Claude Desplan (4) - Denis Duboule (2025-2026)

The lecture provides a comprehensive overview of pheromone-mediated communication and caste determination in social insects, particularly ants. Desplan’s expertise in developmental biology is evident as he connects molecular mechanisms (stochastic gene expression) to organismal and societal outcomes. The argumentation is logical and well-structured, starting with the general principle of stochasticity in development, then narrowing to the olfactory system, and finally to the social organization of ants. The scientific rigor is high, with references to specific examples like leaf-cutter ants and Harpegnathos saltator, and explanations of underlying genetic and physiological processes. However, the lecture is primarily descriptive and lacks detailed citations to specific studies, which would enhance its credibility. The content is accessible to a knowledgeable audience but assumes some background in biology. The title accurately reflects the content, as it is part of a series on determinism and stochasticity in neuronal development, and this lecture focuses on pheromones and societies. Overall, the lecture is informative and thought-provoking, offering insights into the interplay between deterministic and stochastic processes in evolution and development. The lack of visual aids in the transcript limits the ability to fully appreciate the examples, but the verbal descriptions are vivid. The lecture does not explicitly address potential criticisms or alternative hypotheses, but it does raise intriguing questions about the plasticity of caste determination. The quality of information is high, and the lecture serves as an excellent introduction to the topic for students and researchers alike.

The title accurately reflects the content: a lecture by Claude Desplan in the context of the series by Denis Duboule.

8/10

Lecture by a renowned professor at Collège de France, based on established research in developmental biology and sociobiology. The content is scientifically rigorous, but as a single lecture it lacks peer review and detailed citations.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 00:00Introduction: recap of deterministic and stochastic processes in development.
• 02:00Discussion on the importance of pheromones in social insects.
• 05:00Examples of ant castes: leaf-cutter ants and their specialized roles.
• 10:00Introduction to the olfactory system and expansion of odorant receptor genes.
• 15:00Stochastic choice of receptor expression in olfactory neurons.
• 20:00Reproductive division of labor: queens, workers, and males.
• 25:00Life cycle of a colony: production of virgin queens and males, nuptial flight.
• 30:00Longevity differences between queens and workers, link to insulin signaling.
• 35:00Plasticity of caste determination: workers can become reproductive in some species.
• 40:00Conclusion and summary of key points.

• Collège de France - Conférencier invité: Déterminisme et stochasticité au cours du développement neuronal — Official page for the lecture series, providing context and possibly additional resources.
• Collège de France - Chaire Évolution du développement et des génomes — Chair held by Denis Duboule, host of the series.
• YouTube Playlist: Évolution du développement et des génomes — Playlist containing all lectures in the series.

• Collège de France - Conférencier invité: Déterminisme et stochasticité au cours du développement neuronal — Official page for the lecture series, providing context and possibly additional resources.

• www.college-de-france.fr
• www.fondation-cdf.fr
• fr.linkedin.com
• www.threads.net