Technically, anything that crosses the blood-brain barrier is a "mind altering substance", so being nit-picky about the question, the answer is we'd all be dead.
Skipping the semantics for a legit answer, the biggest change would be in the field of medicine. Anti-Depressants (MAOIs & SSRIs), lithium for bi-polar disorder, anesthetics for surgery, even headache medications (acetylsalicylic acid, acetaminophen & ibuprofen) among many others would all be eliminated. Obviously this would have a very negative effect for a significant portion of the population.
If the question were limited to "recreational" drugs, I can't really see that it would have a large change for humanity. Some lives (people who drink in moderation for instance) would be less rich, while others (long time drug abusers) would likely be better, though even that's debatable. Removing drugs as a coping mechanism doesn't ensure that alternative coping mechanisms would have developed in their place, but of course there's no way to tell.
The biggest change to our society if these substances didn't exist would likely be seen in the development of different cultures' religious & spiritual beliefs. OT is not the place to elaborate on this topic, but it's something I have given a lot of thought to in the past.
Skipping the semantics for a legit answer, the biggest change would be in the field of medicine. Anti-Depressants (MAOIs & SSRIs), lithium for bi-polar disorder, anesthetics for surgery, even headache medications (acetylsalicylic acid, acetaminophen & ibuprofen) among many others would all be eliminated. Obviously this would have a very negative effect for a significant portion of the population.
If the question were limited to "recreational" drugs, I can't really see that it would have a large change for humanity. Some lives (people who drink in moderation for instance) would be less rich, while others (long time drug abusers) would likely be better, though even that's debatable. Removing drugs as a coping mechanism doesn't ensure that alternative coping mechanisms would have developed in their place, but of course there's no way to tell.
The biggest change to our society if these substances didn't exist would likely be seen in the development of different cultures' religious & spiritual beliefs. OT is not the place to elaborate on this topic, but it's something I have given a lot of thought to in the past.

