Contemporary Human Populations Research Articles

Test of the minimum supero-inferior femoral neck diameter as a sex predictor in a contemporary documented osteological collection from Portugal

Abstract Adult sex estimation is one of the first and most important steps in forensic examination. While dealing with disturbed burials, the most dimorphic anatomic areas of the skeleton (such as the coxae, the skull and the head of femur and humerus) may be deteriorated or fragmented. In contrast, the minimum supero-inferior femoral neck diameter (SID) is generally much better preserved. The aim of the present research is to identify the discriminatory potential of SID for sex estimation and to test different formulae and mathematical procedures currently available in the forensic literature, on a sample of 295 contemporary individuals from the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal), in order to identify its relevance for application in Portuguese forensic cases. Results showed that SID is a dimorphic variable, with high frequencies and probabilities of cases correctly estimated (0.82 and 0.83, respectively); statistically significant differences between females and males, and a high association between the metrics and sex, were identified. Posterior probabilities allow reliable estimations for all the measurements, excepting those between 31.0 and 31.5 mm, and the procedures that show the highest accuracy are those proposed by Seidemann et al. (1998), Curate et al. (2016) and Luna et al. (2021), with frequencies and probabilities between 0.82 and 0.83 for both sexes. The validation procedures implemented in this study highlight both the need to test quantitative models generated from diverse contemporary human populations, and the value of SID for obtaining reliable adult sex estimates, as they improve the quality of the biological profiles obtained in forensic contexts. Key points

Ethics and Best Practices of Studying Contemporary Human Populations

At the 2021 meeting of the American Association of Biological Anthropologists, the “Ethics and Best Practices of Studying Contemporary Human Populations” symposium brought together a diverse panel of scientists to address the growing concerns related to consent, communication, and ethical practices in biological anthropology research. Drawing from historical parallels and current practices, the panel underscored the responsibilities of researchers to engage transparently and respectfully with the subjects of their studies. This article summarizes some of the topics raised and debated at that meeting, including the specific challenges posed by the COVID-19 pandemic and the resulting surge in studies utilizing biological data from diverse populations, and the meaning of informed consent, genetic privacy, and data justice. The authors emphasize the importance of diversity and inclusion within research teams and leadership roles, and the role this can play in reshaping research approaches and fostering innovation in our field. They challenge the traditional notions of informed consent and encourage a more nuanced understanding that acknowledges the historical context and respects refusals as a form of knowledge production. The diverse perspectives shared at the symposium offer a glimpse into the ongoing efforts of biological anthropologists to navigate ethical challenges in contemporary human population studies. The collective aim is to spark sustained conversations and collaborative endeavors within biological anthropology and to promote continuous improvement in ethical standards and best practices.

Unveiling recent and ongoing adaptive selection in human populations.

Genome-wide scans for signals of selection have become a routine part of the analysis of population genomic variation datasets and have resulted in compelling evidence of selection during recent human evolution. This Essay spotlights methodological innovations that have enabled the detection of selection over very recent timescales, even in contemporary human populations. By harnessing large-scale genomic and phenotypic datasets, these new methods use different strategies to uncover connections between genotype, phenotype, and fitness. This Essay outlines the rationale and key findings of each strategy, discusses challenges in interpretation, and describes opportunities to improve detection and understanding of ongoing selection in human populations.

A weakly structured stem for human origins in Africa

Despite broad agreement that Homo sapiens originated in Africa, considerable uncertainty surrounds specific models of divergence and migration across the continent1. Progress is hampered by a shortage of fossil and genomic data, as well as variability in previous estimates of divergence times1. Here we seek to discriminate among such models by considering linkage disequilibrium and diversity-based statistics, optimized for rapid, complex demographic inference2. We infer detailed demographic models for populations across Africa, including eastern and western representatives, and newly sequenced whole genomes from 44 Nama (Khoe-San) individuals from southern Africa. We infer a reticulated African population history in which present-day population structure dates back to Marine Isotope Stage 5. The earliest population divergence among contemporary populations occurred 120,000 to 135,000 years ago and was preceded by links between two or more weakly differentiated ancestral Homo populations connected by gene flow over hundreds of thousands of years. Such weakly structured stem models explain patterns of polymorphism that had previously been attributed to contributions from archaic hominins in Africa2–7. In contrast to models with archaic introgression, we predict that fossil remains from coexisting ancestral populations should be genetically and morphologically similar, and that only an inferred 1–4% of genetic differentiation among contemporary human populations can be attributed to genetic drift between stem populations. We show that model misspecification explains the variation in previous estimates of divergence times, and argue that studying a range of models is key to making robust inferences about deep history.

Evaluation of sexual dimorphism in human premolars using longitudinal ground sections- A cross sectional study

Introduction: Sex determination plays an important role in forensics. On average, males possess larger tooth crowns than females in contemporary human populations, although the degree of dimorphism varies within different populations. Ground sectioning of teeth can provide an accurate measurement of enamel and dentinal thickness and can be used for gender determination in forensic analysis.
 Aim: The main aim of this study is to evaluate sexual dimorphism in human premolars using longitudinal ground sections.
 Materials & Method: In this study extracted premolar teeth of males and females were taken. Longitudinal ground sectioning of these teeth was made and later examined under light microscope under customized grids.
 Results: Data was statistically analyzed and results were tabulated. It was found that enamel area and average enamel thickness was higher in females than males and coronal dentinal areas were more in males.
 Conclusion: Results of this study suggest that the differences in crown morphology among males and females can be used as a potential tool in forensic analysis.

Ethics and Best Practices of Studying Contemporary Human Populations

Ethics and Best Practices of Studying Contemporary Human Populations

Metric Variation on Neurocranium among Some Ancient and Contemporary Human Populations (Adult Males) of Indian SubContinent

Background: It is always difficult to assess the inter-group relationships by utilizing data based on sample univariate populations. One usually faces the problem of biological taxonomy in this case. To understand such problem multivariate statistical analysis is necessary. This study deals with neurocranium characteristics of four population groups from Indian Sub-Continent. Methods: Skulls of the four populations (Harappa, Kumhar Tekri, Contai, 24 parganas) were studied. Altogether 60 adult male skulls (Harappa=10, Kumhar Tekri=10, Contai=20, 24 Parganas=20) were measured. Four length and four breadth measurements were taken. Cranial index was calculated. From the data obtained, size and shape factors were calculated. D2 P values were calculated and dendrogram was computed on the basis on D2 P values. Results: Highest value of maximum cranial length, glabella inion length, nasion inion length, glabella lambda length and minimum frontal breadth were recorded in Harappa and its lowest values were recorded in Contai skull. While Harappa, Kumhar Tekri and 24 Parganas skull were mainly orthocranial, Contai skull was mainly hypsicranial. Mean values for size and shape distance between 6 pairs were 1.14 and 1.92 respectively. This implies that the four population groups show a tendency to differ more in shape distance than size distance. Dendrogram depicts that Contai and 24 Parganas populations form a cluster. But other two are distantly placed with this cluster. However, the Harappa maintains a far distance with other three population groups. Conclusion: Higher means of shape values than the size is recoded. This implies that the four population groups show a tendency to differ more in shape distance than size distance. Finding of this study is indicative of interesting corroboration between neurocranium characteristics and inter-group relationships.

The value of sociogenomics in understanding genetic evolution in contemporary human populations.

Burt's target article oddly misses the important intellectual contribution of sociogenomics to our understanding of genetic evolution in contemporary human populations. Although social scientists' immediate research agendas are often not evolutionary in nature, I call for a better appreciation of the role of sociogenomics in answering important evolutionary questions.

Research problems in Biological Anthropology: Flaws in sampling and in methods of results analysis

Anthropology has as ambition the study of the whole of humanity. It includes several specialties and sub-specialties that, despite their differences, offer an overall perspective that requires a holistic research approach. In Biological Anthropology, one of its specialties, anthropologists study biological variations in contemporary human populations in order to reveal their characteristics and their genetic relationships and to try, on the basis of analysis of these variations and those revealed in human fossils, to trace the evolution of human lineage through time. In this report, I provide an overview of some research major problems met in biological anthropology. I evoke especially the problems of the use of uncertain results analysis methods and those of incorrect samplings. In addition to the presentation of these problems and their consequences I present alternatives and suitable solutions. I also explain how some classic considerations resulting from some of these problems could hinder scientific progress in the topic in question. Hence, I believe it is time to avoid these problems, to eradicate the resulting considerations and to follow the most realistic research tracks.

A novel perspective suggesting high sustained energy expenditure may be net protective against cancer.

Energy expenditure (EE) is generally viewed as tumorigenic, due to production of reactive oxygen species (ROS) that can damage cells and DNA. On this basis, individuals within a species that sustain high EE should be more likely to develop cancer. Here, we argue the opposite, that high EE may be net protective effect against cancer, despite high ROS production. This is possible because individuals that sustain high EE have a greater energetic capacity (=greater energy acquisition, expenditure and ability to up-regulate output), and can therefore allocate energy to multiple cancer-fighting mechanisms with minimal energetic trade-offs. Our review finds that individuals sustaining high EE have greater antioxidant production, lower oxidative stress, greater immune function and lower cancer incidence. Our hypothesis and literature review suggest that EE may indeed be net protective against cancer, and that individual variation in energetic capacity may be a key mechanism to understand the highly individual nature of cancer risk in contemporary human populations and laboratory animals. Lay summary The process of expending energy generates reactive oxygen species that can lead to oxidative stress, cell and DNA damage, and the accumulation of this damage is thought to be a major contributor to many ageing related diseases that include cancer. Here, we challenge this view, proposing how and why high energy expenditure (EE) may actually be net protective against cancer, and provide literature support for our hypothesis. We find individuals with high sustained EE have greater energetic capacity and thus can invest more in repair to counter oxidative stress, and more in immune function, both of which reduce cancer risk. Our hypothesis provides a novel mechanism to understand the highly individual nature of cancer, why taller individuals are more at risk, why physically active individuals have lower cancer risk, and why regular exercise can reduce cancer risk.

Historical evolution of the social perception on ecosystem services provided by seagrasses through analysis of the written press in North West Spain (1860–2020)

The social recognition of the services delivered by ecosystems takes advantage from knowledge on the historical narratives of their uses and benefits and may facilitate the societal transition towards a more conservation-based perception of natural systems. Historical analysis of ecosystem services have been barely addressed, possibly because of the lack of available information, especially in the case of uncharismatic habitats such as seagrass meadows. In this investigation, we used the written press to reconstruct the historical narrative of seagrass ecosystems in Galicia (NW Spain), a region where this type of information is not stored in scientific publications or public archives. We assessed the social perception of the ecosystem services provided by marine angiosperms and inferred the main conflicts between seagrasses and users of the Galician estuaries over the last 160 years. The NW Spanish population perceived four provision and regulation ecosystem services from seagrasses throughout this period. A distinct temporal succession of the ecosystem services supplied by seagrasses and perceived by the Galician society was identified. Provisioning services, such as seagrass harvesting for fertilizer use or textile fiber, prevailed until the first quarter of the 1900s, whereas the perception of the nursery effect of Zostera meadows became dominant since the second half of the 1900s. The conflict between shellfishing and seagrasses was recurrent all through the past 160 years. New conflicts related to dredging, filling and navigation emerged in the present century. A positive perception of seagrasses is progressively growing mainly associated with an increasing importance of news referring to research, dissemination and conservation of seagrass ecosystems. Our results show that the information retrieved from the written press helps building the social-ecological memory of ecosystem services provided by seagrass meadows. The public outreach of local traditions associated with these habitats, dissemination of the services they delivered to previous generations and the diffusion of the interactions between Zostera and contemporary human populations may contribute to modify social perceptions on this ecosystem, providing valuable information for the design and implementation of social awareness programs encouraging seagrass conservation needed for ecosystem-based coastal management.

Drivers of insect consumption across human populations.

Discussions regarding entomophagy in humans have been typically led by entomologists. While anthropologists devote much time to understanding diverse human subsistence practices, historical and cultural variation in insect consumption remains largely unexplained. This review explores the relation between variable ecologies, subsistence strategies, and social norms on insect consumption patterns across past and contemporary human populations. Ecological factors, such as the nutritional contribution of edible insects relative to those of other foraged or farmed resources available, may help explain variation in their consumption. Additionally, our evolved social learning strategies may help propagate social norms that prohibit or prioritize the consumption of some or all edible insects, independent of their profitability. By adopting a behavioral ecological and cultural evolutionary approach, this review aims to resolve current debates on insect consumption and provide directions for future research.

Mitochondrial genetic variation in human bioenergetics, adaptation, and adult disease.

Mitochondria are critical for the survival of eukaryotic organisms due to their ability to produce cellular energy, which drives virtually all aspects of host biology. However, the effects of mitochondrial DNA (mtDNA) variation in relation to disease etiology and adaptation within contemporary global human populations remains incompletely understood. To develop a more holistic understanding of the role of mtDNA diversity in human adaptation, health, and disease, we investigated mitochondrial biology and bioenergetics. More specifically, we synthesized details from studies of mitochondrial function and variation in the context of haplogroup background, climatic adaptation, and oxidative disease. The majority of studies show that mtDNA variation arose during modern human dispersal around the world. Some of these variants appear to have been positively selected for their adaptiveness in colder climates, with these sequence changes having implications for tissue-specific function and thermogenic capacity. In addition, many variants modulating energy production are also associated with damaging metabolic byproducts and mitochondrial dysfunction, which, in turn, are implicated in the onset and severity of several different adult mitochondrial diseases. Thus, mtDNA variation that governs bioenergetics, metabolism, and thermoregulation may potentially have adverse consequences for human health, depending on the genetic background and context in which it occurs. Our review suggests that the mitochondrial research field would benefit from independently replicating mtDNA haplogroup-phenotype associations across global populations, incorporating potentially confounding environmental, demographic, and disease covariates into studies of mtDNA variation, and extending association-based studies to include analyses of complete mitogenomes and assays of mitochondrial function.

The representativeness of the dental calculus dietary record: insights from Ta\xef chimpanzee faecal phytoliths

In recent years, new applications of microremain dietary analysis using dental calculus as a source of dietary data on ancient human subsistence and behaviours have accelerated. The dental calculus of contemporary human and non-human populations with known diets have been used as reference datasets, including the chimpanzees of Taï National Park (Côte d'Ivoire), but explaining the preservation mechanism involved is challenged by our incomplete knowledge of the microremain content within the diets of these reference populations and our rudimentary information on microremain incorporation into dental calculus. Here, we analyse phytoliths in faecal samples to assess to what extent plant phytoliths of a diet are reflected in the dental calculus as well as in the egested faeces. In this study, we identify and document the faecal phytolith assemblages as an indicator of plant consumption in two Western chimpanzees of the Taï National Park (Côte d'Ivoire) before (wet season), during (dry season) and after (dry season) a dust-rich period. Moreover, observational dietary records of these two individuals were compiled to improve the interpretability of this dental calculus phytolith dataset. The faecal phytolith assemblages vary significantly across samples in terms of abundance and diversity. The most common phytolith morphotypes were eudicot plates, single-cell and multi-cell tracheids, monocot rugulose and echinate spheroids and, to a lesser extent, unspecified thick and thin elongates. High loads of grit and other micro-remains (e.g. diatoms) are found during the dry period. Using observational dietary records as a starting point and our faecal results as a terminus, we consider how dental calculus can accumulate phytoliths. Our findings enable identification of the phytolith morphotypes that are under-represented in dental calculus, which is highly informative for future dental calculus research strategies.

Widespread Denisovan ancestry in Island Southeast Asia but no evidence of substantial super-archaic hominin admixture.

The hominin fossil record of Island Southeast Asia (ISEA) indicates that at least two endemic 'super-archaic' species-Homo luzonensis and H. floresiensis-were present around the time anatomically modern humans arrived in the region >50,000 years ago. Intriguingly, contemporary human populations across ISEA carry distinct genomic traces of ancient interbreeding events with Denisovans-a separate hominin lineage that currently lacks a fossil record in ISEA. To query this apparent disparity between fossil and genetic evidence, we performed a comprehensive search for super-archaic introgression in >400 modern human genomes, including >200 from ISEA. Our results corroborate widespread Denisovan ancestry in ISEA populations, but fail to detect any substantial super-archaic admixture signals compatible with the endemic fossil record of ISEA. We discuss the implications of our findings for the understanding of hominin history in ISEA, including future research directions that might help to unlock more details about the prehistory of the enigmatic Denisovans.

Beyond the Household: Caribbean Families and Biocultural Models of Alloparenting

Alloparental or extramaternal care is an integral aspect of human childrearing. This behavior has been explored both as an extension of the primary mother–infant dyad that evolved to meet the demands of altricial offspring and as an economic exchange of energy and resources. Much of this research centers on foraging or small-scale communities and positions the household as the central unit through which to explore negotiations of care. In this review, I use evidence from Black Caribbean communities living in industrialized countries to challenge the broad applicability of the analytical model of the bounded household and to question whether our current articulations of theory and empirical assessments of extramaternal care are well suited to investigations of these behaviors in the vast majority of contemporary human populations. Alloparental practices in the Caribbean reflect dynamic responses to maternal migration and the local influence of global labor markets. The children who remain at home experience variability in the care received from their surrogate parents. The dynamic aspect of the care practices enacted by these transnational families reveals the behavioral flexibility that has been integral to human survival.

(re)Producing mtEve

In their 1987 Nature publication, “Mitochondrial DNA and Human Evolution,” Rebecca Cann, Mark Stoneking, and Allan C. Wilson gave a new reconstruction of human evolution on the basis of differences in mitochondrial DNA among contemporary human populations. This phylogeny included an African common ancestor for all human mitochondrial DNA (mtDNA) lineages, and Cann et al.’s reconstruction became known as the “Out of Africa” hypothesis. Since mtDNA is inherited exclusively through the maternal line, the common ancestor who was first branded African Eve later became known as Mitochondrial Eve (mtEve, for short).In this paper, I show that mtEve was not a single, successful, or purely scientific discovery. Instead, she was produced many times and in many ways, each of which informed the next. Importantly, though Wilson and colleagues heralded mitochondrial DNA as a source of certainty, objectivity, and consensus for evolutionary inference, their productions of Mitochondrial Eve depended as much on popular assumptions about the certainty of maternal inheritance as they did on new molecular and computational tools. This recognition lets us reevaluate the complex consequences of these productions, which, like mtEve herself, could not be confined to a purely social, material, or scientific dimension.

Population-specific, recent positive directional selection suggests adaptation of human male reproductive genes to different environmental conditions

BackgroundRecent human transcriptomic analyses revealed a very large number of testis-enriched genes, many of which are involved in spermatogenesis. This comprehensive transcriptomic data lead us to the question whether positive selection was a decisive force influencing the evolution and variability of testis-enriched genes in humans. We used two methodological approaches to detect different levels of positive selection, namely episodic positive diversifying selection (i.e., past selection) in the human lineage within primate phylogeny, potentially driven by sperm competition, and recent positive directional selection in contemporary human populations, which would indicate adaptation to different environments.ResultsIn the human lineage (after correction for multiple testing) we found that only the gene TULP2, for which no functional data are yet available, is subject to episodic positive diversifying selection. Using less stringent statistical criteria (uncorrected p-values), also the gene SPATA16, which has a pivotal role in male fertility and for which episodes of adaptive evolution have been suggested, also displays a putative signal of diversifying selection in the human branch. At the same time, we found evidence for recent positive directional selection acting on several human testis-enriched genes (MORC1, SLC9B1, ROPN1L, DMRT1, PLCZ1, RNF17, FAM71D and WBP2NL) that play important roles in human spermatogenesis and fertilization. Most of these genes are population-specifically under positive selection.ConclusionEpisodic diversifying selection, possibly driven by sperm competition, was not an important force driving the evolution of testis-enriched genes in the human lineage. Population-specific, recent positive directional selection suggests an adaptation of male reproductive genes to different environmental conditions. Positive selection acts on eQTLS and sQTLs, indicating selective effects on important gene regulatory functions. In particular, the transcriptional diversity regulated by sQTLs in testis-enriched genes may be important for spermatocytes to respond to environmental and physiological stress.

Archaic hominin introgression into modern human genomes.

Ancient genomes from multiple Neanderthal and the Denisovan individuals, along with DNA sequence data from diverse contemporary human populations strongly support the prevalence of gene flow among different hominins. Recent studies now provide evidence for multiple gene flow events that leave genetic signatures in extant and ancient human populations. These events include older gene flow from an unknown hominin in Africa predating out-of-Africa migrations, and in the last 50,000-100,000 years, multiple gene flow events from Neanderthals into ancestral Eurasian human populations, and at least three distinct introgression events from a lineage close to Denisovans into ancestors of extant Southeast Asian and Oceanic populations. Some of these introgression events may have happened as late as 20,000 years before present and reshaped the way in which we think about human evolution. In this review, I aim to answer anthropologically relevant questions with regard to recent research on ancient hominin introgression in the human lineage. How have genomic data from archaic hominins changed our view of human evolution? Is there any doubt about whether introgression from ancient hominins to the ancestors of present-day humans occurred? What is the current view of human evolutionary history from the genomics perspective? What is the impact of introgression on human phenotypes?

Scientific ethics and the illusion of naïve objectivity

Scientists value observations and inferences made objectively, “…not influenced by personal feelings or opinions in considering and representing facts” (Oxford English Dictionary https​://www.oed.com). Yet scientists have feelings and opinions (worldviews, hereafter) about their own work and that of others. How do we set these aside to generate the best approximations of reality, and how do our worldviews affect the way we communicate our science? The potential consequences of this paradox are particularly acute for the applied sciences, where research can affect the biosphere. Debates and discussions about applying research to policy often include criticisms of advocacy or mission- or agenda-driven science. I find two insights lacking in many of these debates: (1) people confuse the role of objectivity in how science is conducted and in how it is conveyed, and (2) their claims of objectivity are frequently naïve. Resolving this paradox of objectivity among scientists requires that we more clearly distinguish what we observe and infer from our vision of how we wish to change or maintain our planet. This makes it easier to separate the conduct of science (internal domain) from how it is conveyed (external domain). However, success in either domain requires us to dismiss naïve objectivity, which is the claim that scientists can divorce themselves entirely from their own worldviews. To move beyond naïvety, we must acknowledge that science is not conducted in isolation but instead begins with questions posed by society or by curious scientists. Our methods reflect tradition or personal ingenuity, and our interpretations emphasize our priorities, which reflect our values. There is no view from nowhere – all scientists have a viewpoint. Still, rejecting naïve objectivity does not imply the polar opposite, relativism, which proposes no objective reality. Rather, we strive, if imperfectly, toward the best explanation based on observation, inference, and reasoned evidence. Scientific training and process can improve our objectivity and protect us from overwhelming personal biases. Dismissing naïve objectivity would be furthered if we embraced transparent tests of our worldviews. Recall Chamberlin's method of multiple working hypotheses with which “the dangers of parental affection for a favorite theory can be circumvented”. (Chamberlin T. 1890. Science 15: 92–96). Such efforts to expose scientists’ worldviews to rigorous challenge by an alternative worldview would make the internal domain of science more objective. Here, I provide an example from predator control. Anthropocentrism (granting priority to humans) is a worldview commonly applied in environmental science yet rarely handled objectively. In anthropocentric predator control, the prevailing assumption is that killing predators protects human interests. However, if we aim for greater objectivity in how we observe and infer human–environment interactions, then we should scientifically evaluate the anthropocentric worldview against its alternative: non-anthropocentrism, which grants equitable consideration to all beings or ecological communities. Under this worldview, not killing predators protects human and non-human interests. By assuming the anthropocentric position, a scientist might not consider using non-lethal interventions and might only measure the response variable of how contemporary human populations are affected while ignoring outcomes for future generations of humans and non-humans alike. Evaluating only one intervention (killing predators) and one type of response variable (effects on current humans) might be simple; however, it is not based on scientific observation that only those interests exist, but rather on a value judgment that only those interests matter. Some scholars extend a naïve objectivity to criticism of their colleagues’ behavior in the external domain of science – conflating how we represent (communicate or translate) scientific findings with the methods we use to observe and infer (concluding from known or assumed facts). Naïve objectivity might impose restrictions on how, when, or to whom we represent our scientific evidence, such as by criticizing each other for not being dispassionate or for speaking to media or lawyers. There are gray areas certainly, yet important observations and strong inference are not by necessity biased by how one represents them and to whom. Our manner of representing important observations and strong inference lies in the external domain of science, and reflects ethics, social norms, laws, policy positions, personal experiences, and the like. Of course, there are gray areas where differing opinions of the acceptability of tone and style might clash, since we live in a world where scientific ideas must face criticism. Indeed, scientists might be tempted to accuse other researchers of bias when their worldviews differ but ultimately the merits of each set of scientific evidence depend on the methods they used for generating observations and inferences, independent of who conducts the research or their preferred modes of communication. Representing one's science ethically cannot tarnish one's objectivity, no matter how much one dislikes the inferences. ADRIAN TREVES Nelson Institute for Environmental Studies, University of Wisconsin–Madison, Madison, WI