Biological Theory

According to the species-as-individuals thesis (hereafter S-A-I), species are cohesive entities. Barker and Wilson recently pointed out that the type of cohesion exhibited by species is fundamentally different from that of organisms (paradigmatic individuals), suggesting that species are homeostatic property cluster kinds. In this article, I propose a shift in how to approach cohesion in the context of S-A-I: instead of analyzing the different types of cohesion and questioning whether species have them, I focus on the role played by cohesion in the identity of individuals. This shift allows us to recognize why cohesion matters to S-A-I, as well as to reconceive the analogy between species and organisms (paradigmatic individuals), and also allows us to highlight the context sensitivity of both “cohesion” and “individuals.” From this perspective, I identify two problems in Barker and Wilson’s argumentation. Firstly, the authors fail to recognize that species are individuals even if they do not have the same type of cohesion that organisms have. Secondly, their argument relies on a misinterpretation of S-A-I. I conclude that species cohesion is still best framed as a feature of species individuality rather than a feature of species as homeostatic property cluster kinds. The arguments presented here contribute to the re-articulation and reevaluation of S-A-I in the face of contemporary discussions.

In the study reported here we examined the impact of population size and two proxies of risk of resource failure on the diversity and complexity of the food-getting toolkits of hunter–gatherers and small-scale food producers. We tested three hypotheses: the risk hypothesis, the population-size hypothesis, and a hypothesis derived from niche construction theory. Our analyses indicated that the toolkits of hunter–gatherers are more affected by risk than are the toolkits of food producers. They also showed that the toolkits of food producers are more affected by population size than are the toolkits of hunter–gatherers. This pattern is inconsistent with the predictions of both the risk hypothesis and the population-size hypothesis. In contrast, it is consistent with the predictions of the niche construction hypothesis. Our results indicate that niche construction has affected the evolution of technology in small-scale societies and imply that niche construction must be taken into account when seeking to understand technological variation among food producers and the technological changes that occurred in association with the various transitions to farming that have occurred over the last 10,000 years.

I reconstruct the relationship between the evolutionary geneticists Theodosius Dobzhansky (1900–1975) and Richard Lewontin (1929–2021). Using archival research and published texts, I show that Lewontin inherited his dissertation director’s research program as well as his “biology of democracy.” He did so in circumstances in which the molecular revolution in genetics was threatening both Dobzhansky’s science and his anti-racist social ideals. Lewontin’s sometimes rocky relationship with the person he called “my professor” sprang from his perception that Dobzhansky was not up to managing the research program that Lewontin received from him. I explain how Lewontin took charge and the role his Marxist interpretive lens plays in his argument.

The term “legacy effect” has been used in ecology since the early 1990s by authors studying plant succession, invasive-plant impacts, herbivory impacts, ecosystem engineering, and human land-use impacts. Although there is some variability in usage, the term is normally used to describe impacts of a species on abiotic or biotic features of ecosystems that persist for a long time after the species has been extirpated or ceased activity and which have an effect on other species. For example, human agricultural activities may have a legacy effect on soil structure and vegetative communities that lasts for centuries and which alters current communities. The concept may be related to the idea of ecological inheritance in evolutionary biology but would refer only to a subset of the features of this concept. In particular, legacy effects could refer to those kinds of ecological inheritance where a physical or biological change in ecosystem state is caused by one species, where this change persists after the extirpation of the causal species and alters selection pressure of another species much later in time.

Aristotle’s influence on D’Arcy Thompson was praised by Thompson himself and has been recognized by others in various respects, including the aesthetic and normative dimensions of biology, and the multicausal explanation of living forms. This article focuses on the relatedness of organic forms, one of the core problems addressed by both Aristotle’s History of Animals (HA), and the renowned chapter of Thompson’s On Growth and Form (G&F), “On the Theory of Transformations, or the Comparison of Related Forms.” We contend that, far from being an incidental inspiration stemming from Thompson’s classicist background, his translation of HA played a pivotal role in developing his theory of transformations. Furthermore, we argue that Thompson’s interpretation of the Aristotelian method of comparison challenges the prevailing view of Aristotle as the founder of “typological essentialism,” and is a key episode in the revision of this narrative. Thompson understood that the method Aristotle used in HA to compare animal forms is better comprehended as a “method of transformations,” leading to a morphological arrangement of animal diversity, as opposed to a taxonomical classification. Finally, we examine how this approach to the relatedness of forms lay the foundation for a causal understanding of parts and their interconnections. Although Aristotle and Thompson emphasized distinct types of causes, we contend that they both differ in a fundamental sense from the one introduced by Darwin’s theory of natural selection, which was formulated as a solution to the species problem rather than the form problem. We conclude that Thompson’s interpretation of Aristotle’s approach to form comparison has not only impacted contemporary scholarship on Aristotle’s biology, but revitalized a perspective that has regained significance due to the resurgence of the problem of form in evo-devo.

When developing phylogenetic systematics, the entomologist Willi Hennig adopted elements from Nicolai Hartmann’s ontology. In this historical essay I take on the task of documenting this adoption. I argue that in order to build a metaphysical foundation for phylogenetic systematics, Hennig adopted from Hartmann four main metaphysical theses. These are (1) that what is real is what is temporal; (2) that the criterion of individuality is to have duration; (3) that species are supra-individuals; and (4) that there are levels of reality, each of which may be subject to different kinds of law. Reliance on Hartmann’s metaphysics allowed Hennig to ground some of the main theoretical principles of phylogenetic systematics, namely that the biological categories—from the semaphoront to the highest rank—have reality and individuality despite not being universals, and that they form a hierarchy of levels, each of which may require different kinds of explanation. Hartmann’s metaphysics thereby provided a philosophical justification for Hennig’s phylogenetic systematics, both as a theory and as a method of classification.