I’ve been tracing some early uses of the term “missing link”. Paleontologists really hate this term today. It conjures the pre-evolutionary idea of a “Great Chain of Being”, and fails to recognize that the evolutionary process generates a tree of species from common ancestors, not a succession of species one after another.
But paleontologists in the old days used the term “missing link” quite often. They used it in the straightforward sense of an evolutionary intermediate that was not yet known from the fossil record. Google’s Ngram Viewer shows the usage of the term over time, which recently has been as great as ever:
The idea of “missing link” has always been applied far beyond biology. It is an evocative metaphor that is widely useful and understood, and has long been a cliché. One hears of “the missing link in international finance” and other monstrosities. It’s also a very English-specific metaphor; the equivalent phrase in German and French never gained much historical currency. Today, biological uses of the term are rare and probably a small minority of uses, but science writers still bring it into news stories about fossil discoveries.
“Missing link” was still scientifically respectable in the 1980s as applied to other lineages of organisms, but it seemed an anachronism to apply it to fossil hominins by that time. So it looks on the surface like anthropologists were the leading wave of “missing link” rejection. I’m interested in exactly when and how anthropologists turned against it. This post doesn’t answer that question, I’m just collecting some instances.
From the beginning, “missing link” was a metaphor that cut both ways. Darwin claimed that species share common origins, and that demands that there must have once been intermediates between today’s species and their distant common ancestors. This was very easy to believe in cases where forms still exist today that are intermediates between two different species. Darwin used many such forms as arguments in favor of the general idea of evolutionary transformation. But for species like humans, there are no living forms that are apparent intermediates between us and our closest living relatives, the great apes.
During the initial years after Darwin’s Origin of Species, some of the more learned critics of Darwin used the term “missing link” in a derisive sense, noting that intermediates bridging the apparent gap between humans and other animals had never been found. But it was not only used by critics of Darwin, the term “missing link” was a widely-understood metaphor for something anthropologists should be seeking out; an evolutionary forerunner of humans that must have shared many characteristics of apes.
Anthropologists were an odd set of characters in 1860s London. Many of them had social relationships with naturalists and geologists like Lyell and Owen, but they considered the anatomy of humans as a distinct enterprise. For the anthropologists, the highest part of their work was understanding the features that set apart human races. Some of them had been students of phrenologists, and still believed that the shape of the skull was a window into the mind. All were committed to the idea of deep and intrinsic differences between human races, some actively believed that the races should be considered as distinct species. This group included many who believed in the separate creation of different races, an idea known as polygenism.
In 1865, Barnard Davis read a paper on the Neanderthal skull and the questions and commentary after the reading were taken down and published in the Journal of the Anthropological Society of London. The comment by C. Carter Blake uses the term “missing link” to apply to the idea that Neandertals are an evolutionary intermediate between apes and humans. I’ve cited the whole passage to put the phrase into context, as one among many theories to account for the morphology of the Neanderthal specimen (emphasis added by me).
Mr. C. Carter Blake said he felt considerable diffidence in speaking on the subject once more, since, on the 16th of February last, he laid before a meeting of the Society the evidence then possessed respecting the characteristics and probable antiquity of the Neanderthal skull. He begged to call to mind that he then stated the several theories that had been propouncled. One of those theories, advocated by Professor Huxley, was that it resembled the skulls of existing Australians. Another theory was, that the skull represented a distinct species--Professor King said, a distinct genus of mankind. In the opinion of Dr. Pruner Bey, it was merely the skull of a powerfully organised Celt, somewhat resembling the skull of a modern Irishman with low mental organisation. An anonymous writer in the Medical Times and Gazette, to whom they were indebted for a most satisfactory theory, expressed the opinion that it was the skull of an inividual [sic] who had been affected with idiocy and rickets. They had also had more theories since he had the honour to read his paper in February. Dr. Gibb, in a paper read during the last session, suggested that the thickening of the skull was compatible with the theory that the individual was an example of hypertrophic deformation. Professer Mayer of Bonn, in a recent excellent Memoir, took a very different view of the origin of the skull, and instead of ascribing to it great antiquity, conceived that the Neanderthal skull, which had been found in a cave, covered with two feet of mud, was possibly that of one of the Cossacks who came from Russia in 1814. The last thory [sic] he should notice--and certainly the most absurd one--was one which gave the Neanderthal skull still more essentially an abnormal character, for it supposed it to be that of an extinct race who formed the missing link between man and the lower animals. There were other characters in which the Neanderthal skull was supposed to differ, first of all from man in an abnormal condition; and, secondly, from healthy man : and it had been pronounced to be a wonderful pathological conformation. That evening, however, the mythological period was past; they had had the skull taken out of the domain of theory, and once more placed upon the substantial ground of plain anatomical facts, from which those who were desirous of eliciting popular notoriety had warped it. He confessed he felt some gratification at that result, as it had been his duty, in a publication printed in 1861, to protest against the supposition that the Neanderthal skull possessed any race character, on grounds which he then thought sufficient, and he now found that Dr. Davis fully corroborated his opinion.
This is a great example, showing how the idea of the “missing link” was immediately part of the scientific discussion of the Neandertals.
Robert Dunn at the end of 1866 read a paper for the Ethnological Society of London in which he considered how discoveries from prehistoric archaeology might affect the interpretation of observations from ethnography. In this, he referred to the Neanderthal discovery and to contemporary theories of the origin of human races, in both cases making reference to the idea of a missing link. The first passage is from page 315 of the contribution:
But it is not to be forgotten, or overlooked, that another, once celebrated fossil skull of a very different character, is in existence, found in a cave in the Neanderthal, near Dusseldorf, and for which, at first, not only an antiquity was claimed, equally as great as that of the Engis man, but an importance infinitely greater ; for it was looked upon, by some, as "the missing link," in the chain of continuity between the monkey and man, and for which the advocates of the ape origin of the human species had been so earnestly in search. A scrutinising inquiry, however, into its locale and the history of its discovery, and a strict and rigid anatomical examination of its structural peculiarities, have, alas ! for advocates of the ape theory of man, deprived it altogether of its prestige and importance
The Engis skull is now recognized as a Neandertal, in fact the earliest to have been unearthed, although at the time Dunn wrote this was not yet evident. So again, this is a discussion about an actual ancient fossil specimen where the key question is whether it may be an evolutionary intermediate.
On the following page, Dunn refers to the idea that the human races had separate origins from different primate species, one version of the obsolete but then-common scientific idea of human polygenesis:
Need I here remark that "the missing link" is still wanting, and that, as I opine, it never will be found. But, I ought rather to have said the missing links, for according to the ape theory of the origin of the human species, as expounded by Dr. Carl Vogt, of Geneva, and others, the different typical human races are the descendants from different ape ancestors. Now on this subject, I do most heartily join issue with what has so emphatically been said by our venerable President, however I may differ in opinion from him as to whether there may have been more creations than one ; indeed, I need scarcely here observe, that the monogenetic and the polygenetic origin of man is still, and is likely to remain, an open question among ethnologists
Today it is common to hear scientists say that the idea of a “missing link” is a misnomer, because whenever we discover a fossil intermediate between two forms, we create two new gaps on either side of it, both of which now have a “missing link”. Dunn’s formulation here is the first time I can find the same rhetorical objection – that it is not one missing link but many – but here he applies it in the service of polygenism! That is, Dunn implies that a single “missing link” cannot account for the diversity of human races, so there must in fact be several. For Dunn, this was a reason to reject the evolutionary hypothesis. He deploys the idea of the “missing link” in very much the same way that some creationists have done in recent times.
A later edition of the Journal of the Anthropological Society of London recounts a similar discussion following the reading of a paper by W. C. Dendy in 1869. Dendy’s paper presented a polygenist account of human origins, in which he argued that despite the diversity of humankind, the “chasm” between apes and humans had never been bridged over. Again, Dr. Carter Blake was involved in the discussion, and Denby’s reply to his comments included the term “missing link” in a derisive context:
Regarding the Neanderthal and other skulls (casts of which were before him), there had been very great exaggeration. We might light on crania of equal deformity in men of the present day; and with respect to palaeontological "finds", there was often much suspicion. The quarrymen of France were known to practise [sic] frauds--for instance, their own manufactures of them, langues du chat, were often offered and accepted as flint-arrow heads. Mr. Dendy then exhibited the skeleton of a rickety abortion, which he himself had delivered, and which, he believed, had it been found in strata associated with the relics of extinct mammalia, would have been readily accepted as the "missing link". But even if we found the treasure, it would not prove the Transmutation Theory. It might indicate degradation of species, as well as exaltation, the regress as well as the progress of man; favoring the notion of the Oceanic savage that the ape is a dwindled and degraded man.
That’s a horrifying scene.
Still, paleoanthropologists remain pretty rude today.
Blake, C. C. (1865) Comments on: The Neanderthal Skull: Its Formation Considered Anatomically by Barnard Davis. Journal of the Anthropological Society of London, 3: xv-xix.
Dendy, W. C. (1869) Comments on: On Anthropogenesis. Journal of the Anthropological Society of London, 7: xxix-xxxviii.
Dunn, R. (1867) Archaeology and Ethnology: Remarks on Some of the Bearings of Archaeology upon Certain Ethnological Problems and Researches. Transactions of the Ethnological Society of London, 5: 305-317