Down There (Part 5, Conclusion)

What Humans Can Learn from Sex in an MRI Machine

by Richard Conniff

When it comes to human mating, there may be anatomical adaptations we don’t recognize. Even for scientists, it’s not an easy subject to study.  Humans are not June Bugs. Flash-freezing a human couple in mid-coitus and slicing them in two to see how they fit together would generally be deemed a breach of research ethics.  But in the early 1990s Dutch researchers attempted the next best thing, persuading couples to have sex inside a magnetic resonance imaging machine, which produces visual slices of tissue.  The idea was to view and record the internal details of intercourse for the first time ever. 

For many of the couples, the circumstances--the whirring magnetic ring of the MRI, the need to remain motionless in flagrante delicto for 52 seconds per image, the lab-coated scientists viewing the images from behind a curtained glass window, and the “obtrusive and sniffing press hounds” howling and slobbering somewhere in the distance--added up to an overwhelming case of performance anxiety.  Only one couple, amateur street acrobats “trained and used to performing under stress,” rose to the occasion.  The researchers had better luck on a second attempt in the late 1990s, aided by improvements in MRI technology and the arrival of a “godsend” in the form of viagra. 

 What they found was that humans have misunderstood even the rudimentary positioning of the genitalia during sex.  The penis isn’t straight in mid-coitus, as Da Vinci drew it.  Nor do the root and the pendulous parts of the penis form an s-shape, as twentieth-century scientists somehow imagined it.  Instead, the MRI showed that the pendulous part veered upward at a 120-degree angle from the root, like one wing of a boomerang, pressing tight against the nerve-rich forward wall of the vagina.  As has often been the case with science, the female response got slighted in the study, with most of the crucial details “beyond the resolution of our current equipment.”  (Try this excuse on your girlfriend sometime.)  No one has yet attempted to repeat the experiment.

So does any of this make a real difference in our lives?  Does it help to have what is arguably too much information about how birds, and bees, and even spiders really do it?  Bill Eberhard naturally thinks so.  He suggests, for instance, that understanding the internal courtship function of sexual intercourse might help couples attempting artificial insemination. 

Our long coevolution as male and female has presumably made the penis better adapted than a turkey baster (or the medical equivalent) to prepare a woman to become pregnant.  In some species, for instance, the tip of the penis swells up at the moment of ejaculation to perform a mechanical “gate opening” of the cervical canal.  Female orgasm may induce contractions that aid in the transport of sperm and egg alike.  So artificial insemination might achieve a better rate of success, Eberhard suggests, if immediately preceded by an act of natural sexual intercourse. 

And for the rest of us who just want to have fun?  Cooperation and conflict are both undoubtedly part of the picture.  In the lives of every well-adjusted couple, there are moments of happy sex and angry sex, too, and each has its special appeal.  So is it just wishful thinking to suggest that, whatever our reproductive chemicals may be up to, cooperation generally prevails (in the form of laughter, good feelings, making peace, and comforting each other in the craziness and grief of daily living?  The phrase “two shall become one” feels like more than just a Darwinian prophecy about how our DNA will recombine in our offspring.  It’s something we feel when the line between male and female blurs into a single rhythm of body and feeling.  Human beings are among the quintessentially cooperative species on Earth, and never more so than in sex.  (But let’s not get carried away.  The list of other highly cooperative species includes ants.  And honeybees.)

Whether the sex is affectionate or angry, there’s at least one valuable lesson human couples can take away from Bill Eberhard’s study of genitalia in the animal world:  Pay attention to your partner in the copulatory dialogue.  Take your time.  Notice the sighing, the flexing, the sharp intake of breath, the slow stuttering exhalation. It’s like a good naturalist exploring the world of another species:  Satisfaction comes from listening to the nuances.