Hamilton’s indicators of the force of selection

Hamilton quantified the force of selection on an age-specific mutation. Hamilton’s indicators of the age-specific force of selection always decline with age. This result is of profound importance to the theory of the evolution of senescence. Here I derive alternative indicators within Hamilton’s framework. These indicators are as plausible and valid as Hamilton’s and in some circumstances and over some age ranges they increase with age.

The state ratchet

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How ageing is shaped by trade-offs

The evolution of different life history strategies and thus different ageing patterns essentially depends on the nature of the underlying trade-offs between survival and reproduction. To fully comprehend ageing, we need to understand these trade-offs.ageing

Functional Demand Satiation and Industrial Dynamcis - The Emergence of the Global Value Chain for the U.S. Footwear Industry

Around 1940 Schumpeter draws on an analysis of the U.S. footwear industry as an exemplar case to formulate his famous hypothesis about the positive relation between market concentration and innovative activity. Starting in the 1970s the value chain of U.S. footwear producers disintegrates, eventually separating the process of product innovation from manufacturing in this industry. Studies testing Schumpeter’s hypothesis commonly do not account for the modularity and globalization of an industry’s value chain. Schumpeter having neglected the demand side in his theorizing, we argue that the separation of product innovation and manufacturing in the U.S. footwear industry is influenced by functional satiation effects on demand. If the functional requirements of consumers are met, their willingness to pay for ever more product varieties decreases. Since the early 1970s the ‘oversupply’ of new product varieties and the simultaneously decreasing price level drive market growth beyond functional satiation (Frenzel Baudisch, 2006b). In this paper we argue that this simultaneous price and innovation competition separates the product innovation process from manufacturing to gain economies in both of these processes simultaneously. Discussing the consumers’ motivations to buy products beyond their functional requirements offers a deeper qualitative understanding of the business practices revealed in the historical case of the U.S. footwear industry.Industrial organization, Schumpeter hypothesis, Modular Value Chain, Consumer Behavior, Footwear Industry

Senescence vs. sustenance: Evolutionary-demographic models of aging

Humans, and many other species, suffer senescence: mortality increases and fertility declines with adult age. Some species, however, enjoy sustenance: mortality and fertility remain constant. Here we develop simple but general evolutionary-demographic models to explain the conditions that favor senescence vs. sustenance. The models illustrate how mathematical demography can deepen understanding of the evolution of aging.aging, eusociality, evolution, fertility, hydra, mortality, senescence, sustenance

Senescence vs. sustenance: evolutionary-demographic models of aging

Humans, and many other species, suffer senescence: mortality increases and fertility declines with adult age. Some species, however, enjoy sustenance: mortality and fertility remain constant. Here we develop simple but general evolutionary-demographic models to explain the conditions that favor senescence vs. sustenance. The models illustrate how mathematical demography can deepen understanding of the evolution of aging.