Thomas Henry Huxley (1825-1895), British biologist. Huxley was a strong advocate of Darwin's theory of evolution by natural selection. He was often its main supporter in scientific debates, as Darwin shunned publicity. Huxley famously spoke in support of the theory at a meeting of the British Association for the Advancement of Science in Oxford in 1860, where he opposed the anti-selectionist Bishop Wilberforce. Huxley's own research established that humans are primates. He also carried out valuable work on plankton.