Broom, Robert

(b. Paisley, Scotland, 30 November 1866; d. Pretoria, South Africa, 6 April 1951)

paleontology.

Broom was the second son of John Broom, a designer of calicoes and Paisley shawls who, during Robert’s youth, was engaged in business in Glasgow, and of Agnes Shearer Broom. As a child he was afflicted with asthma and other respiratory troubles that obliged him to spend a year at the seaside, where he was introduced to marine biology by a retired army officer, John Leavach. His father, an enthusiastic amateur botanist, encouraged the boy’s interest in natural history, as did contact with well-known Glasgow naturalists who frequently visited at the Broom summer home near Linlithgow. Also from his father Robert acquired his facility at drawing and a liberal religious viewpoint. His mother belonged to the strict sect of the Plymouth Brethren; he retained strong religious beliefs throughout his life and sought to explain organic evolution as the result of some cosmic intelligence or plan.

Broom attended Hutcheson’s Grammar School in Glasgow and in 1883 entered the University of Glasgow, where he assisted in the chemistry laboratory. He attended lectures of Sir William Thomson (later Lord Kelvin), but was most strongly influenced by the botanist F. O. Bower and the anatomist John Cleland, who introduced him to the work of Sir Richard Owen and the embryological researches of W. K. Parker. In 1889 he received his medical degree, and in 1892 he went to Australia. The following year he married Mary Baillie in Sydney, whence she had followed him from Scotland. After a brief visit with his father in Scotland in 1896, he went to South Africa early in 1897, and thereafter made it his home.

Broom practiced medicine most of his life, frequently in remote rural communities. From 1903 until 1910 he held the professorship of zoology and geology at Victoria College (now Stellenbosch University), and from 1934 until his death he served as curator of paleontology at the Transvaal Museum in Pretoria. Throughout his life, his research was interspersed with the duties of his profession. Fossil collecting was his hobby; he also collected paintings and stamps, and played chess.

His major contributions were to the study of the origin of mammals and the structure of their skulls, to the evolutionary history and classification of Permian and Triassic reptiles, and to the discovery and interpretation of the earliest human fossils. Broom also wrote extensively on the cause and mechanism of evolution and on a variety of other topics in zoology, anthropology, medicine, chemistry, and philately.

Broom was invited to deliver the Croonian lecture of the Royal Society of London in 1913; in 1920 he was elected to fellowship in the society. Numerous honorary doctorates, honorary fellowships in distinguished academies, and medals were awarded to him in his later years; these have been listed by Watson and by Cooke.

Between his medical calls in the back country of Australia, Broom began to investigate the anatomy of the native marsupials and primitive egg-laying monotremes. Scientific opinion at the time was divided over the question of the origin of mammals. Cope, Owen, and H. G. Seeley had pointed out many similarities between the structure of mammals and the fossil anomodont and theridont reptiles of South Africa.¹ Most zoologists preferred to derive mammals directly from the amphibians, as advocated by T. H. Huxley.

One of Broom’s earliest investigations was of the development of Jacobson’s organ, a sensory structure in the nose. In monotremes this organ is supported by a pair of small bones that Broom identified with the paired prevomers near the front of the palate of reptiles. In nine papers published between 1895 and 1935 he sought to demonstrate by both embryonic relationships and features of the palate of mammal-like reptiles that the reptilian and mammalian vomers were not homologous. He relied largely upon the similarity between the anomodont reptile Dicynodon and the platypus, despite his recognition that both of these were side branches from the main line of mammalian evolution.² Aside from the vomer question, Broom’s interest in Jacobson’s organ was renewed whenever young specimens of uncommon animals reached his hands, and he reported his findings in fifteen papers published between 1895 and 1939.

In the course of studying the embryonic development of the skull in the Australian phalanger Trichosurus,³ Broom discovered that the mammalian alisphenoid bone does not form in the wall of the braincase but arises from the palate, like the slender epipterygoid bone of lizards and other reptiles (1907). Subsequently he was able to show this transition from reptilian to mammalian condition in the skulls of various mammal-like reptiles. In some ways this is the most important of Broom’s many contributions to vertebrate morphology.

One of the major problems of mammalian development was the origin of the three auditory ossicles;⁴ some students regarded them as the result of fragmentation of the single sound-transmitting bone in the ear of reptiles or amphibians; others followed Reichert (1838) and Huxley in the view that the outer two bones of the mammalian chain represent the articular and quadrate bones that form the jaw articulation of reptiles. Broom accepted the former view in 1890 and 1904, but in 1911 he reversed his opinion⁵ and in 1912 showed how the bones of anomodont reptiles conformed to Reichert’s theory. He presented a series of reconstructions suggesting the mode of transition from the reptilian to the mammalian ear condition.⁶ In 1936 Broom turned again to this question, and noted that evidence of an extracolumellar portion of the stapes in therocephalians confirmed his earlier opinion that the tympanic membrane of mammal-like reptiles lay close behind the quadrate bone, rather than embedded in the notch of the angular.

Other morphological questions that engaged Broom’s attention included the homologies of the variable number of bones at the base of the brain in mammals; the homologies of the coracoid bones of the shoulder region; the peculiarities of the epiphyses at the ends of the metacarpal and metatarsal bones; the arrangement of the reptilian tarsal bones; and the homologies of skull arches in lizards—a problem in which his conclusions based upon embryological and morphological studies were spectacularly confirmed in 1934 when Parrington described a Triassic ancestral lizard, Prolacerta, that shows an extremely early stage in the disappearance of the lower temporal arch.

But it is for the study of the fossil reptiles of the Karroo that Broom is most famous. In 1896, when he visited his father in Britain, he had an opportunity to examine Seeley’s collection of African fossils at the British Museum. Grasping their significance for the problem of the origin of mammals, he sailed for South Africa.

The nineteenth-century work on the mammal-like reptiles by Owen and Seeley was largely descriptive. It had revealed considerable variety in the fauna and had shown that some of these fossils approached the structure of mammals more closely than did other known reptiles. Broom revealed the details of the skull structure of these animals by splitting specimens with a chisel or by sawing cross sections through them. He thus placed their classification on a firm morphological basis; showed that they had been derived from the pelycosaurs of North America, which his contemporaries had classified with the lizard-like Sphenodon of New Zealand; and demonstrated how the distinctive mammalian structures had arisen within the therapsid suborders. As early as 1902 he recognized that certain carnivorous therapsids had a far more primitive palate than the extremely mammal-like cynodonts that Seeley had discovered, and he proposed the suborder Therocephalia for the earlier forms. By 1905 he had arrived at the basic groupings of the African forms, which, modified in the light of later discoveries, are still used.

Beginning in 1905, Broom attempted to record the stratigraphic occurrence of various fossils in the thick sequence of Karroo deposits. Building on the earlier work of Seeley, he established the standard sequence of faunal zones. This attention to stratigraphy as well as to morphological detail prepared him for the brilliant synthesis of the African and North American Permian faunas at which he arrived after seeing the American fossils on a brief visit to the American Museum of Natural History in 1910.

Broom described an unbelievably large number of fossils. His brief descriptions are generally accompanied by rather unfinished sketches, which are praised by some of his colleagues for their remarkable fidelity and intuition, and condemned by others for showing structures still concealed by matrix and for carrying restoration beyond available evidence.⁷

These studies of Karroo fossils, as well as the embryological investigations of mammalian development, formed the basis for numerous essays on the origin of mammals, the earliest in 1908; the Croonian lecture to the Royal Society of London in 1913; and The Origin of the Human Skeleton and The Mammal-like Reptiles of South Africa.

Following World War I, Broom practiced medicine at Douglas, remote from fossil beds and contact with other scientists. It was during this period that his attention first turned to the problems of prehistoric man in Africa and the physical characteristics of African races.⁸ His 1923 survey of the Hottentots, Bushmen, and extinct Korana race defined many of the problems of South African anthropology and laid the basis for subsequent work, which has not confirmed his views of racial relationships.⁹

When Raymond Dart announced the discovery of the Australopithecus skull at Taungs in 1925, Broom, on the basis of a personal examination of the specimen, supported Dart’s conclusions as to its human relationships and phylogenetic importance. After he had been appointed curator of paleontology in the Transvaal Museum, he turned his attention to the Pleistocene cave deposits, hoping to find additional evidence of early man. This quest was rewarded by the discovery of Plesianthropus within a week of Broom’s first visit to Sterkfontein. Other important specimens were found at Kromdraai in 1938, at Sterkfontein again in 1946–1947, and at Swartkrans in 1949. Broom has given a vivid account of the excitement of these discoveries in Finding the Missing Link (1950). He not only collected, but also prepared, illustrated, and described, this material when he was well over eighty years of age.¹⁰

Between the time Broom retired from medical practice in 1928 and his appointment at the Transvaal Museum in 1934, he wrote three books. The Origin of the Human Skeleton (1930) provides a rapid survey of vertebrate evolution, followed by discussion of the transition from reptiles to mammals, as shown by the mammal-like reptiles, and of the various problems that had held his attention for so many years. A final chapter deals with the inadequacies of the views of Lamarck and Darwin as explanations of evolution. The Mammal-like Reptiles of South Africa and the Origin of Mammals (1932) is illustrated with several hundred of Broom’s rough restorations, which he defends as more useful than exact portrayal of fragmentary specimens. The problem of evolution and its causation is explored more boldly.

In The Coming of Man. Was It Accident or Design? (1933) Broom criticizes various theories of evolution in detail. He was fully conversant with the current ideas of geneticists on the roles of mutation and natural selection in producing evolution, but like most paleontologists of the early 1930’s he found this view inadequate. Opposing Darwinism, Lamarckism, and evolution by mutation, Broom suggested there must have been intelligent spiritual agencies behind evolution. Arguing that all major evolutionary advances have come from small, generalized animals, and that all living animals are now too specialized to give rise to a completely new type of life, he concluded that further evolutionary advance is impossible. Evolution was over with the appearance of man, its latest and highest product, which must have been the goal of a directing Intelligence.

Educated at the height of the wave of evolutionary biology that followed Darwin’s work, Broom devoted his career to unraveling the phylogenetic problems that the nineteenth-century morphologists and paleontologists had raised. His unrelenting drive to investigate these problems, his complete willingness to travel to regions where critical material might be found, and especially his unusual talent for combining paleontological and embryological research enabled him to contribute more to the story of mammalian origins than all his contemporaries together. When one considers his good fortune in obtaining fossil hominids at Sterkfontein within a week of his first inquiry there, as well as at other localities, is it any wonder that he strongly believed in his own Special Providence?

NOTES

1. E. D. Cope (1870v); R. Owen (1876, 1880); H. G. Seeley (1889–1895). These and other paleontological works cited below are listed in the bibliographies of vertebrate paleontology by Camp and by Romer, or in O. P. Hay, Bibliographyand Catalogue of the Fossil Vertebrates of North America, U.S. Geological Survey Bulletin 179 (Washington, D.C., 1902).

2. Broom’s illustrations of the palate of Thrinaxodon (“The Vomer-Parasphenoid Question,” Annals of the Transvaal Museum, 18 [1935], 23–31) clearly show the closer similarity of cynodont prevomers to the mammalian vomer, which F. R. Parrington emphasized in support of the opposite interpretation in the same year. In 1940 Parrington and Westoll virtually laid Broom’s contention to rest.

3. This study was commenced in 1898 and published in 1909 (“Observations on the Development of the Marsupial Skull,” Proceedings of the Linnean Society of New South Wales, 34 192–219). It remains a principal source of knowledge of the development of diprotodont marsupials, according to G. R. DeBeer: The Development of the Vertebrate Skull (Oxford 1939), p. 305.

4. The bones in question in mammals and their homologues are the malleus = articular bone of reptilian lower jaw; the incus = quadrate bone, which forms the articulation for the jaw at the back of the skull: and the stapes = part of the single auditory ossicle of reptiles, etc.

5. “On the Structure of the Skull in Cynodont Reptiles,” Proceedings of the Zoological Society of London (1911), p. 917; full article on pp. 893–925.

6. Broom’s study was published a year before the exhaustive analysis of embryological and morphological relationships of the auditory ossicles by Ernst Gaupp, “Die Reichertsche Theorie (Hammer-, Amboss- und Kieferfrage),” Archiv für Anatomie und Entwickelungsgeschichte; anatomische Abteilung des Archives für Anatomie und Physiologie…, Supplement Band 1912.

7. Besides these studies of primitive reptiles, Broom wrote numerous articles on fossil fishes, amphibians, and dinosaurs of South Africa. While in Australia he had collected and described fossil marsupials from Pleistocene caves. In 1909 he first discussed African Pleistocene mammals, and after 1935 devoted much attention to these fossils (at least twenty-three papers). He demonstrated that the faunas associated with early fossil hominids were largely of extinct species and differed considerably from site to site.

8. This interest stemmed from the discovery of the Boskop skull by Fitzsimons in 1913.

9. L. H. Wells (1952) terms this “one of the most important landmarks in Anthropological research in South Africa.”

10. Broom and Schepers (1946); Broom and Robinson (1952); and numerous short papers in various journals.

BIBLIOGRAPHY

I. Original Works. Lists of Broom’s publications are given in R. Broom, “Bibliography of R. Broom, M.D., D.Sc., F.R.S.,” in A. L. DuToit, ed., Robert Broom commemorative volume (Capetown, 1948), pp. 243–256; C. L. Camp et al., Bibliography of Fossil Vertebrates, Geological Society of America, Special Papers, no. 27 (1940), covering 1928–1933; no. 42 (1942), covering 1934–1938; Memoirs, no. 37 (1949), covering 1939–1943; no. 57 (1953); covering 1944–1948; and no. 84 (1961), covering 1949–1953; A. S. Romer et al., Bibliography of Fossil Vertebrates Exclusive of North America 1507–1927, Geological Society of America, Memoirs, no. 87 (1962), I; and D. M. S. Watson (see below).

Broom’s major papers and books are “On the Origin of Mammals,” in Philosophical Transactions of the Royal Society of London, 206B (1914), 1–48, the Croonian lecture of 1913; The Origin of the Human Skeleton; an Introduction to Human Osteology (London, 1930); The Mammal-like Reptiles of South Africa and the Origin of Mammals (London, 1932); The Coming of Man. Was It Accident or Design? (London, 1933); The South African Fossil Ape-Men. The Australopithecinae, Transvaal Museum Memoir no. 2 (Pretoria, 1946), written with G. W. H. Schepers; Finding the Missing Link (London, 1950); and Swarklrans Ape-Man, Paranthropus crassidens, Transvaal Museum Memoir no. 6 (Pretoria, 1952), written with J. T. Robinson.

II. Secondary Literature, Biographical sketches are Raymond A. Dart, “Robert Broom—His life and work” in South African Journal of Science, 48 (1951), 3–19; Austin Roberts, “Historical Account of Dr. Robert Broom and His Labours in the Interest of Science,” in A. L. DuToit, ed., Robert Broom Commemorative Volume (Capetown, 1948), pp. 5–15, an account basic to most published obituaries—see also notes on Broom by Field Marshall J. C. Smuts, W. K. Gregory, and L. H. Wells in the same volume; and D. M. S. Watson, “Robert Broom,” in Obituary Notices of Fellows of the Royal Society, VIII (1952), 37–70.

Twelve other obituaries are listed in Camp et al. (1961). Of these, Sonia Cole, in South African Archeological Bulletin, 6 (1951), 51, portrays his personality; H. B. S. Cooke, in South African Journal of Science, 47 (1951), 277–278, and R.F. Ewer, in Natal University Journal of Science, 8 (1952), 27–29, give additional insight into his methods, attitudes toward scientific research, and religious beliefs; W. E. Le Gros Clark, in Nature, 167 (1951), 752, provides an excellent, concise evaluation and tribute; and L. H. Wells, in Royal Society of Edinburgh Yearbook, 1950–1951 (1952), pp. 9–12, evaluates his contributions to anthropology.

Joseph T. Gregory