Selection against intelligence should definitely not be ruled out, although there are various environmental issues that could be solved.
Female obesity is known to lead to preganancy complications which cause cognitive deficits.
Obesity in general is known to cause systemic inflammation which affects cognition and speeds up dementia.
The opioid crisis and various other types of drug abuse lead to brain damage.
Various nutritional deficiencies could play a role. Historically, iodine deficiency caused the condition of cretinism, but sub-clinical deficiencies can lead to more subtle effects.
Sleep deprivation is known to cause cognitive deficits, and electronic lights and jobs with nocturnal schedules are more common now. Light pollution and spending too much time indoors during the day throws off our circadian rhythms.
We still have various types of neurotoxins plaguing our environments. More people are living in urban environments now, which causes greater exposure to automobile exhaust. Coal plants are still spewing neurotoxins. Lead pipes are still common in many cities.
High indoor CO2, from poor ventilation, is known to cause cognitive deficits.
The most interesting part is that it hasn't affected the US (yet). The US is probably the leader among developed nations in bad environmentalism, blue screens, bad sleep, opioid addiction, etc... so unless there's a reporting issue in the US, that kind of rules out a lot of those conclusions.
The causal link between obesity and low IQ does not seem to be through systemic inflammation. The research I came across suggests that people with lower IQ are more likely to become obese.
> We observed no evidence that obesity contributed to a decline in IQ, even among obese individuals who displayed evidence of the metabolic syndrome and/or elevated systemic inflammation.
> Overall there was an inverse FIQ/obesity association, except in pre-school children. However, after adjusting for educational attainment, FIQ/obesity association was not significantly different. A lower FIQ in childhood was associated with obesity in later adulthood perhaps with educational level mediating the persistence of obesity in later life.
You should only ask for sources if you attempted to find information and failed. All those things have been hackernews articles at some point, most recently the last one. Look it up.
I tried looking some up, but then realized the onus of proof is on the person making claims, not on people who are skeptical of people who make claims.
These are all well known factors to the intellectual development of humans.
There's not an onus of proof on someone who says the sky is blue or water is wet. We need a certain foundation of understanding to have productive conversations.
And we all have stuff to do. Suffice it to say, there is plenty of supporting evidence for the claims.
Ok, but "got any sources for that?" is a rather unsubstantive contribution, and then going on tilt about getting downvoted breaks the site guidelines outright. Would you mind raising the signal/noise ratio of what you post here?
I am with this guy, the above post is a stream of conjectures, half guesses and straight up misinformation. The fact that it’s at the top supports the article. Another noticeable trend is HN’s user base getting dumber and dumber over time.
Female obesity is known to lead to preganancy complications which cause cognitive deficits.
Obesity in general is known to cause systemic inflammation which affects cognition and speeds up dementia.
The opioid crisis and various other types of drug abuse lead to brain damage.
Various nutritional deficiencies could play a role. Historically, iodine deficiency caused the condition of cretinism, but sub-clinical deficiencies can lead to more subtle effects.
Sleep deprivation is known to cause cognitive deficits, and electronic lights and jobs with nocturnal schedules are more common now. Light pollution and spending too much time indoors during the day throws off our circadian rhythms.
We still have various types of neurotoxins plaguing our environments. More people are living in urban environments now, which causes greater exposure to automobile exhaust. Coal plants are still spewing neurotoxins. Lead pipes are still common in many cities.
High indoor CO2, from poor ventilation, is known to cause cognitive deficits.