Misunderstood for decades, pioneering geneticist Barbara McClintock prompted Jack Scanlan to wonder: what’s the point of scientific ideas if we can’t communicate them to others?
Model Specimens is a monthly column that explores the role models who inspired today's scientists. This month, our editor-in-chief Jack Scanlan shares how Barbara McClintock inspires his work in genetics and convinced him about the immportance of explaining your science.
Modern genetics might be seen as a hardcore scientific discipline by the public, but it has nothing on the old-school way of doing things. In the early 20th century, back before the discovery of the beautifully twisted structure of DNA, genes were not much more than abstract concepts and techniques for manipulating them were non-existent. A good geneticist in those days was therefore a patient person, who was able to observe and collect data over many weeks, months and years to gradually piece together the rules and secrets of heredity. You didn’t become a geneticist for instant gratification, but because your passion overrode the crushing tedium of your work.
Barbara McClintock, born in 1902 in Connecticut, USA, was undoubtedly a good geneticist — in fact, she may have been one of the greatest who ever lived. McClintock made multiple landmark discoveries in the fledgling field of genetics, some of which took decades to be recognised and appreciated. Rarely has the phrase “way ahead of her time” been so appropriate.
But for all her scientific success, McClintock was a curious figure — as much an inspiration as a cautionary tale. For budding geneticists like me, she simultaneously demonstrates the raw power of hard work, dedication and emotional connection to your research, but also the necessity of the community aspects of science. Barely anyone knew of her in her day, and now only die-hard geneticists do. Ever since learning about her story, a question has been bubbling up in my brain: if no one but you understands your research, are you really doing science?
The corn-draped shrine
My first exposure to Barbara McClintock was through an undergraduate textbook, in the sort of preliminary chapter on the history of genetics that students are only too happy to forget. Once I moved into graduate study, however, I couldn’t avoid her, as one of my labs had a photo of McClintock on the wall, beneath a cluster of dried ears of corn. That someone would go to the trouble of setting up something of a secular shrine to this scientist intrigued me. She was obviously important — the dramatic black and white portrait suggested as much — but I wondered why her in particular. What had she done?
If you dig into McClintock’s history, the reasons for her veneration become immediately obvious. In the early 1930s, after completing a PhD in the new field of cytogenetics (the study of chromosomes), she published the first evidence of the physical ordering of genes on chromosomes. While a trivial fact today, it was an important turning point in the study of genes — and their physical locations pulled scientists towards the truth of genes-as-objects. Such a thing had been assumed for decades, based on work done in my own research organism of choice, the fruit fly. But while fruit flies can be bred rapidly in the lab, with generation times less than two weeks, McClintock’s organism, maize (more commonly known as corn), takes many months to grow. Personally, all the waiting around would have driven me insane, but McClintock was strongly attached to maize and didn’t mind — leading her to see what others did not.
I start with the seedling, and I don't want to leave it. I don't feel I really know the story if I don't watch the plant all the way along. So I know every plant in the field. I know them intimately, and I find it a real pleasure to know them.
– Barbara McClintock quoted in Charles Birch, Biology and the Riddle of Life (1999)
Her early breakthroughs had relied on her developing new methods for staining and identifying maize chromosomes, a laudable feat itself in the pre-molecular age. Spotting subtle differences in size and shape between chromosomes allowed the plant’s traits — or at least the genes encoding them — to be mapped to specific chromosomal regions, something at which McClintock excelled. The secrets of maize were slowly unravelling, and McClintock was enjoying a particularly successful career, being elected to the National Academy of Sciences at the age of 42 and eventually becoming the first female president of the Genetics Society of America in 1945. She was undoubtedly one of the best maize geneticists in the world.
But in the late 1940s, McClintock noticed something entirely unexpected, and her story shifted from a notable, albeit traditional, tale of scientific achievement to one tangled with misunderstanding and confusion. Her maize genes started jumping.
Genes were meant to be static, beads on the chromosomal string. Indeed, McClintock’s work in the 1930s seemed to verify this model — genes didn’t move between chromosomes, they had a fixed address, each a little city on a map. And yet, she saw, they moved. Some genes on maize chromosomes could shift position, and in the process, switch other genes on and off. In McClintock’s eyes, this was a major discovery and seemed to suggest that the movement of genes could control the development of organisms.
Not everyone agreed, and describing this result to her colleagues had limited success. Breaking orthodoxy in science is a curious thing. While it is frequently disparaged, it is absolutely necessary and a researcher needs to strong both in their knowledge and their persuasiveness to change the minds of others. McClintock was not, and had a very hard time selling the importance of jumping genes to scientists outside her research institute. Her thought processes were reportedly hard to follow and she could rarely explain her scientific reasoning. McClintock being a female researcher in the mid-20th century surely didn’t help either.
It is often thought that data speak for themselves. But this is far from true. Science is a human endeavour filled with human personalities, far from the stereotypes of cold, logical scientists dispassionately discussing objective truth. People’s preconceptions and biases colour their perception of new information, and McClintock’s work was too outside-the-box for many. That she had trouble articulating her ideas, in a field as conceptually demanding as classical genetics, didn’t help. If she couldn’t hold her colleagues’ hands and walk them through the steps to arrive at her conclusions, they had to do it on their own. And many failed.
Nevertheless, her first paper on jumping genes, or mobile genetic elements, as they are known today, was published in 1950, and was followed by many others. On the surface, it appeared as though her ideas were getting out there. But they received relatively little traction and didn’t substantially alter the frameworks of the time. McClintock’s ideas slowly faded from relevance, even as she continued to work diligently in the lab, building on her discoveries in her own semi-private world.
They thought I was crazy, absolutely mad.
– Barbara McClintock quoted in Claudia Wallis, 'Honoring a Modern Mendel', Time (24 Oct 1983)
Part of this was due to McClintock’s communication style, but it was also due to the content of her ideas. While mobile genetic elements excited her, they mainly did so in the context of her slowly burgeoning hypotheses about the nature of development — the movement of genes might be, according to McClintock, a compelling account of how genes were regulated. Very few other scientists agreed. Ultimately, her theories of development failed to be substantiated by new discoveries, and by the time molecular genetics truly arrived in the 60s, they had no plausible foundation. She formally retired in 1967.
Retired, but not forgotten
But that’s not quite the end of it. The molecular revolution vindicated McClintock’s jumping genes idea. In the late 70s and early 80s, it became clear that mobile genetic elements infected the DNA of many organisms, most of which were inactive. But the active ones played inadvertent roles in everything from cancer biology to antibiotic resistance. They didn’t regulate development, but they did mess around with it. The genetic chaos of evolution was largely due to the process of DNA movement, or transposition, and their importance in biology was now no longer in question. In belated recognition of her discovery of transposition, McClintock was awarded a Nobel Prize in 1983 at the age of 81, over 30 years after her initial observations.
I often wonder what would have happened to the study of genetics if McClintock had been able to more persuasively convince others of her ideas. A more dynamic view of genetics in the early stages of the field would have had huge implications for evolutionary biology, and a greater appreciation for transposition may have led to their discovery in other organisms far sooner. But McClintock’s ideas could quite easily have never been understood at all, had she been entirely unable to convince others of their worth. And what would have been the purpose of that?
If you know you are on the right track, if you have this inner knowledge, then nobody can turn you off... no matter what they say.
– Barbara McClintock
These days, it’s common to hear calls for scientists to engage more with the public, to bring their research to the world and explain its importance. This is a noble goal, of course, and it’s one that motivates publications such as the one you’re reading. But science communication is important within science, as well. Just as science divorced from wider society means nothing, a new scientific finding or idea, unable to be freed from the mind of a researcher, is of little use to the world. Science is a group activity. Scientists do not study in isolation, as tortured geniuses cut off from the world — we benefit from discussions, debates and the sharing of information. Bringing other people into your head, to show them what you see in an act of intellectual empathy, is one of the greatest skills a scientist can have.
I don’t work with maize, I’m an insect man. But I’m still a child of McClintock’s influence — one of the children of her corn, if you like horror movie references. Her place up on the wall of my lab is more than deserved — indeed, some of her later work in maize may have even preempted the study of epigenetics by nearly half a century, further cementing her status as a pioneer. While I admire her work, it is her inability to explain her scientific ideas that helps drive my desire to articulate my research openly and (hopefully) effectively. My conference talks need to be effective, my discussions with other researchers need to be productive.
After all, what’s the point of learning if you’re not going to share with others?