Is Human Longevity a Consequence of Cultural Change or Modern Biology? Rachel Caspari 1 * and Sang-Hee Lee 2 1 Department of Sociology, Anthropology and Social Work, Central Michigan University, Mt. Pleasant, Michigan 48859 2 Department of Anthropology, University of California at Riverside, Riverside, California 992521-0418 KEY WORDS adult survivorship; modern human origins; West Asia; Neandertals ABSTRACT Increased longevity, expressed as the number of individuals surviving to older adulthood, rep- resents a key way that Upper Paleolithic Europeans dif- fer from earlier European (Neandertal) populations. Here, we address whether longevity increased as a result of cultural/adaptive change in Upper Paleolithic Europe, or whether it was introduced to Europe as a part of mod- ern human biology. We compare the ratio of older to younger adults (OY ratio) in an early modern human sample associated with the Middle Paleolithic from Western Asia with OY ratios of European Upper Paleo- lithic moderns and penecontemporary Neandertals from the same region. We also compare these Neandertals to European Neandertals. The difference between the OY ratios of modern humans of the Middle and Upper Paleo- lithic is large and significant, but there is no significant difference between the Neandertals and early modern humans of Western Asia. Longevity for the West Asian Neandertals is significantly more common than for the European Neandertals. We conclude that the increase in adult survivorship associated with the Upper Paleolithic is not a biological attribute of modern humans, but reflects important cultural adaptations promoting the demographic and material representations of modernity. Am J Phys Anthropol 129:512–517, 2006. V V C 2005 Wiley-Liss, Inc. Increased longevity, expressed as the proportion of adults surviving to older adulthood, represents an impor- tant way that Upper Paleolithic Europeans differ from earlier European populations. In a recent study compar- ing Neandertals with their Upper Paleolithic anatomi- cally modern successors, we showed a fivefold increase in the ratio of older to younger adults (OY ratio, a cate- gorical assessment) in the Upper Paleolithic (Caspari and Lee, 2004). We suggested that the increase in lon- gevity we documented was associated with the demo- graphic and cultural changes marking that period (Tem- pleton, 2002; Shennan, 2001). However, it was unclear whether this increase in older adult survivorship is an attribute of the Upper Paleolithic itself, or whether it was already present in earlier anatomically modern humans migrating into Europe from elsewhere. In this paper, we address this question, using data that include pivotal fossil material from Western Asia and an expanded sample of European modern humans. 1 Our question is whether the increase in adult survivor- ship is a biological attribute of a modern human species, or whether nonphylogenetic causes for longevity may be more explanatory, such as culturally driven demographic change (Shennan, 2001). Here, we address this issue with three sets of comparisons. 1) We compare the OY ratio of earlier modern humans associated with the Middle Paleo- lithic of Western Asia with the OY ratio of Upper Paleo- lithic Europeans to look for evidence of similarity. 2) We compare the earlier modern humans associated with the Middle Paleolithic of Western Asia with contemporary Middle Paleolithic Western Asian Neandertals to further assess the relative contributions of phylogeny and culture to adult survivorship. 3) We compare Neandertals of West- ern Asia with European Neandertals to address these issues and also the potential role of ecology as a contribu- ting factor in OY ratio variation. We examine the death distributions for changes in the rel- ative number of adults who lived to be old, rather than for changes in the life span older adults attained, because this provides the best evidence for selection favoring the survi- vorship of older adults. While OY is not the ratio of older to younger adults that would be expected in living populations (Deevey, 1947), it does reflect it. There is a nonlinear rela- tionship between dead and living OY ratios. OY ratios of the dead diverge from the living to a greater degree as OY val- ues increase, yet there is a clear pattern of tracking between the OY ratios of the dead and the living. Therefore, observ- able changes in OY ratios provide some insight into the evo- lution of age structure in the human fossil record. MATERIALS AND METHODS Samples The Middle Paleolithic hominids from Western Asia (Tabun, Skhul, Qafzeh, Amud, Kebara, and Shanidar) 1 In this paper, we refer to non-Neandertal Middle Paleolithic hominids as ‘‘modern humans,’’ recognizing that this term is contro- versial. Definitions of modernity are complex, and ‘‘modern humans’’ may not represent a distinct taxonomic entity. Nevertheless, it is conventional to use this term to refer to non-Neandertal Middle Paleolithic specimens from West Asia, and we employ it here. *Correspondence to: Rachel Caspari, Department of Sociology, Anthropology and Social Work, Central Michigan University, Mt. Pleasant, MI 48859. E-mail: caspa1r@cmich.edu Received 22 November 2004; accepted 10 June 2005. DOI 10.1002/ajpa.20360 Published online 9 December 2005 in Wiley InterScience (www.interscience.wiley.com). V V C 2005 WILEY-LISS, INC. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 129:512–517 (2006)