Natural selection. IV. The Price equation

The Price equation partitions total evolutionary change into two components. The first component provides an abstract expression of natural selection. The second component subsumes all other evolutionary processes, including changes during transmission. The natural selection component is often used in applications. Those applications attract widespread interest for their simplicity of expression and ease of interpretation. Those same applications attract widespread criticism by dropping the second component of evolutionary change and by leaving unspecified the detailed assumptions needed for a complete study of dynamics. Controversies over approximation and dynamics have nothing to do with the Price equation itself, which is simply a mathematical equivalence relation for total evolutionary change expressed in an alternative form. Disagreements about approach have to do with the tension between the relative valuation of abstract versus concrete analyses. The Price equation's greatest value has been on the abstract side, particularly the invariance relations that illuminate the understanding of natural selection. Those abstract insights lay the foundation for applications in terms of kin selection, information theory interpretations of natural selection, and partitions of causes by path analysis. I discuss recent critiques of the Price equation by Nowak and van Veelen

Knowledge, Belief, and Assertion

The traditional answer to the question what it is to make an\ud assertion appeals to belief (see Grice 1989 and Searle\ud 1969). To assert something, so the analysis goes, is to\ud express a belief by way of uttering a sentence. Timothy\ud Williamson claims (1) that on the traditional analysis\ud assertion is constitutively governed by the truth rule (242):1\ud One must: assert p only if p is true.\ud He argues (2) that the traditional analysis is mistaken, and\ud (3) that assertion is constitutively governed by the\ud knowledge rule instead (243):\ud One must: assert p only if one knows p.\ud I will argue that all three of these claims are false

Receptor uptake arrays for vitamin B12, siderophores and glycans shape bacterial communities

Molecular variants of vitamin B12, siderophores and glycans occur. To take up variant forms, bacteria may express an array of receptors. The gut microbe Bacteroides thetaiotaomicron has three different receptors to take up variants of vitamin B12 and 88 receptors to take up various glycans. The design of receptor arrays reflects key processes that shape cellular evolution. Competition may focus each species on a subset of the available nutrient diversity. Some gut bacteria can take up only a narrow range of carbohydrates, whereas species such as B.~thetaiotaomicron can digest many different complex glycans. Comparison of different nutrients, habitats, and genomes provide opportunity to test hypotheses about the breadth of receptor arrays. Another important process concerns fluctuations in nutrient availability. Such fluctuations enhance the value of cellular sensors, which gain information about environmental availability and adjust receptor deployment. Bacteria often adjust receptor expression in response to fluctuations of particular carbohydrate food sources. Some species may adjust expression of uptake receptors for specific siderophores. How do cells use sensor information to control the response to fluctuations? That question about regulatory wiring relates to problems that arise in control theory and artificial intelligence. Control theory clarifies how to analyze environmental fluctuations in relation to the design of sensors and response systems. Recent advances in deep learning studies of artificial intelligence focus on the architecture of regulatory wiring and the ways in which complex control networks represent and classify environmental states. I emphasize the similar design problems that arise in cellular evolution, control theory, and artificial intelligence. I connect those broad concepts to testable hypotheses for bacterial uptake of B12, siderophores and glycans.Comment: Added many new references, edited throughou

Microbial metabolism: optimal control of uptake versus synthesis

Microbes require several complex organic molecules for growth. A species may obtain a required factor by taking up molecules released by other species or by synthesizing the molecule. The patterns of uptake and synthesis set a flow of resources through the multiple species that create a microbial community. This article analyzes a simple mathematical model of the tradeoff between uptake and synthesis. Key factors include the influx rate from external sources relative to the outflux rate, the rate of internal decay within cells, and the cost of synthesis. Aspects of demography also matter, such as cellular birth and death rates, the expected time course of a local resource flow, and the associated lifespan of the local population. Spatial patterns of genetic variability and differentiation between populations may also strongly influence the evolution of metabolic regulatory controls of individual species and thus the structuring of microbial communities. The widespread use of optimality approaches in recent work on microbial metabolism has ignored demography and genetic structure

Capital\u27s Offense: Law\u27s Entrenchment of Inequality

Reviewing Thomas Piketty, Capital in the Twenty-First Century (Harvard University Press, 2014) Piketty’s Capital in the Twenty-First Century is a rare scholarly achievement. It weaves together description and prescription, facts and values, economics, politics, and history, with an assured and graceful touch. So clear is Piketty’s reasoning, and so compelling the enormous data apparatus he brings to bear, that few can doubt he has fundamentally altered our appreciation of the scope, duration, and intensity of inequality. This review explains Piketty’s analysis and its relevance to law and social theory, drawing lessons for the re-emerging field of political economy. The university enables interdisciplinary work, and political economy is an ideally hybrid discursive space for this process of mutual inspiration and correction. Lawyers are particularly well-suited to the task of studying political economy, because we are the ones drafting, interpreting, and applying the rules governing the interface between state actors and firms. Integrating the long-divided fields of politics and economics, a renewal of modern political economy could unravel problems inadequately addressed by narrower specializations. Piketty’s work shows how inquiries in both law and political economy will be enriched by their interaction

The Editor\u27s Song

The program of the 2011 Mathfest\u27s opening banquet was MAA-The Musical!\u27 Produced by Annalisa Crannell and starring the MAA Players (active MAA members all), it highlighted activities of the Association and of Mathfest itself. This song represents the journals. It was sung by past editor Frank Farris to the tune of A Wand\u27ring Minstrel I, from Gilbert and Sullivan\u27s the Mikado

Variable Side-Look Angle Concept For Radar Mapping

Radar mapping of planets can be accomplished at lower cost and with reduced emphasis on propulsion system capability from spacecraft operating in elliptical orbit than from circular orbit