Occam’s butter knife

Let’s play a game. The game is called “radical environmentalism.” The goal is to create the most parsimonious environmental explanation for a given set of results. Ready?

Create the most parsimonious environmental explanation for the following set of data [4]:

Given the following:

1. The individuals identified as White (Europeans) and African Americans were done so on the basis of corresponding self and interviewer identification. The 116 individuals identified as mixed race individuals were done so on the basis of corresponding self identification and parental self-identification (102) or parental self identification (14). Mean age = 16.

2. The individuals identified as mixed race were judge by the interviewer as looking African-American.

3. The mean differences were uncorrelated or weakly correlated:

4. The SES adjusted IQ means were equivalent to 103.2, 100.7, and 93.3.

5. IQ, sexual proclivity, and birth weight are moderately to highly heritable within populations [1,2].

My attempt below.


[1] Cherkas, et al., 2004. Genetic Influences on Female Infidelity and Number of Sexual Partners in Humans: A Linkage and Association Study of the Role of the Vasopressin Receptor Gene (AVPR1A). [Heritability of .4 for sexual proclivity in 1st word western nations]

[2] Magnusa, et al., 2001. Paternal contribution to birth weight. [heritability of .25 for birth weight in 1st world western nations.]

[3] Nettle, D. (2010). Dying young and living fast: Variation in life history across English neighbourhoods. Behavioral Ecology

[4] Rowe, 2002. IQ, birth weight, and number of sexual partners in White, African American, and mixed race adolescents.


Here’s what I came up with:

a) The three way trait difference between African-American/mixed and white kids results from the former picking up patters of behaviors from African-American culture (i.e. 3 patterns of cultural expectations). This explains why the differences are present in the tested population even though SES is controlled for. b) The African Americans cultural patterns result from a life history program that kicks in when individuals live in low SES conditions [ 3]. This explains why the differences exist and are uncorrelated in the tested population (i.e. there are three non-causally related cultural tendencies that result from a SES induced life history program). c) The differences between mixed race individuals and African-American individuals is due to a white parental cultural influence — which again results a different life history program. This explains the difference between African-Americans and Mixed-Americans even though the mixed race differences appeared African-American. d) While the parental-child IQ correlation is explained genetically, the between Black-White racial difference is explained by a) and a number (say 3) of additional cultural+ factors (such as stereotype threat (.2 SD), low motivation (.4 SD), and ?). This explains why cultural differences can cumulatively create an equivalent of 1.3 SD between group differences. (The SD of difference divided by the square root of the between-family environment and IQ correlation at age 16 (~.2) gives the amount of equivalent within group environmental difference, precluding g x e interactions and x- factors, needed to account for the difference; (.6/.45) = 1.3 SD. )

That’s an 8 factor model. See if you can beat that!

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8 Responses to Occam’s butter knife

  1. statsquatch says:

    Good start. Can you think of a non-genetic but biological? Maybe a parasite that evolved in the antebellum that only attacks african americans and causes more K than r type behaviors. Some mixed race kids are immune becuase of their gene signature but some are not. Maybe a virus was concocted by the CSA.

  2. JL says:

    I think stereotype threat could explain all three outcome differences. Lower IQ in blacks results from conforming to the stereotype of blacks having lower IQs, promiscuous behavior is caused by the stereotype of oversexed blacks, and low birth weight is due to mothers of black children unwittingly adopting practises that are detrimental to the fetus after, say, reading about racial differences in birth weight. Mixed-race individuals are influenced by stereotypes about blacks to a lesser extent because they know they’re partly white.

    • jewamongyou says:

      JL, while your explanation is possible, it is certainly not the one Occam would have chosen. Especially if these patterns hold true across cultures; in that case, we should be asking, “how did these stereotypes get started?”

    • Chuck says:

      JL, stereotype threat is a type of performance anxiety (i.e. performance anxiety supposedly induced by social stereotypes). How would performance anxiety result in hyper sexuality? (Failure to commit? — I’m guessing that our players aren’t losing their nerve at the alter). Also, stereotype threat alone can’t explain a .8 SD between group IQ difference (at most it could explain .2 SD — refer to Statsquach’s post on it). So, you would need multiple factors to explain the Black IQ gap in addition to a theory of stereotype conformity to explain the sexual differences. As for the birth weights, it was assumed that readers were familiar with table 2 in this post. As you can see, White women who sire children with Blacks have children with a lower average birth weight than White women who sire children with White fathers — so you would need a theory of communicable stereotype osmosis.

      So, as of now you have a 4 factor model with 3 plausible ad hocs — stereotype threat, mitigated stereotype threat (for mixed), stereotype conformity, mitigated stereotype conformity (for mixed). I’ll give you the ad hocs. You still have to explain the birth weight pattern and .6SD of IQ in under 4 factors (since mine was an 8 factor model.)

      Try again, my son.

  3. nikcrit says:

    JL says, “Mixed-race individuals are influenced by stereotypes about blacks to a lesser extent because they know they’re partly white.

    JL, I’m of mixed black-and-white racial lineage; whenever I hear the kind of logic you stated in the above quote, I wonder: should someone with my bloodlines be the instigator of black stereotypes? Or merely the passive ‘victim’ of their oh-so mighty effect?
    Somewhat more seriously, working in the education field, I’ve sometimes wondered from my own perspective about a possible factor among learning between the races that might be considered ‘stereotype threat.’
    But make no mistake; I fully feel the ‘wince factor’ upon hearing such a term; seeing urban education up close only makes me more cynical in that way…. but call it what you will, I see among a lot of low-income black kids who, in whateve moment or circumstance, may be genuinely enthused about a particular academic subject, almost consciously reel-in their spontaneous excitement and focus and then re-adapt a sort-of lackadaisical indifference in the way that’s common among young city black kids, usually male; I think Chuck at GW once referred to the kind of situation I”m trying to describe here as a “Peer Group penalty,’ felt by urban kids hwo’ve come to particularly value an indifference to educational attainment; (eg., the whole ‘learning is acting-white’ phenom, etc.).
    So, while I’ll never utter a phrase like ‘stereotype threat’ aloud as part of a racially partisan argument or bit of dissent, I quite honestly see it manifesting in urban education if one is willing to see such a possibility in terms of adolescent peer pressure.

    Anyhow, to me, if i’m right,, this is quite troubling and very alien to the teen academic background of this particular half-breed ‘NAM.’

    • statsquatch says:

      You may observe it but will it explain the gap? I thought this acting “Acting White” theory was dismissed as an explanation for the gap since no one could prove (at a population level) that blacks who did well actually had problems with their peers.

  4. nikcrit says:

    You may observe it but will it explain the gap?

    I wasn’t (and wouldn’t) try to say that it did; I’m agnostic on that question and, if presse, would likely say it’s a bit of nature and nurture; i just wonder just what percentage of the ‘nurture’ can be accounted for by that lackadaisical attitude amongst black kids that i mentioned.

    • Chuck says:


      You’re probably right when it comes to some inner city blacks or some suburban black caught up in gangster culture. I saw what you describe when I taught in the inner city. Yet, the gap persists for affluent and motivated blacks, so that can’t be “the” explanation. Read through this article.

      (The B-W grade gap found was about .6 SD; W-B A+B gap=.7SD; B-W C+D gap = .5 SD)

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