It is often questioned as to why fewer women enter science. This study assesses whether a cognitive style characterized by systemizing being at a higher level than empathizing (S greater than E) is better than sex in predicating entry into the physical sciences compared to humanities. 415 students in both types of discipline (203 males, 212 females) were given questionnaire and performance measures of systemizing and empathy. 59.1% of the science students were male and 70.1% of the humanities students were female. There were significant sex differences on the Empathy Quotient (EQ) (females on average scoring higher) and on the Systemizing Quotient (SQ) (males on average scoring higher), confirming earlier studies. Scientists also scored higher on the SQ, and scored lower on the EQ, compared to those in the humanities. Thus, independent of sex, SQ was a significant predictor of entry into the physical sciences. Results from questionnaire data and performance data indicate an S greater than E profile for physical science students as a group, and an E greater than S profile for humanities students as a group, regardless of sex. We interpret this as evidence that whilst on average males show stronger systemizing and females show stronger empathizing, individuals with a strong systemizing drive are more likely to enter the physical sciences, irrespective of their sex.