Human Biology

Human Biology
Volume 75, Number 4, August 2003

Special Issue in honor of Frank B. Livingstone:
Papers Presented at the 2002 Annual Meeting
of the American Association of Physical
Anthropologists, Buffalo, New York,
April 10-13, 2002

Edited by Virginia J. Vitzthum and Dennis H. O'Rourke


Contents

Articles

    Wood, James W., 1949-
    Ferrell, Rebecca J.
    Dewitte-Aviña, Sharon N.
  • The Temporal Dynamics of the Fourteenth-Century Black Death: New Evidence from English Ecclesiastical Records
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    Subject Headings:
    • Black Death -- England -- Coventry -- History -- Sources.
    • Black Death -- England -- Lichfield -- History -- Sources.
    • Church records and registers -- England -- Coventry.
    • Church records and registers -- England -- Lichfield.
    Abstract:
      Recent research has questioned whether the European Black Death of 1347-1351 could possibly have been caused by the bubonic plague bacillus Yersinia pestis, as has been assumed for over a century. Central to the arguments both for and against involvement of Y. pestis has been a comparison of the temporal dynamics observed in confirmed outbreaks of bubonic plague in early-20th-century India, versus those reconstructed for the Black Death from English church records—specifically, from lists of institutions (appointments) to vacated benefices contained in surviving bishops' registers. This comparison is, however, based on a statistical error arising from the fact that most of the bishops' registers give only the dates of institution and not the dates of death. Failure to correct for a distributed (as opposed to constant) lag time from death to institution has made it look as if the Black Death passed slowly through specific localities. This error is compounded by a failure to disaggregate the information from the bishops' registers to a geographical level that is genuinely comparable to the modern data. A sample of 235 deaths from the bishop's register of Coventry and Lichfield, the only English register to list both date of death and date of institution, shows that the Black Death swept through local areas much more rapidly than has previously been thought. This finding is consistent with those of earlier studies showing that the Black Death spread too rapidly between locales to have been a zoonosis such as bubonic plague. A further analysis of the determinants of the lag between death and institution, designed to provide a basis for reexamining other bishops' registers that do not provide information on date of death, shows that the distribution of lags could vary significantly by time and space even during a single epidemic outbreak.
    Keywords:
      the black death, epidemiology, historical demography, infectious disease dynamics, medieval church history
    Long, Jeffrey C.
    Kittles, Rick A.
  • Human Genetic Diversity and the Nonexistence of Biological Races
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    Subject Headings:
    • Human genetics -- Variation.
    • Race.
    Abstract:
      Sewall Wright's population structure statistic, FST, measured among samples of world populations is often 15% or less. This would indicate that 85% of genetic variation occurs within groups while only 15% can be attributed to allele frequency differences among groups. In this paper, we show that this low value reflects strong biases that result from violating hidden assumptions that define FST. These limitations on FST are demonstrated algebraically and in the context of analyzing dinucleotide repeat allele frequencies for a set of eight loci genotyped in eight human groups and in chimpanzees. In our analyses, estimates of FST fail to identify important variation. For example, when the analysis includes only humans, FST = 0.119, but adding the chimpanzees increases it only a little, FST = 0.183. By relaxing the underlying statistical assumptions, the results for chimpanzees become consistent with common knowledge, and we see a richer pattern of human genetic diversity. Some human groups are far more diverged than would be implied by standard computations of FST, while other groups are much less diverged. We discuss the relevance of these findings to the application of biological race concepts to humans. Four different race concepts are considered: typological, population, taxonomic, and lineage. Surprisingly, a great deal of genetic variation within groups is consistent with each of these concepts. However, none of the race concepts is compatible with the patterns of variation revealed by our analyses.
    Keywords:
      FST, gene identity, race
    Jungers, William L., 1948-
    Pokempner, Amy A.
    Kay, Richard F.
    Cartmill, Matt.
  • Hypoglossal Canal Size in Living Hominoids and the Evolution of Human Speech
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    Subject Headings:
    • Hypoglossal nerve -- Size.
    • Hominids.
    • Speech.
    • Human evolution.
    Abstract:
      The relative size of the hypoglossal canal has been proposed as a useful diagnostic tool for the identification of human-like speech capabilities in the hominid fossil record. Relatively large hypoglossal canals (standardized to oral cavity size) were observed in humans and assumed to correspond to relatively large hypoglossal nerves, the cranial nerve that controls motor function of the tongue. It was suggested that the human pattern of tongue motor innervation and associated speech potential are very different from those of African apes and australopithecines; the modern human condition apparently appeared by the time of Middle Pleistocene Homo. A broader interspecific analysis of hypoglossal canal size in primates conducted in 1999 has rejected this diagnostic and inferences based upon it. In an attempt to resolve these differences of opinion, which we believe are based in part on biased size-adjustments and/or unwarranted assumptions, a new data set was collected and analyzed from 298 extant hominoid skulls, including orang-utans, gorillas, chimpanzees, bonobos, siamang, gibbons, and modern humans. Data on the absolute size of the hypoglossal nerve itself were also gathered from a small sample of humans and chimpanzee cadavers. A scale-free index of relative hypoglossal canal size (RHCS) was computed as 100 8 (hypoglossal canal area0.5/oral cavity volume0.333). No significant sexual dimorphism in RHCS was discovered in any species of living hominoid, but there are significant interspecific differences in both absolute and relative sizes of the hypoglossal canal. In absolute terms, humans possess significantly larger canals than any other species except gorillas, but there is considerable overlap with chimpanzees. Humans are also characterized by large values of RHCS, but gibbons possess an even larger average mean for this index; siamang and bonobos overlap appreciably with humans in RHCS. The value of RHCS in Australopithecus afarensis is well within both human and gibbon ranges, as are the indices computed for selected representatives of fossil Homo. Furthermore, the size of the hypoglossal nerve itself, expressed as the mass of nerve per millimeter of length, does not distinguish chimpanzees from modern humans. We conclude, therefore, that the relative size of the hypoglossal canal is neither a reliable nor sufficient predictor of human-like speech capabilities, and paleoanthropology still lacks a quantifiable, morphological diagnostic for when this capability finally emerged in the human career.
    Keywords:
      hypoglossal canal, living hominoids, fossil hominids, human speech, evolution
    Hunt, Kevin D.
  • The Single Species Hypothesis: Truly Dead and Pushing Up Bushes, or Still Twitching and Ripe for Resuscitation?
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    Subject Headings:
    • Fossil hominids.
    • Species.
    • Primates -- Evolution.
    • Science -- Methodology.
    Abstract:
      Frank Livingstone proclaims himself to be the last living proponent of the single species hypothesis. In sharp contrast, a species-rich, bushy phylogeny is favored by most human paleontologists. Is Livingstone's proclamation merely contrarian posturing, or does closer inspection warrant reconsideration of just how speciose the hominin lineage is? The high-speciation perspective draws on evidence of speciosity in the Cercopithecoidea and punctuated equilibria theory for support. If blue monkeys and redtail monkeys are indistinguishable skeletally, this reasoning goes, or if red colobus and black and white colobus are likewise indistinguishable, should we not expect that there are more species of hominin than is apparent from skeletal evidence alone? A contrarian perspective notes that not all monkey taxa are speciose. Importantly, two broadly distributed, partly terrestrial monkeys have not speciated at all: vervets and baboons. Nor are monkeys the first choice as a hominin speciation model. If expectations of species numbers are based on the Hominoidea, a taxon more closely related to hominins, more similar in body size, and found in more hominin-like habitats than monkeys, a single-species perspective is more appealing. No great ape genus has even two sympatric species. Moreover, despite a separation of 1.6 Ma, West African chimpanzees have not speciated from P.t. troglodytes nor P.t. schweinfurthii. It is notable that no two contemporaneous species of hominin were separated by significantly more than this interval. A biological—as opposed to an ecological or geographical—species definition would place all hominins in a single, phenotypically diverse species. Since divergence from the chimpanzee, "species" distinctness in hominins may have been maintained by temporary allopatry and centripetal niche separation. The hominin lineage may have evolved as a single, phenotypically diverse, reticulately evolving species.
    Keywords:
      speciosity, hominin, biological species, human evolution, species definition
    Olsen, Carolyn L.
    Cross, Philip K.
    Gensburg, Lenore J.
  • Down Syndrome: Interaction between Culture, Demography, and Biology in Determining the Prevalence of a Genetic Trait
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    Subject Headings:
    • Down syndrome -- New York (State)
    • Childbirth -- New York (State)
    • Prenatal diagnosis -- New York (State)
    Abstract:
      The incidence of Down syndrome (DS) at conception is highly dependent upon the maternal age distribution and age-specific pregnancy rates. Live-birth prevalence of DS reflects these factors and fetal deaths. Since the introduction of prenatal diagnosis in the early 1970s, the role of fetal deaths in the equation has increased. Between 1920 and the early 1980s, DS live-birth prevalence decreased in many populations due to declining fertility rates, particularly among older women. In the late-1970s the trend reversed, as the median age of populations and birth rates among older women steadily increased. This paper illustrates these interactions using data we have analyzed for New York State (NYS) and comparative data obtained from the literature. Between 1983 and 1997 DS live-birth prevalence in NYS remained stable at about 9.9 per 10,000 live births. The number of prenatal tests performed increased by 158%, and the number of DS fetuses detected prenatally more than quadrupled. Fertility rates of women aged 35-49 continued to increase. The proportion of DS cases born to these older mothers increased from 23% in 1985 to 43% in 1997. We estimated that without prenatal diagnosis, DS live-birth prevalence would have been 17.0 per 10,000 live births by 1995. Cultural factors influence demographic trends, birthing technologies, physician practices, and women's decision-making regarding prenatal screening and diagnosis for DS.
    Keywords:
      down syndrome, prenatal diagnosis use, amniocentesis, age-structure and evolution
    Gage, Timothy B.
  • The Evolution of Human Phenotypic Plasticity: Age and Nutritional Status at Maturity
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    Subject Headings:
    • Phenotype.
    • Human reproduction -- Age factors.
    • Pregnancy -- Nutritional aspects.
    Abstract:
      Several evolutionary optimal models of human plasticity in age and nutritional status at reproductive maturation are proposed and their dynamics examined. These models differ from previously published models because fertility is not assumed to be a function of body size or nutritional status. Further, the models are based on explicitly human demographic patterns, that is, model human life-tables, model human fertility tables, and, a nutrient flow-based model of maternal nutritional status. Infant survival (instead of fertility as in previous models) is assumed to be a function of maternal nutritional status. Two basic models are examined. In the first the cost of reproduction is assumed to be a constant proportion of total nutrient flow. In the second the cost of reproduction is constant for each birth. The constant proportion model predicts a negative slope of age and nutritional status at maturation. The constant cost per birth model predicts a positive slope of age and nutritional status at maturation. Either model can account for the secular decline in menarche observed over the last several centuries in Europe. A search of the growth literature failed to find definitive empirical documentation of human phenotypic plasticity in age and nutritional status at maturation. Most research strategies confound genetics with phenotypic plasticity. The one study that reports secular trends suggests a marginally insignificant, but positive slope. This view tends to support the constant cost per birth model.
    Keywords:
      evolution, life histories, age and size at maturity
    Vitzthum, Virginia J.
  • A Number No Greater than the Sum of Its Parts: The Use and Abuse of Heritability
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    Subject Headings:
    • Human genetics -- Variation.
    • Physical anthropology.
    Abstract:
      Though widely used in quantitative genetics, in the study of human variation perhaps no statistic is more easily misinterpreted than heritability. While the contribution of genetic heritage to complex biological and behavioral phenotypes cannot be lightly dismissed, nonetheless we remain profoundly ignorant of how that legacy plays out in any environmental context. To be sure, it is not reducible to a single number. Nor does the preference among anthropologists for analyzing biological rather than behavioral phenotypes improve what heritability can reasonably say about the sources of human variation. This paper discusses the meaning of heritability, the methods for its estimation, the fallacies underlying its misuse, and its utility for inquiries in evolutionary anthropology and epidemiology. Progress in anthropological genetics will be realized through greater sophistication in study designs, including the measurement of environmental (physical and sociocultural) variation and the judicious choice of phenotypes for study. Elucidating the ontogenetic processes underlying adaptive plasticity is particularly critical to understanding the evolution of human biological variation. Such advancements will also shed light on the feasibility of genotype-targeted biomedical treatments. Failure to appreciate the limits of such approaches can divert resources from demonstrably effective environmentally based health interventions that benefit entire populations. Simplistic notions of genetic determinism should be challenged for the sake of our theories and the well-being of larger communities. As exemplified by the work of Frank B. Livingstone, anthropological genetics is at its best when incorporating anthropology into the study of human phenotypic variation.
    Keywords:
      heritability, quantitative variation, norm of reaction, phenotypic plasticity, flexible response model, nature/nurture, quantitative trait loci
    Eckhardt, Robert B.
  • Polymorphisms Past and Present
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    Subject Headings:
    • Genetic polymorphisms.
    • Human genetics -- Variation.
    Abstract:
      Polymorphisms, particularly genetic variants of the red blood cell, have served as a major focus for the research of Frank B. Livingstone over the course of a long and productive career. Recent investigations confirm the value of key insights that he contributed to this area more than four decades ago. As Livingstone recognized, the same underlying evolutionary model that guides genetic studies in present populations also provides a productive framework for interpreting patterns of variation in the skeleton and dentition throughout past human evolution. Examples explored in detail here include polymorphisms in hominoid nasal bone shapes and fourth lower premolar roots. This work provides both empirical and theoretical contexts for investigating patterns of human variation over the last 6 to 8 million years.
    Keywords:
      polymorphism, paleobiology, human evolution, craniofacial morphology, nasal bones, dental morphology premolar roots
    Williams, Robert C.
  • The Mind of Primitive Anthropologists: Hemoglobin and HLA, Patterns of Molecular Evolution
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    Subject Headings:
    • Natural selection.
    • HLA histocompatibility antigens.
    • Hemoglobin.
    • Molecular immunology.
    Abstract:
      Frank Livingstone played a central role in defining the population genetics of the sickle cell mutation at position 6 of the human beta globin gene, the most famous amino acid substitution in evolutionary biology. Its discovery occurred at a time when traditional, 19th-century principles of natural selection were being joined with the newly discovered mechanics of DNA structure and protein synthesis to produce Neo-Darwinian theory. When combined with the epidemiology of malaria in Africa, differential mortality for both homozygotes, and the resulting advantage of the heterozygote, sickle cell became the classic balanced polymorphism. Human HLA-A has 237 molecular alleles. The histocompatibility system has as its primary function the presentation of peptides to T-cell receptors and plays an essential role in the immune system. Nearly all of the alleles are codominant and fully functional. Despite almost 30 years of disease-association studies with HLA-A, no convincing evidence has been found for differential fertility or mortality at this locus. Yet the dogma in the histocompatibility field is that this extensive human polymorphism is maintained by "balancing selection." Explaining HLA-A polymorphism is what one might call the sickle-cell-effect. This one mutation, coming as it did at the historical convergence of Darwinian theory and modern genetics, and carrying with it the strong relationship between mutation, disease, and allele frequency, has conditioned our discussion of human genetic variation and population genetics. Has the strength of this early idea made evolutionary biologists uncritical of systems like HLA-A and retarded the search for new mechanisms of molecular evolution? Is it now time to move away from a focus on mutation and polymorphism in evolutionary genetics and toward a systems theory that would explain the origin and evolution of hemoglobin and HLA-A and the biochemical pathways that surround them?
    Keywords:
      histocompatibility system, balancing selection, Darwinian theory, systems theory, biochemical pathways
    Poolsuwan, Samerchai.
  • Testing the "Malaria Hypothesis" for the Case of Thailand: A Genetic Appraisal
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    Subject Headings:
    • Malaria -- Thailand-- Genetic aspects.
    • Hemoglobin polymorphisms.
    • Human population genetics -- Thailand.
    Abstract:
      This study provides statistical analyses of allele frequencies for populations of Thailand, with an attempt to trace the roles of differential malarial selection and genetic admixtures on the observed frequency variation of certain red cell genetic abnormalities (the two ß-globin variants—hemoglobin E and ß-thalassemia—and G-6PD deficiency), probably evolving under malarial endemicity. It is found that frequencies of hemoglobin E vary accordingly with those of G-6PD deficiency, and with diverse malarial ecology. The levels of genetic diversity are greater for hemoglobin E and G-6PD deficiency than for most other nonmalarial related genetic markers, suggesting the evolution of these two genetic abnormalities under differential selection. Results of the Mantel's statistical test for correspondence between distance matrices suggest distinctive patterns of allele frequency differentiation between malarial-related and nonmalarial-related genetic loci. Correlations between ß-globin and G-6PD genetic distances, as well as those between both sets of distances and the malarial distances, are statistically significant. On the other hand, a correlation between malarial distances and the genetic distances for nonmalarial-related genetic loci is not significant statistically. A correlation between the ß-globin genetic distances and the genetic distances for nonmalarial-related genetic loci is, however, statistically significant. The latter result could be attributed largely to the clustering of relatively high hemoglobin E frequencies among genetically closely related populations of northeastern Thailand, whose recent homeland was Laos. The consistently low frequencies of ß-thalassemia observed in most studied populations are explained as a result of the replacement of this genetic variant by hemoglobin E, under long-term malarial selection.
    Keywords:
      malarial ecology, beta-globin variants, g-6pd deficiency, natural selection
    Fix, Alan G.
  • Simulating Hemoglobin History
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    Subject Headings:
    • Hemoglobin polymorphisms.
    • Kin selection (Evolution)
    • Human population genetics.
    Abstract:
      In one of the truly classic works in anthropological genetics, Frank Livingstone established the interrelationships between agriculture, mosquito ecology, malaria, and, consequently, the frequencies of sickle cell hemoglobin in West Africa. A major inference from Livingstone's study was the recency of malaria as a selective agent in human populations, only becoming significant after the adoption of agriculture in the last few thousand years. Clines of the abnormal hemoglobin alleles might therefore represent continuing waves of advance of adaptive alleles. In order to model the complex interaction of several hemoglobin alleles, selection, and gene flow spreading adaptive mutants, Livingstone turned to computer simulation. Numerous insights concerning the competitive increase of different alleles (hemoglobins S, C, and E and thalassemia), the rate of allele spread under different migration scenarios, including the potential importance of long-range migration, came out of these studies. These experiments also stimulated others to search for mechanisms that might increase the diffusion rate of hemoglobin variants, including kin-structured migration and epidemic disease selection. Recent molecular studies have substantiated major aspects of Livingstone's work (including the recent origin of falciparum malaria) and posed challenges to some of his assumptions (such as the number of mutations to hemoglobins S and E). But whatever the fate of his specific hypotheses, his emphasis on the interaction of genetics, ecology, and culture stands as a model for the anthropological approach to the understanding of human variation and evolution.
    Keywords:
      hemoglobin variants, wave of advance, kin-structured migration, epidemic disease selection
    Steegmann, Theodore.
  • Anthropology at the University of Michigan in the Late 1950s
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    Subject Headings:
    • Anthropology -- Study and teaching (Higher) -- Michigan -- Ann Arbor -- History -- 20th century.
    • University of Michigan. Dept. of Anthropology -- History -- 20th century.
    Abstract:
      By 1958, the Anthropology Department at the University of Michigan had emerged as a major center in the discipline. Its excellence derived from a strong faculty, commitment to an integrated view of the field, and broader support from a rising national tide of scholarship. While many new intellectual currents developed, among the strongest was biological-behavioral theory—somewhat ironically flourishing in a biological anthropology program that viewed itself as a nexus of population genetics. The biological anthropology faculty thought like anthropologists. From this environment, Frank Livingstone not only drew intellectual support, but also became a key player in demonstrating the importance of historical and cultural factors to shaping biological patterns. A biocultural perspective is evident in Michigan research to this day.
    Keywords:
      history, anthropology, physical anthropology

Personal Reminiscences

    Weiss, Kenneth M.
  • THINK! Being a Student of Frank B. Livingstone
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    Subject Headings:
    • Livingstone, Frank B. -- Influence.
    • Human genetics -- Study and teaching (Higher) -- Michigan -- Ann Arbor -- History -- 20th century.

Limerick




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