Blute Blog

I have been away from this blog for awhile – spring is travel time for many academics and I recently had interesting visits to Paris and Montreal. I came home, among other things, to a couple of issues of Nature. One interesting article by Malmgren et. al. (June 3, gated) on the role of mentorship in science related to a question I had been asked while away .

I had been asked why I talk about offspring “production” and “re-production” rather than the more common replication (for asexuals) or reproduction (for sexuals). The reason I use the term “offspring production” is that reproduction or replication has not taken place until the complete life-cycle has been repeated. Consider for example a semelparous (“big bang”) life cycle in which individuals grow and then produce offspring all at the end of the life cycle. Such an individual grows and produces offspring, but its life cycle has not actually been repeated until those offspring have grown and produced offspring in turn – i.e. until grand-offspring have been born. Until then, it is more logical to say the parents have “produced” offspring rather than saying they have replicated or reproduced.

As for the term “re-production”, it obviously means something like ‘producing again’. Much of the literature in evolutionary ecology uses the term “offspring quality” vaguely without specifying what is meant, e.g. see the discussion in an article by Wilson et. al. in TREE in April on “What is individual quality? (gated). I am saying what I mean (and commonly what others implicitly mean) that by making fewer larger as opposed to more numerous smaller spores, gametes, offspring etc. (and more generally engaging in parental care), parents are assisting their offspring with producing their own offspring in turn. But if I said “reproduce” it would be confused with the conventional meaning i.e. what I mean by produce. So I emphasize the ‘again’ by calling it “re-produce”. Specifically, just as the low-density in size relative to resources favouring consumption can be contrasted with the high-density favouring digestion (deriving more breakdown products from each unit of food consumed), the low-density in numbers favouring offspring production can be contrasted with the high-density favouring re-production (deriving more grand-offspring from each offspring produced).

What has all this to do with mentorship in science? Well using data from some 7,259 mathematicians who graduated between 1900 and 1960, Malmgren et. al. showed not only that success in science (number of publications, USNAS membership) is correlated with mentorship fecundity, but that the same trade-off discussed above between production and re-production obtains there. Mentors with low fecundity (< 3) train protégés that go on to have fecundities 37% higher than expected throughout their careers. “Somewhat counter-intuitive”? Not at all. All other things being equal, as all evolutionists know there is a trade-off between quantity and quality of offspring and, it should be emphasized, high quality offspring go on to produce more grand-offspring. The meaning of their other findings is less obvious however and will be the topic of a later post.