Field of Science

The Ibis in myth, science and palaeontology

"Every one has heard of the Ibis, the bird to which the ancient Egyptians paid religious worship; which they brought up in the interior of their temples, which they allowed to stray unharmed trough their cities, and whose murderer, even though involuntary, was pnished by death; which they embalmed with as much care as their own parents."
"Description of the bird called the Ibis by the ancient Egyptians", CUVIER 1831

The war of Napoleon in Egypt in the years 1798 to 1801 against the British supremacy in the Mediterranean region was not only a military, but also scientific expedition.
Prominent French Historians and Naturalists accompanied the army, like the biologists Étienne Geoffroy Saint-Hilaire or the mineralogist Déodat Gratet de Dolomieu.
From this expedition a mummified bird was send back to Paris, a specimen that arouse great interest by George Cuvier. Based on historic accounts, for example by Herodotus, depictions in Egyptian art and the recovered mortal remains Cuvier recognized in 1800 that the former classification of the bird as "Tantalus ibis", a stork, was erroneous. He attributed it to a new species of Ibises-birds, which he named "Numenius ibis" and considered only a subgenus of the "genus Ibis" (today cl
assified as family Threskiornithinae) and therefore comparable if not identical to the modern Sacred Ibis Threskiornis aethiopicus.

Fig.1. The skeleton of the sacred ibis of the ancient Egyptians, as found in mummified form in Egyptian tombs, from a paper Cuvier had published in 1804. Cuvier identified this bird to be comparable to modern species. However since it was distinctly different from the living bird commonly identified as the same species, it had been used (by other naturalists) as evidence for the gradual "transformation or evolution of animals over long periods of time (from RUDWICK 1997).

After the defeat of the Frenchs in 1801 Saint-Hilaire returned to Paris, bringing with him a large collection and variety of mummified animals.
The French naturalists Bernard-Germain-Étienne de La Ville-sur-Illon, comte de Lacépède (1756-1825) published in 1802, assisted by Cuvier and Lamarck, an extensive report of the collection of mummies
, he regarded the preserved specimen as essential to test the hypothesis that animals change through time:

"For a long time it has been desirable to know whether species change their form in the course of time…[]…this question, apparently futile, is in fact essential to the history of the globe."

(all quotes from "Rapport des professeurs", 1802)


Lacépède in this statement addresses the two dominant, and opposed views of paleontological change and geological time discussed in this period, the sudden catastrophism as proposed by Cuvier or the gradual change as foreseen by Lamarck. As naturalists he assumed that 3.000 years, the estimated age of the mummified bodies, were time enough to observe the proposed change in anatomy and morphology in animals.

"So one day it will be interesting to see, arranged in three series, today´s animals, these others already so ancient, and lastly those of an origin incomparably more remote, hidden in the better sealed tombs of the mountains over which our globe´s terrible catastrophes extended."

The final conclusions of Lacépède seem clear:

"[]...these animals are perfectly similar to those of today."


Based on these results Lamarck´s hypothesis of a transmutation of animals was rejected by Cuvier, and consequently by the French scientific establishment.


Who knows what Lacépède and Cuvier would say seeing the much older and unusual remains of a fossil ibis found in Pleistocene
deposits on the island of Jamaica.
The species Xenicibis xympithecus provide a typical example of a flightless bird found on an island; still such a modification is quite rare in the ibises. But Xenicibis is even more particular in secondary and unique properties of the bones of his wings described now in a paper by
LONGRICH & OLSON 2011.
The wings are not reduced or missing, in contrast the bones are elongated, grotesquely inflated and possess extremely thick walls, making them more resistant to mechanical stress. The authors of the discovery suggest that the wings were used by the birds for defence, as sort of club, or for intraspecific fights, an unique adaption not seen in any other modern ibises...

Fig.2. Skeletal reconstruction of Xenicibis xympithecus based on the fossils from the Red Hills Fissure cave deposits, Saint Andrews Parish, Jamaica (from LONGRICH & OLSON 2011).

Bibliography:


LONGRICH, N.R. & OLSON, S.L. (2011): The bizarre wing of the Jamaican flightless ibis Xenicibis xympithecus: a unique vertebrate adaptation. Proc. R. Soc. B published online 5 January 2011: doi: 10.1098/rspb.2010.2117

RUDWICK, M.J.S. (1997): Georges Cuvier, Fossil Bones, and Geological Catastrophes - New Translations & Interpretations of the Primary Texts. University of Chicago Press, Chicago & London: 301

First image from the papyrus of Hunefer - the "Book of the Death", British Museum

2 comments:

  1. A very well written and presented article, tying in aspects of Larmarckism whilst relating the importance of this new work on the genus Xenicibis. The lack of native predators, (excepting the presence of one or two birds of prey), leads me to suspect that the wings evolved for intraspecific combats, perhaps over nesting sites. After all, a number of extant Ibis are extremely territorial.

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  2. The authors mention also snakes as potential predators - however they also prefer the intraspecific concurrence in the end, seem´s more plausible also to me - if the natural selection by predators would be so great why reduce fligth capability in first term

    There is an excellent review of the study and evolution of birds by B. Switek:
    http://www.wired.com/wiredscience/2011/01/the-fightin-ibis-xenicibis-and-evolutions-arrow/

    David

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