Scott Alexander explores a theory suggesting that complex features of human biology evolved as defenses against parasite manipulation, discussing its implications for understanding psychiatric medications and biological complexity. Longer summary

This post discusses a theory proposed by Marco del Giudice in his paper 'Brain Evolution Through The Lens Of Parasite Manipulation'. The theory suggests that many complex features of human biology, particularly in neurotransmitter systems, evolved as defenses against parasite manipulation of host behavior. The post outlines various strategies that organisms might use to defend against such manipulation, including complicated signaling cascades, feedback loops, pulse-based communication, individual variability, and the use of antimicrobial substances as neurotransmitters. Scott Alexander explores the implications of this theory for understanding psychiatric medications, tolerance effects, and the complexity of human biology. He concludes by discussing the strengths and potential weaknesses of the theory, noting that while it's an interesting perspective, it's too early to determine its full validity or impact. Shorter summary

Scott examines how rare but severe drug side effects often lead to underprescription compared to drugs with common but less severe side effects, potentially resulting in suboptimal patient care. Longer summary

This post discusses the issue of rare but severe side effects in psychiatric medications versus common but less severe side effects. Scott uses two main examples: nefazodone vs SSRIs for depression, and modafinil vs Adderall for stimulants. He argues that drugs with rare but spectacular side effects (like nefazodone and modafinil) are often underprescribed compared to drugs with more common but less severe side effects (like SSRIs and Adderall). The post explores the reasons for this, including doctors' risk aversion, lawsuit concerns, and media coverage of rare side effects. Scott suggests that this pattern may lead to suboptimal treatment choices for patients. Shorter summary