is that human nature has changed in the last few hundred years. If you could go back to 1708 and replace all of the babies at conception with babies conceived today, my prediction is that the alternative history from 1708 to 2008 would have less violence, more economic growth, and faster scientific progress. Conversely, if you were to replace babies being conceived today with babies conceived in 1708, they would grow up to produce staggering increases in crime and violence, along with severe economic decline.
I take the Flynn effect to be a true indicator that intelligence has gone up over the past few generations. Even if nothing else in human nature has changed, the IQ difference would produce the results I predict in the thought experiment. But other parts of human nature probably have changed as well.
Tyler Cowen is into this question of what is your most absurd belief. It means a belief to which you assign a much higher probability of truth than would other intelligent truth-seekers.
Here is a check.
Determine if, over generations, football players who beget football players specifically breed for size.
I think they do.
Wow, that really is an absurd belief!
Mine is that if a great multitude of people, say ten thousand, or better yet, one hundred thousand, want something really badly - it will happen. And I don't mean they vote for it, I just mean they will it into reality.
As I'm sure you are aware, your belief, if true, has some serious "bell curve" like implications.
well, we know that selection works on disease alleles within a few hundred years. you just need the heritability + differential reproduction. with DNA extraction techniques + better behavioral genomics we can perhaps test this hypothesis within the next decades.
If the Flynn effect is largely a result of improved nutrition and/or neonatal care, then your experiment fails.
Don't isolated tribes of indigenous peoples provide a kind of natural experiment for that hypothesis?
Has anybody done any research on the IQ of babies adopted from indigenous tribes?
That seems to be something like Greg Clarck's theory. Also Greg Cochran's. "The past is another country" and "The bow begat the Bushmen".
Nothing has occurred over the past 300 years that would increase the likelihood that people with the traits you favor (less violent, more logical, more intelligent, more inventive) would have significantly more children than violent, illogical, stupid, and uninventive people. In the past 100 years, there has been a significant trend towards fewer children born to people with the traits you favor. Therefore, your scenario is completely unlikely. Randomly chosen conceptuses from today would become the same (or slightly worse) if born in 1700.
Gregory Clark at UC-Davis makes this argument. He analysed the last wills of people in pre-industrial England and he found that economically successful people had more children, but were also more selfish. They gave less to the poor and to religious institutions. It is plausible that this resulted in genetic changes in the long run.
http://video.google.com/videoplay?docid=-1126442488002484108
I agree with Dr T that - because the past 100 plus years has seen considerable 'dysgenic' selection with respect to IQ and the personality trait of Conscientiousness - the (non-Hispanic White US) people of 1708 would be significantly better (harder working/ smarter) than the people of 2008 - if they were given the benefits of modern living conditions.
... is that human nature has changed in the last few hundred years.
Selection pressures are not the same everywhere, so 'human nature' would not move as a constant like this.
Are you saying then that you believe that less violent/more intelligent people have reproduced more in the last 300 years in Western Europe? Or that less violent/more intelligent people have reproduced more everywhere (Andaman Islanders, Yanomamo, Aka, etc).
The latter is indeed an absurd belief, but the former is likely true to some extent. But remember, people of higher socioeconomic status started reproducing less at the end of the 19th century, and according to Clark there hasn't been a relationship at all since at least 1980 in Canada, the US, the UK, Germany, Sweden, and Finland (A Farewell to Alms pp 294-295). And there is evidence that less intelligent and less conscientious people specifically have reproduced more since this demographic transition.
So for almost half the time you speak of there has not been a move in that direction. Children from 1858 would probably do better than children from both 1708 and 2008.
There is no empirical evidence that the genetic or other elemental structures that comprise the sources of the nature of humans which generates their interactions and reactions to circumstances has changed within any knowable time-frame.
What has been changing are the circumstances in which those interactions and reactions occur, which might be perceived as a "learning curve" (even if at the lowest moving points on a logarithmic graph).
This may become more clear as western civilization continues its eastward march. Will there be some who would say the human nature of the middle eastern male has changed?
A correction:
There is some empirical evidence that the brain cavity areas have been increasing in some parts of the human species over the 300 years in question.
Whether and how that may affect the contents and the functions: increased or more refined, more rapid synapses, etc. etc. does nor even appear to be under examination. But then, how could they?
While positive selection is still undoubtedly occurring in humans (it's absurd to believe evolution just stopped all of a sudden in humans), I think it much more likely that the differences in humans have been due to greater complexity of brain wiring in response to changing sociocultural conditions. That's why you see people in, say, contemporary MIddle Eastern countries acting like Medieval Christians did. Those two groups have/had the same psychosocial complexity. The larger your world, the more people you have in that world, the more people you consider to be in your tribe, the kinder/more tolerant you are to more people.