img: Oran Maguire

a majestic review of over 600 brain imaging studies over 30 years concludes that men's brains are 11% bigger than women's because men are bigger than women. otherwise they're identical. dump the dimorphism!  

original article: Eliot et al., 2021 (Neuroscience and Biobehavioral Reviews), reported in: The Daily Mail by Dan Avery on 8th March 2021 & Twitter by Lise Eliot on 20th April 2021 image source

this story was in episode 7 #sex #male #female #dimorphism #MRI

the error bar says

the Daily Mail and Twitter report what may be the most impressive review article i've ever seen. Professor Eliot & colleagues review hundreds of brain imaging studies over three decades to answer one question: are men's and women's brains different?

their conclusion is that men's bodies are bigger than women's, which means that their brains are 11% bigger too. this 11% difference is an extremely strong statistical effect, & would allow you very easily to distinguish male & female brains with high probability, just by measuring their size. the authors wryly note, however, that there are easier ways to tell the sexes apart

but apart from overall size, do human brains show sexual dimorphism - clear differences in the shape or size of specific parts of the brain?


you can find some differences that are relatively consistent across studies, but when you control for total brain size & are very careful about exactly how the data are analysed, any remaining differences are so small as to be statistically irrelevant

are men & women's brains really the same?


this is an apotheosis of the paper; a titan of a text; a megafauna of a manuscript

the publication of this review has led me to ask the question: what is a scientific paper? some papers are just 'letters', reporting experiments or observations that might have taken a day, or a week or work. others, like this one, take at least several person-years of work

yet each paper, whether it represents a week or years or work will end up as a single entry into research databases and the author's cv. the careers of researchers, their impact, citations of their work, & their influence cannot be measured in the number of papers, citations, or other so-called article-level metrics

only by opening each paper & reading it can we judge a paper's worth. this one is solid gold


this is brain science at its best. the human brain is not sexually dimorphic


The Daily Mail: fact - scientific story reported well

Twitter: fact - scientific story reported well