Morphology, Paleoanthropology, and Neanderthals

THE ANATOMICAL RECORD (NEW ANAT.) 113

FEATURE ARTICLE

IAN TATTERSALL AND JEFFREY H. SCHWARTZ

Morphology carries the primary signal of events in the evolutionary history of any group of organisms but has been relatively neglected by paleoanthropologists, those who study the history of the human species. Partly this is the result of historical influences, but it is also due to a rather fundamentalist adherence among paleoanthropologists to the tenets of the Neodarwinian Evolutionary Synthesis. The result has been a general paleoanthropological desire to project the species Homo sapiens back into the past as far and in as linear a manner as possible. However, it is clear that the human fossil record, like that of most other taxa, reveals a consistent pattern of systematic diversity—a diversity totally unreflected in the conventional minimalist interpretation of that record. Thus, the Neanderthals, both morphologically and behaviorally as distinctive a group of hominids as ever existed, are conventionally classified simply as a subspecies of our own species Homo sapiens—a classification that robs these extinct relatives of their evolutionary individuality. Only when we recognize the Neanderthals as a historically distinctive evolutionary entity, demanding understanding in its own terms, will we be able to do them proper justice. And we will only be able to do this by restoring morphology to its proper place of primacy in human evolutionary studies. Anat. Rec. (New Anat.) 253:113–117, 1998. ௠ 1998 Wiley-Liss, Inc. KEY WORDS: human evolution; morphology; systematics; species; Neanderthals

Morphology is the very keystone of adventitious influences, and the tem- virtually all fossil humans of the last 2 studies of the fossil record, for, in poral ranges of fossil taxa are invari- million years as members of Homo dramatic contrast to both time and ably incompletely known; but, at some sapiens irrespective of what they actu- geography, the other basic attributes level of resolution, morphology invari- ally look like and who seek the roots of of the ancient teeth and bones that ably carries the signal of phylogenetic today’s major modern geographic make up this record, it is morphology relationship. Yet it takes no more than groups of humans very deep in time.3 alone that bears the clear imprint of a glance at the history and current Any such interpretation of the remark- evolutionary history.1 Spatial distribu- practice of paleoanthropology to indi- ably diverse human fossil record tion is affected by a wide variety of cate that morphology has never occu- known today involves giving primacy pied the central place it merits in the of place to considerations of time and science of human origins.2 geography and relegating morphology This deficit is due at least in part to to a minor role at best. Dr. Tattersall is a curator in the Depart- ment of Anthropology at the American historical accident. Unlike other fields Another factor contributing to this Museum of Natural History, New York of vertebrate paleontology, which origi- unusual situation is the reluctance of City. He is especially interested in the nated in the study of comparative paleoanthropologists at large to move integration of evolutionary theory with the fossil record and has worked most anatomy and whose practitioners are beyond a relatively fundamentalist ad- extensively on the lemurs of Madagas- necessarily interested in the origins of herence to the tenets of the ‘‘Syn- car and the human fossil record. His latest book is Becoming Human: Evolu- diversity in groups of organisms, hu- thesis’’ that came to dominate evolution and Human Uniqueness (Harcourt man paleontology was founded by stu- tionary biology during the 1950s. Brace, 1998). His fax number is 212– dents of human anatomy. The work of According to the Synthesis, virtually 769–5334; his e-mail address is iant@ amnh.org. Dr. Schwartz is Professor of these scientists and their intellectual all evolutionary phenomena can be Anthropology at the University of Pitts- descendants has combined an exquis- reduced to the shifting of gene frequen- burgh and Research Associate at the American Museum of Natural History. ite sensitivity to within-species varia- cies in populations over vast periods His major research interest is in devel- tion with a desire to project the single of time under the action of natural opmental processes and the systemat- species Homo sapiens as far back into selection (differential reproductive ics of fossil and living primates. He is 4 5 the author of the forthcoming The New the past as the record permits—and success). Since the early l970s it has, Evolution: Fossils, Genes and the Ori- preferably in the most linear manner however, been evident that the mecha- gin of Species. His fax number is 412– possible. Today this tradition is most nisms of evolution are much more 648–7535; his e-mail address is jhsϩ@ pitt.edu energetically upheld by those students complex and varied than this gradual- of the human fossil record who regard ist model admits and that the mecha-

௠ 1998 Wiley-Liss, Inc. 114 THE ANATOMICAL RECORD (NEW ANAT.) FEATURE ARTICLE nisms of adaptive change and lineage or that it never be found outside that recognize that in some cases real bio- splitting may in fact be quite distinct.6 species before it can be regarded as a logical species (those distinguished by Such considerations strongly suggest characteristic of the particular species only minor morphological disparities) that we should abandon strictly linear in question. Yet this is to misunder- will escape recognition under this ap- models of human evolution and look stand the very nature of variation it- proach, but erring thus on the side of instead for evidence of species diver- self. Every species is a close relative of caution ensures that, while the actual sity in the human fossil record. And another, living or extinct, because the phylogenetic picture will be simpli- this endeavor dictates in turn that process of speciation involves the es- fied, it will not be materially distorted. paleoanthropologists begin to afford tablishment of reproductive isolation In the rest of this article we apply this morphology the attention it deserves. between a parent and a daughter popu- criterion to the Neanderthals, next to lation that formerly belonged to the Homo sapiens incomparably the best same species. And examination of very known of all hominids. SPECIATION AND closely related species among living MORPHOLOGICAL CHANGE mammals confirms that they rarely if ever differ hugely in the characters of In some ways giving morphology the THE NEANDERTHALS the bones and teeth that are all we attention it deserves is more easily The first to be discovered of all extinct normally have to go on in fossils.8 In said than done. Comparative surveys hominid groups, the Neanderthals most characters, indeed, ranges of of the extant fauna show clearly that emerged as a distinct morphological variation in parent/daughter or sister speciation, the process whereby a new entity at some point over about 200 species will usually show much or species buds off from an old one to thousand years (kyr) ago and became even total overlap. Demonstration of create a new lineage, is not simply an widespread over Europe and western such overlap in this or that character inevitable result of the accumulation, Asia (from the Atlantic to Uzbekistan or even a set of characters is thus adaptive or otherwise, of morphologi- and from north Wales to the Levant) cal novelty.7 Instead, as we’ve sug- before their extinction after 30 kyr gested above, the processes lying be- ago, presumably as a result of the hind morphological change and We should always be incursion of modern humans into their speciation are quite different. And the home territory.10 The Neanderthals had corollary of this is that there is no careful not to confuse brains as large as our own, which specifiable degree of morphological intraspecies variation in seems to be the primary factor influ- difference with which speciation is encing most paleoanthropologists of necessarily associated.7 For system- the morphological this half-century to include them in atists (those whose business it is to characters we are our own species, despite the fact that catalog and classify diversity in the most mammalian genera contain mul- living world) who work with living looking at with tiple species with brains of essentially creatures, this often is not a practical interspecies variation. the same size. Those brains were, how- problem, for species are generally re- ever, housed in crania of distinctly garded as the largest reproductive different shape from ours (Figs. 1, 2). units, so that reproductive behaviors Traditional lists of cranial differences and other properties can be invoked in meaningless as an indicator of species of Homo neanderthalensis from Homo determining species status. For paleon- identity. Similarly, even though nor- sapiens generally include the follow- tologists, however, the problem is mal within-population variation will ing: the hafting of the face in front of acute, for morphology is the sole key include the nonexpression of certain (rather than below) a long, low vault to knowing whether two fossils that characters (e.g., the anterior mastoid with relatively thick bone; the face differ only slightly belong to the same tubercle in some Neanderthals9), it itself large and protruding, with a very or different species. entails a large loss of information to large nasal aperture and fossa (cavity) We thus have to be careful how we exclude such characters from consider- and curiously receding zygomatics proceed. And we should always be ation entirely. And, given the close (cheek bones); a distinct double-arched careful not to confuse intraspecies genetic similarity of sister species, it and smoothly rolled supraorbital to- variation in the morphological charac- would hardly be surprising that occa- rus (forehead ridge), continuous across ters we are looking at with interspe- sionally a morphological variant typi- the glabella (the surface just above the cies variation. But, by being exces- cal of one should exceptionally turn bridge of the nose); frontal sinuses sively attentive to the former, up in another. with marked lateral expansion; unde- paleoanthropologists have clearly been What, then, is the paleontologist to veloped chin; thick, horizontal occipi- able to paint far too simplistic a pic- do? Our own preference is to take tal torus; pitted suprainiac depression, ture of human evolution, minimizing what appears to us to be a rather with raised margins, in the midline the number of species recognized and conservative stance and to recognize above the torus; occipitomastoid pro- conferring a spurious appearance of the existence of separate species when cess at least as salient as mastoid linearity upon the process. For ex- distinct morphs (i.e., recognizable mor- process; vaginal and mastoid pro- ample, it is routinely demanded that a phological entities distinguished by cesses not in contact; anterior mastoid particular anatomical condition be reasonably consistent sets of charac- tubercle present; chin lacking or poorly present in every specimen of a species ters) are present in a fossil sample. We expressed; retromolar space present; FEATURE ARTICLE THE ANATOMICAL RECORD (NEW ANAT.) 115

first entered Europe about 40 kyr ago. Significantly, adherence to either sce- nario renders detailed considerations of anatomy effectively superfluous. It may be this that accounts for what we may reasonably consider the overreaction to the first of our discov- eries relating to Neanderthal morphology. It has long been acknowledged that Neanderthal crania are distinguished by large nasal apertures and capacious nasal fossae, and indeed these features have long figured in speculations that these extinct humans were somehow ‘‘cold-adapted.’’14 Yet, as far as we could determine, it had never been remarked that just within the Neanderthal nasal aperture reside some very unusual structures indeed—structures that are particu- larly evident in the Gibraltar skull (discovered before l848), which hap- pened to be the first Neanderthal fossil Fig. 1. Anterior view of two hominid skulls. A. Cranium of Homo neanderthalensis from the site of Gibraltar. Distinctively Neanderthal are the projecting snout and puffy lower face, the smoothly rolled brow that is continuous above the nasal region, the upwardly angled and posteriorly receding zygomatic arches, and the prominent medial projections within the large All in all, we have in the nasal aperture. The specimen is in the Natural History Museum, London. Photograph ௠ Jeffrey H. Schwartz. B. Cranium of recent Homo sapiens (San, Africa). Compared to a typical Neander- Neanderthals a morph thal, a modern human is itself distinguished by having a bipartite brow, which has a more bulging medial portion (minimally expressed in this specimen) and plate-like lateral extremities. that is undeniably Homo sapiens is primitive cranially, however, in the general configuration of the lower face, the zygomatic arches, nasal aperture, and conchae within the nasal cavity. This specimen is in the distinct from that American Museum of Natural History, New York. Photograph ௠ Jeffrey H. Schwartz. represented by Homo sapiens. etc. Above all, though, the general separate evolutionary history for a con- proportions of the skull and the rela- siderable period of time.11 we examined (Fig. 3). In this indi- tionship of its major areas to each When, a few years ago, we began vidual there is a secondary internal other are quite distinct; and the Nean- our study of the Neanderthal and re- margin to the bottom of the nasal derthal postcranial skeleton boasts at lated fossil records, we naturally asked aperture (itself occasionally present in least as many differences from us ourselves what we could possibly dis- (Homo sapiens) as may be found in the cover in these extinct hominids that modern humans) that expands superi- skull. All in all, we have in the Neander- had not been noticed in the almost orly (and uniquely) into a pronounced thals a morph that is undeniably dis- century-and-a-half since the descrip- medial projection which partly oc- tinct from that represented by Homo tion of the first Neanderthal fossil. We cludes the entrance to the nasal fossa. sapiens (as evidenced by the fact that it rapidly discovered that a great deal of Behind this medial projection, the lat- has been felt necessary to give them an Neanderthal morphology had been ne- eral wall of the fossa expands mark- informal name). At the very least, then, glected by paleoanthropologists, pre- edly medially, yet further constricting we have here a fully individuated homi- sumably because their adherence to a the airway. There is no conchal crest nid that requires to be recognized as gradualist view of human evolution marking the anterior articulation of its own species. Indeed, in the context had made morphology secondary to the inferior nasal concha, as is found of all human fossils known from Eu- considerations of time. Paleoanthropo- in Homo sapiens and in other species rope over the past half-million years logical opinion was (and to a dismay- of Homo. In general, this conforma- or so, the evidence has long been ingly large extent still is) effectively tion suggests a turbinate system to- available to show Homo neanderthalen- divided between those who consid- tally unlike not only those of other sis to have been simply the best- ered the Neanderthals to be the direct hominids and other primates but also known component of a larger endemic precursors of modern Europeans12 and of all other mammals (if any reader European/western Asian clade (group those who considered them to be no knows of any parallels, we would be of related species) that shares a com- more than an unusual subspecies of most interested to hear of them). The mon ancestry with our own African- Homo sapiens13 that was genetically internal nasal region is commonly derived clade but that has had a swamped by the modern humans who damaged in fossils, but we have subse- 116 THE ANATOMICAL RECORD (NEW ANAT.) FEATURE ARTICLE

Fig. 2. Lateral view of an early modern human cranium (left) (Cro-Magnon, France) compared with that of a Neanderthal (right) (La Ferrassie 1, France). Scale bars ϭ 1 cm. Drawings by Don McGranaghan.

quently observed this unusual nasal level made morphology superfluous to themes, and we should recognize them morphology in all Neanderthal fossils their enterprise. It is not altogether as such. we have seen in which this region is unrealistic to conclude that today Interestingly, the remarkable se- preserved—although naturally there is many believe that the Neanderthals quencing of 378 kb of mtDNA from some variation in the degree to which are unusual Homo sapiens at least in the hypervariable region I of the origi- the medial projection is expressed. part because in the preevolutionary nal Neanderthal (Feldhofer) fossil An independent study has confirmed days of 1856 Hermann Schaaffhau- (probably between 50 and 100 kyr old) this peculiar conformation of the na- sen, the describer of the original Nean- has shown this individual to be a very 15 sal fossa in Neanderthals, but, rather derthal fossil, had no option to think distant outlier when compared to all 18 than welcoming this additional infor- otherwise; and it is also fair to observe modern human populations. Fur- mation about our closest well-known that many paleoanthropologists pro- ther, the researchers involved esti- relatives, the paleoanthropological ceed as if phylogenetic analysis were mated that the Neanderthal and Homo community, in a perhaps predictable mainly an exercise in joining up points sapiens lineages diverged as long ago reaction, has rejected it out of hand. on a stratigraphic chart. as around 600 kyr—an estimate also Ironically, though, while one school On the systematic level, this insular- quite reasonable on morphological has sought to invalidate our data by grounds.19 In an age of technophilia, ity is thrown into dramatic relief by showing that medial projections do one might have expected that this com- the energy expended in (so far unsuc- not exist in Neanderthals (R. Francis- pelling evidence should force rethink- cessful) attempts to find one or two cus, personal communication), an- ing about the status of the Neander- examples of Neanderthal-like medial other has attempted to achieve the thals as a distinct species. Alas, no. projections among the many thou- same end by showing that this mor- Supporters of linear models of human sands of modern human crania repre- phology is actually present in Homo evolution were as quick to reject this sented in museum collections.16 sapiens!16 In the event, neither demon- The new category of information as reflex- stration is possible, for the morphol- fundamental point here is not that it ively as they had rejected morphology speaks for itself, and these denials might potentially be possible to find ogy.20 The argument thus continues, are based on misidentification of the an example of a Neanderthal morphol- as listlessly as before. morphologies observed by the authors ogy in a modern Homo sapiens (as has Yet in our view it is crucially impor- concerned. indeed been inaccurately claimed in tant not to write off the Neanderthals While we welcome the opportunity the case of the skull rears of some very as bizarre or inferior versions of Homo to point this out, it seems to us that the early modern Europeans, e.g. sapiens. The Neanderthals are a major larger issue is the more important one: Mladec17). If so, so what? The point is presence in the human fossil record attention to the details of comparative that both Homo neanderthalensis and not because they are the source from morphology (and the development of Homo sapiens are variable and that, which Homo sapiens sprang, for cer- the characters compared) has been crucially, they vary around very differ- tainly they are not, but because they sorely neglected in paleoanthropology ent means, even were a point or two of are incomparably better known ar- simply because the historical biases overlap to be identified. In short, chaeologically than any other extinct and evolutionary paradigms favored moderns and Neanderthals are varia- hominid species. In this sense, they by paleoanthropologists have at some tions on two distinctly different are the best yardstick we have by FEATURE ARTICLE THE ANATOMICAL RECORD (NEW ANAT.) 117

Human Evolution. New York: Oxford Univer- sity Press. 3 Wolpoff MH, Thorne AG, Jelinek J, Zhang Y (1993) The case for sinking Homo erec- tus: 100 years of Pithecanthropus is enough! Cour Forschungsinst Senckenb 171:341– 361. 4 Mayr E (1963) Animal Species and Evolu- tion. Cambridge, MA: Belknap. 5 Eldredge N, Gould SJ (1972) Punctuated equilibria: An alternative to phyletic gradu- alism. In Schopf TJM (ed): Models in Paleo- biology. San Francisco: Freeman Cooper, pp 82–115. 6 Tattersall I (1998) Becoming Human. New York: Harcourt Brace. 7 Tattersall I (1986) Species recognition in human paleontology. J Hum Evol 15:165– 175. 8 Tattersall I (1992) Species concepts and species identiﬁcation in human evolution. J Hum Evol 22:341–349. 9 Schwartz JH, Tattersall I (1996) Toward distinguishing Homo neanderthalensis from Homo sapiens and vice versa. Anthropologie (Brno) 34:79–88. 10 Tattersall I (1995) The Last Neanderthal. The Rise, Success and Mysterious Extinc- tion of Our Closest Human Relatives. New York: Macmillan. 11 Schwartz JH, Tattersall I (1996) Signiﬁ- cance of some previously unrecognized apo- morphies in the nasal region of Homo neanderthalensis. Proc Natl Acad SciUSA 93:10852–10854. 12 Wolpoff MH (1980) Paleoanthropology. New York: Knopf. 13 Stringer CB, Hublin JJ, Vandermeersch B (1984) The origin of anatomically modern humans in western Europe. In Smith FH, Spencer F (eds): The Origins of Modem Humans: A World Survey of the Fossil Evi- dence. New York: Liss, pp 51–136. Fig. 3. View of the right wall of the nasal fossa in the Gibraltar Neanderthal cranium showing 14 Coon CS (1962) The Origin of Races. the internal margin that enlarges above into the medial projection (mp). Behind this is seen New York: Knopf. evidence of the posterior swelling (ps), partly obscured in this view by matrix. The arrow 15 Marquez S, Gannon PJ, Reidenberg JS, indicates the hole in the wall of the swelling that reveals the enlarged maxillary sinus. Photo Laitman JT (1998) Breathing the air in the ௠ Jeffrey H. Schwartz. later Pleistocene: Examination of nasal complex morphology in the Broken Hill and Gibraltar 1 crania. Am J Phys Anthro- which to measure our own unique- terms. And if we are to achieve such pol 26(Suppl):155. ness, for the archaeological record of justice as well as a reasonable perspec- 16 Murphy MS, Monge J, Mann A (1998) the Neanderthals shows that they were tive on diversity in the human fossil Unique Neandertal noses: Variation in the internal morphology of the nose. Am J Phys creatures of another order from us record, we have to restore morphology Anthropol 26(Suppl):168. who dealt with the world in a very to its rightful place of primacy in the 17 Wolpoff MH (1996) Human Evolution. different way.6 It is wrong to feel that analysis of that record. New York: McGraw-Hill. excluding the Neanderthals from 18 Krings M, Stone A, Schmitz RW, Homo sapiens is reprehensible dis- LITERATURE CITED Krainitzki H, Stoneking M, Pabo S (1997) crimination, for in reality quite the Neandertal DNA sequences and the origin reverse is true. We can do these re- 1 Eldredge N, Tattersall I (1975) Evolution- of modern humans. Cell 30:19–30. markable extinct humans justice only ary models, phylogenetic reconstruction, 19 Tattersall I (1998) Neanderthal genes: and another look at hominid phylogeny. In What do they mean? Evol Anthropol. 6(5): if we regard them as an evolutionary Szalay FS (ed): Approaches to Primate Paleo- 157–158. phenomenon in their own right, a biology. Basel: Karger, pp 218–243. 20 Kahn P, Gibbons A (1997): DNA from an phenomenon that demands under- 2 Tattersall I (1995) The Fossil Trail: How extinct human. Science 277:176–178 [quot- standing and explanation in its own We Know What We Think We Know About ing M.H. Wolpoff].