Poor_mother_and_children,_Oklahoma,_1936_by_Dorothea_Lange from the United States Library of CongressA recent study published in the prestigious journal Nature Neuroscience claimed that there is a correlation between parental income and children’s brain size. The publication was followed by researchers arguing that “These early life circumstances make it tougher for many children and it’s on many of us in society to make sure that children have equal possibilities”. Hum… There is always something fishy in this type of correlation studies where well-meaning social scientists try to deal with very complex issues. It was pretty obvious that the research would be picked up as a scientific endorsement by The Guardian, but when you see it splashed on other newspapers, you know it is time for discussing some unsupported-claims.

Let’s forget for a second that the size of the brain does not determine intelligence (otherwise the MM696elephants would be ruling the earth and men would be more intelligent than women(1)…). Let’s also overlook the fact that correlation does not mean causation and that it is always tricky to draw conclusions from correlations alone.

Several studies(2,3,4) involving twins and adoptive families have shown that a big chunk of variability in intelligence is heritable (30 to 80%); no study has concluded otherwise. The authors of this study -tacitly admitting that there is also a genetic basis to brain size- took care in correcting their measurements by ethnicity (because –the horror, the horror- it is known that brain’s size differs among races). However, the authors completely ignored the direct effect of parental genes (they did not measure the brains of the parents); they simply assumed that parental income was more important than parental genes. When they investigated the relation between children’s brain size and the parents’ years in education (which is not the same as intelligence, not to mention brain size) they did find a correlation. They did not investigate the correlation between parental education and income, something of capital importance if you really want to prove that children’s brain size is affected by parents’ income and not by other factors such as parents’ education/intelligence or (following the authors’ quasi- interpretation of the world) brain size.

In summary, the work has the taste of research that has been conducted not to provide a valid scientific insight but to prove a pre-conceived point: being poor is bad for children. Not being concerned with the truth this type of research is generally carried out in a sloppy fashion. I by and large agree with the point that being poor is bad for children, but I cannot agree with the article’s evidence or implications.

I am a firm believer in government intervention to provide good quality free education for all and to prevent child suffering. I do not think however, that we need to deface science to promote these policies; this is bad for science and bad for policy. The defence of state-supervised child protection and nurture (both physical and intellectual) must be done on moral grounds or on valid scientific grounds but not on sloppy research.

 (1) Mol Psychiatry. 2011 Oct;16(10):996-1005

(2) Nat Rev Neurosci. 2010 Mar;11(3):201-211

(3) Behav Genet. 2012 Sep;42(5):699-710

Image: Poor mother and children by Dorothea Lange; the United States Library of Congress.


Phrenology is a pseudoscience primarily focused on measurements of the human skull, based on the concept that the brain is the organ of the mind.

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  • Lillian Cruz-Orengo 29/04/2015 at 5:47 am

    Thank you so much for sharing. I totally agree with you and I think this kind of research do more harm than good. It promotes social discrimination based on pseudoscientific stereotypes. If these findings were true, my grandmother’s efforts to make sure that her children will get out of the slum through education had been pointless from the very beginning. Likewise, I will not hold a doctorate degree and a faculty position because I am coming from a poor & clumsy background.

    • Ariel Poliandri 29/04/2015 at 6:04 am

      I guess that I am in the same socioeconomic club than you Lillian and I have the same feeling about this “research”. The authors may have been well intentioned but their poor experimental design and conclusion advance neither science nor society.
      Or, as a Ioannis says: I guess that –as postdocs- we are aiming for small-brained children then.

  • Ioannis Kokkinopoulos 29/04/2015 at 5:45 am

    Then we are aiming for little brain kids as postdocs

  • Emmanuel Ani 28/04/2015 at 4:30 pm

    If there is a link between money and quality of brain training, and another between quality of brain training and brain size. Both would demand being true.

    • John Kugelman 28/04/2015 at 4:31 pm

      Qualities can demand? Who knew?!

      • Emmanuel Ani 28/04/2015 at 4:32 pm

        I mean links demand being true.

        • John Kugelman 28/04/2015 at 4:33 pm

          I don’t understand, “…links demand being true” just doesn’t make sense in English. Can you say what you mean? Do you mean links are necessarily true, never false? Because that simply is wrong. LInks have no true or false attached to them, they are simply tools used to take us someplace.

          • Emmanuel Ani 28/04/2015 at 7:27 pm

            If there is a link between money and quality of brain training, and another between quality of brain training and brain size. Both (links) would demand being true.
            There only need to be links at all for links between the said parties to be true. The rest (they are simply tools used to take us someplace) as you said, can then follow.
            The mention of link is only an invitation to further discussion (correlation, causality, nomological necessity and so on). The first question, however, is whether there are any links at all.
            So we can ask:
            (1) Any links (I do not want to use ‘relationship’, that might be saying too much at once)
            (2) If there is, what kind?

          • John Kugelman 29/04/2015 at 5:41 am

            I think I see; my confusion lied in the fact that you were using 2 different meanings for ‘link’; both are correct meanings, though very different; if you question whether there are any demonstrable links/relationships there, I agree, there aren’t any. Like Ariel said, the researchers ‘assumed’, and you know what they say about saying/using ‘assume’, it makes an ‘ass’ of ‘u’ and ‘me’. And they do seem to be the south end of horses going north. :)

    • Ariel Poliandri 28/04/2015 at 7:30 pm

      Hi Emmanuel,
      I am not sure what you mean by ‘quality of brain training’. If I am right in my assumption of what you meant though, I don’t think that you will be able to pick changes in brain structures due to the learning of a new skill with a CT scan (which is what this researchers used). That is assuming that there’ll be a macroscopic change at all, which it is a long shot anyway.
      The main problem with this study is that the researchers seem to have assumed that intelligence correlates with brain size and that both are independent of genetic factors. The first assumption is doubtful and the second plain wrong.

  • John Kugelman 28/04/2015 at 6:52 am

    Seems counterintuitive–we all know how many children of the mega-rich turn out to be as empty-headed as their pockets are full. Maybe the silver spoon in their mouths taints their brains, like cucumbers in brine become pickles. :)
    In short, BALDERDASH. OMG, do people actually write such garbage??

  • Patrick Smith 28/04/2015 at 6:30 am

    I think I detect an interesting and insightful comment in this – who gives a fig for brain size. I will take intelligence any old day over a fat brain.

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