The “Balance of Nature”—Evolution of a Panchreston

The earliest concept of a balance of nature in Western thought saw it as being provided by gods but requiring human aid or encouragement for its maintenance. With the rise of Greek natural philosophy, emphasis shifted to traits gods endowed species with at the outset, rather than human actions, as key to maintaining the balance. The dominance of a constantly intervening God in the Middle Ages lessened interest in the inherent features of nature that would contribute to balance, but the Reformation led to renewed focus on such features, particularly traits of species that would maintain all of them but permit none to dominate nature. Darwin conceived of nature in balance, and his emphasis on competition and frequent tales of felicitous species interactions supported the idea of a balance of nature. But Darwin radically changed its underlying basis, from God to natural selection. Wallace was perhaps the first to challenge the very notion of a balance of nature as an undefined entity whose accuracy could not be tested. His skepticism was taken up again in the 20th century, culminating in a widespread rejection of the idea of a balance of nature by academic ecologists, who focus rather on a dynamic, often chaotic nature buffeted by constant disturbances. The balance-of-nature metaphor, however, lives on in large segments of the public, representing a fragile aspect of nature and biodiversity that it is our duty to protect.The notion of a “balance of nature” stretches back to early Greeks, who believed gods maintained it with the aid of human prayers, sacrifices, and rituals [1]. As Greek philosophers developed the idea of natural laws, human assistance in maintaining the balance did not disappear but was de-emphasized. Herodotus, for instance, the earliest known scholar to seek biological evidence for a balance of nature, asked how the different animal species each maintained their numbers, even though some species ate other species. Amassing facts and factoids, he saw divinely created predators'' reproductive rates lower than those of prey, buttressing the idea of a providentially determined balance with a tale of a mutualism between Nile crocodiles beset with leeches and a plover species that feeds on them [1]. Two myths in Plato''s Dialogues supported the idea of a balance of nature: the Timaeus myth, in which different elements of the universe, including living entities, are parts of a highly integrated “superorganism,” and the Protagoras myth, in which gods created each animal species with characteristics that would allow it to thrive and, having run out of biological traits, had to give man fire and superior intelligence [1]. Among Romans, Cicero followed Herodotus and Plato in advancing a balance of nature generated by different reproductive rates and traits among species, as well as interactions among species [1].The Middle Ages saw less interest in such pre-set devices as differential reproductive rates to keep nature in balance, perhaps because people believed in a God who would maintain the balance by frequent direct intervention [1]. The Reformation, however, fostered further development of the concept of a providential balance of nature set in motion at creation. Thomas Browne [2] added differential mortality rates to factors maintaining the balance, and Matthew Hale [3] proposed that lower rates of mortality for humans than for other animals maintain human dominance within a balanced nature and added vicissitudes of heat from the sun to the factors keeping any one species from getting out of hand.The discovery of fossils that could not be ascribed to known living species severely challenged the idea of a God-given balance of nature, as they contradicted the idea of species divinely created with the necessary features for survival [4]. John Ray [5] suggested that the living representatives of such fossils would be found in unexplored parts of the earth, a solution that was viable until the great scientific explorations of the late 18th and early 19th centuries [4]. Ray also argued that what would now be termed different Grinnellian ecological niches demonstrated God''s provision of each species with a space of its own in nature.According to Egerton [1], the earliest use of the term “balance” to refer specifically to ecology was probably by Ray''s disciple, William Derham [6], who asserted in 1714 that:

“The Balance of the Animal World is, throughout all Ages, kept even, and by a curious Harmony and just Proportion between the increase of all Animals, and the length of their Lives, the World is through all Ages well, but not over-stored.”

Derham recognized that human populations seemed to be endlessly increasing but saw this fact as a provision by God for future disasters. This explanation contrasts with that of Linnaeus [7], who saw human and other populations endlessly increasing but believed the size of the earth was also increasing to accommodate them. Derham grappled with the issue of theodicy but failed to reconcile plagues of noxious animals with the balance of nature, seeing them rather as “Rods and Scourges to chastise us, as means to excite our Wisdom, Care, and Industry” [1].Derham''s contemporary Richard Bradley [8],[9] focused more on biological facts and less on Providence in sketching a more comprehensive account of an ecological balance of nature, taking account of the rapidly expanding knowledge of biodiversity, noting that each plant had its phytophagous insects, each insect its parasitic wasps or flies and predatory birds, concluding that “all Bodies have some Dependence upon one another; and that every distinct Part of Nature''s Works is necessary for the Support of the rest; and that if any one was wanting, all the rest must consequently be out of Order.” Thus, he saw the balance as fragile rather than robust, in spite of a constantly intervening God. Linnaeus [10] similarly marshaled observations of species interactions to explain why no species increases to crowd out all others, adding competition to the predation, parasitism, and herbivory adduced by Bradley and also emphasizing the different roles (we might now say “niches”) of different species as allowing them all to coexist in a sort of superorganismic, balanced whole.Unlike Derham, Georges-Louis Leclerc, Comte de Buffon [11] managed to reconcile animal plagues with a balanced nature. He perceived the balance of nature as dynamic, with all species fluctuating between relative rarity and abundance, so that whenever a species became overabundant, weather, predation, and competition for food would bring it back into balance. Buffon''s successor as director of the Jardin des Plantes in Paris, Jacques-Henri Bernardin de Saint-Pierre [12], was probably the first to associate ecological damage caused by biological invasions with a disruption of the balance of nature. Observing damage to introduced trees from insects accidentally introduced with them, he argued that failure to introduce the birds that would eat the insects led to the damage. William Paley [13], perhaps the inspiration for today''s advocates of “intelligent design,” analogized nature to a watch. One would assume a smoothly running watch was designed with purpose, and so too nature was designed by God with balance and a purpose.In the 19th century, evolution burst on the scene, greatly influencing and ultimately modifying conceptions of a balance of nature. Fossils that seemed unrelated to any living species, as noted above, conflicted with the balance of nature, because they implied extinction, a manifestly unbalanced event that furthermore could be seen to imply that God had made a mistake. Whereas Ray had been able to argue that living exemplars of fossil species would be found in unexplored parts of the earth, by the 19th century, this explanation could be rejected. Jean-Baptiste Lamarck [14] resolved the conflict in a different way, arguing that species continually change, so the balance remains the same. The fossils thus represent ancestors of living species, not extinct lineages. Robert Chambers [15], another early evolutionist, similarly saw fossils not as a paradox in a balanced nature but as a consequence of the fact that, as the physical environment changed, species either evolved or went extinct.Alfred Russel Wallace was perhaps the first to question the very existence of a balance of nature, in a remarkable notebook entry, ca. 1855:

“Some species exclude all others in particular tracts. Where is the balance? When the locust devastates vast regions and causes the death of animals and man, what is the meaning of saying the balance is preserved… To human apprehension there is no balance but a struggle in which one often exterminates another” [16].

In modern parlance, Wallace appears almost to be asking how “balance” could be defined in such a way that a balance of nature could be a testable hypothesis.Darwin''s theory of evolution by natural selection certainly explained the existence of fossils, and his emphasis on inevitable competition both between and within species downplayed the role of niche specialization propounded by Plato, Cicero, Linnaeus, Derham, and others [1]. Darwin nevertheless saw the ecological roles of the diversity of species as parts of an almost superorganismic nature, and his main contribution to the idea of a balance of nature was his constant emphasis on competition and other mortality factors that kept all species'' populations in check [1]. His many metaphors and examples of the interactions among species, such as the tangled bank and the spinsters-cats-mice-bumblebees-clover stories in The Origin of Species [17], contributed to a sense of a highly balanced nature, but one driven by natural selection constantly changing species, rather than by God either intervening or creating species with traits that ensure their continued existence. Unlike Wallace, Darwin did not raise the issue of whether nature was actually balanced and how we would know if it was not.As ecology developed in the late 19th and early 20th centuries, it was inevitable that Wallace''s question—how to define “balance”—would be raised again and that increasingly wide and quantitative study, especially at the population level, would be brought to bear on the matter. The work of the early dominant plant ecologist Frederic Clements and his followers, with Clements'' notion of superorganismic communities [18], provided at least tacit support for the idea of a balance of nature, but his contemporary Charles Elton [19], a founder of the field of animal ecology and a leading student of animal population cycles, forcefully reprised Wallace''s concern:

“‘The balance of nature’ does not exist, and perhaps never has existed. The numbers of wild animals are constantly varying to a greater or lesser extent, and the variations are usually irregular in period and always irregular in amplitude. Each variation in the numbers of one species causes direct and indirect repercussions on the numbers of the others, and since many of the latter are themselves independently varying in numbers, the resultant confusion is remarkable.”

Despite Elton''s explicit skepticism, his depiction of energy flow through food chains and food webs was incorporated as a superorganismic analog to the physiology of individuals (e.g., [20]). Henry Gleason, another critic of the superorganism concept, who depicted populations distributed independently, rather than in highly organized communities, was ignored at this time [21].However, beginning with three papers in Ecological Monographs in 1947, the superorganism concept was increasingly questioned and, within 25 years, Gleason was vindicated and his views largely accepted by ecologists [22]. During this same period, extensive work by population biologists again took up Elton''s focus on population trajectories and contributed greatly to a growing recognition of the dynamism of nature and the fact that much of this dynamism did not seem regular or balanced [21]. The idea of a balanced nature did not immediately disappear among ecologists. For instance, a noteworthy book by C. B. Williams [23], Patterns in the Balance of Nature, described the distribution of abundances within communities or regions as evincing statistical regularity that might be construed as a type of “balance of nature,” at least if changes in individual populations do not change certain statistical features (a hypothesis that Williams considered untested at the time). But the predominant view by ecologists of the 1960s saw the whole notion of a balance as, at best, irrelevant and, at worst, a distraction. Ehrlich and Birch [24], for example, ridiculed the idea:

“The existence of supposed balance of nature is usually argued somewhat as follows. Species X has been in existence for thousands or perhaps millions of generations, and yet its numbers have never increased to infinity or decreased to zero. The same is true of the millions of other species still extant. During the next 100 years, the numbers of all these species will fluctuate; yet none will increase indefinitely, and only a few will become extinct… Such ‘observations’ are made the basis for the statement that population size is ‘controlled’ or ‘regulated,’ and that drastic changes in size are the results of upsetting the ‘balance of nature.’”

Another line of ecological research that became popular at the end of the 20th century was to equate “balance of nature” with some sort of equilibrium of numbers, usually of population sizes [25], but sometimes of species richness. The problem remained that, with numbers that vary for whatever reason, it is still arbitrary just how much temporal variation can be accommodated within a process or phenomenon for it still to be termed equilibrial [26]. Often the decision on whether to perceive an ecological process as equilibrial seems to be based on whether there is some sort of homeostatic regulation of the numbers, such as density-dependence, which A. J. Nicholson [27] suggested as an argument against Elton''s skepticism of the existence of a balance. The classic 1949 ecology text by Allee et al. [28] explicitly equated balance with equilibrium and cited various mechanisms, such as density-dependence, in support of its universality in nature [25]. Later similar sorts of mathematical arguments equated the mathematical stability of models representing nature with a balance of nature [29], although the increasing recognition of stochastic aspects and chaotic mathematics of population fluctuations made it more difficult to perceive a balanced nature in population trajectories [21].For academic ecologists, the notion of a balance of nature has become passé, and the term is widely recognized as a panchreston [30]—a term that means so many different things to different people that it is useless as a theoretical framework or explanatory device. Much recent research has been devoted to emphasizing the dynamic aspects of nature and prominence of natural or anthropogenic disturbances, particularly as evidenced by vicissitudes of population sizes, and advances the idea that there is no such thing as a long-term equilibrium (e.g., [31],[32]). Some authors explicitly relate this research to a rejection of the concept of a balance of nature (e.g., [33]–[35]), Pickett et al. [33] going so far as to say it must be replaced by a different metaphor, the “flux of nature.”The issue is confounded by the fact that the perception of balance can be sought at different levels (populations, communities, ecosystems) and spatial scales. Much of the earlier discussion of a balance was at the population and community levels—Browne, Hale, Bradley, Linnaeus, Buffon, Bernardin de Saint-Pierre, and Darwin saw balance in the limited fluctuations of populations and the interactions of populations as one force imposing the limits. The proponents of density-dependent population regulation fall in this category as well [36],[37]. As a balance is sought at the community and ecosystem levels, the sorts of evidence brought to bear on the matter become more complicated and abstract [37],[38]. It is increasingly difficult to imagine what sorts of empirical or observational data could test the notion of a balance. For instance, Williams''s balance of nature—evidenced by a particular statistical distribution of population sizes—would not be perceived as balanced by many observers in light of the fact that entire populations can crash, explode, or even go extinct within the constraint of a statistical distribution of a given shape. Early claims of a balance at the highest level, such as the various superorganisms (Plato''s Timaeus myth, Paley''s watch metaphor, Clements''s superorganismic plant community) can hardly be seen as anything other than metaphors rather than testable hypotheses and have fallen from favor. The most expansive conception of a balance of nature—the Gaia hypothesis [39]—has been almost universally rejected by scientists [40]. The advent and growing acceptance of the metapopulation concept of nature [41] also complicates the search for balance in bounded population fluctuations. Spatially limited individual populations can arise, fluctuate wildly, and even go extinct, while suitable dynamics maintain the widespread metapopulation as a whole.Yet, the idea of a balance of nature lives on in the popular imagination, especially among conservationists and environmentalists. However, the usual use of the metaphor in an environmental context suggests that the balance, whether given by God or produced by evolution, is a fragile balance, one that needs human actions for its maintenance. Through the 18th century, the balance of nature was probably primarily a comforting construct—it would protect us; it represented some sort of benign governance in the face of occasional awful events. When Darwin replaced God as the determinant of the balance with natural selection, the comfort of a balance of nature was not so overarching, if there was any comfort at all. Today, ecologists do not even recognize a balance, and those members of the public who do, see it as something we must protect if we are ever to reap benefits from it in the future (e.g., wetlands that might help ameliorate flooding from storms and sea-level rise). This shift is clear in the writings of Bill McKibben [42],[43], who talks frequently about balance, but about balance with nature, not balance of nature, and how humankind is headed towards a catastrophic future if it does not act promptly and radically to rebalance society with nature.     

“The Instinct Concept of the Early Konrad Lorenz”

Peculiar to Konrad Lorenz’s view of instinctive behavior is his strong innate-learned dichotomy. He claimed that there are neither ontogenetic nor phylogenetic transitions between instinctive and experience-based behavior components, thus contradicting all former accounts of instinct. The present study discusses how Lorenz came to hold this controversial position by examining the history of Lorenz’s early theoretical development in the crucial period from 1931 to 1937, taking relevant influences into account. Lorenz’s intellectual development is viewed as being guided by four theoretical and practical commitments as to how to study and explain behavior. These four factors, which were part of the general approach of Lorenz but not of other animal psychologists, were crucial in bringing about his specific position on instinctive behavior.     

The Soft Underbelly of Evolution?

Evolution and the origin of life are separate, if connected, topics, but they are frequently conflated??especially by creationists. Regarding the natural origin of life as ??the soft underbelly?? of evolution, creationists argue that it is impossible, improbable, or insusceptible to scientific investigation. Underlying their arguments is the hope that the failure of scientific research on the origin of life is evidence for a supernatural account. It is crucial for teachers to understand the nature of science in order to be able to explain why appeals to the supernatural are out of place in explaining the origin of life and why scientific research on the origin of life is not intrinsically a threat to faith.     

Early Evolution of the Vertebrate Eye—Fossil Evidence

Evidence of detailed brain morphology is illustrated and described for 400-million-year-old fossil skulls and braincases of early vertebrates (placoderm fishes). Their significance is summarized in the context of the historical development of knowledge of vertebrate anatomy, both before and since the time of Charles Darwin. These ancient extinct fishes show a unique type of preservation of the cartilaginous braincase and demonstrate a combination of characters unknown in other vertebrate species, living or extinct. The structure of the oldest detailed fossil evidence for the vertebrate eye and brain indicates a legacy from an ancestral segmented animal, in which the braincase is still partly subdivided, and the arrangement of nerves and muscles controlling eye movement was intermediate between the living jawless and jawed vertebrate groups. With their unique structure, these placoderms fill a gap in vertebrate morphology and also in the vertebrate fossil record. Like many other vertebrate fossils elucidated since Darwin’s time, they are key examples of the transitional forms that he predicted, showing combinations of characters that have never been observed together in living species.     

The Early Evolution of the Phosphagen Kinases—Insights from Choanoflagellate and Poriferan Arginine Kinases

Arginine kinase (AK) is a member of a large family of phosphoryl transfer enzymes called phosphagen (guanidino) kinases. AKs are present in certain protozoans, sponges, cnidarians, and both lophotrochozoan and ecdysozoan protostomes. Another phosphagen kinase, creatine kinase (CK), is found in sponges, cnidarians, and both deuterostome and protostome groups but does not appear to be present in protozoans. To probe the early evolution of phosphagen kinases, we have amplified the cDNAs for AKs from three choanoflagellates and from the hexactinellid sponge Aphrocallistes beatrix and the demosponges Suberites fuscus and Microciona prolifera. Phylogenetic analysis using maximum likelihood of these choanoflagellate and sponge AKs with other AK sequences revealed that the AK from the choanoflagellate Monosiga brevicollis clusters with the AK from the glass sponge Aphrocallistes and is part of a larger cluster containing AKs from the demosponges Suberites and Microciona as well as basal and protostome invertebrates. In contrast, AKs from Codonosiga gracilis and Monosiga ovata form a distinct cluster apart from all other AK sequences. tBLASTn searches of the recently released M. brevicollis genome database showed that this species has three unique AK genes—one virtually identical to the M. brevicollis cDNA and the other two showing great similarity to C. gracilis and M. ovata AKs. Three distinct AK genes are likely present in choanoflagellates. Two of these AKs display extensive similarity to both CKs and an AK from sponges. Previous work has shown CK evolved from an AK-like ancestor prior to the divergence of sponges. The present results provide evidence suggesting that the initial gene duplication event(s) leading to the CK lineage may have occurred before the divergence of the choanoflagellate and animal lineages.     

The Early History of “Photosynthetica”, “Photosynthesis Research”, and their Publishers

The history of the journals Photosynthetica and Photosynthesis Research is traced from its beginning. Their development is related to the history of several publishers (Dr W. Junk Publishers, Martinus Nijhoff, Kluwer Academic Publishers). This account is based on recollections and records of the authors, Ad C. Plaizier, and René Marcelle (the first Editor-in-Chief of Photosynthesis Research).     

Evolution of the Tribosphenic Molar Pattern in Early Mammals,with Comments on the “Dual-Origin” Hypothesis

Development of the tribosphenic molar was a fundamental event that likely influenced the rise of modern mammals. This multi-functional complex combined shearing and grinding in a single chewing stroke, and provided the base morphology for the later evolution of the myriad dental morphologies employed by mammals today. Here a series of morphotypes are presented that represent stepwise acquisition of characters of the molar crown, in an effort to clarify homologies and functional analogies among molars of tribosphenic and tribosphenic-like mammals, as well as their putative sister groups. This is accomplished by evaluation of wear features, which provide direct evidence of occlusal function, and mapping these features on molars of the various morphotypes demonstrates their utility in determining homology. The original singular lower molar talonid cusp is homologous with the hypoconid, and upper molar cusp C in early mammals is homologous with the metacone (cusp “C” is a neomorph with variable occurrence). The lingual translation of the metacone to a position more directly distal to the paracone (as in Peramus) creates an embrasure for the lower molar hypoconid, and is accompanied by the development of the hypoconulid and a new shearing surface. Lastly, the Gondwanan radiation of tribosphenic-like mammals, the Australosphenida (including monotremes), is determined to be functionally non-tribosphenic. The Tribosphenida are restricted to Laurasian taxa, with an origin at or just prior to the Jurassic-Cretaceous boundary.     

Opening the “Black Box”: The Genetic and Biochemical Basis of Eye Evolution

Eyes provide a rich narrative for understanding evolution, having attracted the attention of preeminent scientists and communicators alike. Until recently, this narrative has focused primarily on the evolution of eye structure and far less on biochemistry or genetics. Although eye biochemistry was once likened to an unknown “black box;” the flood of discoveries in biochemistry is now allowing an increasingly detailed understanding of the processes involved in vision. As a result, evolutionary comparative (“tree-thinking”) analyses that use these data currently allow a new and still unfolding narrative, both richer in detail and more comprehensive in scope. Rather than toppling evolutionary theory by finding irreducibly complex molecular machines, eye evolution provides detailed accounts of how natural processes tinker with existing genetic components, duplicating and recombining them, to yield complex, intricate, and highly functional eyes. Understanding the new biochemical narrative is critical for researchers and teachers alike, in order to answer anti-evolutionist claims, and to provide an up-to-date account of the state of knowledge on the subject of eye evolution.     

Early Evolution of Membrane Lipids: How did the Lipid Divide Occur?

The ubiquitous distribution, homology over three domains, and key role in the membrane formation of the enzymes of the CDP-alcohol phosphatidyltransferase family, as well as phylogenetic analyses of lipid synthesizing enzymes suggest that the membranes of Wächtershäuser’s hypothetical pre-cells (universal common ancestor) [Mol Microbiol 47:13–22 (2003)] comprised a lipid bilayer with four types of core lipids [G-1-P-isoprenoid ether (Ai), G-3-P-fatty acyl ester (Bf), G-1-P-fatty acyl ester (Af) and G-3-P-isoprenoid ether (Bi)]. Here, a complementary hypothesis is presented to explain the difference between archaeal and bacterial lipids (lipid divide). The main driving force of lipid segregation is assumed to be glycerophosphate (GP) enantiomers, as Wächtershäuser proposed, but in the present study the hydrocarbon chains bound to each backbone are also hypothesized to affect lipid segregation. It is assumed that segregation was stimulated by different hydrocarbon chains bound to different GP backbones (Ai:Bf or Af:Bi). Because Ai and Bi are diastereomers and Af and Bf are enantiomers, Ai:Bf and Af:Bi are not equivalent. G-1-P-isoprenoid ether is provisionally assumed to segregate more easily from Bf than Bi does from Af. G-1-P-isoprenoid ether and Bf could more easily achieve the more stable homochiral membranes that are the ancestors of Archaea and Bacteria. This can explain why the extant archaeal and bacterial membrane lipids are mainly composed by Ai and Bf lipids, respectively. Because polar head groups were localized in the cytoplasmic compartment of pre-cells, they were equally carried over to Archaea and Bacteria during differentiation. Consequently, the both descendants shared the main head groups of membrane phospholipids.     

The Emergence and Evolution of Life in a “Fatty Acid World” Based on Quantum Mechanics

Quantum mechanical based electron correlation interactions among molecules are the source of the weak hydrogen and Van der Waals bonds that are critical to the self-assembly of artificial fatty acid micelles. Life on Earth or elsewhere could have emerged in the form of self-reproducing photoactive fatty acid micelles, which gradually evolved into nucleotide-containing micelles due to the enhanced ability of nucleotide-coupled sensitizer molecules to absorb visible light. Comparison of the calculated absorption spectra of micelles with and without nucleotides confirmed this idea and supports the idea of the emergence and evolution of nucleotides in minimal cells of a so-called Fatty Acid World. Furthermore, the nucleotide-caused wavelength shift and broadening of the absorption pattern potentially gives these molecules an additional valuable role, other than a purely genetic one in the early stages of the development of life. From the information theory point of view, the nucleotide sequences in such micelles carry positional information providing better electron transport along the nucleotide-sensitizer chain and, in addition, providing complimentary copies of that information for the next generation. Nucleotide sequences, which in the first period of evolution of fatty acid molecules were useful just for better absorbance of the light in the longer wavelength region, later in the PNA or RNA World, took on the role of genetic information storage.     

Evolution and University-level Anthropology Textbooks: The “Missing Link”?

Although studies analyzing the content of evolution curriculum usually focus on courses within the context of a biological sciences department or program, research must also address students and courses outside of the biological sciences. For example, using data solely from biological courses will not fully represent the scope of coverage of evolution in university education, as other fields, like anthropology, also utilize evolutionary principles. We analyzed the content of 31 university-level anthropology textbooks for the following: (1) presence of a definition of evolution in various sections of the textbooks, (2) accuracy and consistency of the definitions provided in the textbook sections, and (3) differences between textbooks for cultural and physical anthropology. Results of this study suggest that anthropology textbooks do not necessarily (1) provide a single definition of evolution or (2) provide an accurate, “baseline” definition of evolution when present. Additionally, substantive differences were observed between definitions provided in different sections within a single textbook, as well as between textbooks written for cultural anthropology and physical anthropology/archaeology courses. Given the inclusion of anthropology courses in general education curriculum at the university-level, we conclude that this situation may further exacerbate the misunderstanding of the basic tenets of evolution that university students have been repeatedly shown to demonstrate. We stress the role of the instructor in choosing textbooks that provide accurate information for students, as well as the responsibility they hold in providing a concise, accurate definition of evolution in social sciences courses.     

The Teaching of “Adaptation”

The use of the data from various athletic sports for exercises in the interpretation of data is proposed, and accounts are given of two such exercises. The first looks at the relationship between time and distance in world records for men running. When the logarithm of the time is plotted against the logarithm of the distance a straight line is produced. Thefactors that govern the speeds at which various distances are run are discussed and the application of these to other sports and to animals other than man is briefly mentioned. The second exercise looks at anomalous performances by men running in the 1968 Olympic Games which took place at high altitude. It is shown that while the lowered air resistance increased the speeds in sprint events, and the lowered oxygen content slowed down speeds in long distance events, these were not the only factors involved in limiting speeds.

Among the advantages of the use of such data are that they are readily and easily available, that they are the result of a lengthy selection process involving many subjects, that they appeal to students interested in sport and that they can link courses in biology and physical education.