THE ANATOMICAL RECORD (NEW ANAT.) 113 FEATURE ARTICLE Morphology, Paleoanthropology, and Neanderthals 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 evolu- tion 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 jhs1@ 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.