How do you differentiate a real cultural shift from a manufactured one? Cyber ethnographer Ruby Justice Thelot studies culture through TikToks. He scores thousands of them by category and sentiment to measure what people do versus what they post. In this conversation with a16z's Elena Burger, they point that method at the wellness boom: why Silicon Valley gets credit for a peptide trend it did not start, what 400 years of thinness reveals about what we value, why the people who quantified…