FORWARD
About ten years ago Jean presented on “Darwin and Statistics” at an IHPST workshop on “Evolution and Ecology.” At the time, I was starting a project about how Darwin used a variety of techniques to analyze statistical data in order to develop evolutionary ideas. So, I was keen on what Jean had to say. My interest was the same as Jean’s, to rebuff the common claim among historians and philosophers (including Jean) that through Darwin’s emphasis on variation and chance he made evolution “ripe” for statistical methods, though he lacked the abilities to apply statistical methods himself. Like me, Jean had discovered in Darwin’s private notebooks and correspondences (1856-58) that Darwin was applying the botanical arithmetic in creative ways, and that this work “deeply affected central pieces of Darwin’s evolutionary thinking: varieties as "incipient species" principle of divergence, and the "diagram" (Chapter Four of the Origin of Species 4). A few years later, I contacted Jean to share some of my additional discoveries and ask him if he would like to collaborate on an essay. He agreed and sent me his PowerPoint. Regretfully, I set the project aside to work on other things.
Several years later, I met Jean for lunch where mentioned that I was writing a manuscript on Darwin and statistics and he expressed interest in reading a draft as well as rekindling the joint project of fleshing out his 2012 presentation on the botanical arithmetic. At the end of the lunch Jean warned me to “hurry up” because the cancer he was battling shifted to a more aggressive form. There is no good end to this story. Regretfully, I did not complete the project and my
future attempt will be without Jean’s guidance. The focus of this workshop, in July 2022, dedicated to Jean’s memory, concerns the Descent of Man which contains no application of the botanical arithmetic. So, our joint project will have to wait another occasion…

Yet Darwin’s discussion of “the proportion of sexes in relation to natural selection” in Chapter Eight of the Descent of Man contains an extensive analysis of statistical information about sex ratios for a variety of species. So, it fits within the overall theme of our project and is suitable for the present volume and, I hope, Jean would have enjoyed discussing it (whether he would have agreed with what I have to say is another story
altogether).