Quote:
Originally Posted by isaidso
We're likely the only species that have a large number who are extremely low functioning. Natural selection would normally have killed off these people long ago; the modern world keeps them safe. By saving these people from themselves we're actually making our species dumber and less resilient over time.
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I see where you're coming from but I actually don't believe that that's true. Evolution tends to work over extremely long time frames, such a tens of thousands or millions of years (at least for larger animals with slower reproductive cycles) and modern society has been around for a blink of an eye in evolutionary terms. So modern society can still be significantly affecting evolutionary dynamics without us seeing or feeling any of the effects for quite some time.
That being said, I don't believe modern society actually is protecting the stupid. If anything it's giving the bright a much more pronounced advantage than ever before since for much of human history our survival was far more dependant on physical strength and stamina than it is now. Everyone needed to be involved in basics such as food procurement and defense and there was no opportunity to excel through specialized roles that we have today. The fact that these "low functioning" people's genes even made it to our modern era despite the harshness of pre-modern conditions rather than making them too stupid to avoid being eaten means high intelligence must not have been pre-requisite. Yet we now do see a marked difference in lifespans and mortality rates between people in different professions, in different subcultures, with different education/income levels, etc. especially on a global scale and there can be correlations between those things and intelligence. Large numbers of people still die pre-maturely through things such as accidents, crime/conflict, and lifestyle choices.
If you crunch the numbers using exponential growth/decay formula, if there are 100 people with a certain trait that makes them 1/100 less likely to pass on their genes, that trait would die out in about 458 generations which would look like (1>100(1-.01)^x). If we assume the average generation is about 25 years, that would take the trait about 11,450 years to die out. That's pretty quick in evolutionary terms, but still not something we could expect to observe during our lifetimes. So I suspect that even with modern laws and protections, many traits will die out at breakneck speeds due to the rapid evolutionary pressure civilization will exert, but we're still talking in terms of thousand of years.