In this article, we discuss epistemological limitations relating to the use of ethnoracial categories in biomedical research as devised by the Office of Management and Budget’s institutional guidelines. We argue that the obligation to use ethnoracial categories in genomics research should be abandoned. First, we outline how conceptual imprecision in the definition of ethnoracial categories can generate epistemic uncertainty in medical research and practice. Second, we focus on the use of ethnoracial categories in medical genetics, particularly genomics-based precision medicine, where (...) ethnoracial identity is understood as a proxy for medically relevant differences among individuals. Notably, extensive criticisms have been made already against the genetic interpretation of races, but, nonetheless, the concept of race remains a key element of contemporary genomics. This motivates us to explore possible reasons why such criticisms may have been ineffective in redirecting attention to other (non-race-based) ways of controlling for human variability. We contend that popular arguments against the idea that human races have a genetic basis, though convincing in many respects, are not sufficient to exclude the pragmatic use of race and ethnicity as proxies for genetic variability related to complex phenotypes. Finally, we provide two further arguments to support the idea that ethnoracial categories are unlikely to provide meaningful insights into medical genetics, which implies that even the interpretation of race as a useful tool to stratify disease risk is unwarranted. (shrink)

This article reviews the edited volume “Evolvability: A Unifying Concept in Evolutionary Biology?” through biological and philosophical lenses. The book provides diverse angles on evolvability, which is affected by various hierarchical levels, timescales, and types of variation, thus moving beyond a purely genomics perspective. Evolvability is important to biosemiotics because understanding the dynamics of topological genotype spaces could help one better comprehend the phenotypic spaces of meaning, as developmental codes and interrelations can influence the emergence of biological novelty over time. (...) This book is successful in provoking thought on evolvability's role as both a product and a driver of evolutionary innovations and explores the philosophical implications of how evolution has the capacity to generate novel forms of meaning. (shrink)

Advances in developmental genetics and evo-devo in the last several decades have enabled the growth of novel developmental approaches to the classic theme of homology. These approaches depart from the more standard phylogenetic view by contending that homology between morphological characters depends on developmental-genetic individuation and explanation. This article provides a systematic re-examination of the relationship between developmental and phylogenetic homology in light of current evidence from developmental and evolutionary genetics and genomics. I present a qualitative model of the processes (...) that cause de-coupling of morphological and molecular evolution by developmental system drift (DSD), and hypothesize that DSD is a widespread and regular stochastic process that is predictable from parameters such as population size, pleiotropy, and regulatory redundancy. These theoretical findings support an integrative approach in which models of DSD aid in determining when developmental-genetic explanations of homology apply and when other explanations such as stabilizing selection are needed. I argue that a phylogenetic monism about the definition and criteria of homology supports the integration of different explanations into a theory of homology better than pluralism does. (shrink)

The logic of genetic discovery has changed little over time, but the focus of biology is shifting from simple genotype–phenotype relationships to complex metabolic, physiological, developmental, and behavioral traits. In light of this, the traditional reductionist view of individual genes as privileged difference‐making causes of phenotypes is re‐examined. The scope and nature of genetic effects in complex regulatory systems, in which dynamics are driven by regulatory feedback and hierarchical interactions across levels of organization are considered. This review argues that it (...) is appropriate to treat genes as specific actual difference‐makers for the molecular regulation of gene expression. However, they are often neither stable, proportional, nor specific as causes of the overall dynamic behavior of regulatory networks. Dynamical models, properly formulated and validated, provide the tools to probe cause‐and‐effect relationships in complex biological systems, allowing to go beyond the limitations of genetic reductionism to gain an integrative understanding of the causal processes underlying complex phenotypes. (shrink)

There have been repeated attempts in the history of comparative biology to provide a mechanistic account of morphological homology. However, it is well-established that homologues can develop from diverse sets of developmental causes, appearing not to share any core causal architecture that underwrites character identity. We address this challenge with a new conceptual model of Character Identity Mechanisms. ChIMs are cohesive mechanisms with a recognizable causal profile that allows them to be traced through evolution as homologues despite having a diverse (...) etiological organization. Our model hypothesizes that anatomical units at different levels of organization—cell types, tissues, and organs—have level-specific ChIMs with different conserved parts, activities, and organization. Relying on a methodology of conceptual engineering, we show how the ChIM concept advances our understanding of the developmental basis of morphological characters, while forging an important link between comparative and mechanistic biology. (shrink)

Evolutionary biology is paying increasing attention to the mechanisms that enable phenotypic plasticity, evolvability, and extra‐genetic inheritance. Yet, there is a concern that these phenomena remain insufficiently integrated within evolutionary theory. Understanding their evolutionary implications would require focusing on phenotypes and their variation, but this does not always fit well with the prevalent genetic representation of evolution that screens off developmental mechanisms. Here, we instead use development as a starting point, and represent it in a way that allows genetic, environmental (...) and epigenetic sources of phenotypic variation to be independent. We show why this representation helps to understand the evolutionary consequences of both genetic and non‐genetic phenotype determinants, and discuss how this approach can instigate future areas of empirical and theoretical research. (shrink)

Comparative biology builds up systematic knowledge of the diversity of life, across evolutionary lineages and levels of organization, starting with evidence from a sparse sample of model organisms. In developmental biology, a key obstacle to the growth of comparative approaches is that the concept of homology is not very well defined for levels of organization that are intermediate between individual genes and morphological characters. In this paper, we investigate what it means for ontogenetic processes to be homologous, focusing specifically on (...) the examples of insect segmentation and vertebrate somitogenesis. These processes can be homologous without homology of the underlying genes or gene networks, since the latter can diverge over evolutionary time, while the dynamics of the process remain the same. Ontogenetic processes like these therefore constitute a dissociable level and distinctive unit of comparison requiring their own specific criteria of homology. In addition, such processes are typically complex and nonlinear, such that their rigorous description and comparison not only requires observation and experimentation, but also dynamical modeling. We propose six criteria of process homology, combining recognized indicators with novel ones derived from dynamical systems modeling. We show how these criteria apply to animal segmentation and other ontogenetic processes. We conclude by situating our proposed dynamical framework for homology of process in relation to similar research programs, such as process structuralism and developmental approaches to morphological homology. (shrink)