Nobel Prize winner Francis Crick's 1994 book on consciousness, The Astonishing Hypothesis: The Scientific Search for the Soul posits:

'You', your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behaviors of a vast assembly of nerve cells and their associated molecules.

This wasn't a popular hypothesis. Crick's critics argued that his approach was too reductionist and without philosophical rigor.