Criticisms of the “container” model of pregnancy picturing female and embryo as separate entities multiply in various philosophical and scientific contexts during the last decades. In this paper, we examine how this model underlies received views of pregnancy in evolutionary biology, in the characterization of the transition from oviparity to viviparity in mammals and in the selectionist explanations of pregnancy as an evolutionary strategy. In contrast, recent evo-devo studies on eutherian reproduction, including the role of inflammation and new maternal cell types, gather evidence in favor of considering pregnancy as an evolved relational novelty. Our thesis is that from this perspective we can identify the emergence of a new historical individual in evolution. In evo-devo, historical units are conceptualized as evolved entities which fulfill two main criteria, their continuous persistence and their non-exchangeability. As pregnancy can be individuated in this way, we contend that pregnant females are historical individuals. We argue that historical individuality differs from, and coexists with, other views of biological individuality as applied to pregnancy (the physiological, the evolutionary and the ecological one), but brings forward an important new insight which might help dissolve misguided conceptions.

Since the late 1970s, the field of evolutionary biology has undergone empirical and theoretical developments that have threaten the pillars of evolutionary theory. Some evolutionary biologists have recently argued that evolutionary biology is not experiencing a paradigm shift, but an expansion of the modern synthesis. Philosophers of biology focusing on scientific practices seem to agree with this pluralistic interpretation and have argued that evolutionary theory should rather be seen as an organized network of multiple problem agendas with diverse disciplinary contributors. In this paper, I apply a computational analysis to study the dynamics and conceptual structure of one of the main emerging problem agendas in evolutionary biology: evolvability. I have used CiteSpace, an application for visualizing and analyzing trends and patterns in scientific literature that applies cocitation analysis to identify scientific specialities. I analyze the main clusters of the evolvability cocitation network with the aim to identify the main research lines and the interdisciplinary relationships that structure this research front. I then compare these results with the existing classifications of evolvability concepts, and identify four main conceptual tensions within the definitions of evolvability. Finally, I argue that there is a lot of usefulness in the inconsistency in which the term evolvability is used in biological research. I claim that evolvability research has set up "trading zones" in biology that make possible interdisciplinary exchanges.

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By examining development at the level of tissues and processes, rather than focusing on gene expression, we have formulated a general hypothesis to explain the dorso-ventral and anterior-posterior placement of paired appendage initiation sites in vertebrates. According to our model, the number and position of paired appendages are due to a commonality of embryonic tissue environments determined by the global interactions involving the two separated layers (somatic and visceral) of lateral plate mesoderm along the dorso-ventral and anterior-posterior axes of the embryo. We identify this distribution of developmental conditions, as modulated by the separation/contact of the two LPM layers and their interactions with somitic mesoderm, ectoderm, and endoderm as a dynamic developmental entity which we have termed the lateral mesodermal divide (LMD). Where the divide results in a certain tissue environment, fin bud initiation can occur. According to our hypothesis, the influence of the developing gut suppresses limb initiation along the midgut region and the ventral body wall owing to an "endodermal predominance." From an evolutionary perspective, the lack of gut regionalization in agnathans reflects the ancestral absence of these conditions, and the elaboration of the gut together with the concomitant changes to the LMD in the gnathostomes could have led to the origin of paired fins.