In this paper, I plan to show that the use of a specific population concept—Millstein’s Causal Interactionist Population Concept (CIPC)—has interesting and counter-intuitive ramifications for discussions of the reality of biological race in human beings. These peculiar ramifications apply to human beings writ large and to individuals. While this in and of itself may not be problematic, I plan to show that the ramifications that follow from applying Millstein’s CIPC to human beings complicates specific biological racial realist accounts—naïve (...) or otherwise. I conclude with the notion that even if biological races do exist—by fulfilling all of the criteria needed for Millstein’s population concept (which, given particular worries raised by Gannett (Synthese 177:363–385, 2010), and Winther and Kaplan (Theoria 60:54–80, 2013) may not)—the lower-bound limit for the scope of biological racial realism is at the level of populations, and as such they cannot say anything about whether or not individual organisms themselves have races. (shrink)

The development of a biological notion of “population” over the first century of the theory of evolution has been commented upon by a number of historians and philosophers of biology. Somewhat less commonly discussed, however, is the parallel development of the statistical concept of a population over precisely the same period, in some cases driven by the same historical actors (such as Francis Galton and R. A. Fisher). We explore here these parallel developments, first from the perspective of a (...) reconstruction of the historical development of each concept, then with the aid of a digital analysis of a corpus of literature drawn from the journals Biometrika and Journal of Genetics, between 1900 and 1960. These twin analyses show both points of interesting overlap between these two historical trends as well as points of important divergence. The biological and statistical notions of “population” seem to be relatively clearly distinguishable over these six decades, in spite of the fact that a number of authors contributed clearly to both traditions. The complex interplay of continuity and discontinuity across these two notions of “population” makes them a particularly interesting case study of scientific conceptual change. (shrink)

During the past few decades, philosophers of biology have debated the issue of reductionism versus anti-reductionism, with both sides often claiming a ‘pluralist’ position. However, both sides also tend to focus on a single research paradigm, which analyzes living things in terms of certain macromolecular components. I offer a case study where biologists pursue other analytic pathways, in a tradition of quantitative genetics that originates with the initially purely mathematical theories of R. A. Fisher, J. B. S. Haldane, and Sewall (...) Wright in the 1930s. Aster Models offers a class of statistical models designed for studying the fitness of plant and animal populations, by integrating the measurements of separate, sequential, non-normally distributed fitness components in novel ways. Their work generates important theoretical and practical results that do not require elaboration by molecular biology, and thus serves as a counterexample to the claims of philosophers whose ‘pluralism’ still harbors reductionist assumptions. (shrink)

I defend a radical interpretation of biological populations—what I call population pluralism—which holds that there are many ways that a particular grouping of individuals can be related such that the grouping satisfies the conditions necessary for those individuals to evolve together. More constraining accounts of biological populations face empirical counter-examples and conceptual difficulties. One of the most intuitive and frequently employed conditions, causal connectivity—itself beset with numerous difficulties—is best construed by considering the relevant causal relations as (...) ‘thick’ causal concepts. I argue that the fine-grained causal relations that could constitute membership in a biological population are huge in number and many are manifested by degree, and thus we can construe population membership as being defined by massively multidimensional constructs, the differences between which are largely arbitrary. I end by showing that positions in two recent debates in theoretical biology depend on a view of biological populations at odds with the pluralism defended here. 1 Introduction2 Biological Population, Broad and Narrow3 Difficulties with Narrow Biological Population Conditions3.1 Against the genealogical condition3.2 Against the conspecificity condition3.3 Against the proximity condition3.4 Against the typology condition4 Causal Connectivity5 Massively Multidimensional Population Constructs6 Population Uniqueness and Natural Selection6.1 Statisticalism and its discontents6.2 Price at what price?7 Conclusion. (shrink)

This paper examines the history of animal behavior studies after the synthesis period. Three episodes are considered: the adoption of the theory of natural selection, the mathematization of ideas, and the spread of molecular methods in behavior studies. In these three episodes, students of behavior adopted practices and standards developed in population ecology and population genetics. While they borrowed tools and methods from these fields, they made distinct uses that set them relatively apart and led them to contribute, in their (...) own way, to evolutionary theory. These episodes also highlight some limitations of “conjunction narratives” centered on the relation between a discipline and the modern synthesis. A trend in conjunction narratives is to interpret any development related to evolution in a discipline as an “extension,” an “integration,” or as a “delayed” synthesis. I here suggest that this can lead to underestimate discontinuities in the history of evolutionary biology. (shrink)

This paper aims to illustrate one of the primary goals of the philosophy of biology⎯namely, the examination of central concepts in biological theory and practice⎯through an analysis of the concepts of population and metapopulation in evolutionary biology and ecology. I will first provide a brief background for my analysis, followed by a characterization of my proposed concepts: the causal interactionist concepts of population and metapopulation. I will then illustrate how the concepts apply to six cases that differ in their (...) population structure; this analysis will also serve to flesh out and defend the concepts a bit more. Finally, I will respond to some possible questions that my analysis may have raised and then conclude briefly. (shrink)

This paper analyses the broad methodological structure of population-biological theorising. In it, I show that the distinction between initial exploratory, hypothesis-generating research and the subsequent process-reconstructing, hypothesis-testing type of research is not being made. Rather, the hypotheses generated in population biology are elaborated in such detail that students confound the initial research phase with the subsequent hypotheses-testing phase of research. In this context, I therefore analyse some testing procedures within the exploration phase and show that, as an extreme form (...) of confusion, statistical null-models are mistakenly given the status of causal population-biological theory. (shrink)

I defend a radical interpretation of biological populations—what I call population pluralism—which holds that there are many ways that a particular grouping of individuals can be related such that the grouping satisfies the conditions necessary for those individuals to evolve together. More constraining accounts of biological populations face empirical counter-examples and conceptual difficulties. One of the most intuitive and frequently employed conditions, causal connectivity—itself beset with numerous difficulties—is best construed by considering the relevant causal relations as (...) ‘thick’ causal concepts. I argue that the fine-grained causal relations that could constitute membership in a biological population are huge in number and many are manifested by degree, and thus we can construe population membership as being defined by massively multidimensional constructs, the differences between which are largely arbitrary. I end by showing that positions in two recent debates in theoretical biology depend on a view of biological populations at odds with the pluralism defended here. (shrink)

In view of the confusion about the use of the term ‘population’ in biology, an analysis has been made of the use of the concept of population in biology. Origin and development, logic and epistemology of the population-concept have been investigated for that purpose. It appears that several concepts of population coexist in biology. The term ‘population’ is used for all these concepts, so it is not amazing that confusion has arisen. This confusion is the more dangerous, since ‘population’ plays (...) an important part in the theory of evolution. A modus has been suggested to diminish this confusion by defining ‘population’ in a very wide sense of the term and by proposing a ‘deme’—terminology to specify the various special concepts of population. (shrink)

“The Strategy of Model Building in Population Biology” published by Richard Levins in 1966 has been cited over 2500 times. For a paper concerned with modeling approaches in population biology a surprisingly large part of the attention. The Strategy received comes from history and philosophy of biology, and specifically from accounts on model and model formulation. The Strategy is an unusual paper; it presents neither new data nor a new formal model; at times it reads like a manifesto for some (...) modeling approach, without specifying which broader program that approach intends to support. When these peculiarities of The Strategy are even mentioned, the philosophical literature tends to explain them away by invoking Levins’ Marxist commitments. In contrast, I argue that those peculiarities can be explained by examining the programmatic purpose of the paper; starting from his doctoral work, Levins was trying to establish a research program meant to account for the relations between fitness and environment in different terms than the prevalent lock-and-key view. My paper brings that program back to the discussion, explains its relation to competing approaches and examines Levins’ approach to modeling in light of that context. (shrink)

What is the role (or roles) of mathematical theory in ecology and evolutionary biology? How does the construction of such theory advance our understanding? The lack of clear answers to this pair of questions has been a source of controversy both within the sciences themselves, and in the philosophical discussions of these sciences as well. In an attempt to shed some light on these issues, I look at what some biologists have had to say on the matter and at some (...) particular examples. I then draw some morals about the constraints on a successful philosophical treatment of the problem and on the limitations of current philosophical approaches to this type of theoretical explanation. (shrink)

At least below the level of species, biological populations are not mind‐independent objects that scientists discover. Rather, biological populations are pragmatically constructed as objects of investigation according to the aims, interests, and values that inform particular research contexts. The relations among organisms that are constitutive of population‐level phenomena (e.g., mating propensity, genealogy, and competition) occur as matters of degree and so give rise to statistically defined open‐ended biological systems. These systems are rendered discrete units to (...) satisfy practical needs and theoretical preferences associated with specific contexts of investigation. While it may be possible to defend a realist position regarding biological relations among organisms, biological populations are “made” when contextual features determine which kinds and degrees of relations to privilege over others, and so how to bound genes in space and time. Consequently, the objectivity of population‐based approaches to species genome diversity cannot rest in the mind‐independence of populations themselves. (shrink)

In this essay, I argue for four related claims. First, Richard Levins’ classic “The Strategy of Model Building in Population Biology” was a statement and defense of theoretical population biology growing out of collaborations between Robert MacArthur, Richard Lewontin, E. O. Wilson, and others. Second, I argue that the essay served as a response to the rise of systems ecology especially as pioneered by Kenneth Watt. Third, the arguments offered by Levins against systems ecology and in favor of his own (...) methodological program are best construed as “pragmatic”. Fourth, I consider limitations of Levins’ arguments given contemporary population biology. (shrink)

Contemporary biology has inherited two key assumptions from the Modern Synthesis about the nature of population lineages: sexual reproduction is the exemplar for how individuals in population lineages inherit traits from their parents, and random mating is the exemplar for reproductive interaction. While these assumptions have been extremely fruitful for a number of fields, such as population genetics and phylogenetics, they are increasingly unviable for studying the full diversity and evolution of life. I introduce the “mixture” account of population lineages (...) that escapes these assumptions by dissolving the Modern Synthesis’s sharp line separating reproduction and development and characterizing reproductive integration in population lineages by the ephemerality of isolated subgroups rather than random mating. The mixture account provides a single criterion for reproductive integration that accommodates both sexual and asexual reproduction, unifying their treatment under Kevin de Queiroz’s generalized lineage concept of species. The account also provides a new basis for empirically assessing the effect of random mating as an idealization on the empirical adequacy of population genetic models. (shrink)

Ecologist Richard Levins argues population biologists must trade‐off the generality, realism, and precision of their models since biological systems are complex and our limitations are severe. Steven Orzack and Elliott Sober argue that there are cases where these model properties cannot be varied independently of one another. If this is correct, then Levins's thesis that there is a necessary trade‐off between generality, precision, and realism in mathematical models in biology is false. I argue that Orzack and Sober's arguments fail (...) since Levins's thesis concerns the pragmatic features of model building not just the formal properties of models. (shrink)

My thesis is that biology is most plausibly regarded as a universal, as distinct from a provincial, science. First, I develop the general notion of a provincial science, formulate three criteria for applying the concept, and present brief examples illustrating their use. Second, I argue that a consideration of population genetics as a characteristic example of a basic biological theory strengthens the prior presumption that biology is not a provincial science. Finally, I examine two arguments to the effect that (...) biology is a provincial science. The first concerns biology's exclusively terrestrial evidence base, the second the logical character of its laws. I introduce considerations that weaken the persuasiveness of the first argument and then show that the second one rests upon a false premise and so should be rejected. (shrink)

Two new modes of thinking have spread through systematics in the twentieth century. Both have deep historical roots, but they have been widely accepted only during this century. Population thinking overtook the field in the early part of the century, culminating in the full development of population systematics in the 1930s and 1940s, and the subsequent growth of the entire field of population biology. Population thinking rejects the idea that each species has a natural type (as the earlier essentialist view (...) had assumed), and instead sees every species as a varying population of interbreeding individuals. Tree thinking has spread through the field since the 1960s with the development of phylogenetic systematics. Tree thinking recognizes that species are not independent replicates within a class (as earlier group thinkers had tended to see them), but are instead interconnected parts of an evolutionary tree. It lays emphasis on the explanation of evolutionary events in the context of a tree, rather than on the states exhibited by collections of species, and it sees evolutionary history as a story of divergence rather than a story of development. Just as population thinking gave rise to the new field of population biology, so tree thinking is giving rise to the new field of phylogenetic biology. (shrink)

and was correct to conclude that the way a biological population is described should affect conclusions about whether natural selection occurs, but wrong to conclude that natural selection is therefore not a cause. After providing a new argument that ignored crucial biological details, I give a biological illustration that motivates a fairly extreme dependence on description. I argue that contrary to an implication of , biologists allow much flexibility in describing populations, as contemporary research on recent (...) human evolution shows. Properly understood, such description-dependence is consistent with descriptions capturing different causal relations involving the same population. I thus show that Walsh’s arguments fail for reasons that have not previously been understood; I argue that Walsh’s more recent “Sure Thing” argument fails for similar reasons. The resulting view provides a new perspective on causation in evolutionary processes. (shrink)

On the one hand, much has been written on Theodosius Dobzhansky’s central role in the development of the field of population genetics and modern evolutionary theory, as well as on his sociopolitical worldview in the middle of the Twentieth Century. On the other hand, much has also been written on Dobzhansky’s role in the institutionalization of genetics in Brazil, where he spent a considerable amount of time. Unfortunately, these literatures developed without any points of intersection or cross-reference. This article places (...) Dobzhansky’s work in Brazil in the broader contexts of the science and politics of its historical period. (shrink)

Population involves the counting of a group in a place. To count is to know. To know is to intervene. Knowing and intervening are complicated practices. Assigning groups to places is complicated as well. This set of essays, that examine how scientists make Latin American groups into "objects of inquiry and intervention" allows for a fundamental examination of how practicing population can involve seemingly disparate accounts of the relationship of groups to places. North American scientists tend to constitute the (...) class='Hi'>populations described in these papers as biologically essential groups located in timeless landscapes or as malleably cultural groups within national territories, while... (shrink)

The scope of this paper can be clarified by means of a well-known phenomenon that is usually called ‘industrial melanism’: the fact that the melanic form of the peppered moth became dominant in industrial areas in England in the second half of the nineteenth century. Such changes in relative phenotype frequencies are important explananda for population biologists. Apart from trying to explain such changes over time, population biologists also often try to explain differences between populations, e.g. why yellow shell (...) colour is dominant in certain colonies of land snails and almost absent in other colonies. The causal explanations that are given to address such explananda are the objects of analysis in this paper. Our primary aim is to explicate their structure: we want to capture the typical ingredients of causal explanations in population biology, and their organisation. Based on this explication, we discuss how natural selection fits into recent mechanical philosophy of science, and engage in the debate on the nature of evolutionary theory. (shrink)

The recent literature in philosophy of biology has drawn attention to the different sorts of explanations proffered in the biological sciences—we have molecular, biomedical, and evolutionary explanations. Do these explanations all have a common structure or relation that they seek to capture? This paper will answer in the negative. I defend a pluralistic and pragmatic approach to explanation. Using examples from classical population genetics, I argue that formal demonstrations, and even strictly “mathematical truths,” may serve as explanatory in different (...) historical contexts. (shrink)

Population genetics attempts to measure the influence of the causes of evolution, viz., mutation, migration, natural selection, and random genetic drift, by understanding the way those causes change the genetics of populations. But how does it accomplish this goal? After a short introduction, we begin in section (2) with a brief historical outline of the origins of population genetics. In section (3), we sketch the model theoretic structure of population genetics, providing the flavor of the ways in which population (...) genetics theory might be understood as incorporating causes. In sections (4) and (5) we discuss two specific problems concerning the relationship between population genetics and evolutionary causes, viz., the problem of conceptually distinguishing natural selection from random genetic drift, and the problem of interpreting fitness. In section (6), we briefly discuss the methodology and key epistemological problems faced by population geneticists in uncovering the causes of evolution. Section (7) of the essay contains concluding remarks. (shrink)

The biology of race has a long and contentious history, particularly in theUnited States. Thus, it should not be surprising that the use of racial and ethnic categories by some biomedical researchers over the past 20 years has occasioned heated debate among historical, sociological, anthropological, bioethical, genetic, biomedical and molecular biological circles. Differences between the genetics of populations have generated vastly more controversy than genetic differences among individuals of a particular population (Fujimura, Duster, and Rajagopalan 2008). Contemporary racial (...) categories are largely inherited from Carl von Linné (Linnaeus) and Johann Friedrich Blumenbach, both of whom were dedicated to the .. (shrink)

Genetic epidemiology is a rapidly advancing field due to the recent availability of large amounts of omics data. In recent years, it has become possible to obtain omics information at the single‐cell level, so genetic epidemiological models need to be updated to integrate with single‐cell expression data. In this perspective paper, we propose a cell population‐based framework for genetic epidemiology in the single‐cell era. In this framework, genetic diversity influences phenotypic diversity through the diversity of cell population profiles, which are (...) defined as high‐dimensional probability distributions of the state spaces of biomolecules of each omics layer. We discuss how biomolecular experimental measurement data can capture the different properties of this distribution. In particular, single‐cell data constitute a sample from this population distribution where only some coordinate values are observable. From a data analysis standpoint, we introduce methodology for feature extraction from cell population profiles. Finally, we discuss how this framework can be applied not only to genetic epidemiology but also to systems biology. (shrink)

The book presents a new way of understanding Darwinism and evolution by natural selection, combining work in biology, philosophy, and other fields.

The concept of population thinking was introduced by Ernst Mayr as the right way of thinking about the biological domain, but it is difficult to find an interpretation of this notion that is both unproblematic and does the theoretical work it was intended to do. I argue that, properly conceived, Mayr’s population thinking is a version of trope nominalism: the view that biological property-types do not exist or at least they play no explanatory role. Further, although population thinking (...) has been traditionally used to argue against essentialism about biological kinds, recently it has been suggested that it may be consistent with at least some forms of essentialism—ones that construe essential properties as relational. I argue that if population thinking is a version of trope nominalism, then, as Mayr originally claimed, it rules out any version of essentialism about biological kinds. (shrink)

Understanding modeling in biology requires understanding how biology is organized as a discipline and how this organization influences the research practices of biologists. Biology includes a wide range of sub-disciplines, such as cell biology, population biology, evolutionary biology, molecular biology, and systems biology among others. Biologists in sub-disciplines such as cell, molecular, and systems biology believe that the use of a few experimental models allows them to discover biological universals, whereas biologists in sub-disciplines such as ecology and evolutionary biology (...) believe that the use of many different experimental and mathematical models is necessary in order to do this. Many practitioners of both approaches misunderstand best practices of modeling, especially those related to model testing. We stress the need for biologists to better engage with best practices and for philosophers of biology providing normative guidance for biologists to better engage with current developments in biology. This is especially important as biology transitions from a “data-poor” to a “data-rich” discipline. If 21st century biology is going to capitalize on the unprecedented availability of ecological, evolutionary, and molecular data, of computational resources, and of mathematical and statistical tools, biologists will need a better understanding of what modeling is and can be. (shrink)

Biologists studying ecology and evolution use the term “population” in many different ways. Yet little philosophical analysis of the concept has been done, either by biologists or philosophers, in contrast to the voluminous literature on the concept of “species.” This is in spite of the fact that “population” is arguably a far more central concept in ecological and evolutionary studies than “species” is. The fact that such a central concept has been employed in so many different ways is potentially problematic (...) for the reason that inconsistent usages (especially when the usage has not been made explicit) might lead to false controversies in which disputants are simply talking past one another. However, the inconsistent usages are not the only, or even the most important reason to examine the concept. If any set of organisms is legitimately called a “population,” selection and drift processes become purely arbitrary, too. Moreover, key ecological variables, such as abundance and distribution, depend on a nonarbitrary way of identifying populations. I sketch the beginnings of a population concept, drawing inspiration from the Ghiselin-Hull individuality thesis, and show why some alternative approaches are nonstarters. (shrink)

Darwinian evolution is a population-level phenomenon. This paper deals with a structural population concept within the framework of generalized Darwinism, resp. within a generalized theory of evolution. According to some skeptical authors, GD is in need of a valid population concept in order to become a practicable research program. Populations are crucial and basic elements of any evolutionary explanation—biological or cultural—and have to be defined as clearly as possible. I suggest the “causal interactionist population concept”, by R. Millstein (...) for this purpose, and I will try to embed the approach into a generalized evolutionary perspective by mathematically formalizing its key definitions. Using graph-theory, populations as described in the CIPC can serve as proper clusters of evolutionary classification based on the rates of interactions between their elements. I will introduce the concept of a cohesion index as a measurement of possible population candidates within a distribution of elements. The strength of this approach lies in its applicability and interactions are relatively easy to observe. Furthermore, problems of clustering tokens via typicality, e.g. their similarity in intrinsic key characteristics, can be avoided, because CIPC is a external approach. However, some formal problems and conceptual ambiguities occur within a simple version of this CI, which will be addressed in this paper as well as some possible applications. (shrink)

The status of population genetics has become hotly debated among biologists and philosophers of biology. Many seem to view population genetics as relatively unchanged since the Modern Synthesis and have argued that subjects such as development were left out of the Synthesis. Some have called for an extended evolutionary synthesis or for recognizing the insignificance of population genetics. Yet others such as Michael Lynch have defended population genetics, declaring "nothing in evolution makes sense except in the light of population genetics" (...) (a twist on Dobzhansky's famous slogan that "nothing in biology makes sense except in the light of evolution"). Missing from this discussion is the use of population genetics to shed light on ecology and vice versa, beginning in the 1940s and continuing until the present day. I highlight some of that history through an overview of traditions such as ecological genetics and population biology, followed by a slightly more in-depth look at a contemporary study of the endangered California Tiger Salamander. I argue that population genetics is a powerful and useful tool that continues to be used and modified, even if it isn't required for all evolutionary explanations or doesn't incorporate all the causal factors of evolution. (shrink)

Ernst Mayr has argued that Darwinian theory discredited essentialist modes of thought and replaced them with what he has called "population thinking". In this paper, I characterize essentialism as embodying a certain conception of how variation in nature is to be explained, and show how this conception was undermined by evolutionary theory. The Darwinian doctrine of evolutionary gradualism makes it impossible to say exactly where one species ends and another begins; such line-drawing problems are often taken to be the decisive (...) reason for thinking that essentialism is untenable. However, according to the view of essentialism I suggest, this familiar objection is not fatal to essentialism. It is rather the essentialist's use of what I call the natural state model for explaining variation which clashes with evolutionary theory. This model implemented the essentialist's requirement that properties of populations be defined in terms of properties of member organisms. Requiring such constituent definitions is reductionistic in spirit; additionally, evolutionary theory shows that such definitions are not available, and, moreover, that they are not needed to legitimize population-level concepts. Population thinking involves the thesis that population concepts may be legitimized by showing their connections with each other, even when they are not reducible to concepts applying at lower levels of organization. In the paper, I develop these points by describing Aristotle's ideas on the origins of biological variation; they are a classic formulation of the natural state model. I also describe how the development of statistical ideas in the 19th century involved an abandoning of the natural state model. (shrink)

Comparing alternative scientific theories obviously is relevant to theory assessment, but are comparativists (like Laudan) correct when they also make it necessary? This paper argues that they are not. Defining rationality solely in terms of theories' comparative problem-solving strengths, comparativist philosophers of science like Laudan subscribe to what I call the irrelevance claim (IC) and the necessity claim (NC). According to IC, a scientific theory's being well or poorly confirmed is "irrelevant" to its acceptance; NC is the claim that "all (...) evaluations of research traditions and theories must be made within a comparative context," how any theory "compares with its competitors" (Laudan 1977, 21, 120). Using current competing theories (T1 and T2) of population viability assessment (PVA) for the Florida panther, the paper investigates IC/NC. In part because dominant T2 panther biologists accept IC/NC (which T1 theorists reject), the paper argues that they appear both to have accepted flawed T2 and to have contributed to flawed panther science and policy. Correcting Laudan's Comparativist Philosophy of Science (LCPS), underlying the T1-versus-T2 debate, thus may hold promise for helping resolve both the scientific and policy controversy over panther PVA. (shrink)

In our 1993 paper, “A Critical Look,‘ Elliott Sober and I concluded that the famous claim about model formulation and constraints made by Richard Levins in his influential 1966 article on model building in population biology is neither true nor normative. Here, I comment upon the claim of Odenbaugh that the conclusions of “A Critical Look‘ are incorrect. My conclusions remain that Levins’ claim about the tradeoff between model properties lacks logical coherence, generates an arbitrary model classification, and lacks normative (...) utility. Accordingly, I view his claim as providing no useful insight into the nature of models and model building in population biology. (shrink)

Biologists and philosophers have offered differing concepts of biological race. That is, they have offered different candidates for what a biological correlate of race might be; for example, races might be subspecies, clades, lineages, ecotypes, or genetic clusters. One thing that is striking about each of these proposals is that they all depend on a concept of population. Indeed, some authors have explicitly characterized races in terms of populations. However, including the concept of population into concepts of (...) race raises three puzzles, all having to do with time. In this paper, I extend the causal interactionist population concept (CIPC) by introducing some simple assumptions about how to understand populations through time. These assumptions help to shed light on the three puzzles, and in the process show that if we want to understand races in terms of populations, we will need to revise our concept(s) of race. (shrink)