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Robert M. May «The ecology of dragons»

Nature Vol. 264 November 4 1976

from Robert M.May

Although much studied in earlier times, dragons and their ilk have been largely neglected in the recent upsurge of interest in animal ecology and behaviour. An article by Hogarth (Bull. Brit. ecol. Soc., 7[2], 2-5; 1976 [1]) seeks to remedy this neglect.

In view of the lack of contemporary observational evidence, Hogarth necessarily relies on a survey of earlier sources. Most of these are from the 17th and early 18th century, an age when scientific curiosity was flowering. Later publications are increasingly sceptical, although Hogarth notes published doubts on the existence of dragons as early as Caxton's (1481) Mirror of the World.

Dragons appear to have been both omnivorous and voracious. Different records testify to their diet having been highly variable in both composition and quality: one dragon ate two sheep every day, and another which was kept captive by Pope St Sylvester consumed 6,000 people daily. The population density was also highly variable (presumably in a way which correlated with the per capita food requirements): "in England, indigenous dragons were solitary and it is doubtful whether the resident population averaged more than a few dozen, although occasional migrant flocks of up to 400 were seen: in India, by contrast, the marshes and mountains were described as being 'full' of dragons". Estimates of their life table parameters are scrappy. But there seems to be general agreement on a typical lifespan of the order of 10^3-10^4 years.

The sexual display behaviour of dragons includes at least one remarkable and unparalleled manifestation, recorded by an 18th century author: "Dragons, being incited to lust through the Heat of the Season, did frequently, as they flew through the Air, Spermatise in the Wells and Fountains". This may be conjectured to have had adaptive value in reducing intrinsic fecundity. Such long-lived beasts would seem to have been at the extreme K-selected end of the r-K continuum, and would therefore be likely to exhibit behaviour which had the effect of keeping population levels steady.

Hogarth concludes with speculation on the causes of extinction of dragons: despite persistent accounts of dragons and similar animals even in the present century, the typical mediaeval dragon was certainly extinct by the late 18th century. One contributing factor was commercial over-exploitation, primarily for pharmacological purposes. Only once was conservation legislation passed to protect dragons. This was in Rhodes, in 1345, when the king for-bade any knight to attempt to slay a local dragon (although Hogarth conjectures that this edict stemmed from concern for the knights, not the dragon). If we accept the notion that dragons were extreme K-selected animals, then their rapid extinction under the diverse pressures exerted by man is not surprising (see for example, Nature, 257, 737-738; 1975).

Hogarth's article is undoubtedly seminal, but I find it in some respects excessively uncritical. In discussing the evolution of dragons, and other "related species such as the cockatrice and griffon". Hogarth suggests they "probably originated as a distinct group only 5,000 years ago". Quite apart from the inherent implausibility of this statement, it is well to begin by getting clear the morphological details of the animals loosely grouped together here. These can be obtained from bestiaries, or from any heraldry text. Setting aside relatively minor differences, such as whether the feet have talons or claws, or whether the head has teeth or a beak, the basic difference is that the griffon and the canonical dragon are six-limbed (four legs, two wings), whereas the wyvern and cockatrice are four-limbed (two legs. two wings).

This is an absolutely fundamental distinction. One of the most conservative features of vertebrate evolution is the tetrapod morphology: this may be seen in any museum exhibit of the 500,000,000 years of evolution from lobe-finned fishes through amphibians and reptiles to birds and mammals. This underlying conservatism in skeletal structure, despite great variation in outward form and function, probably reflects the relative ease of modification of genes which govern timing in development, as opposed to those governing basic structure (see for example, King and Wilson, Science, 188, 107-116; 1975). The wyvern and cockatrice have this basic vertebrate tetrapod morphology, but the six-limbed dragon and griffon do not. The probable ancestry of these latter two, as an entirely separate group, there-fore dates back at least to the Devonian. This basic distinction applies to other now-extinct beasts: despite superficial similarities, unicorns belong with the familiar tetrapods, but the pegasus belongs with the six-limbed dragon-griffon vertebrate phylum, as do centaurs. Some angels (the humanoid- plus-wings kind) also belong in this phylum. but in view of the bewildering complications of angel morphology (once one includes cherubim. seraphim. and so on: see Davidson, Dictionary of Angels: Including the Fallen Angels, Free Press, 1967). this point is best not pursued.

In brief, wyvern and cockatrice can be envisaged as radiations from the basic vertebrate theme. But dragons, griffons, centaurs and angels belong to an entirely different lineage, the evolutionary history of which is shrouded in mystery.

The loose association of these two fundamentally different groups provides a striking example of the pre-Darwinian tendency to regard each species as a separate act of creation, rather than to trace logical phylogenetic relationships.

On the other hand, grouping together dragons, wyverns and the like is understandable in the light of the similarities of their ecology, behaviour and superficial appearance. They provide a dramatic example of evolutionary convergence, in the face of phylogenetic differences at least 400,000,000 years old. Such convergence implies some very tight evolutionary constraint somewhere in the "dragon" niche. a constraint hardly hinted at in Hogarth's account of their highly generalist diet and behaviour. This constraint may lie in the tendency exhibited by most dragons of record to be obsessive custodians of hordes of gold.

I conclude with the time-worn call for further research, modified by the highly contemporary remark that (if the above speculation is correct) such research may yield the literally golden fruits that grant-giving agencies increasingly desire.

Nature Vol. 264 December 16 1976

The ecology of dragons: a reply

I am glad that Robert May thought my article (Hogarth, Bull. Brit. ecol. Soc., 7, 2; 1976; May, Nature, 264, 16; 1976) seminal;

I must, nevertheless, disagree with him on one of his criticisms. In classifying the wyvern and cockatrice separately from the dragon, he attaches more significance to limb number than to other characteristics which these three types held in common. In particular, 1 refer to their supernatural qualities which seem to me to be of sufficient importance to justify setting them apart in a taxonomic category separate from that of the vertebrates. Four legs do not make a tetrapod; it is no more logical to include wyverns and cockatrices with conventional vertebrates than to classify a 12-legged dragon as a myriapod. Convergent evolution has indeed occurred to a remarkable extent, but between dragons and their allies on the one hand and vertebrates on the other: not, as May suggests, between vertebrates (including the wyvern and cockatrice) and dragons.

My estimate of 5,000 years BP for the emergence of dragons is therefore feasible. The total dependence on human imagination for their existence (a unique ecological relationship) precludes an origin earlier than, say, the late Pleistocene. The absence of convincing representations of dragons in upper Paleolithic art, and their frequent occurrence in literature and art from the time of Babylon onwards, indicates the chronological limits on the possible time of emergence.

Between these limits, 5,000 years ago seems a reasonable, albeit imprecise, estimate.


[1] Peter Hogarth, “Ecological Aspects of Dragons” Bulletin of the British Ecological Society 7 (1976): 2-5
Peter Hogarth, “Ecological Aspects of Dragons” Journal of Biological Education Volume 23, Issue 2, 1989

Примечание: разыскивается статья Peter Hogarth, “Ecological Aspects of Dragons”, изданная в журналах, указанных в сноске. На данный момент имеется одна-единственная страница