@SteveStuWillさん：THREAD: The Greater Male Variability Hypothesis (GMVH)20180909－

Steve Stewart-Williams @SteveStuWill

The basic idea is that, in species where males can potentially have more offspring than females, selection favours greater male risk-taking – not just behaviourally but developmentally. As a result, more males win big, but more also crash and burn. psyarxiv.com/ms524 [14/12] pic.twitter.com/JTmntBYvT2

拡大

Steve Stewart-Williams @SteveStuWill

If greater male variability has a biological basis, why might it have evolved? Not sure! One popular theory, though, traces greater male variability in general to another, more fundamental sex difference: greater male variability in reproductive success. [13/12] pic.twitter.com/uJsIPBUMl2

拡大

Steve Stewart-Williams @SteveStuWill

And third, sex differences in within-sex variability are not unique to humans, but are found in many other species. This suggests, at the very least, that non-biological explanations that apply only to humans are unlikely to tell the whole story. psyarxiv.com/ms524 [12/12] pic.twitter.com/Etemli4toM

拡大

Steve Stewart-Williams @SteveStuWill

Second, sex differences in psychological variability emerge in early childhood. The sex difference in IQ variability, for example, appears before children begin preschool. sciencedirect.com/science/articl… HT @Rosalind_Arden_ @RobertPlomin [11/12] pic.twitter.com/bzek2u60co

拡大

Steve Stewart-Williams @SteveStuWill

First, greater male variability is found not only in psychological traits, but in traits that are largely impervious to socialization and cultural norms, such as height, birth weight, and BMI. onlinelibrary.wiley.com/doi/abs/10.100… [10/12] pic.twitter.com/S2HIY7AVJ6

拡大

Steve Stewart-Williams @SteveStuWill

What might account for sex differences in within-sex variability? At this stage, we don't know for sure. But we do have at least some reason to think that biological factors are an important part of the story. [9/12]

Steve Stewart-Williams @SteveStuWill

Here are some questions to ask about the claim. psyarxiv.com/ms524 [8/12] pic.twitter.com/mkxFwtRkaa

拡大

Steve Stewart-Williams @SteveStuWill

As mentioned, the claim that males are more variable than females in cognitive ability is controversial. Worryingly, activists recently managed to get a paper on the topic struck from the scientific record. quillette.com/2018/09/07/aca… HT @QuilletteM [7/12]

Steve Stewart-Williams @SteveStuWill

...although see sciencedirect.com/science/articl… for a recent failure to replicate this pattern in a large, nationally representative Romanian sample. [6/12] pic.twitter.com/Aq9mDg0EnK

拡大

Steve Stewart-Williams @SteveStuWill

It also includes general cognitive ability or IQ: Males seem to somewhat outnumber females among the minority at the top, and among the minority at the bottom. citeseerx.ist.psu.edu/viewdoc/downlo… [5/12] pic.twitter.com/6OyyOwHrkX

拡大

Steve Stewart-Williams @SteveStuWill

More controversially, males appear to be somewhat more variable in a number of cognitive traits. This includes various specific cognitive capacities, such as verbal, mathematical, and spatial ability. annualreviews.org/doi/pdf/10.114… [4/12] pic.twitter.com/hL7TNdMhsC

拡大

Steve Stewart-Williams @SteveStuWill

It also appears to be the case for a range of psychological traits, including creativity sciencedirect.com/science/articl…, aggression psycnet.apa.org/buy/2003-99845…, and at least four of the Big 5 personality traits. sciencedirect.com/science/articl… [3/12] pic.twitter.com/GDvcvEi7c3

拡大

Steve Stewart-Williams @SteveStuWill

This is the case for various physical traits, including birth weight, adult weight, adult height, BMI, running speed, and various aspects of brain structure. onlinelibrary.wiley.com/doi/abs/10.100… academic.oup.com/cercor/article… [2/12] pic.twitter.com/o9KZbpakMx

拡大

拡大

Steve Stewart-Williams @SteveStuWill

THREAD: The Greater Male Variability Hypothesis (GMVH) Based on psyarxiv.com/ms524, pp. 23-30. In a wide variety of traits, males are more variable than females: The male distribution is slightly flatter and stretches out somewhat further on both sides of the mean. [1/12] pic.twitter.com/UcGf6UubmI

拡大