system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't psychologists prescribe medicine like psychiatrists, & how did the two professions come to exist as separate beings?

I'm very aware one can prescribe medicine and the other essentially is only there to talk with you about your life but if I'm not mistaken, both are doctors correct? So why can only one prescribe medicine when they both seem to have intimate knowledge of the mind? What I mean is, how did the two ever get distinguished? Were they ever just one profession? 

Also, which one came first? (In a professional sense. I assume that people have been talking about their problems for a long time)
gpt
Psychiatrists go through medical school and (normally) 4 years of residency after receiving their B.S. They are the typical "medical doctors." Clinical psychologists usually have a M.S. or a Ph.D. in psychology. If their title is "doctor," it is because of the doctorate degree (like how professors may address each other). Keep in mind that there are other jobs you can take as a psychologist, such as research and counseling, some even with just a B.S. Whereas the psychologist has probably studied basic biology as an undergraduate and understands the general workings of the human body (outside of psychology), the MD has had extensive training on every organ system, dysfunctions of these organ systems, and pharmaceuticals + their effects.

Simply put, psychologists know how the brain and behavior work and what psychiatric medications do, but psychiatrists know how the rest of the body works, what effects the medications have on the rest of the body, and what non-psychiatric drugs/substances are contraindicted with these drugs. They are also required to have many more years of clinical experience before they are allowed to practice independently.

You can also compare it to eye care: an optometrist goes to optometry school and can do eye exams and prescribe limited medications for specific diseases. An opthamologist goes to medical school + residency and can do what an optometrist can, prescribe any medication to treat any eye disease, and perform eye surgery.