For three decades, Carl Zimmer has researched and written on both professional and popular understandings of science and technology for readers of Discover and The New York Times, as well as contributing regularly to NPR’s Radiolab and This American Life. His books and articles on evolutionary theory and microbiology have covered the winding histories of scientific revolutions and the broad impacts of expert knowledge entering into public discourse. In She Has Her Mother’s Laugh, Zimmer turns to the troublesome science of heredity, tracing its changing manifestations, from Gregor Mendel to the eugenics movement, from the Double Helix to 23andMe.
David Gerstle: The popular imagination of heredity has often come with socio-economic metaphors of inheritance as a kind of “capital.” How do you think this legacy shapes contemporary discussions of heredity and genetics?
Carl Zimmer: The word heredity, itself, comes from hereditas in Latin, which has to do with actual inheritance of the rights of someone to their possessions. In the Middle Ages, people in power wanted to demonstrate that they had a right to their positions and possessions, being passed down through some continuous line. So the word “heredity” was gradually borrowed to describe something biological. I think that we carry over some of those notions of heredity as involving some sort of property – things that you get from your parents and grandparents. If it’s something that you’re proud of, you tend to think “this is something that was passed down to me,” the same way that, say, a piano is passed down through a family.
DG: Where do you see the lingering impacts of the eugenics movement in people’s understanding of heredity? Has it contributed to ambivalence toward the science, itself?
CZ: It is striking how readily people will talk about genes in the same way that eugenicists did. They make huge generalizations. Seeing differences between groups of people, they’ll just claim “that’s totally genetic,” the implication being that what they see is totally natural. Nothing can be done about the situation they perceive, even if these are questions about justice or fairness. Unfortunately, some of the underlying ways of thinking about heredity which made eugenics possible are enduring.
And certainly the legacy of eugenics makes a lot of groups wary of being involved in genetics research. There’s a big gap in our understanding of genetic diversity when it comes to Native Americans, African Americans, and other groups. There’s a lot of suspicion because of the ways that the language of genes has been used to try to classify these groups as inferior. There is a paradox, on the other hand, that the African American community has been widely using direct-to-consumer genetic tests as a way of overcoming the gaps in genealogy that were created through slavery. There’s a big interest in that. So, there are some paradoxes in the ways that people are viewing this kind of technology, being very suspicious of it in some contexts and embracing it in others.
DG: What, in your experience, do people find empowering in the results of direct-to-customer ancestry tests like 23andMe? What aspects of this interest to you find troubling?
CZ: I’ve talked to people about their experiences with these tests, including my own relatives, trying to understand what their power is. The relative finder functions on sites like Ancestry.com are increasingly powerful and transformative, because they may show you that, say, your brother is really your half brother or that you have a second cousin that you didn’t know about. Perhaps there was a chapter in your family history that someone wasn’t very honest about. The science behind that is actually quite solid. It’s basic genetics that if somebody has a series of very long stretches of DNA identical to yours – stretches that go on for thousands or millions of bases – then you two are related biologically.
For me, personally, it’s kind of an awkward experience if a relative of mine says, “Hey, it turns out we have these cousins we didn’t know about over in England! I’m going to Skype with them today!” I’ll say, “Well, what are we supposed to talk about? We have no common experience whatsoever.” But my relatives will be on Skype for an hour. So, it’s a fascinating piece of the human experience for me.
The other side of this business is the ancestry element. In other words, the results of these tests that tell you that you are 14% Irish and 22% Southern European. I’m concerned that those test results are being rushed out before the science is very strong. It’s not that there is something conceptually wrong with the methods, but they can only be as good as the databases to which your DNA is compared. If you are of Filipino descent, and a lab only has someone from Taiwan and someone from Hawaii in their database, you’re going to get a result back that basically circles the entire Pacific. Consumers may look at these results as being incredibly precise and absolute, like measuring your heart rate. They’re not. They are rough statistical measurements on your DNA compared to a certain set of other people’s DNA. But it does seem like people are embracing these results, and they are being pushed to do so by these companies. There are ads on TV claiming that you are going to discover something important about your essence by taking one of these tests.
DG: Discourses on intelligence and heredity are deeply controversial. In your book, you give them a generally even-handed, historical treatment. What do you think are some of the more important “take-away” points about this kind of research?
CZ: You can’t tell the story of heredity without talking about intelligence, because it really drove the origins of the science. Francis Galton wanted to know why the boys he went to Cambridge with were so smart. He was struck by his impression that students that were smart tended to have brothers or fathers who were smart. Women, of course, didn’t matter to him. This was a driving obsession of his for decades. It got carried over into the early days of child psychology and intelligence testing. Then it was at the heart of eugenics, which was focused on intelligence or – on the flip side – what they would call ‘feeble-mindedness’. These were central obsessions from the start. So, deciding that intelligence is not worth talking about because it is controversial, that’s not an acceptable choice.
I show in the book that some of the leading scientists in the United States in the early 1900s embraced absurdly bad data in order to claim that intelligence and feeble-mindedness were entirely heredity. That led to terrible public policy, like sterilization or limiting immigration from certain countries because they supposedly had a high level of feeble-mindedness. This certainly should not happen again.
At the same time, intelligence tests clearly are measuring something. For one, intelligence tests correlate, and to some extent predict, different aspects of our lives. These can have to do with our survival rates or our likelihood of getting certain diseases. These same variants correlate how people do on intelligence tests to risks of certain conditions, for example, schizophrenia. Studying intelligence is a valid field of research today, 100 years later. But, those scientists who study it need to be mindful of just how badly their research has been distorted and used for awful social ends.
DG: Genetically Modified Organisms inspire a sense of dread in many people. Do you see this reaction as having historical underpinnings in the study of human genetics?
CZ: If you look at plant breeding and animal breeding, obviously humans have been doing that for over 10,000 years. But nobody talked about it in terms of heredity for thousands of years. Go to some guide to farming written during the Roman Empire, and you will not find anything about how to breed a better crop. It’s only in the Renaissance that you start to see people talking about “noble races” of dogs or horses or falcons, and the best way to breed them. Then, in the 1700s, Robert Bakewell produced an entirely new breed of sheep on his own farm. That really shocked a lot of people. Most people don’t know who Bakewell is now, but there’s a lot of resonance from him. Decades later, Charles Darwin wanted to understand what Bakewell had done, and Gregor Mendel and his community were very influenced by him. This was an idea that you could create a new strain of life. It was the power of the Enlightenment: to change life.
In the United States, throughout the 19th century, individuals were creating new breeds, the most famous of which was Luther Burbank, who was called a ‘wizard’ for his ability to make the Burbank potato or the Shasta daisy. This seemed like a sort of magic. People admired this and wanted to buy his plants. Genetics transformed that magic into a somewhat more concise process. People might blast corn plants with x-rays to induce random mutations and grow them, just to see what came of it. But, it was only when scientists started putting genes from one species into another that came this feeling that we were ‘playing God’ – something dangerous and unnatural. Attitudes actually first turned in the 1970s, with recombinant DNA being used to put genes into E. coli. Human insulin, for example, was considered by some to be a terrible development that would lead to diabetic epidemics. The same anxiety transferred over to food. In a way, people resist GMOs because they seem to violate the rules of heredity, because heredity is supposed to work in a particular way: an organism acquires genes from its ancestors. We know this isn’t true. Genes can actually be transferred horizontally between species. But as far our folk sense about how heredity is supposed to work, GMOs seem to violate this.
I’m wondering what is going to happen with CRISPR, because now you don’t have to take a gene from, say, an insect and insert it into a strawberry. With CRISPR, you might just change one letter of DNA in one gene, or you might snip out five letters. In other words, making tiny adjustments to a plant’s DNA on the same scale that arise naturally. You know that you need to make this mutation or that mutation to make this crop resistant to drought. It’s not breaking any sort of species barrier anymore. It will be interesting to see if some people view that as being unnatural.
DG: Thanks so much for a great interview!
CZ: Thanks for the chance to chat.