5 ms·

I would be surprised if humans are getting smarter. Show me the selective pressure on intelligence in the modern world, because I don't see it. You don't have t

by weeksie 12y ago

I would be surprised if humans are getting smarter. Show me the selective pressure on intelligence in the modern world, because I don't see it. You don't have to be smart to be evolutionarily fit. Not even close. I'd be very surprised if humans were changing much as far as cognitive capability is concerned, animals that become domesticated almost universally have smaller brains than their wild counterparts.

jacobolus 12y ago
There doesn’t need to be DNA change to make people smarter. Just having a few generations in a row with adequate diet, not breathing smoke from a wood fire every day, less damage from childhood disease, etc. could make a huge difference.
- nicolethenerd 12y ago
  On the contrary, the evolutionary argument here is that a few generations under these conditions would allow more biologically "stupider" humans to survive (since intelligence isn't being selected for) and pass on their genes, creating future generations of dumber humans. Jared Diamond makes a similar argument in Guns, Germs, and Steel for why the people of New Guinea are smarter than their western counterparts.
  - JoeAltmaier 12y ago
    Deny. There's no reason dying of wood smoke or disease selects for the smart or the dumb. Removing those pressures has no obvious effect on the intelligence of the survivors.
    - JoeAltmaier 12y ago
      By that I mean, no evolutionary pressure on intelligence. Of course a healthy upbringing will increase exhibited intelligence.
  - Retric 12y ago
    Human evolution is almost meaningless on those time scales.
    - weeksie 12y ago
      There has been shrinkage in the average brain size over the last five thousand years. Intelligence is a very complicated thing and brain size might not be the only factor—that shrinkage might not even be relevant. But that does not mean that evolutionary change cannot take place on thousand year timelines.
      - Retric 12y ago
        Current theory is skull size was adapting based on temperature not intelligence. http://en.wikipedia.org/wiki/Brain_size#mediaviewer/File:Brain_Size_Map.png http://en.wikipedia.org/wiki/Brain_size#mediaviewer/File:Bra... Also, there are likely more people alive now with larger brain volumes vs five thousand years ago and the same apples to just about any trait you can name due to the rapid population boom. The important thing to note is the human population covers the globe. There are plenty of sifts in populations like Lactose tolerance becoming widespread over the last 7,500 years, but even that is a long way from becoming effectively universal.
        weeksie 12y ago
        I think that was my point. You said that ten thousand years of civilization was too short for meaningful evolution. At least that was my understanding.
        Retric 12y ago
        10,000 years is long enough for significant beneficial traits to spread widely. It's not enough time to Change neutral traits that used to be beneficial. That's generally a vary slow change consider most animals don't need dietary vitamin C even if there diets provide plenty of the stuff. However, you used the term "a few generations" as in below 1,000 years and that's rediculusly fast for a species that takes as long as we do to reproduce and have so few children.
- VLM 12y ago
  This does seem to appear in height data http://en.wikipedia.org/wiki/Human_height#History_of_human_height http://en.wikipedia.org/wiki/Human_height#History_of_human_h... There is a fundamental mistake in assuming a "couple generation" linear trend will continue to infinity providing us with 30 foot tall men with IQs of 200+. We are probably at or around peak height and peak IQ right now for various rather obvious income inequality reasons, and we can expect both to decline in the future. There is a coupling between womens pelvis size and newborn head size and medically assisted survival during childbirth which could provide some multigenerational effect to growth. There have been a lot of arguments relying on generational inheritance of intelligence / IQ, however: "As Flynn pointed out in his Ted Talk on the Flynn Effect, in 1900 only 3% of Americans performed "cognitively demanding" jobs - now the figure is 35%" That would imply the percentage of humanity where cognition has no effect on their job, and presumably lifestyle, is at least 65% and has always historically been higher, as high as 97%, so an evolutionary argument for IQ growth seems extremely weak. It would be as if doctrine were peacock females select their mates based on tail feather size leading to large tail feathers, yet actual data shows 97% to 65% of actual living peacocks come from bald ancestors.
  - deleted 12y ago
    [deleted]
Terr_ 12y ago
> Show me the selective pressure on intelligence in the modern world, because I don't see it Other humans! You have to outsmart them and avoid being outsmarted by them, because they compete for the same resources and some of them will act in a predatory manner.
- adrianN 12y ago
  Yeah, smarter people have more money. But smarter people have fewer kids. So, in fact, there is negative pressure on intelligence.
  - bmillare 12y ago
    Evidence for such negative pressure is inconclusive [1]. Such an effect may be more a result of socioeconomic status, not intelligence. As for a counter example of positive pressure on intelligence, I would expect the trait of humor [2], an attractive trait that is a by product of intelligence, to increase the probability of fertility. 1. http://en.wikipedia.org/wiki/Fertility_and_intelligence http://en.wikipedia.org/wiki/Fertility_and_intelligence 2. Kaufman, Scott Barry, et al. "The role of creativity and humor in human mate selection." Mating intelligence: Sex, relationships, and the mind’s reproductive system (2008): 227-262.
  - Terr_ 12y ago
    Why are you assuming that the sheer number of first-round offspring generated is the only winning strategy for genes? It's a heck of a lot more complex than "who can pop the most babies the most quickly". What about the multi-generational odds of survival and reproduction? What about surviving famines or predators? What about competition in sexual selection? Idiocracy was an amusing movie, but it's underlying premise was never realistic.
Florin_Andrei 12y ago
Just speculating here - I wonder if the human cortex is somehow "special" in that regard. What if evolutionary pressure in the past drove the increase of computing power in the cortex so much that now you could have new emerging properties and "features" and so on come out by simply re-wiring what's already there. You know, like when you're Amazon and you build a huge infrastructure to serve existing business, only to realize later you could do a lot more with it by simply re-purposing and re-configuring.
api 12y ago
Outbreeding is one possibility. There are now more people migrating than ever before, and over long distances. In the past most people stayed very close to where they were born, which greatly increased the odds of inbreeding especially among lower classes. Today we have ubiquitous cheap transportation and more than 50% of the human population is now urban -- meaning bigger gene pools and lower odds of breeding between close relatives. http://en.wikipedia.org/wiki/Heterosis http://en.wikipedia.org/wiki/Heterosis http://en.wikipedia.org/wiki/Heterozygote_advantage http://en.wikipedia.org/wiki/Heterozygote_advantage I also must point out that "hard selection" (differential survival) is not the only operating mechanism in evolution. In complex organisms that reproduce sexually, it might not even be the dominant mechanism. You've got sexual selection and genetic drift, which in a species with low infant mortality and low mortality in general (a.k.a. us) are probably the dominant mechanisms. Beyond those you have things like the Baldwin effect, which get very interesting when coupled with epigenetics. Epigenetics is unquestionably real but as yet is not well understood. There could be all kinds of interesting things going on here. http://en.wikipedia.org/wiki/Baldwin_effect http://en.wikipedia.org/wiki/Baldwin_effect http://en.wikipedia.org/wiki/Epigenetics http://en.wikipedia.org/wiki/Epigenetics
- weeksie 12y ago
  The first point—increased mate choice—seems to invalidate the second. At least to my understanding, a larger population makes genetic drift less likely to fix on a trait.
  - api 12y ago
    My point was pretty general -- that there are multiple overlapping mechanisms at work, and some poorly understood. People often have this really simple flat "survival of the fittest" view of evolution, and that isn't accurate.
lukevdp 12y ago
It doesn't need to be an evolutionary change, it could be that education, health, and societal pressure has created the change
wturner 12y ago
I heard a radio show recently where the host mentioned a study in the 50's where people were asked what rabbits and dogs had in common, and the answers were usually something along the line of "they both have two ears". The same question was asked some time in the 2000's and the more common answers relied on abstraction like " they are both mammals". I'm not sure if that is reflective of a shift in "intelligence" but I do think it's a shift in thinking.
savanaly 12y ago
Standards going up play a big role in all of this, in my opinion. To clarify what I mean, could you consider track running or swimming? In these and other physical sports, it is evident that world records keep climbing year after year, to the now much-noted point that the best high schoolers typically are "faster" than the world best for a few decades ago. Obviously nothing has happened on an evolutionary scale in the timespan of a century, so what explains it? It's almost like how a goldfish will grow to the size of its bowl-- new humans will grow to and exceed the standards of the last generation, it's just human nature. It's a bit trickier to apply the principle to creative pursuits than it is to physical ones, but I think it may help explain why students could appear cleverer over time without anything changing biologically. To give one final example that doesn't involve sports. I am a trumpet player and am pretty familiar with the phenomenon that the best of the best in trumpet playing goes up as the decades go by. Rafael Mendez, Maynard Ferguson, etc. will forever be considered as the all time great virtuosoes, but the cold hard fact is that their technical abilities were only good in light of the time-- exceeded by hundreds if not thousands of the best trumpet players today. It's all about context.
Shorel 12y ago
May be that's the answer: we domesticated ourselves with school, police and other institutions and therefore we no longer need all our intelligence to survive. We evolved to be the master hunters and nowadays our children aren't even aware meat comes from animals. This same limited amount of intelligence we evolved with, is then free to do something else, like literature, art and music.

by weeksie 12y ago

jacobolus 12y ago

There doesn’t need to be DNA change to make people smarter. Just having a few generations in a row with adequate diet, not breathing smoke from a wood fire every day, less damage from childhood disease, etc. could make a huge difference.

nicolethenerd 12y ago
On the contrary, the evolutionary argument here is that a few generations under these conditions would allow more biologically "stupider" humans to survive (since intelligence isn't being selected for) and pass on their genes, creating future generations of dumber humans. Jared Diamond makes a similar argument in Guns, Germs, and Steel for why the people of New Guinea are smarter than their western counterparts.
- JoeAltmaier 12y ago
  Deny. There's no reason dying of wood smoke or disease selects for the smart or the dumb. Removing those pressures has no obvious effect on the intelligence of the survivors.
  - JoeAltmaier 12y ago
    By that I mean, no evolutionary pressure on intelligence. Of course a healthy upbringing will increase exhibited intelligence.
- Retric 12y ago
  Human evolution is almost meaningless on those time scales.
  - weeksie 12y ago
    There has been shrinkage in the average brain size over the last five thousand years. Intelligence is a very complicated thing and brain size might not be the only factor—that shrinkage might not even be relevant. But that does not mean that evolutionary change cannot take place on thousand year timelines.
    - Retric 12y ago
      Current theory is skull size was adapting based on temperature not intelligence. http://en.wikipedia.org/wiki/Brain_size#mediaviewer/File:Brain_Size_Map.png http://en.wikipedia.org/wiki/Brain_size#mediaviewer/File:Bra... Also, there are likely more people alive now with larger brain volumes vs five thousand years ago and the same apples to just about any trait you can name due to the rapid population boom. The important thing to note is the human population covers the globe. There are plenty of sifts in populations like Lactose tolerance becoming widespread over the last 7,500 years, but even that is a long way from becoming effectively universal.
      - weeksie 12y ago
        I think that was my point. You said that ten thousand years of civilization was too short for meaningful evolution. At least that was my understanding.
        Retric 12y ago
        10,000 years is long enough for significant beneficial traits to spread widely. It's not enough time to Change neutral traits that used to be beneficial. That's generally a vary slow change consider most animals don't need dietary vitamin C even if there diets provide plenty of the stuff. However, you used the term "a few generations" as in below 1,000 years and that's rediculusly fast for a species that takes as long as we do to reproduce and have so few children.
VLM 12y ago
This does seem to appear in height data http://en.wikipedia.org/wiki/Human_height#History_of_human_height http://en.wikipedia.org/wiki/Human_height#History_of_human_h... There is a fundamental mistake in assuming a "couple generation" linear trend will continue to infinity providing us with 30 foot tall men with IQs of 200+. We are probably at or around peak height and peak IQ right now for various rather obvious income inequality reasons, and we can expect both to decline in the future. There is a coupling between womens pelvis size and newborn head size and medically assisted survival during childbirth which could provide some multigenerational effect to growth. There have been a lot of arguments relying on generational inheritance of intelligence / IQ, however: "As Flynn pointed out in his Ted Talk on the Flynn Effect, in 1900 only 3% of Americans performed "cognitively demanding" jobs - now the figure is 35%" That would imply the percentage of humanity where cognition has no effect on their job, and presumably lifestyle, is at least 65% and has always historically been higher, as high as 97%, so an evolutionary argument for IQ growth seems extremely weak. It would be as if doctrine were peacock females select their mates based on tail feather size leading to large tail feathers, yet actual data shows 97% to 65% of actual living peacocks come from bald ancestors.
- deleted 12y ago
  [deleted]

Terr_ 12y ago

> Show me the selective pressure on intelligence in the modern world, because I don't see it Other humans! You have to outsmart them and avoid being outsmarted by them, because they compete for the same resources and some of them will act in a predatory manner.

adrianN 12y ago
Yeah, smarter people have more money. But smarter people have fewer kids. So, in fact, there is negative pressure on intelligence.
- bmillare 12y ago
  Evidence for such negative pressure is inconclusive [1]. Such an effect may be more a result of socioeconomic status, not intelligence. As for a counter example of positive pressure on intelligence, I would expect the trait of humor [2], an attractive trait that is a by product of intelligence, to increase the probability of fertility. 1. http://en.wikipedia.org/wiki/Fertility_and_intelligence http://en.wikipedia.org/wiki/Fertility_and_intelligence 2. Kaufman, Scott Barry, et al. "The role of creativity and humor in human mate selection." Mating intelligence: Sex, relationships, and the mind’s reproductive system (2008): 227-262.
- Terr_ 12y ago
  Why are you assuming that the sheer number of first-round offspring generated is the only winning strategy for genes? It's a heck of a lot more complex than "who can pop the most babies the most quickly". What about the multi-generational odds of survival and reproduction? What about surviving famines or predators? What about competition in sexual selection? Idiocracy was an amusing movie, but it's underlying premise was never realistic.

Florin_Andrei 12y ago

Just speculating here - I wonder if the human cortex is somehow "special" in that regard. What if evolutionary pressure in the past drove the increase of computing power in the cortex so much that now you could have new emerging properties and "features" and so on come out by simply re-wiring what's already there. You know, like when you're Amazon and you build a huge infrastructure to serve existing business, only to realize later you could do a lot more with it by simply re-purposing and re-configuring.

api 12y ago

Outbreeding is one possibility. There are now more people migrating than ever before, and over long distances. In the past most people stayed very close to where they were born, which greatly increased the odds of inbreeding especially among lower classes. Today we have ubiquitous cheap transportation and more than 50% of the human population is now urban -- meaning bigger gene pools and lower odds of breeding between close relatives. http://en.wikipedia.org/wiki/Heterosis http://en.wikipedia.org/wiki/Heterosis http://en.wikipedia.org/wiki/Heterozygote_advantage http://en.wikipedia.org/wiki/Heterozygote_advantage I also must point out that "hard selection" (differential survival) is not the only operating mechanism in evolution. In complex organisms that reproduce sexually, it might not even be the dominant mechanism. You've got sexual selection and genetic drift, which in a species with low infant mortality and low mortality in general (a.k.a. us) are probably the dominant mechanisms. Beyond those you have things like the Baldwin effect, which get very interesting when coupled with epigenetics. Epigenetics is unquestionably real but as yet is not well understood. There could be all kinds of interesting things going on here. http://en.wikipedia.org/wiki/Baldwin_effect http://en.wikipedia.org/wiki/Baldwin_effect http://en.wikipedia.org/wiki/Epigenetics http://en.wikipedia.org/wiki/Epigenetics

weeksie 12y ago
The first point—increased mate choice—seems to invalidate the second. At least to my understanding, a larger population makes genetic drift less likely to fix on a trait.
- api 12y ago
  My point was pretty general -- that there are multiple overlapping mechanisms at work, and some poorly understood. People often have this really simple flat "survival of the fittest" view of evolution, and that isn't accurate.

lukevdp 12y ago

It doesn't need to be an evolutionary change, it could be that education, health, and societal pressure has created the change

wturner 12y ago

I heard a radio show recently where the host mentioned a study in the 50's where people were asked what rabbits and dogs had in common, and the answers were usually something along the line of "they both have two ears". The same question was asked some time in the 2000's and the more common answers relied on abstraction like " they are both mammals". I'm not sure if that is reflective of a shift in "intelligence" but I do think it's a shift in thinking.

savanaly 12y ago

Standards going up play a big role in all of this, in my opinion. To clarify what I mean, could you consider track running or swimming? In these and other physical sports, it is evident that world records keep climbing year after year, to the now much-noted point that the best high schoolers typically are "faster" than the world best for a few decades ago. Obviously nothing has happened on an evolutionary scale in the timespan of a century, so what explains it? It's almost like how a goldfish will grow to the size of its bowl-- new humans will grow to and exceed the standards of the last generation, it's just human nature. It's a bit trickier to apply the principle to creative pursuits than it is to physical ones, but I think it may help explain why students could appear cleverer over time without anything changing biologically. To give one final example that doesn't involve sports. I am a trumpet player and am pretty familiar with the phenomenon that the best of the best in trumpet playing goes up as the decades go by. Rafael Mendez, Maynard Ferguson, etc. will forever be considered as the all time great virtuosoes, but the cold hard fact is that their technical abilities were only good in light of the time-- exceeded by hundreds if not thousands of the best trumpet players today. It's all about context.

Shorel 12y ago

May be that's the answer: we domesticated ourselves with school, police and other institutions and therefore we no longer need all our intelligence to survive. We evolved to be the master hunters and nowadays our children aren't even aware meat comes from animals. This same limited amount of intelligence we evolved with, is then free to do something else, like literature, art and music.