HARVARD NATURALIST DESTROYS THEORY OF MULTIPLICITY OF THE GORILLA SPECIES

The gorilla has but one species of two subspecies and not 15 or more, as scientists previously believed, declares H. J. Coolidge, Jr. '27, assistant curator of mammals at the Museum of Comparative Zoology, after the first exhaustive study ever made of most of the material now available on the subject throughout the world. His findings are set forth in a monograph just published by the Museum of Comparative Zoology under the title "A Revision of the Genus Gorilla."

As leader of the Indo-China division of the Kelley-Roosevelts-Field Museum Expedition which returned from Indo-China in the fall of this year, Mr. Coolidge came into prominence in the press of this country. As a member of the Harvard African Expedition led by Dr. Strong in 1927, he was enabled to study the gorilla at first hand, in the mountains of the Eastern Belgian Congo. Since that time, through study in the museums of several countries, he has had access to the major part of the material available throughout the world upon the subject.

Differentiates Subspecies

Mr. Coolidge's monograph is remarkable, not only because he reduces the genus Gorilla to one species, but because he has differentiated two specific subspecies, the "mountain" and the "coast" gorillas. To his study he appends a map which limits the area within which gorillas are to be found in Africa to not more than 40,000 square miles but of 11,500,000 square miles in the entire continent, or 3-10 of one per cent of the entire area. It is a feature of the work which is bound to interest laymen, because it shows for the first time how narrow are the areas within which all the gorillas in the world, outside of zoos, are confined. The map also raises a problem for scientists in the difficulty of explaining why the gorilla should not be found elsewhere, and also why a forest belt 750 miles wide should separate the homes of the two known subspecies.

The method of discovery of the gorilla goes far to explain the erroneous notions as to variety of species which have grown up throughout the world, and explains too why science has waited for such an exhaustive study as this one by Mr. Coolidge to reduce the classification to one single species of two subspecies. The first specimen in any museum in the world was that in the Boston Society of Natural History and now in the Agassiz Museum. It was discovered by Savage, a missionary in the Gaboon, and sent in 1847 to Dr. Geoffries Wyman, then Professor in the Harvard Medical School.

This specimen was the basis for the first scientific description of the genus gorilla on record. Dr. Wyman delivered a speech describing the gorilla to the Boston Society of Natural History. As time went on, and other specimens were discovered, they were sent back to museums on the continent of Europe and to England, as well as to the United States.

Species Named for Discoverers

Naturalists, reading the descriptions of specimens which followed that found by Savage, compared these descriptions with their specimens and found great variations. New "species" were named after their discoverers, and competition between museum and museum grew up to secure "firsts" of new species.

In order that the claims of these specimens to special classification might be shown to be in error, an exhaustive study had to be made of virtually all the available material about gorillas extant throughout the world. It is such a study which Mr. Coolidge has just completed, and it is upon such a study that his findings rest.

His study is intended as a means of clarifying and bringing together the hitherto scattered findings of a host of the world's most outstanding investigators such as Richard Owen, Geoffroy St. Hilaire. Ales Hrdlicka. R. Selenka, Paul Matschie, L. Bolk, Lord Rothschild. Sir Arthur Keith, and D. G. Elliot.

He lists fifteen forms of gorillas currently recognized in nomenclature and takes them up in their chronological order. Many of these he finds to be isolated examples not substantiated by sufficient evidence, based, in some instances, on not more than one speci- men. These he lists as extreme variants of a type. Some of these genera are differentiated by such characteristics as length of hair and length of beard which do not seem to him fundamental because specimens from the same limited regions present such wide variation in these respects.

He describes the general external characteristics in the adult male which distinguish the Mountain from the Coast Gorilla as, "a longer palate and often a narrower skull, a thicker pelage or belt, shorter arms and longer legs, large amount of black hair, and prominent fleshy callosity on the chest."

The Coast skulls he has studied are grouped as West Cameroons, Cameroons and Gaboon. The eastern Congo or Mountain skulls are grouped as Kiva and Eastern Mountain gorillas.

Mr. Coolidge employs four means of studying the skulls: the voluminous literature on the subject, x-ray pictures, scale photographs, and comparative measurements. He devotes the major part of his study to the skull, as is the custom in scientific research. He studied over 400 of them besides examining many hides and skeletons which also show great variation and are of accessory value in classification.

He has made a comprehensive study of most of the available works on the gorilla, with special emphasis on habits in the field that might affect the growth of its skull, also a study of the writings on the gorilla's brain and skull by such anatomists as Anthony, Bolk, Duckworth, Elliot Smith, Selenka, Keith, and Harris, often supplemented by discussion with these men.

He has personally taken a set of thirty measurements of each of 400 skulls, reduced them to percent-ages, grouped them by locality and plotted the curves of variation. He made these computations without any preconceived theory as to what he might find and studied the curves of variation which resulted. On these he discovered that certain measurements showed sufficiently great differences between regions to warrant calling them different subspecies. Study of the curves forced him to divide the species into Gorilla gorilla gorilla (Savage & Wyman) or Coast, and Gorilla gorilla beringei (Matschie) or Mountain. It happens that the first of these races is the one found on the West Coast of Central Africa and the second race is found in the mountains of the Eastern Congo separated from the first by 750 miles of tropical jungle.

New System of Photography

He has introduced in zoology a system of photographing skulls against a scale background, a method previously employed by anthropologists. He has a series of over four hundred scale pictures, taken with the assistance of the following museums: Berlin Museum, Hamburg Museum, Oslo Museum, Anatomy Museum at Amsterdam, Congo Museum at Tervueren. Lord Bothschild's museum at Tring, Major PowellCotton's Museum, Dr. Duckworth's collection, and the Museum of Comparative Zoology.

His conclusion is that "the gorilla, particularly the adult male, shows a large individual variation even within the limits of a small area; that there is no difference in kind between the Coast and the Mountain Gorillas such as to justify making of them two separate species, but that there is a distinct difference in degree sufficiently important to constitute a subspecific difference between the two groups.