the question I want to ask about is what is it about humans, culture and brains that allows for such high variance within the species, that isn’t true about mice and chimps?
Some points to consider:
1. Has it been demonstrated that variations in intelligence is that much greater for humans than for mice or chimps? This may be true, but you didn’t indicate any references.
Whereas I could imagine a test for chimp intelligence, and even timed maze experiments on mice, the concept of what we mean by intelligence becomes increasingly attenuated as we deal with ever simpler life forms; so that, at some point, and maybe even quite early, experts will begin disagreeing on what they are trying to measure.
2. Modern day humans have a big advantage not only over other animals, but also over our cognitively equivalent ancestors of 12+ thousand years ago. Thanks to the invention of culture, we pass knowledge to our offspring, meaning that knowledge can be accumulated from generation to generation. Variations in cognitive performance isn’t only a consequence in variations in intelligence, but also reflects large differences in the quality of acculturation.
3. I wonder if your decision to compare interspecies variations in intelligence follows from a mistaken analogy. Consider, that intelligence is a human specialty. Other species have their own specialities. For instance, maybe we should be comparing variations in human intelligence with variations in the maximum speed of healthy, adult cheetahs. (I wonder, whether anyone has ever done this?)
4. The idea that we can assign a number to the variation in human intelligence is suspect. True, we can claim that the standard deviation in IQ is 15% of average IQ value. But it doesn’t follow that a +1 sigma individual is 15% smarter than an average individual, because the IQ scale itself is arbitrary and intelligence has never been defined apart from performance on the test. To make the point in another way, 1-sigma variations in intelligence was arbitrarily set to 15 IQ points purely for convenience. We might just as well have set the mark at 900 IQ points. But that wouldn’t mean that the +1-sigma individual was then ten times as intelligent as average.
Compare the situation with the cheetahs, where a statement like: “the ratio between the standard deviation in maximum running speeds and the average individual’s maximum running speed is .15”, really means something in terms of performance that can be measured with a metre and stopwatch.
What would be wanted to put IQ and maximum speed on par, would be credible results showing that a certain superiority in IQ is closely connected with a certain improved ability in raising fertile offspring to maturity, which is the definition of evolutionary success.
Some points to consider:
1. Has it been demonstrated that variations in intelligence is that much greater for humans than for mice or chimps? This may be true, but you didn’t indicate any references.
Whereas I could imagine a test for chimp intelligence, and even timed maze experiments on mice, the concept of what we mean by intelligence becomes increasingly attenuated as we deal with ever simpler life forms; so that, at some point, and maybe even quite early, experts will begin disagreeing on what they are trying to measure.
2. Modern day humans have a big advantage not only over other animals, but also over our cognitively equivalent ancestors of 12+ thousand years ago. Thanks to the invention of culture, we pass knowledge to our offspring, meaning that knowledge can be accumulated from generation to generation. Variations in cognitive performance isn’t only a consequence in variations in intelligence, but also reflects large differences in the quality of acculturation.
3. I wonder if your decision to compare interspecies variations in intelligence follows from a mistaken analogy. Consider, that intelligence is a human specialty. Other species have their own specialities. For instance, maybe we should be comparing variations in human intelligence with variations in the maximum speed of healthy, adult cheetahs. (I wonder, whether anyone has ever done this?)
4. The idea that we can assign a number to the variation in human intelligence is suspect. True, we can claim that the standard deviation in IQ is 15% of average IQ value. But it doesn’t follow that a +1 sigma individual is 15% smarter than an average individual, because the IQ scale itself is arbitrary and intelligence has never been defined apart from performance on the test. To make the point in another way, 1-sigma variations in intelligence was arbitrarily set to 15 IQ points purely for convenience. We might just as well have set the mark at 900 IQ points. But that wouldn’t mean that the +1-sigma individual was then ten times as intelligent as average.
Compare the situation with the cheetahs, where a statement like: “the ratio between the standard deviation in maximum running speeds and the average individual’s maximum running speed is .15”, really means something in terms of performance that can be measured with a metre and stopwatch.
What would be wanted to put IQ and maximum speed on par, would be credible results showing that a certain superiority in IQ is closely connected with a certain improved ability in raising fertile offspring to maturity, which is the definition of evolutionary success.