The Human Question

In a discussion on Unbelievable?, she stated that there is no such thing as a self: just a collection of cells or atoms (so said she in a friendly debate with Charles Foster). She also let it be known that she belongs to a humanist society (don't know the exact name). My thought on that: it seems rather hard to be a humanist when you don't believe that human beings really exist. Further point: how can we possess mathematical and scientific truths if these truths themselves have an identity and we don't? Is there one neuron that possesses one truth and another that possesses another? Do they share truths with each other? Or does one neuron possess one part of one truth and another neuron possess another part of the other truth? And if many neurons somehow work together to possess a truth and the neurons themselves constantly undergo change, how is it that the truth itself doesn't change slightly? She criticizes the notion that there is an individual within us...