title: Sex beyond the genitalia: The human brain mosaic.
abstract: Whereas a categorical difference in the genitals has always been acknowledged, the question of how far these categories extend into human biology is still not resolved. Documented sex/gender differences in the brain are often taken as support of a sexually dimorphic view of human brains ("female brain" or "male brain"). However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females) and internally consistent (i.e., a brain has only "male" or only "female" features). Here, analysis of MRIs of more than 1,400 human brains from four datasets reveals extensive overlap between the distributions of females and males for all gray matter, white matter, and connections assessed. Moreover, analyses of internal consistency reveal that brains with features that are consistently at one end of the "maleness-femaleness" continuum are rare. Rather, most brains are comprised of unique "mosaics" of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our findings are robust across sample, age, type of MRI, and method of analysis. These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare. Our study demonstrates that, although there are sex/gender differences in the brain, human brains do not belong to one of two distinct categories: male brain/female brain.
authors.affiliation: School of Psychological Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel; Sagol School of Neuoroscience, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel; djoel@post.tau.ac.il.
authors.forename: Daphna
authors.initials: D
authors.lastname: Joel
authors.affiliation: Sagol School of Neuoroscience, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Zohar
authors.initials: Z
authors.lastname: Berman
authors.affiliation: Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Ido
authors.initials: I
authors.lastname: Tavor
authors.affiliation: School of Mathematical Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Nadav
authors.initials: N
authors.lastname: Wexler
authors.affiliation: School of Psychological Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Olga
authors.initials: O
authors.lastname: Gaber
authors.affiliation: School of Mathematical Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Stein
authors.affiliation: School of Psychological Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel; Sagol School of Neuoroscience, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Nisan
authors.initials: N
authors.lastname: Shefi
authors.affiliation: Max Planck Research Group for Neuroanatomy & Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
authors.forename: Jared
authors.initials: J
authors.lastname: Pool
authors.affiliation: Max Planck Research Group for Neuroanatomy & Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
authors.forename: Sebastian
authors.initials: S
authors.lastname: Urchs
authors.affiliation: Max Planck Research Group for Neuroanatomy & Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany;
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Margulies
authors.affiliation: Max Planck Research Group for Neuroanatomy & Connectivity, Max Planck Institute for Human Cognitive and Brain Sciences, 04103 Leipzig, Germany; Division Neuropsychology, Department of Psychology, University of Zurich, 8050 Zurich, Switzerland.
authors.forename: Franziskus
authors.initials: F
authors.lastname: Liem
authors.affiliation: Division Neuropsychology, Department of Psychology, University of Zurich, 8050 Zurich, Switzerland.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hänggi
authors.affiliation: Division Neuropsychology, Department of Psychology, University of Zurich, 8050 Zurich, Switzerland.
authors.forename: Lutz
authors.initials: L
authors.lastname: Jäncke
authors.affiliation: Sagol School of Neuoroscience, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel; Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat Aviv, Tel-Aviv 6997801, Israel;
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Assaf
mesh_terms: D001519:Behavior; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D005835:Genitalia / Q000033:anatomy & histology*; D066128:Gray Matter / Q000033:anatomy & histology; D006801:Humans; D008297:Male; D009929:Organ Size; D012727:Sex Characteristics
keywords: behavior; brain connectivity; brain structure; gender differences; sex differences