Scott Alexander investigates the unexpectedly high prevalence of joint hypermobility in transgender individuals, exploring various theories and presenting survey data on the phenomenon. Longer summary

Scott Alexander explores the puzzling connection between transgender identity and hypermobile joints, particularly Ehlers-Danlos syndrome (EDS). He presents four theories to explain this correlation: 1) It's a spurious result due to 'Instagrammable' conditions clustering together, 2) Estrogen effects on joints in trans women, 3) Genetic link between gender divergence and joint issues, and 4) Autism as a shared causative factor. Scott favors a theory linking proprioception issues to different reasoning styles, potentially leading to both autism and transgender identity. He presents data from his own survey showing higher rates of joint issues in trans respondents, though with some limitations. The post concludes with plans for further investigation in future surveys. Shorter summary

Scott Alexander hypothesizes a link between transgender identity, optical illusions, and NMDA receptor function, based on survey data and existing research on schizophrenia and autism. Longer summary

Scott Alexander explores a potential link between transgender identity, optical illusions, and NMDA receptor function in the brain. He presents survey data suggesting that transgender individuals, like those with schizophrenia and autism, are less susceptible to certain optical illusions. He hypothesizes that this might be related to NMDA receptor hypofunction, which is also associated with dissociation, a common experience among transgender people. The post explores how estrogen, which enhances NMDA function, alleviates dissociation in trans women. Scott connects these findings to broader research on NMDA receptors in schizophrenia and autism, noting the higher prevalence of these conditions in transgender populations. The post concludes with several caveats and suggestions for future research to validate these speculative connections. Shorter summary