Hello Reddit! We are: Hakhamanesh Mostafavi: Graduate student in biology at Columbia University Molly Przeworski: Professor of biology at Columbia University Joe Pickrell: CEO at personal genomics company Gencove and professor at the New York Genome Center. We are a few of the authors of a recent paper Identifying genetic variants that affect viability in large cohorts where we sought to use biomedical data sets to learn about mutations that affect survival. This paper was covered in a number of news outlets with titles like Massive genetic study shows how humans are evolving, and there was a great discussion of the paper on r/science What does it mean for humans to still be evolving? For a species to evolve simply means that mutations—the accidental changes to the genome that happen in the process of copying DNA—are increasing or decreasing in frequency in the population over time. Our basic idea was that mutations that affect the chance of survival should be present at lower frequency in older individuals. For example, if a mutation becomes harmful at the age of 60 years, people who carry it have a lower chance to survive past 60, and so the mutation should be less common among those who do. We therefore looked for mutations that change in frequency with age among around 60,000 individuals from California (as part of the GERA cohort) and around 150,000 from the UK Biobank. Across the genome, we found two variants that endanger survival in these individuals: (i) a mutation in the APOE gene, which is a well-known risk factor for Alzheimer’s disease, drops in frequency beyond age 70, and (ii) a mutation in the CHRNA3 gene, associated with heavy smoking, starts to decrease in frequency at middle-age in men.We found genetic mutations linked to a number of diseases and metabolic traits to be associated with survival: individuals who are genetically predisposed to have highertotal cholesterol, LDL cholesterol, risk of heart disease, BMI, risk of asthma, or lower HDL cholesterol, tend to die younger than others. Perhaps more surprisingly, we discovered that people who carry mutations that delay puberty or the age at which they have their first child tend to live longer. Thanks for having us, this was a lot of fun