Seeds show important variation as plant regenerative units among species, but their evolutionary co-variations with other plant characteristics are still poorly understood. Whilst a positive association of seed mass with genome size (GS) and life forms has already been documented, a broad-scale quantification of their evolutionary correlation and adaptive selection has never been conducted. Here, we tested for correlated evolution of seed mass and GS towards distinct selective regimes related to life form in angiosperms. In particular, we tested the hypothesis that the selection toward lighter seeds and smaller genomes is stronger for annual plants, ensuring high regenerative potential. Using multivariate evolutionary models over a dataset containing 3242 species, we showed an overall positive correlated evolution of seed mass and GS deviating from a pure drift process. Instead, evolutionary changes in seed and genome sizes were driven by adaptive selection towards optimal values differing among life forms. Specifically, the evolutionary optima towards which the seed and genome sizes evolve show a covariation toward small values in annuals, intermediate values in perennial herbs and a trade-off between seed mass and GS in woody plants. Moreover, the evolutionary correlation between seed mass and GS is strongest in annuals as an adaption to complete their life cycle in a short time window, when environmental conditions are favourable for regeneration and development to maturity. The asymmetry in the correlated evolution acting on seed and genome sizes due to life form could explain how life-history traits interplay with functional traits and how plants have evolved diverse successful life-history strategies.

Professor Hodgson in his review of my A Culture of Growth (Princeton University Press, 2016) raises a number of important issues. One of them is the usefulness of the concept of a ‘market for ideas’ as an analytical tool in discussing the way cultural change affects economic change. Even though there is no price mechanism that clears the market, many basic components of the economic analysis of markets carry through and enriched by evolutionary concepts. A second question is the importance of cultural entrepreneurs, who play an important role in my book. It should be stressed that such ‘Vital Few’ were rarely indispensable, yet their influence on subsequent events may have imparted a direction on events and accelerated them. In any event, the success of such entrepreneurs was an indication of an intellectual environment sufficiently open to new ideas to be consistent with major new ideas such as the possibility and desirability of sustained economic progress.