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Marc Breedlove

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Marc Breedlove
Born1954 (age 71–72)
Springfield, Missouri, U.S.
Alma mater
Known forResearch on biological influences on sexual orientation
Scientific career
Fields
Institutions
Websitemarcbreedlove.com

Stephen Marc Breedlove (born 1954)[1][2][self-published source?] is the Barnett Rosenberg professor of neuroscience at Michigan State University in East Lansing, Michigan.[3] He was born and raised in the Ozarks of southwestern Missouri.[2] After graduating from Central High School (Springfield, Missouri) in 1972,[4] he earned a bachelor's degree in psychology from Yale University in 1976,[2] and a PhD in psychology from UCLA in 1982.[2] He was a professor of psychology at the University of California, Berkeley from 1982 to 2003,[2] moving to Michigan State in 2001.[2] He works in the fields of behavioral neuroscience and neuroendocrinology. He is a member of the Society for Neuroscience[5] and the Society for Behavioral Neuroendocrinology,[6] and a fellow of the Association for Psychological Science (APS)[7] and the Biological Sciences section of the American Association for the Advancement of Science (AAAS).[8]

Research

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In numerous papers, Breedlove has demonstrated that steroid hormones and sexual behavior affect the developing and adult spinal cord and brain. He also reported that the average digit ratio of lesbians is more masculine than that of straight women,[9] a finding that has been replicated in his[10] and many other labs[11][12][13][14][15][16][17][18][19][20][21] and which indicates that lesbians, on average, are exposed to more prenatal testosterone than are straight women. This finding joins many others that biological influences, such as prenatal testosterone and fraternal birth order,[22] act before birth to affect the later unfolding of human sexual orientation.

He is sole author of two textbooks, Principles of Psychology and Foundations of Neural Development, and has co-authored textbooks in biological psychology and behavioral neuroendocrinology.[23][24][25][26]

A 2009 study co-authored by Breedlove examined whether post-traumatic stress disorder might contribute to erectile dysfunction. Male rats subjected to single prolonged stress, an experimental protocol that models PTSD, showed reduced gastrin-releasing peptide (GRP) in the lumbar spinal cord and weakened penile reflexes. Treatment with a GRP receptor agonist restored the reflexes. The authors proposed the spinal GRP system as a possible therapeutic target for psychogenic erectile dysfunction in men with PTSD.[27]

He also researched how GRP in the lumbar spinal cord could be pharmacologically stimulated to restore male reproductive function. It was found that female rats and male rats with non-functional androgen receptors had only a vestigial GRP system in this region. Once GRP receptors were stimulated in castrated male rats, penile reflexes and ejaculation were restored. During the experiment, simple erections, dorsal flips of the penis, and cup-like flaring erections of the distal glans were measured in the rats before and after administration of a GRP receptor agonist.[28]

Breedlove examined the sex differences in animals to gain an understanding of the sex differences in humans. As a graduate student at UCLA, he and his doctoral advisor Arthur P. Arnold discovered the spinal nucleus of the bulbocavernosus (SNB), a sexually dimorphic motor nucleus in the lumbar spinal cord of rats.[29] It was found in rats that the males had higher cell numbers in the SNB than the female rats. These motor neurons appear in both male and female rats at birth, but die off in the female rats during early development. Testosterone was also found to be the key hormone that is responsible for the differences between males and females by preventing this perinatal cell death in males.[30]

Breedlove researched the sexual preferences of homosexual men. Using personal ads from homosexual and heterosexual men, it was found that the two groups did not vary in mating preferences. Even though their partnerships with men cannot produce offspring, homosexual males, like heterosexual males, prefer to be with a younger partner. The authors concluded that both groups' partner preferences were independent of reproductive considerations.[31]

See also

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References

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  1. ↑ Who's Who in the West 1996–1997. Marquis Who's Who, LLC. November 1995. ISBN 978-0-8379-0926-4.
  2. 1 2 3 4 5 6 Breedlove, S. Marc (March 18, 2009). "Curriculum Vitae" (PDF). Retrieved October 31, 2009.
  3. ↑ "Cellular/Molecular Neuroscience Faculty". Michigan State University. 2008. Retrieved October 31, 2009.
  4. ↑ "Neuroscientist and Springfield native shares view on sexual orientation". Archived from the original on May 2, 2014.
  5. ↑ "Donald B. Lindsley Prize in Behavioral Neuroscience".
  6. ↑ "Hormones & Behavior Editorial Board".
  7. ↑ "List of APS Fellows". Archived from the original on April 22, 2003. Retrieved January 6, 2010.
  8. ↑ "AAAS Members Elected as Fellows".
  9. ↑ Williams, Terrance J.; Pepitone, Michelle E.; Christensen, Scott E.; Cooke, Bradley M.; Huberman, Andrew D.; Breedlove, Nicholas J.; Breedlove, Tessa J.; Jordan, Cynthia L.; Breedlove, S. Marc (March 2000). "Finger-length ratios and sexual orientation" (PDF). Nature. 404 (6777): 455–456. Bibcode:2000Natur.404..455W. doi:10.1038/35006555. PMID 10761903. S2CID 205005405.
  10. ↑ Brown, Windy M.; Finn, Christopher J.; Cooke, Bradley M.; Breedlove, S. Marc (February 2002). "Differences in finger length ratios between self-identified 'butch' and 'femme' lesbians" (PDF). Archives of Sexual Behavior. 31 (1): 123–127. doi:10.1023/A:1014091420590. PMID 11910785. S2CID 10259939.
  11. ↑ Tortorice, J. L. (2002). Written on the body: butch/femme lesbian gender identity and biological correlates (Ph.D. Dissertation). Rutgers University. OCLC 80234273.
  12. ↑ McFadden, Dennis; Shubel, Erin (December 2002). "Relative lengths of fingers and toes in human males and females". Hormones and Behavior. 42 (4): 492–500. Bibcode:2002HoBeh..42..492M. doi:10.1006/hbeh.2002.1833. PMID 12488115. S2CID 1360679.
  13. ↑ Hall, Lynn S.; Love, Craig T. (February 2003). "Finger-length ratios in female monozygotic twins discordant for sexual orientation". Archives of Sexual Behavior. 32 (1): 23–28. doi:10.1023/A:1021837211630. PMID 12597269. S2CID 1743441.
  14. ↑ Rahman, Qazi; Wilson, Glenn D. (April 2003). "Sexual orientation and the 2nd to 4th finger length ratio: evidence for organising effects of sex hormones or developmental instability?". Psychoneuroendocrinology. 28 (3): 288–303. doi:10.1016/S0306-4530(02)00022-7. PMID 12573297. S2CID 21071741.
  15. ↑ Csathó, Árpád; Osváth, Anikó; Bicsák, Éva; Karádi, Kázmér; Manning, John; Kállai, János (February 2003). "Sex role identity related to the ratio of second to fourth digit length in women". Biological Psychology. 62 (2): 147–156. doi:10.1016/S0301-0511(02)00127-8. PMID 12581689. S2CID 38339150.
  16. ↑ Putz, David A.; Gaulin, Steven J. C.; Sporter, Robert J.; McBurney, Donald H. (May 2004). "Sex hormones and finger length: What does 2D:4D indicate?" (PDF). Evolution and Human Behavior. 25 (3): 182–199. Bibcode:2004EHumB..25..182P. doi:10.1016/j.evolhumbehav.2004.03.005. Archived from the original (PDF) on January 7, 2010.
  17. ↑ Rahman, Qazi (May 2005). "Fluctuating asymmetry, second to fourth finger length ratios and human sexual orientation". Psychoneuroendocrinology. 30 (4): 382–391. doi:10.1016/j.psyneuen.2004.10.006. PMID 15694118. S2CID 39896938.
  18. ↑ Kraemer, Bernd; Noll, Thomas; Delsignore, Aba; Milos, Gabriella; Schnyder, Ulrich; Hepp, Urs (2006). "Finger length ratio (2D:4D) and dimensions of sexual orientation". Neuropsychobiology. 53 (4): 210–214. doi:10.1159/000094730. PMID 16874008. S2CID 201838.
  19. ↑ Wallien, Madeleine S. C.; Zucker, Kenneth J.; Steensma, Thomas D.; Cohen-Kettenis, Peggy T. (August 2008). "2D:4D finger-length ratios in children and adults with gender identity disorder". Hormones and Behavior. 54 (3): 450–454. doi:10.1016/j.yhbeh.2008.05.002. PMID 18585715. S2CID 6324765.
  20. ↑ Grimbos, Teresa; Dawood, Khytam; Burriss, Robert P.; Zucker, Kenneth J.; Puts, David A. (2010). "Sexual orientation and the second to fourth finger length ratio: a meta-analysis in men and women". Behavioral Neuroscience. 124 (2): 278–287. doi:10.1037/a0018764. PMID 20364887.
  21. ↑ Breedlove, S. M. (2010). "Organizational Hypothesis: Instances of the Fingerpost". Endocrinology. 151 (9): 4116–4122. doi:10.1210/en.2010-0041. PMC 2940503. PMID 20631003.
  22. ↑ Puts, David A.; Jordan, Cynthia L.; Breedlove, Stephen M. (July 2006). "O brother, where art thou? The fraternal birth-order effect on male sexual orientation" (PDF). Proceedings of the National Academy of Sciences of the United States of America. 103 (28): 10531–10532. Bibcode:2006PNAS..10310531P. doi:10.1073/pnas.0604102103. PMC 1502267. PMID 16815969.
  23. ↑ Breedlove, S. Marc (2015). Principles of Psychology. Oxford University Press. ISBN 978-0-19-932936-6.
  24. ↑ Breedlove, S. Marc; Watson, Neil V. (2013). Biological Psychology: An Introduction to Behavioral and Cognitive Neuroscience (7th ed.). Sinauer Associates. ISBN 978-0-87893-927-5.
  25. ↑ Watson, Neil V.; Breedlove, S. Marc (2016). The Mind's Machine: Foundations of Brain and Behavior (2nd ed.). Sinauer Associates. ISBN 978-1-60535-276-3.
  26. ↑ Becker, Jill B.; Breedlove, S. Marc; Crews, David; McCarthy, Margaret M. (2002). Behavioral Endocrinology (2nd ed.). MIT Press. ISBN 978-0-262-52321-9.
  27. ↑ Sakamoto, Hirotaka; Matsuda, Ken-Ichi; Zuloaga, Damian G.; Nishiura, Nobuko; Takanami, Keiko; Jordan, Cynthia L.; Breedlove, S. Marc; Kawata, Mitsuhiro (2009). "Stress Affects a Gastrin-Releasing Peptide System in the Spinal Cord That Mediates Sexual Function: Implications for Psychogenic Erectile Dysfunction". PLOS ONE. 4 (1) e4276. Bibcode:2009PLoSO...4.4276S. doi:10.1371/journal.pone.0004276. PMC 2627921. PMID 19169356.
  28. ↑ Sakamoto, Hirotaka; Matsuda, Ken-Ichi; Zuloaga, Damian G.; Hongu, Hisayuki; Wada, Etsuko; Wada, Keiji; Jordan, Cynthia L.; Breedlove, S. Marc; Kawata, Mitsuhiro (June 2008). "Sexually dimorphic gastrin releasing peptide system in the spinal cord controls male reproductive functions". Nature Neuroscience. 11 (6): 634–636. doi:10.1038/nn.2126. PMC 3954789. PMID 18488022.
  29. ↑ Breedlove, S. Marc; Arnold, Arthur P. (October 1980). "Hormone accumulation in a sexually dimorphic motor nucleus of the rat spinal cord". Science. 210 (4469): 564–566. Bibcode:1980Sci...210..564B. doi:10.1126/science.7423210. PMID 7423210.
  30. ↑ Morris, John A.; Jordan, Cynthia L.; Breedlove, S. Marc (October 2004). "Sexual differentiation of the vertebrate nervous system". Nature Neuroscience. 7 (10): 1034–1039. doi:10.1038/nn1325. PMID 15452574.
  31. ↑ Gobrogge, Kyle L.; Perkins, Patrick S.; Baker, Jessica H.; Balcer, Kristen D.; Breedlove, S. Marc; Klump, Kelly L. (October 2007). "Homosexual Mating Preferences from an Evolutionary Perspective: Sexual Selection Theory Revisited". Archives of Sexual Behavior. 36 (5): 717–723. doi:10.1007/s10508-007-9216-x. PMID 17674179.

Further reading

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