People are becoming more stupid
The intelligence is surely waning, at least in the industrialized countries.
It only takes reasonable observation and reasoning skills to make this conclusion.
The reasons are quite clear, at least to those who understand brain biology:
In this ready world or ours there is no need for intellectual efforts. The brain is hardly needed to use services that are made easy. "Use it or lose it" also applies to the brain.
Obesity makes one stupid. The same high blood sugar that makes you fat, also impairs brain development of overweight children and starts rapidly degenerating the brains of the working-age population. Logically, the overweight also get more memory diseases. Alzheimer's disease is proved to be the third diabetes.
Exercise would be necessary for the development of intelligence. The amount of exercise has diminished dramatically and is diminishing in all age groups. Couch potatoes are of all ages and there is hardly any physical work anymore.
Watching TV is proved to make one stupid. At least people in the industrialized world watch TV 3-4 h / day, including children. We can see what kind of crap most of the TV programs are today. There are very few stimulating documentaries or science programs, and even fewer watch them.
The hand skills that develop the brain are disappearing. Only a small number of children and young people have the skills that develop technical problem-solving and motoric coordination. E-games develop the brain very narrowly.
The deterioration of mental health impairs intelligence indirectly. A mentally ill person also declines intellectually.
Nutrition is deteriorating. Industrially made, highly processed junk food that is made of additives and poor carbohydrates, does not provide the brain with the essential nutrients. Again, this is crystal clear to all biochemists.
A wise political and public health instructions on people's lifestyles and environment could again begin to increase intelligence.
It may be that the elected decision-makers don’t have the understanding anymore, not to mention courage.