The human-designed world and its unintended consequences can be hidden at times. Especially since we use natural elements in creating our designs.
Consider botanical sexism.
According to a friend of mine who works at a tree nursery, cities and landscapers request male trees (which produce pollen, but no seeds) much more often than female trees. They prefer not having to clean up pods, acorns or maple seeds come Fall.
The result is that there are many more male trees in urban and suburban areas, substantially increasing the amount of pollen in the air. In turn, seasonal allergies in those areas are worse than they might otherwise be.
Unintended side effects can be sneaky.
