Let’s do a thought experiment.  Imagine that human reproduction worked this way: at a certain age you are blindfolded and led to a massive field with a hundred other blindfolded people roaming about it.  The rule is that the first person you come into contact with is the person you mate with.  While that random system might account for a lot of fun, from a reproductive standpoint it would be an absolute disaster, as only 50% of the time would your couplings even possibly result in offspring.  We “higher” beings are fortunate in possessing advanced capacities, like sight and speech and Tinder, for overcoming that disadvantage, but for organisms that meet each other only by blind chance, it’s a potentially massive problem which each kingdom must solve as best it can.  

Dr. Cardy Raper (b. 1925) spent the whole of her long career unraveling the intricacies of nature’s more extreme solutions to the random mating problem.  Three quarters of a century ago, researchers began realizing that gender is a markedly fluid concept for certain water molds: whether you acted the part of the “male” or “female” depended largely on who your partner was, so that one specimen might play the female role when confronted by a particularly male specimen, but might be simultaneously the male for a particularly female one.

Such a complicated set of relations must surely have a fascinating chemical signaling network underlying it, itself likely underpinned by an even more intriguing genetic system, and it was the fate of a young Carlene “Cardy” Allen to do her graduate work in the laboratory of one John “Red” Raper, who was studying the reproductive strategies of the Achlya genus of the water molds.  It was an unconventional field to find one’s self in, but then convention and Cardy Allen had hardly been regular companions.  The youngest child, and only daughter, in a gaggle of six siblings, her youth had been marked by rough and tumble rites of passage and the constant need to assert her worth in the face of well-intentioned but difficult fraternal ribbing.  

She had decided at the age of eight on a career in science after a once-a-week visiting teacher in third grade fired her with the realization that science could be a journey of discovery and not a mere matter of rote recitation of known facts.  After high school she attended Syracuse University, where she fell in with a group of three students with a reputation for rebellion.  Amidst a student body dedicated to the proposition that college was a matter of marking time until a husband could be found, this fiery quartet smoked, discussed politics, cross dressed, and generally sought experience and knowledge wherever it was in the offering.  

Syracuse, it turned out, was too stifling an environment for young Allen, so she transferred to the University of Chicago, which was transforming itself into an academic force that put scholarship first and “rah-rah” style collegiate theatrics a distant second.  The lecture hall and the research lab, not the football field, was the center of school life, and as graduation approached in 1946 Allen knew she wanted to continue with science, but wasn’t sure how to go about it until a friend introduced her to John Raper, Assistant Professor of Botany at the University of Chicago, who was returning to his work studying water molds after a stint on the Manhattan Project during the Second World War.  She found his research fascinating – what was behind the gender role selection process in Achlya, and what might the emerging science of genetics bring to bear on its mysteries?

Allen joined Raper’s project as a graduate student and the relationship, at first one of mutual work and interests (in addition to science, both loved classical music and sailing) became over time a romantic one, complicated by the fact that Raper was already married, with a newborn son.  The three years that separated the beginning of their professional relationship in 1946 and their marriage in 1949 were rife with agony and self-doubt on both sides, as Raper was consumed with guilt for his feelings and actions, and Allen was torn between what she felt was the moral choice of fleeing to another part of the country to start over, and what her heart told her was a never-to-return chance at fulfillment on both the intellectual and emotional levels.  

Ultimately, Allen stayed, and Raper went off on a slime mold collecting mission in England for a year to gather his thoughts and feelings, and when he returned, the decision was made at last to leave his wife and begin a new life with Allen.  While Cardy worked at the Argonne Laboratory establishing the toxicity of nitrogen mustard (which gives mustard gas its caustic properties), Red carried on with his research at the University of Chicago, aided by her on weekends when she had the time.  

But soon thoughts turned to starting a new family, and in 1952 they had their first child.  Cardy left her research work to become a full-time mother, and in 1954 Red took up a position at Harvard, allowing them to move into a neighborhood better suited to the raising of children.  

There were rewards in these years, but also a heavy toll was paid as Cardy no longer participated as intensely in the joint research that had made her and Red such a solid unit initially, with the result that Red slowly drifted into a relationship with another woman which was only ended when that other woman definitively refused to be the cause of a broken home and turned down anything but his friendship.  

The Rapers would remain together until Red’s sudden death in 1974, and as the children grew up and found their independence, it allowed Cardy at last to rejoin Red’s laboratory, which had moved from the water spore Achlya to the fungus Schizophyllum commune, which had a mating mechanism even more profoundly strange than the water spores.  In the days before PCR and cDNA microarrays, the only way to investigate the complicated gene networks contributing to an organism’s physical properties and behavior was to produce a multitude of mutations that altered that organism in measurable ways.  Cardy and the other lab workers had success in creating mutant mating types, and Cardy hypothesized that the two mating type genes, named A and B, contained within them code for transmitting mating type data and also code for receiving such data, an idea which would have to wait for modern genetic techniques to get its final proof.

In the meantime, Red’s death meant the end of Cardy’s work at Harvard.  As the wife of the former biology chair, she was given some leeway to continue her work, but without a PhD her future was limited and so, at age 52, she hit the books, created her own research program, and at last earned the degree that would allow her to set up her own lab, out from under the long shadow of Red.  

She sent out applications to various universities, but met with only rejection until Wellesley at last agreed to take her on as a three quarter time, non tenure track instructor for introductory biology.  It was not her dream job, but with nothing else on the table, she had to accept, and for the next five years she spun her wheels trying to connect with the larger classes which took issue with her teaching style and gave her correspondingly poor evaluations that ultimately ended her career there in 1982.

At that point, she was 57 years old and had weathered just about every professional and personal setback that the mid Twentieth Century could hurl at a woman researcher, but Raper’s response was, characteristically, not despair but rather a determination to recreate herself.  She went to UC Davis to learn the new genetic techniques that would allow her to definitively answer a lifetime’s worth of accumulated questions as to the genetics of fungal mating types, and ended up establishing a lab at the University of Vermont where she could put those methods to work.

There, between her own work and that of her close colleagues, the amazing diversity of the fungal mating system was finally uncovered.  It turned out that Schizophyllum has not one gender, or three, or ten, but rather something on the order of 23,000 distinct mating types.  To produce offspring, remember, you just need to hook up with something of a different mating type than yourself.  We humans have two choices – male and female – and a correspondingly dismal 50% chance of reproductive success upon randomly mating with whatever human happens to be nearby.  But Cardy’s fungus, as analysis revealed, possesses over four hundred genetic locations that determine mating type, meaning that when a fungus meets a random fungus, there is a 98% chance they will have a difference in gender and will be able to mate successfully through an elaborate system of pheromone signaling and receiving that Raper had predicted decades earlier.  

Four decades earlier, a young grad student had been lured by curiosity to the lab of Red Raper to get to the bottom of a biological mystery: What lies beneath the startling diversity of sex in the lower kingdoms?  She had pursued that curiosity through the ensuing years of emotional distress, late career professional re-creation, and loss, to emerge at last with an answer not only startling in its scale, but rich in potential as a model for studying signaling mechanisms in “higher” organisms.  She had been considered academically Finished multiple times throughout her career as too old or too undistinguished to possibly pick up the pieces and begin again, but the girl who refused to give way through the barrage of elder sibling roughhousing became the woman who would not quit, though the journey be decades in the undertaking, who got her answers and enriched the scientific world by her resolute example.  

Dr. Cardy Raper retired, but not really, in 1994, and then did it for real in 2004, at the age of seventy-nine.

Photo credit: Dr. Cardy Raper


FURTHER READING: Raper’s memoir, A Woman in Science: An Extraordinary Journey of Love, Discovery, and the Sex Life of Mushrooms (2013) is a thoroughly candid and frank assessment of her life and work, which sticks to honesty as its watchword in all things. Her complicated relationship with Red, the small betrayals and large acts of temper of her co-workers, and her frustrations during the long years away from the lab are all investigated in a spirit of rigorous self-analysis.  There is also an absurdly charming piece of video of her talking about Lake Champlain here

And for more awesome Women in Science comics, check out the archive and my books, Illustrated Women in Science – Volume 12 and 3