During my studies of the history of paleontology I have often stumbled upon the work of the same scientists over and over again. The 19th century anatomists Richard Owen and Thomas Henry Huxley, especially, worked on a variety of fossil vertebrates and were critical to the establishment of paleontology as an evolutionary science, yet there are other influential researchers who have not retained the same level of notoriety. The Scottish paleontologist Robert Broom, an immigrant to South Africa who belonged to the generation of scientists after Owen and Huxley, was among these lesser-known figures.
What Broom is best known for will depend on who you ask. A paleoanthropologist will tell you that Broom was one of the few scientists who believed that Raymond Dart's 1925 discovery of Australopithecus africanus was important to understanding human origins. While Dart put his paleoanthropological research on hold after the discovery, Broom scoured the fossil deposits of South Africa to find mind fossil "ape-men." A dinosaur specialist, however, might tell that Broom's description of the archosaur Euparkeria appeared to throw support to the idea that both birds and dinosaurs had evolved from a group of bipedal, crocodile-like creatures that were called "thecodonts" at that time. (Though we now know that birds are only modified dinosaurs.) This work was related to Broom's description of the Permian synapsids/stem mammals of the Karoo desert, and his efforts to establish the evolutionary proximity of these fossils to mammals were especially important.
Yet Broom should not be viewed only in the light of the number of fossils he found or genera he described. Broom had his own unique view of how evolution worked, and he shared these views most prominently in multiple works towards the end of his life. Succinctly put, in his last works Broom stated that evolution had halted for every species except humans, and he believed that evolution in the past had been driven by supernatural factors.
Like Richard Owen, Broom rejected both natural selection and Lamarckism as potential factors for evolutionary change. Instead he believed that the evolution of life occurred through a sequence fore-ordained by a Creator, and that once humans had evolved the transmutation of other species was halted for our benefit. Only our species could keep reaching up the evolutionary ladder set before us. While Broom couched this belief in the scientific-sounding claim that all living animal species were too-specialized to evolve any further, his peers could not accept his view of evolution as supernaturally-guided.
(This rejection is interesting given the popularity of the idea among paleontologists during Broom's time that evolution might be driven by internal factors and even directed towards certain endpoints. Perhaps such ideas were not as offensive to researchers because they could be squared with theology without actually allowing a place for theology within scientific discourse.)
As historian Marc Swetlitz has pointed out, however, Broom's books on this subject, like The Coming of Man: Was it Accident or Design?, had a significant influence on Julian Huxley. Huxley, grandson of T.H. Huxley and a popularizer of the "Modern Synthesis" of evolution that coalesced in the mid-20th century, had long espoused a belief in human progressive development. Huxley was tired of seeing humans go to war over competing economic and social ideals. If we took our cues from evolution, a natural phenomenon which had clearly made our species superior, then we could form a more peaceful and productive society.
This "progressive" view of life made Broom's work instantly appeal to Huxley. Huxley could not accept some of Broom's religious conclusions, but he used Broom's work to support the idea that evolution had come to a halt in every species except our own. Broom's work provided the scientific basis for what Huxley wanted to believe.
Ultimately, though, this aspect of Broom's work only seems to be remembered by historians of science and modern creationists who wish to capitalize on Broom's teleological vision of life's history. Not only did Broom work during a time that is often overlooked by science popularizers (the public could be forgiven for thinking that paleontology/evolutionary science lay dormant between 1870 and the late 20th century), but he proposed a spiritually-infused version of evolution that was generally rejected by this colleagues. Like many scientists of decades past, Broom continues to be cited but his work is rarely fully understood.
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The still-in South Africa "mammal-like-reptiles" you mention in an earlier post are, along with the hominid fossils (for those in the Transvaal Museum), kept in what we affectionately call the "Broom Closet."
Hey Brian,
Any chance you'll be posting about Anchiornis huxleyi, the new feathered dinosaur fossil?
Hey Dave; All my dinosaur posts go up over at Dinosaur Tracking. I posted something about Anchiornis this morning. - http://tinyurl.com/y95vmyr
Keep watching Dinosaur Tracking for my posts on new discoveries and general dino-blogging.
"We" do not "now know that birds are only modified dinosaurs." An arboreal member of the Euparkeria-class of archosaurs remains a likely ancestor of Aves. Paleontologists have no response to biologists and ornithologists who point out the chronological and developmental impossibility of their cherished unicorn.
They're left to shout them down as heretics and point to the (convergent) similarity between some Aves and some very late Theropoda who appeared 100 million years after birds achieved powered flight. The "Downy Dino" flapping feathered winglets at dragonflies on the covers of today's popular science magazines will (hopefully, soon) join its evolutionary predecessors, Piltdown Man and Perry at the North Pole.
Hi Brian,
I read somewhere that Broom's other finds included Sts 5, a superb fossil skull, and Sts 14, a partial skeleton which consisted of much of a pelvis, femur, and vertebral column and proved convincingly that australopithecines had walked upright. Did Robert Broom also prove that australopithecines walked upright?
Thanks
Marc; If you are that convinced of your own position there is practically no point in arguing with you. If birds evolved from an Euparkeria-like ancestor all I can say is "Show me the fossils!", something paleotologists have been asking folks like Feduccia and Martin to do for years. To deny that birds are dinosaurs in light of all the evidence that has been discovered, and instead prefer some hypothetical sequence that is not backed up by any fossil evidence, makes no sense to me at all. Feduccia and like-minded colleagues have failed to propose a clear alternative hypothesis based on solid evidence.
Letitia; Yes, Broom did discover Sts 5 and 14. Raymond Dart initially proposed bipedalism for A. africanus, and while I am more familiar with Broom's work on bipedalism, I do know that the conclusions of W.E. le Gros Clark were extremely important to getting australopithecines accepted as human ancestors (and le Gros Clark spends considerable time talking about traits linked to bipedalism in his descriptions of the SA fossils).
This may not really have much to do with the main post, but has more to do with the comments about feathered fossils. A friend and I were sifting through science books in Borders and I opened up one of the tomes of dinosaur encyclopedia. A very large amount of them were portrayed as feathered (or at least the ones I, by chance, flipped to). Growing up, all of my dinosaur books had no feathered dinosaurs (except the Archaeopteryx). My friend presumed that all the feathers were more of an artist's representation, rather than fact. We were mainly discussing Utahraptor, and I couldn't find in the book, but have seen Velociraptor portrayed with feathers as well.
I'm curious as to why Dromaeosauridae are depicted often with feathers--either speculation or fossil evidence. (And apologies if you wrote this somewhere else!)
Fossil evidence. See for instance:
http://scienceblogs.com/notrocketscience/2009/09/evidence_that_velocira…
and:
http://scienceblogs.com/tetrapodzoology/2008/10/epidexipteryx_at_last.p…
and:
http://scienceblogs.com/tetrapodzoology/2007/03/feathers_and_filaments_…
LK; I am headed out the door so a more detailed response will have to wait, but feathers on dromaeosaurs and other coelurosaurs are not just speculation. That might have bee true when Gregory S. Paul put feathers on theropods in his Predatory Dinosaurs of the World, but not anymore. So far all the dinosaurs found with feather impressions have been coelurosaurs, the group to which dromaeosaurs belong. In fact, most of the lineages within that group appear to have had some feathered genera, including tyrannosauroids. At this point it looks like feathers may even be a common feature for the group and depicting coelurosaurs with feathers is not more controversial than showing hominins with hair (depicting dromaeosaurs as "naked" is just as much a hypothesis as showing them with feathers).
In the case of Velociraptor specifically, though, paleontologists have found quill knobs on their forearms that would have supported feathers like those seen on the wings of birds like turkey vultures. Even though no Velociraptor with feathers has yet been found, we now how osteological evidence that it had feathers!
I have read quite a bit about Broom, but never knew he embraced anthrocentrism and supernaturalism. While this doesn't take away from his contributions to science, it's still kind of a bummer to find these things out.
@Laelaps; Thank you very much! This clears things up for me and my friend. I figured that rather than give him an answer, I should ask someone much more knowledgeable in the field. We both grew up watching Jurassic Park as kids, so our immediate image of a Velociraptor was, of course, 6' tall and featherless.
They're left to shout them down as heretics and point to the (convergent) similarity between some Aves and some very late Theropoda who appeared 100 million years after birds achieved powered flight.
Ironic that this should be posted in the middle of a conversation about Anchiornis, of all things.
"An arboreal member of the Euparkeria-class of archosaurs remains a likely ancestor of Aves"
For me this is the most puzzling thing about the "birds are not dinosaurs" faction. If this is their alternate theory, then birds and dinosaurs share a common ancestor very close to the origin of dinosauria as a distinct clade, and birds and dinosaurs are still the most closely related of all archosaur groups. That hardly seems that substantially different from the majority view - not much different from proposing that humans are more closely related to gorillas than chimpanzees. I do not understand the vitriol involved. It's like trying to start an intellectual war over the pronunciation of "tomato".
That said, in the absence of any fossil evidence, how does one justify the use of terms like "likely", or for that matter "arboreal"?
Do you have the chronology of Broom's life at hand? I think he went to Australia before he went to South Africa, and described Burramys parvus from a subfossil specimen: it's one of the famous examples of an extant species first described from fossil remains. And has dentition reminiscent enough of that of many Multituberculates that its dietary habits are described in the great 1979 survey "Mesozoic Mammals - the first two thirds of mammalian history" as a possible guide to the habits of Multis.
this was not really any help i need to know his middle name not facts on him