convincingly questioned by many macroevolutionists. All the typical examples of large-scale competition in the fossil record turned out to be clearly wrong or unproven assumptions (for references and comprehensive analyses see BENTON 1987).

Periodicity of mass extinctions in the fossil record: Beginning with the pioneering studies of Raup and Sepkoski, several modern investigators have suggested that major mass extinctions exhibit a periodicity through time, with a period ranging from about 26 to 32 million years (esp. RAUP & SEPKOSKI 1984, 1986, 1987; RAMPINO & SLOTHERS 1984; KITCHELL & PENA 1984; MULLER 1985, 1988; CONNOR 1986; FOX 1987; RAUP 1986, 1991b, c; SEPKOSKI 1986, 1989, 1990). Really, although surrounded by controversy, the surprisingly uniform spacing of large extinction events, especially in Mesozoic-Cenozoic time, is markedly different from the phenomena caused randomly by independent factors. Of course, these nonrandom, periodic occurrences are explained conventionally by extrinsic forces - impacts of large extraterrestrial bodies which really may occur with a certain periodicity.

On the other hand, to say that extinctions are primarily caused by impacts of extraterrestrial bodies is an unjustified oversimplification. It ought to be stressed that, at least, the principal question should be whether the extraterrestrial factors themselves represent the ultimate or proximate cause of extinctions.

Proximate and ultimate causes of contemporary extinctions: By "proximate" (final) cause it is generally meant the reason why the last few individuals of a given species die, while the so-called "ultimate" (first) cause of extinction occurred much earlier and led to the situation in which there remains only a small, terminal population (SIMBERLOFF 1986). Today, it seems that at least in many cases human activities represent both the ultimate as well as proximate causes of contemporary extinctions. However, it is well- known that some proximate causes are not anthropogenous and that a large portion of them is not external at all. Such an intrinsic (internal) portion of causes is poorly known because once a species is so rare that it is endangered by extinction, it is immoral to do scientific experiments (SIMBERLOFF 1986). From the traditional evolutionary standpoint it seems to be self-evident that in the fossil record, the ultimate causes are mostly external (esp. the most fashionable impacts of large extraterrestrial bodies), while the proximate ones may be very complex, both internal and external.

Proximate and ultimate causes of individuals’ deaths: The same problem appears in the death of individuals. In many cases, it is very problematical to assign the "exact cause" of death, especially without specifying the ultimate and proximate cause. For instance, the cause of many deaths is listed as "heart failure", but it is mostly the "proximate" cause because the 88-year-old man was brought to his pass by ageing processes in late adulthood. Ageing itself seems to represent the very ultimate cause of natural death.

Internal factors of contemporary extinctions: In considering extinctions, it must be stressed that some contemporary species have certain internal (intrinsic) characteristics that make them more susceptible to extinction. Such internal characteristics, commonly known to ecologists, are summarized by MILLER (1988, p. 225) as follows: 1) critical population density and population size (below this point, population size continues to decline even if the species is protected), 2) low reproductive rate, 3) specialized food requirements, 4) high trophic levels of the extinction-prone species, 5) large body size, 6) limited or specialized nesting or breeding areas, 6) endemism, 8) fixed migratory patterns, 9) preying on livestock or people, and 10) certain behavioural patterns. In the endangered species the characteristics above listed are frequently combined (e.g., the blue whale exhibits the characteristics 1, 2, 3, 5, 8).

Internal factors as part of final causes of extinction are thoroughly discussed in SIMBERLOFF (1986). He has stressed large body size, long developmental time, low reproduction, long life expectancy, etc. as internal factors that might place a species at higher risk of extinction. After the latter author, the three main internal factors of contemporary extinctions are related to: demographic stochasticity (random variation in population variables, e.g. male-biased sex ratio), genetic deterioration (lose of alleles by genetic drift and inbreeding), or social dysfunction (behavioural characteristics rendering small populations to be more liable to extinction). In many cases several causes frequently combine.

A typical internal factor of extinction is certainly the population size. In relation to climate change (e.g. the contemporary global warming), species are more likely to become extinct if their remaining populations are small, if they occupy a small geographic range, if there are physical barriers to dispersal or if a species’ internal (intrinsic) dispersal rate is low (PETERS 1989).

Today, many ecologists discuss the possible restoration of devastated animal populations (for reference see LEWIN 1989) and found again interesting internal extinction factors: population size, body size, longevity of individuals within the population, potential rate of population increase, and inherent population size fluctuation over time. The influence of these intrinsic factors on extinction rates is, however, far from simple because all are combined and closely interrelated. There are many mysterious problems. For instance, in small populations of birds, the small-bodied species will be at greater risk from extinction, while in large populations, large bodied species are at greater risk (therefore, there is an internal tendency of large-bodied animals to have lower populations). On the other hand, one can find species that have the characteristics listed above but do not exhibit any threat of extinction.

Body size as an internal factor of extinctions in the fossil record: Internal factors of extinctions in the fossil record were probably of the same type as those today but, unfortunately, they are seldom discussed in the literature. The only exception from this is a highly heritable and highly polygenic trait - body size, which must play very important role in speciation and extinction, especially during the periods of mass extinctions (see esp. LABARBERA 1986 and references therein). For instance, it seems that during the K-T boundary event almost all large-bodied vertebrates became extinct.

Although the trend towards larger body size in animal lineages may form partly an artifact (we know of many interesting examples of dwarfing!), there are well-documented cases of persisting body-size increases in numerous phylogenetic lineages in the fossil record. This frequent phenomenon is well-known as an empirical "Cope’s Rule", ascribed to the author of the palaeontological "Law of Unspecialized Ancestor" (of which the "Cope’s Rule" forms a special part), the great neo-Lamarckian American biologist and palaeontologist Edward Drinker Cope (1840-1897). Most higher taxa have clearly arisen from ancestors of relatively smaller body sizes. Large (descendant) forms are specialists (opportunists) while small (ancestral) types are generalists. The "Cope’s Rule" holds for many animal groups but is problematical in arthropods, bryozoans, brachiopods and graptolites (NEWELL 1949). More recently, STANLEY (1973) has suggested an important challenge to the "Cope’s Rule" (Gould has argued that we should speak of "Stanley’s Rule", see GOULD 1988), viewing it as evolution from small body size, rather than towards large body size. After the latter author, the increasing body size seems to be only a result (byproduct) of "random walk" in changing variance of body sizes.

Comparable species "lifespan" within phylogenetic groups in relation to oxygen consumption: A very important study has been published by McALESTER (1970). He has suggested that taxa that have had high extinction rates have high present-day rates of oxygen consumption while those with relatively stable histories show low present-day oxygen requirements. After McAlester: "Past susceptibility to family-level extinctions within major taxa of fossil animals shows a close positive correlation... with oxygen uptake in Recent representatives of the same taxa."

The latter discovery seems to be extremely important because many biologists point to the interesting influence of oxygen consumption on the ageing. In many and many cases, the rate of oxygen consumption (metabolic rate) influences how long individuals of a given species can live. Generally, there is an upper limit to the amount of oxygen (metabolic potential) consumed in a lifetime. This limit is very probably determined intrinsically, i.e. genetically. For example, although insects of a given species are much more active and age much more rapidly in warmer environments than in cooler ones, their metabolic potential does not change, i.e. the total number of heartbeats remains constant (see e.g., ALLEN 1992). McALESTER’s (1970) calculations concerning the possible causes of extinctions are slightly different because he has stated: "If atmospheric oxygen fluctuations have been an important cause of animal extinctions, then it seems reasonable to predict that taxa with high overall oxygen requirements should have been more susceptible to such extinction than those with low oxygen requirements." On the other hand, the primarily intrinsic properties of the oxygen consumption seem to be self- evident.

Ageing in phylogenetic groups: VAN VALEN (1973) has found that the probability of extinction within any group remains constant through time (Van Valen’s "Law of Constant Extinction"), i.e. a species might disappear at any time, irrespective of how long it has already existed. It is misleading and it certainly does not mean that extinctions are essentially random. There are many factors that might affect extinction rates and many of them are linked.

For example, we have the neutral theory of evolution (KIMURA 1968, 1983) which provides a foundation for the hypothesis of molecular evolutionary clock. The rate of neutral mutations is expected to remain constant through evolutionary time (the number of molecular differences between species reflect the time elapsed). As mentioned above, when speciation and extinction rates are statistically expressed (per lineage per million years), the two rates are approximately the same (RAUP 1981). Of course, simple answers are not readily derivable from such a "database" but a kind of relation between evolution and extinction seems to be evident and not random. Moreover, there are higher taxa that exhibit markedly high extinction rates and there are others that have low ones. For example, from the evolutionary point of view, the phenomenon of the so-called living fossils can be pictured as a reflection of low rates of speciation within a given clade (VRBA 1983).

Keeping in mind the analogous patterns in life histories of trilobites and dinosaurs outlined above, it must be stressed that some modern macroevolutionists point to internal factors in extinction processes. For instance, Elisabeth Vrba has proposed her "Effect Hypothesis" concerning the degree of species specialization. She has argued that species- opportunists both speciate and become extinct frequently, while species-generalists speciate and become extinct infrequently (VRBA 1980, 1983; LEWIN 1980). Of course, Vrba’s reasoning derives from very old premises mentioned above in relation to the body size.Every palaeontologist is well aware of "Cope’s Law of Unspecialized Ancestor", originally known as "Law of the Unspecialized" or "Doctrine of the Unspecialized" formulated as follows:

"... the highly developed, or specialized types of one geologic period have not been the parents of the types of succeeding periods, but ...the descent has been derived from the less specialized of preceding ages...

... plants not especially restricted to definite soils, temperatures, or degrees of humidity, would survive changes in these respects better than those that have been so restricted. Animals of omnivorous food-habits would survive where those which required special foods, would die. Species of small size would survive a scarcity of food, while large ones would perish...

the lines of descent of Mammalia have originated or been continued through forms of small size. The same is true of all other Vertebrata...

Degeneracy is a fact of evolution ... and its character is that of an extreme specialization, which has been, like an overperfection of structure, unfavorable to survival.

In general,.then, it has been the "golden mean" of character which has presented the most favorable condition of survival, in the long run." (COPE 1896, p. 173-174).

The Cope*s note on the "golden mean" reminds us of the "principle of the best" (creation of the best possible states as a production of a maximum effect with the least expenditure, i.e. a most economical state of affairs) of the great German philosopher and scientist Gottfried Wilhelm Leibniz (1646-1715). The latter author wrote:

"... though it may sometimes happen that the more perfect is excluded by the more imperfect, all and all that method of creating a world is chosen which involves more reality or perfection, and God acts like the greatest geometer, who prefers the best construction of problems." (LEIBNIZ 1995, p. 76).

As outlined in the particular cases of trilobites and dinosaurs, and as is well known even among orthodox neodarwinists, many groups exhibit flexibility during early diversification but these same features give way to conservatism. At the final stage of the group history the capacity for flexibility is very weak. This changing capacity is clearly an inherent (internal) characteristic. Keeping in mind this logic, we should view extinctions, at least partly, as a result of group ageing. In fact, in the evolutionary theory, the developmental approach to extinctions is not new. The last attempt is, however, that of the old typostrophic theory by German palaeontologist Otto Schindewolf (see SCHINDEWOLF 1929-1957) who suggested ageing processes in phylogenetic lineages (esp. his concept of typolysis).

Multicausal mass extinction hypothesis: The outstanding American palaeontologist and interpreter of evolution, George Gaylord Simpson has clearly stated that: "the essential features of the Cretaceous-Tertiary crisis cannot really be localized just at the boundary between those periods. The episodes are parts of a long and essentially continuous process" (SIMPSON 1965, p. 36). And he was clearly right. Therefore, some recent specialists search for an improved, so-called multicausal mass extinction hypothesis. After KAUFFMAN & ERWIN (1995), of the 15 large Phanerozoic mass extinctions known, high-resolution interdisciplinary data sets are now available for about eight of them. Typically, multiple stratigraphic levels of abrupt extinctions are clustered around (and particularly before!) the main events (KAUFFMAN & ERWIN 1995, p. 158). Such smaller preceding extinction events span about 1-3 million years and are ecologically graded (tropical reefs are affected first and most severely). Sometimes there are even no excursions in trace elements, stable isotopes, sea-level changes or no evidence of impacts.

Therefore, from the current evolutionary point of view, it is clear that there are different causes for different mass extinctions. This seems to be a self-evident truth, an "intiuitive principle" or axiom. But in modern evolutionary palaeontology, there are to be found several similar axioms which do not deserve to be called an axiom at all. We must remember that even the evolutionary theory per se possesses ideology, no axioms. We have no right to impose a priori assumptions upon thought. Why there is any periodicity with different causes at different etapes? Evolutionary palaeontologists are surprisingly slow to address this question.

Developmental paradigm for the history of life: In modern palaeontology, biology and evolutionary theory, there is obviously no analogy between the death of an individual organism and the extinction of species or higher taxa. It is the modern conventional wisdom that extinctions are viewed simply as extrinsic events, a sort of sudden cataclysms, i.e. of catastrophic killing off of species or higher taxa. Even the Raup’s well-known sentence "Bad genes or bad luck?" represents only a "working metaphore" and is meant in different way. "Bad genes" are assigned for the description of the Darwinian model of selective extinctions, while "bad luck" describes purely random causes (see e.g., RAUP 1981). In contrast to the evolutionary paradigm, the apparent analogy between the death of individuals and the extinctions of species or higher taxa can be viewed as a developmental paradigm of the history of life.

It seems that the "evolution" of a given group, once set in process, cannot be halted when it has reached an optimum, but must continue inexorably, resulting in final group extinction. Similarly, once set in motion, the developmental processes cannot be halted when they have reached an optimum, but must continue untiringly, resulting in the destruction and death of the individual organism. It seems that there is a clear analogy. Both processes represent fundamentally a continuation of the course of development. From this point of view, each new stage of the so-called "evolution" is a realization of a plan that had been present from the start.

Of course, if there are internal factors in extinctions, species and higher taxa are not essentially immortal. Both the development of an individual organism as well as "evolution" of a given taxon are processes that are regulated by the interaction of internal and external influences. People generally go through life without thinking about death. Death becomes little more than impersonal statistics on the evening news (PAPALIA & OLDS 1992). Sci-fi authors invariably picture their imaginative future worlds as if mankind itself will live forever. What is responsible for this denial of death? It is, at least partly, the present-day evolutionary paradigm of accidental character of extinctions as well as origins of species. We can argue that "development" seems to be a much more suitable word than "evolution".

Smooth continuum between "background" and "mass" extinctions: We know that the so-called "Big Five" mass extinctions are responsible for only 4% of all species extinctions in the Phanerozoic (e.g., RAUP 1993). Lesser events and the so-called "background extinctions" are responsible for the other 96%. Present evidence also suggests that there appears to be a "smooth continuum between background and mass extinctions". The "clustering" of extinctions at mass extinctions "cannot be explained by the chance coincidence of independent events". In fact, it is unreasonable to distinguish between "mass" and "background" extinctions (RAUP 1993).

It seems impossible to make realistic correlations of so continuous process with intermittent impact episodes. But it does not mean that the continuous character of the extinctions suggests that there is no connexion with particular impacts of extraterrestrial bodies. Rather, the precise nature of the relationship, unexplainable using any possible hypothesis or theory of the evolutionary paradigm, is still in need of discussion.

Destabilizing effect of great ecosystem complexity: What does the continuum of extinctions mean ecologically? How do internal ecosystem properties, specifically the extent of interdependence among components, affect the response of ecosystems to external disturbances? Beginning 1970 (GARDNER & ASHBY 1970), numerous models and empirical studies (for references see PLOTNICK & MCKINNEY 1993) have indicated that as ecosystems decrease in the number of their components (i.e, as the diversity decreases), they become more stable and they are less likely to collapse or suffer further losses. Taken as a whole, the continuously increasing number of extinctions may reduce the destabilizing effect of great ecosystem complexity (complexity works against stability; see also MAY 1972, 1973; TAYLOR 1989).

Functional groups and keystone species: Since the 1960s, ecologists have shown that during extinctions there are two important species types in ecosystems. Sometimes, the community integrity depends on a single species, typically a top predator, or keystone species which determines the integrity of the community and its unaltered persistence through time. Removing such a species from the community may cause an explosive invasion of hundreds of new organisms. On the other hand, there are whole groups of organisms with equivalent functions in the ecosystem, so-called functional groups. If a particular species of such a group was removed, other species of the group take over the same function (STONE 1995). The latter concept makes an important challenge to the Gause’s Principle according to which one would expect great diversity only when species are very different or at least closely related but exploiting different food resources (see e.g., WATT 1987). Analogous situation probably occurred after the main extinction events.

Biological rhythms in individuals, species and ecosystems: It is self-evident that individuals must cope with temporal variations of the physical environment and adjust their physiology and behaviour to them. Therefore, individuals, as well as whole species, are provided with intrinsic, innate, endogeneous rhythmic "programs" that match the astronomical cycles and allow the "adjustment" of all biological activities to these temporal changes. The best known of them are daily periodicities (rotation of the Earth, movements of the Sun and of the Moon in relation to the Earth). Not only daily biological rhythms of individuals and species but also annual rhythms of the whole ecosystems are related to these cycles. From our annual experience we all know that the rhythms at the ecosystem level, with cycle duration of a year, are seasonally evident. Of course, the causation is now problematical. It is unreasonable to think, for instance, that an afternoon, around 3 to 5 p.m., first half of October, when the moon is in the first or last quarter, represents the "factor" and the spawning in the littoral crinoid Comanthus japonicus "response". There are no clear "factors" and "responses" because of the self-evident fact that such a kind of phenomena constitutes a whole.

"...the whole is a pattern, a complex wiggliness, which has no separate parts. Parts are fictions of language, of the calculus of looking at the world through a net which seems to chop it up into bits. Parts exist only for purposes of figuring and describing, and as we figure the world out we become confused if we do not remember this all the time. Once this is clear, we have shattered the myth of the Fully Automatic Universe where human consciousness and intelligence are a fluke in the midst of boundless stupidity. For if the behavior of an organism is intelligible only in relation to its environment, intelligent behavior implies an intelligent environment. Obviously, if "parts" do not really exist, it makes no sense to speak of an intelligent part of an unintelligent whole. It is easy enough to see that an intelligent human being implies an intelligent human society, for thinking is a social activity - a mutual interchange of messages and ideas based on such social institutions as languages, sciences, libraries, universities, and museums. But what about the nonhuman environment in which human society flourishes?

Ecologists often speak of the "evolution of environments" over and above the evolution of organisms. For man did not appear on earth until the earth itself, together with all its biological forms, had evolved to a certain degree of balance and complexity. At this point of evolution the earth "implied" man, just as the existence of man implies that sort of a planet at that stage of evolution. The balance of nature, the "harmony of contained conflicts", in which man thrives is a network of mutually interdependent organisms of the most astounding subtlety and complexity. Teilhard de Chardin has called it the "biosphere," the film of living organisms which covers the original "geosphere," the mineral planet. Lack of knowledge about the evolution of the organic from the "inorganic," coupled with misleading myths about life coming "into" this world from somewhere "outside," has made it difficult for us to see that the biosphere arises, or goes with, a certain degree of geological and astronomical evolution. But, as Douglas E. Harding has pointed out, we tend to think of this planet as a life-infested rock, which is as absurd as thinking of the human body as a cell-infested skeleton. Surely all forms of life, including man, must be understood as "symptoms" of the earth, the solar system, and the galaxy - in which case we cannot escape the conclusion that the galaxy is intelligent.

If a first see a tree in the winter, I might assume that it is not a fruit-tree. But when I return in the summer to find it covered with plums, I must exclaim, "Excuse me! You were a fruit-tree after all." Imagine, then, that a billion years ago some beings from another part of the galaxy made a tour through the solar system in their flying saucer and found no life. They would dismiss it as "Just a bunch of old rocks!" But if they returned today, they would have to apologize: "Well - you were peopling rocks after all!" You may, of course, argue that there is no analogy between the two situations. The fruit- tree was at one time a seed inside a plum, but the earth - much less the solar system or the galaxy - was never a seed inside a person. But, oddly enough, you would be wrong.

I have tried to explain that the relation between an organism and its environment is mutual, that neither one is the "cause" or determinant of the other since the arrangement between them is polar. If, then, it makes sense to explain the organism and its behavior in terms of the environment, it will also make sense to explain the environment in terms of the organism. (Thus far I have kept this up my sleeve so as not to confuse the first aspect of the picture.) For there is a very real, physical sense in which man, and every other organism, creates his own environment.

Our whole knowledge of the world is, in one sense, self-knowledge. For knowing is a translation of external events into bodily processes, and especially into states of the nervous system and the brain: we know the world in terms of the body, and in accordance with its structure. Surgical alterations of the nervous system, or, in all probability, sense- organs of a different structure than ours, give different types of perception - just as the microscope and telescope change the vision of the naked eye. Bees and other insects have, for example, polaroid eyes which enable them to tell the position of the sun by observing any patch of blue sky. In other wordsbecause of the different structure of their eyes, the sky that they see is not the sky that we see. Bats and homing pigeons have sensory equipment analogous to radar, and in this respect see more "reality" than we do without our special instruments..." (WATTS 1970)

Biological rhythms on a planetary scale: Today, many evolutionary palaeontologists theorize about periodicity of mass extinctions in relation to possible astronomical influences as "triggers". Interestingly, hardly anybody has argued for the mutual interaction of the impacts with the continuous character of extinctions - an extraordinary oversight, considering the amount of facts and literature. Is it reasonable to consider different causes at different etapes of a single periodic phenomenon? The consistent neglect of an intrinsic cause results from ideology of the contemporary metaphysical paradigm.

It is more real to think of rhythms on a higher level, with cycle duration of as long as about 26 million years. Of course, planetary rhythmicities on such a time scale are impossible from the viewpoint of the contemporary theories. But in true science, fact must yield perception, not the other way around. The modern evolutionary theory itself is a religion resting on the myth of intraspecific competition and natural selection. Developmental processes on a planetary scale are unreal in a Darwinian world composed of aggregated pieces of material stuff which is in random and pointless motion. They are perfectly normal in developmental cosmologies (SALTHE 1993).


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