인지 능력의 성차에 대해 글을 작성해 놓고자 자료를 뒤적거리고 있었는데 마침 흥미로운 논문을 발견했다.
Sex differences in brain volume are related to specific skills, not to general intelligence
Intelligence 40 (2012) 60–68
Miguel Burgaleta, Kevin Head, Juan Álvarez-Linera, Kenia Martínez, Sergio Escorial, Richard Haier, Roberto Colom
신체 사이즈를 통제해도 남자가 여자보다 뇌가 더 큰데 이 때문에 학자들은 이런 차이가 인지능력의 차이와 관련되지 않을까 추측해 왔다. 한 가지 가설에 따르면 남자가 가지고 있는 여분의 뇌는 삼차원 공간 처리와 관련이 있으며 이는 과거 진화사에 비추어 볼 수 있다는 것이다. 이번 연구를 진행한 연구자들은 뇌 크기에서의 성차는 공간 능력과 관계되고 일반지능과는 관계되지 않는다는 것을 밝혀냈다. 좀더 검토가 필요하고 한계점이 있긴 하지만 남녀의 공간 능력 차이를 이해하는 데에 큰 도움을 줄 것이라는 사실은 변함이 없다. 앞으로 이런 종류의 연구가 많이 수행되어 후속 연구에서도 적극적으로 검증해 볼 필요가 있을 것이다.
아래는 벨 커브의 저자인 charles murray의 언급.
For a long time, psychometricians have known that males have larger brain volume than females, on average, even after adjusting for body size, and that brain volume correlates with IQ (Sorry, Steve Gould fans. A lot of the things he told you about IQ just aren’t true).* So what are men doing with that extra brain volume? Are they smarter than women?
One theory has been that men use that extra brain volume to process three-dimensional spatial data. Out on the prehistoric savanna, being able to throw a spear accurately and find one’s way home after a long hunt had clear survival value, and the demand on men to do these things was a lot higher than the demand on women. Hence, a sex difference in spatial abilities evolved, but one that would not necessarily translate into a sex difference in the overall general mental ability g.
An article on sex differences in cognitive ability has just appeared that is based on state-of-the-art science and provides strong evidence that this conjecture is correct. Using precise measurements of gray matter and white matter plus a complete battery of mental tests, the researchers found that sex differences in brain volume were not related tog, but were related to sex differences in spatial skills.
How can this be? As a rough analogy, consider how much computing power you need. If you are a photographer and manipulate large images on Photoshop, you need a lot faster chip and more memory than if you are a writer and using only Microsoft Word. But that doesn’t have anything to do with the cognitive complexity of the different tasks. Again very roughly: Men tend to be better at certain spatial tasks, which require a lot of neurons; women tend to be better at verbal tasks, which require fewer neurons.
This article is not dispositive—there’s a lot left to be learned about all of these issues. But it is a big step forward, has the advantage of making sense, and is another vindication for those of us who think there are lots of important sex differences—and vive le différence.
*Gould didn’t just misrepresent the literature. He sometimes made things up.