Most historians and social scientists undoubtedly would not agree with genetic explanations (whether plastic or not) for events in human history such as the Industrial Revolution. Even if evolution minded, they would more likely point to cultural or sociocultural evolution involving cultural innovation, transmission by social learning through observation or linguistically encoded instructions, and selection, that is, differences in the viability and rates of spread of innovations (e.g., Blute Reference Blute2010; Boyd & Richerson Reference Boyd and Richerson1985; Cavalli-Sforza & Feldman Reference Cavalli-Sforza and Feldman1981). However, Life History Theory (LHT, including adaptive phenotypic plasticity) could be considered in that context, as well.
To the extent that there is a general evolutionary biological general theory of LHT (and it is commonly denied that there is [e.g., Jones et. al. Reference Jones, Scheuerlein and Salguero-Gómez2014; Reznick et al. Reference Reznick, Bryant and Bashey2002; Roff Reference Roff2002], preferring instead to deal with the relevant pairs of properties individually), the most general theory ever proposed is that of density-dependent selection (MacArthur Reference MacArthur1962; MacArthur & Wilson Reference MacArthur and Wilson1967) expressed in the S-shaped logistic function:
The function relates the growth of a population at time t (the tangent to the curve relating population size to time) to the existing population size (N t) and two parameters – the intrinsic rate of increase (r) and the carrying capacity of the environment (K). The theory maintains that at low densities relative to resources (or a history of catastrophes in a growing population), selection should act to maximize r by means of rapid growth and development, a small body size, many small offspring in a batch with little invested in each at short interbirth intervals, and a short life cycle. By contrast, at high densities relative to resources (or it should be added with a history of bonanzas in a declining population), selection should act to cope with K by means of longer slower growth and development, a large body size, few large offspring in a batch with a lot invested in each, at long interbirth intervals, and a long life cycle. Think mice versus men. It has been suggested that these are because small organisms, with their disproportionate surface area relative to volume, are adapted to consume (eat and excrete) more and produce more numerous smaller offspring but fewer potential grand offspring from each. On the other hand, the large, with their disproportionate volume relative to surface area, are adapted to digest (break down and build up mechanisms to disperse in time, space, and/or niche) more and produce fewer larger offspring but more potential grand offspring from each (Blute Reference Blute2016). These r-versus-K properties are all quantity versus quality and current versus future orientation – more or less the reverse of how Baumard has it!
On reflection, however, I was intrigued by his analysis. I think the difference is that evolutionary ecologists commonly deal with the benefits of alternative strategies under particular conditions (explicitly or implicitly assuming that costs are equal) with r selection if resources are plentiful and K selection if they are scarce. Baumard, on the other hand, is implicitly paying more attention to costs. According to him, the English made the Industrial Revolution because they were affluent and could therefore afford to innovate because resources were plentiful. “Innovation” is not a term in LHT but there are two possible interpretations – mutation and plasticity. Because mutations normally occur during DNA replication, they are likely more common in r-selected organisms with their short generation times and many offspring (although not necessarily per capita if somatic mutations are taken into account). Plasticity is normally theoretically associated with uncertainty – uncertainty favouring bet hedging and uncertainty with reliable cues favouring adaptive phenotypic plasticity. However, plasticity is likely more common in K-selected organisms, with their large body size and long life cycle yielding more time and space for morphological, physiological, and behavioural flexibility.
Plasticity is likely to be less beneficial in r-selected organisms and more beneficial in K-selected organisms, enabling the latter to escape from scarcity in time, space, and/or niche but here is the point. Plasticity could conceivably be less costly in r-selected organisms and more costly in K-selected organisms. I would not hazard an opinion on what caused the industrial evolution in eighteenth-century Britain, including whether or not the psychology of individuals was what was important. If so however, it is clear to me that both LHT and Baumard should explicitly include both benefits and costs. For example, they should consider the case in which benefits are low and costs high of plasticity under good resource conditions and the case in which benefits are high and costs low under poor resource conditions more like a LHT view. Or, alternatively, consider the case in which benefits and costs of plasticity are low under good resource conditions and high under poor resource conditions, which would at least neutralize the way in which the life history approach seems to contradict Baumard. In any event, I enjoyed reading the article, which raised these issues for me.
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Most historians and social scientists undoubtedly would not agree with genetic explanations (whether plastic or not) for events in human history such as the Industrial Revolution. Even if evolution minded, they would more likely point to cultural or sociocultural evolution involving cultural innovation, transmission by social learning through observation or linguistically encoded instructions, and selection, that is, differences in the viability and rates of spread of innovations (e.g., Blute Reference Blute2010; Boyd & Richerson Reference Boyd and Richerson1985; Cavalli-Sforza & Feldman Reference Cavalli-Sforza and Feldman1981). However, Life History Theory (LHT, including adaptive phenotypic plasticity) could be considered in that context, as well.
To the extent that there is a general evolutionary biological general theory of LHT (and it is commonly denied that there is [e.g., Jones et. al. Reference Jones, Scheuerlein and Salguero-Gómez2014; Reznick et al. Reference Reznick, Bryant and Bashey2002; Roff Reference Roff2002], preferring instead to deal with the relevant pairs of properties individually), the most general theory ever proposed is that of density-dependent selection (MacArthur Reference MacArthur1962; MacArthur & Wilson Reference MacArthur and Wilson1967) expressed in the S-shaped logistic function:
The function relates the growth of a population at time t (the tangent to the curve relating population size to time) to the existing population size (N t) and two parameters – the intrinsic rate of increase (r) and the carrying capacity of the environment (K). The theory maintains that at low densities relative to resources (or a history of catastrophes in a growing population), selection should act to maximize r by means of rapid growth and development, a small body size, many small offspring in a batch with little invested in each at short interbirth intervals, and a short life cycle. By contrast, at high densities relative to resources (or it should be added with a history of bonanzas in a declining population), selection should act to cope with K by means of longer slower growth and development, a large body size, few large offspring in a batch with a lot invested in each, at long interbirth intervals, and a long life cycle. Think mice versus men. It has been suggested that these are because small organisms, with their disproportionate surface area relative to volume, are adapted to consume (eat and excrete) more and produce more numerous smaller offspring but fewer potential grand offspring from each. On the other hand, the large, with their disproportionate volume relative to surface area, are adapted to digest (break down and build up mechanisms to disperse in time, space, and/or niche) more and produce fewer larger offspring but more potential grand offspring from each (Blute Reference Blute2016). These r-versus-K properties are all quantity versus quality and current versus future orientation – more or less the reverse of how Baumard has it!
On reflection, however, I was intrigued by his analysis. I think the difference is that evolutionary ecologists commonly deal with the benefits of alternative strategies under particular conditions (explicitly or implicitly assuming that costs are equal) with r selection if resources are plentiful and K selection if they are scarce. Baumard, on the other hand, is implicitly paying more attention to costs. According to him, the English made the Industrial Revolution because they were affluent and could therefore afford to innovate because resources were plentiful. “Innovation” is not a term in LHT but there are two possible interpretations – mutation and plasticity. Because mutations normally occur during DNA replication, they are likely more common in r-selected organisms with their short generation times and many offspring (although not necessarily per capita if somatic mutations are taken into account). Plasticity is normally theoretically associated with uncertainty – uncertainty favouring bet hedging and uncertainty with reliable cues favouring adaptive phenotypic plasticity. However, plasticity is likely more common in K-selected organisms, with their large body size and long life cycle yielding more time and space for morphological, physiological, and behavioural flexibility.
Plasticity is likely to be less beneficial in r-selected organisms and more beneficial in K-selected organisms, enabling the latter to escape from scarcity in time, space, and/or niche but here is the point. Plasticity could conceivably be less costly in r-selected organisms and more costly in K-selected organisms. I would not hazard an opinion on what caused the industrial evolution in eighteenth-century Britain, including whether or not the psychology of individuals was what was important. If so however, it is clear to me that both LHT and Baumard should explicitly include both benefits and costs. For example, they should consider the case in which benefits are low and costs high of plasticity under good resource conditions and the case in which benefits are high and costs low under poor resource conditions more like a LHT view. Or, alternatively, consider the case in which benefits and costs of plasticity are low under good resource conditions and high under poor resource conditions, which would at least neutralize the way in which the life history approach seems to contradict Baumard. In any event, I enjoyed reading the article, which raised these issues for me.