I received my bachelor's degree (1995) with a major in anthropology and a minor in mathematics from Kenyon College (Gambier, Ohio) and my master's degree (1999) and Ph.D. (2004) in biological anthropology from the University of Pittsburgh. In graduate school, I was especially interested in sexual selection and the evolution of behavioral and morphological sex differences in humans. My dissertation was entitled 'Female Choice, Male Dominance, and the Evolution of Low Voice Pitch in Men,' and my advisors were Steve Gaulin and Michael Siegel. I continue to study the role of sexual selection on voice both here in the Breedlove/Jordan lab and in collaboration with Steve Gaulin, now at UC, Santa Barbara.
My interest in the evolution of behavioral sex differences led me to want to know more about their development and neural bases. This is why I came to the Breedlove/Jordan lab, one of the leading laboratories in the world researching this topic.
I am currently interested in sex differences in spatial problem solving ability, often measured by the ability to rotate pictures of 3D block figures mentally or to navigate in real or virtual environments. I am interested in this area partly because the greatest human cognitive sex differences have been found here, and partly because a lot has been written about both the evolutionary and developmental causes of this sex difference. In other words, spatial ability represents an ideal area to merge my research interests in both the evolutionary and the neuroendocrine causes of behavioral sex differences. Thus, my current research involves studying the effects of sex hormones on spatial ability and the structure of related brain regions.
However, I am interested in other topics, too. For example, I am interested in the development of sexual orientation. Sexual orientation is related to finger length ratios in women and number of biological older brothers in men. The ratio of the lengths of the index and ring fingers differs between males and females from early on in gestation, and this difference is probably caused by differential exposure to prenatal androgens. The fact that homosexual women tend to have more masculine finger length ratios suggests that early androgen exposure might also affect sexual orientation in women. Male sexual orientation is affected by the number of biological older brothers through the mother, regardless of the amount of time reared with these siblings, and no other sibling type, including older step-brothers and older brothers through the father has an effect. At present, a maternal immune response to antigens produced by male fetuses is the most plausible explanation for these effects. I am currently exploring relationships between finger length ratios, number of older brothers and several behavioral traits. What I have written on these topics can be found by clicking on this link to my CV.
Some of this research has received some media attention recently. Here are some of the citations with links, where available:
Attractiveness, Dominance and Men's Voices
- National Public Radio, "All Things Considered," "Why do men have deeper voices than women?" by Erika Engelhaupt, 16 December 2006.
- Pravda (Russian newspaper), "Women prefer men with lower voices for short-term sexual flings," by Alexander Timoshik, 1 September 2006.
- Science Update (American Association for the Advancement of Science news site), "Voice Dominance." Podcast interview by Justin Warner, 28 August 2006. Also included in podcast of 1 September 2006 with Bod Hirshon.
- derStandard (German newspaper), "Dominance Behavior: Where Men are Like Dogs," 14 August 2006.
- LiveScience News, "Men Act Like Dogs to Determine Dominance," by Ker Than, 31 July 2006.
- NRC Handelsblad (Dutch newspaper), "Dark, threatening, dominant: Low male voice makes impression on women and competitors," by Sander Voormolen, 14 March 2006.
Older Brothers and Sexual Orientation
- CBC Radio News (Canadian Broadcasting Corporation). Radio interview about fraternal birth order effect on male sexual orientation, 26 June 2006.
- Associated Press, "Men with Older Brothers More Likely to be Gay," by Randolph E. Schmid, 26 June 2006.
- The Guardian (British newspaper), "Sexual Orientation 'Affected by Number of Older Brothers'," by Alok Jha, 27 June 2006.
- ORF (Austrian news), "Homosexuality: 'Brother phenomenon' is Biological in Nature," 27 June 2006.
- Pravda (Russian newspaper), "Men Having Older Brothers Become Gay," by Alexander Timoshik, 27 June 2006.
- MedPage Today, "Gay from the Womb if Biological Older Brothers Matter," by Michael Smith, 27 June 2006
- Fox Radio News, Bill O'Reilly "No Spin" show. Radio interview about fraternal birth order effect on male sexual orientation, 29 June 2006.
In between injuries, I like to play ultimate frisbee, basketball, tennis, and pretty much every other sport. (I played football and ran track in college.) I also like to play chess and Scrabble. I value personal relationships very highly and appreciate the collegiality between members of the Breedlove/Jordan lab.