The evening of Friday, July 18, Paul Nelson presented a poster at the annual meeting of the Society for Developmental Biology (SDB) in Seattle. (As an SDB member myself, I was there.)
For those of you who have never been to such an event: A poster session at a scientific conference takes places in a large hall filled with large upright boards to which attendees pin posters that report some aspect of their work. The posters are generally several feet wide and several feet tall. Also in the hall are exhibits from companies that sell materials relevant to the topic of the conference. During a poster session, hundreds or thousands of participants wander around the hall, looking at posters that interest them and occasionally engaging in discussion with the poster presenters, who stand nearby.
SDB poster sessions are also social mixers; in addition to soft drinks and snacks, wine and beer are provided. This makes the evening more relaxed — except perhaps for some of the presenters who might have to defend their work against critics.
Scientific poster sessions are also competitions. Some or all of the posters are evaluated by judges, and prizes are awarded at the end of the conference for what were judged to be the best.
I wandered around looking at the hundreds of posters in the hall. The vast majority dealt with standard molecular biology: If we knock out a particular piece of DNA or RNA we get a particular defect, suggesting that the DNA or RNA is necessary to prevent the defect. A few dealt with correlations among physical processes and developmental outcomes. Many mentioned "evolution," though usually as a politically correct gloss on work that had no obvious connection to it.
The title of Paul’s poster was "The Target Problem in Characterizing Early Metazoan Developmental Sequences." According to its abstract:
In 1978, [Rupert] Riedl described what he called "the paradox of teleological evolution." Today the paradox remains unsolved. Evolution by natural selection is not an end-directed process, but metazoan development is. Normally developing embryos "head towards" functional targets (e.g., differentiated cell, tissue, organ, and body plan states) lying temporally in the distance. The paradox arises when one employs an undirected process such as evolution to explain the step-by-step acquisition of developmental stages, such as initial cleavage patterns, which, while not themselves viable endpoints, are necessary to reach distant functional states. This is the target problem: characterizing and explaining the origin of developmental stages required for organismal viability and reproductive capability, where the selectable consequence is a future (developmentally remote) state.
The body of the poster elaborated on these points using as an example the well-studied roundworm C. elegans. For his allotted ninety minutes, Paul stood next to the poster holding a beer (see photo above).
I observed many people stopping to read Paul’s poster, though I don’t know if anyone actually engaged him in conversation about it. This was not surprising: Like my own training in developmental biology, the participants’ training was focused on molecular or mechanical experimentation, not on thinking deeply about problems in evolutionary theory. Nevertheless, those who stopped to read Paul’s poster were exposed to such thinking — something they got nowhere else in the conference.