Conversation so far:
What was Julian's Huxley's secular humanism?
Huxley's humanism came from his appreciation that mankind was in charge of its own destiny, and this raised the need for a sense of direction and a system of ethics.
What else did Sir Julian Huxley do besides secular humanism?
Sir Julian Sorell Huxley FRS was a British evolutionary biologist, eugenicist, and internationalist.
Are there any other interesting things about Julian Huxley besides being a British evolutionary biologist, eugenicist, and internationalist?
Julian Huxley presided over the founding Congress of the International Humanist and Ethical Union.
Who did Julian Huxley serve with in the Congress of the International Humanist and Ethical Union?
Julian Huxley served with John Dewey, Albert Einstein and Thomas Mann.

Question: On what?
Self-contained rewrite: What did Julian Huxley serve on?