Testing Limits
THE POLYMERASE CHAIN REACTION
By the mid- to late 1980s, the search for DNA from ancient and extinct organisms was attracting both professional and popular attention, but scientists were aware of their need for better technology that could reliably amplify the decayed and damaged DNA characteristic of old specimens. They knew that new technologies and techniques were necessary if they wanted to transform the search for DNA from fossils into a full-fledged research program. Rather conveniently, the innovation of a new molecular biological technique, the polymerase chain reaction (PCR), coincided with this search for ancient DNA, presenting a convenient solution. PCR was first developed in the 1980s by Kary B. Mullis and fellow colleagues at Cetus Corporation, a biotechnology company in Berkeley, California. Following a presentation of its application at the Cold Spring Harbor Symposium in 1986—the same symposium where James Watson first described in detail the DNA double helix thirty years earlier—and several publications from 1985 to 1987, PCR became the most widely used technique in molecular biology.1 As various researchers incorporated the technique into their work, it began to transform the field of molecular biology and the related areas of systematics, forensics, and medicine. In fact, PCR proved so revolutionary that Mullis was awarded the 1993 Nobel Prize in Chemistry for its invention.2
The advantage of PCR was its automatic amplification of DNA. This took the mental and physical strain out of the previously manual process of cloning using vectors to create multiple identical copies of the DNA of interest, as was the case when scientists first extracted DNA from the quagga. Overall, PCR could create billions of copies of DNA sequences from only a few strands, or even just one strand, of DNA. Ancient DNA was often preserved in short strands, and PCR was specifically well suited for amplifying these damaged and degraded fragments. Furthermore, PCR was quick and inexpensive. It used repeated cycles of heating and cooling to copy the DNA. First, heat would be applied to separate double-stranded DNA into single-stranded DNA. Then the single-stranded DNA would be exposed to primers. These primers would attach themselves to the appropriate sites of desired DNA to be amplified. Finally, a copy of the targeted DNA would be produced. This process would continue as a chain reaction, ultimately creating millions to billions of copies of the targeted DNA.3 New Scientist called it “a tool of unbelievable power.”4
As an early player in the search for ancient DNA, Allan Wilson’s lab at the University of California, Berkeley, was the first to apply the technique to the study of old specimens. Wilson was already well connected with Cetus Corporation, where PCR had been designed and developed. Furthermore, Cetus was not too far from the university, so Wilson sent Higuchi to learn the method and bring it back to the lab.
Svante Pääbo—by this time a new postdoctoral researcher in the lab—set out to test PCR’s utility on a range of specimens of different ages and from different environments.5 Pääbo’s goal in this study was twofold. First, he was interested in testing PCR’s technical advantages. If PCR could be easily and reliably applied to old specimens, then this could have notable implications for using museum specimens and other archeological and paleontological samples to answer unresolved questions about evolutionary history. Second, he was interested in testing the limits of DNA preservation in various specimens and how the chemical composition of DNA could be affected by modifications that occur through the desiccation of tissues as a result of hydrolytic and oxidative processes. In better understanding the properties of DNA and processes that contribute to its degradation, he hoped to find observable and generalizable patterns.
With the availability of PCR, Pääbo extracted DNA from a four-year-old piece of pork, fragments of mummy material, the remains from an extinct wolf-like species called a thylacine, and a thirteen-thousand-year-old extinct ground sloth. To his surprise, he found that the age of the sample did not necessarily correlate to the amount of DNA preserved or the degree to which it was damaged. The preservation potential of DNA appeared quite fickle and definitely subject to internal and external processes of degradation. However, PCR greatly increased the possibility and ease of extracting and amplifying DNA sequences from ancient samples—but its very virtue, namely its ability to exponentially amplify even the smallest amounts of DNA, was also its vice. PCR was extremely sensitive in that it could detect and amplify a single molecule. This was convenient for ancient DNA because it was often preserved in short fragments. However, if there was any other DNA in the sample, especially DNA that had been introduced during the handling or studying of the specimen in the lab, then that DNA—being much more recent and better preserved—would be preferentially detected and amplified by PCR instead of the actual ancient DNA of interest. To control for contamination, Pääbo suggested “rigorous precautions” when preparing and handling samples, solutions, and materials in the lab.6
In a review article in the late 1980s, Pääbo, Wilson, and Russell Higuchi expanded on the implications of PCR as a technological development within the broader context of molecular evolutionary biology, especially highlighting the use of PCR in making the search for ancient DNA possible, as well as the risk of contamination that came along with it. According to them, the general frustration of molecular evolution was the current challenge of reconstructing evolutionary history with only the DNA from living organisms. Without DNA from ancient and extinct organisms, they claimed, it was difficult if not impossible to understand evolution over time. PCR, however, was one potential solution for overcoming this “ ‘time trap.’ ” “The recently achieved ability to study DNA from museum specimens and archaeological finds via PCR,” they wrote, “opens up the possibility of studying molecular evolution by actually going back in time and directly approaching DNA sequences that are ancestral to their present-day counterparts.”7 Sure enough, a growing body of evidence demonstrated PCR’s utility in testing hypotheses in evolutionary biology.
Although PCR was a welcome innovation with many advantages, there were drawbacks to the technology that researchers had to first acknowledge in order to accommodate or avoid them. Pääbo, Higuchi, and Wilson took the lead on this, outlining a short but succinct list of criteria to control for contamination when working with paleontological and archeological material. Here, they recommended three criteria. First, they suggested comparing sequences obtained from an ancient organism to the sequences of its closest living relatives, then using the accuracy of the resulting phylogenetic analysis as an indication of ancient DNA authenticity. Next, they advised using control extracts to detect for contamination in any of the solutions or reagents in the lab, as well as independent extracts in order to recover and demonstrate authentic DNA sequences from more than one sample. Finally, they recommended a “strong inverse correlation between amplification efficiency and size of the amplification product.” In other words, they hypothesized that DNA from long-dead organisms should yield shorter sequences, approximately 150–500 base pairs, rather than longer sequences. These shorter sequences were expected to reflect the fragmented nature of ancient material, while longer sequences might signal contamination from modern material. They argued for the importance of understanding the potential for contamination and the need to take steps to control for it in order to determine the authenticity and reliability of ancient DNA. “When the three above criteria . . . are fulfilled,” they argued, “a given sequence is considered likely to be of ancient origin.”8
With the newfound availability of PCR, Wilson, Pääbo, Richard H. Thomas (another postdoctoral researcher in the lab), and Walter Schaffner (a molecular biologist from the University of Zurich) next attempted the extraction of DNA from the thylacine, an extinct wolf-like marsupial. The last thylacine, also known as the Tasmanian tiger, died at the Beaumaris Zoo of Australia in 1936. At the time of its death, no one seemed to care that this creature was the last of the species Thylacinus cynocephalus. In fact, more than five months passed before its death and the extinction of the species were even noticed and announced.9 The thylacine was an unusual animal—wolf-like in face and body, marsupial-like in anatomy and physiology, carnivorous in appetite, and nocturnal in behavior. It had a kangaroo pouch and resembled a tiger with a yellow-brown coat and dark stripes across its back. Like the quagga, the thylacine was a sentimental species because of its extinction, but it was also an obvious object of study for its mysterious evolutionary history. Indeed, systematists had long argued over its phylogenetic placement. Some suggested a closer connection to an extinct group of South American marsupials, while others considered the thylacine to be related to Australian marsupials. The debate among scientists came down to the fossil evidence and different interpretations of it. For example, the thylacine and South American borhyaenids shared similar dental and pelvic traits, while the thylacine and Australian dasyurids shared similar hind limbs.
In 1989, Thomas and colleagues published their findings on DNA from the thylacine. Initially, they had attempted to recover DNA from a number of samples but were only able to extract DNA from one of them. From this, however, they were able to sequence 219 base pairs of mitochondrial DNA. Despite being such a short DNA sequence, it provided enough material that the team could compare it to the mitochondrial DNA of six other marsupials. After analysis, they concluded that the thylacine was most related to Australian dasyurids, which include the Tasmanian devil. This suggested that the thylacine was native to Australia, not South America as some had supposed.10
Based on the thylacine DNA sequences, the question of its evolutionary history seemed resolved. For some scientists, however, the fossil data gave evidence of a different history. Morphological data, such as fossils, and molecular data, such as protein or DNA sequences, provide important but different kinds of information about an organism’s life. While researchers consider both types of data when trying to reconstruct the evolutionary history of organisms, the information can be inconsistent. For the thylacine, for example, the genetic data suggested an Australian origin but the fossil data seemed more consistent with a South American origin. In this instance, the team sided with the genetic evidence and concluded that the thylacine, based on both DNA and protein evidence, originated in Australia.11 Thomas and colleagues were confident in the fact that the sequences they recovered were authentic to the thylacine. To reconcile the inconsistencies between the fossil and genetic data, researchers explained the similarities between the Australian thylacine and South American marsupials as an example of convergent evolution, where two species evolve similar features independently of one another.12 Overall, the thylacine study, like the quagga study, helped confirm the significance of studying DNA from ancient and extinct museum specimens, opening an unchartered territory of research.
FUNDING A NEW FIELD
Although the extraction, amplification, and sequencing of DNA from fossils were first explored in the United States, specifically at Berkeley, it was in the United Kingdom that ancient DNA research first received funding on a substantial scale. The quagga study provided evidence that DNA could be recovered from ancient specimens, but in doing so, it introduced more questions than answers, inspiring other scientists to join the search for DNA from damaged and degraded material.13 In November 1988, the Natural Environment Research Council (NERC)—the largest funding body for the environmental sciences in the United Kingdom—awarded a £600,000 grant for the search for molecules in fossil material. Over the next four years, the “Special Topic in Biomolecular Palaeontology” would fund a host of scientists to search for ancient lipids, proteins, RNA, and DNA from a variety of specimens.14
“The Special Topic in Biomolecular Palaeontology” would prove to be an invaluable initiative in the conceptual, organizational, and financial development of ancient DNA research as a young scientific field. Indeed, it financed some of the earliest, perhaps most exploratory research of the time. Among the numerous applications the NERC received in response to this grant was an application from a young group of scientists proposing to extract DNA from ancient bone—and not just any bone but ancient human bone. One interviewee involved in the review process recalled this particular proposal, as well as their immediate reaction to it: “I had a look at it, and it was the most stupid idea. It was this young team and they wanted to get DNA from fossil bones.” The proposal, at least according to this scientist, was absurd. One reason had to do with the available evidence for the longevity of not just DNA but other molecules such as proteins. At the time, proteins were not expected to survive intact for thousands, let alone millions, of years. “DNA is much less stable than proteins,” explained this interviewee. “There’s no way you could get DNA to survive in fossil bones” (Interviewee 9).
There were a number of other reasons this proposal seemed so far-fetched. Although it might be more likely to recover DNA from skin or muscle tissue, as was the case with the quagga and mummy studies, it seemed less likely scientists could recover DNA from a substance like bone. A fully mineralized fossil, such as an ancient human bone, would be highly unlikely to preserve DNA, because its organic components would have decayed and been replaced by minerals from the surrounding sediment in which the organism died. Furthermore, even if DNA could survive the test of time and remain untouched in a substance like bone, it would be extremely difficult to verify the DNA’s authenticity. That is, it would be next to impossible to demonstrate that the ancient human DNA extracted from the ancient human bone was not a contaminate from being handled by human curators and researchers in the lab.
As the reviewers continued assessing the proposal, however, they came across some important information that made them change their minds. Indeed, the applicants had some rather convincing empirical evidence to back up their proposal. According to a researcher, just as they were disputing the proposal’s feasibility, a fellow colleague and reviewer excitedly pointed to one of the pages: “Look! . . . We’ve actually got a gel.” Surprised, this interviewee took a look and quickly replied, “Oh! Well, if they got the band from the gel we should give them funding!” (Interviewee 9). What the reviewers found themselves looking at was photographic evidence of DNA, a run of small dark bands spread across a gel-like substance. It was a classic experimental technique—gel electrophoresis—for the purpose of visualizing DNA fragments, should they in fact be present. The researchers had inserted a dye into the extracted DNA sample, then inserted that sample into a small rectangular gel. Afterward, an electric current reacted through the gel, moving the DNA along the gel and separating the shorter fragments from the longer ones. For the reviewers, this was evidence enough. In the end, “We gave them a positive review,” explained this interviewee, “and that funded Erika Hagelberg. And the band [on] the gel was the band [on] the gel that then appeared in Nature as the first record for DNA recovery from old bones” (Interviewee 9).
The next year, 1989, Nature published a paper by Erika Hagelberg, Bryan Sykes, and Robert Hedges at the University of Oxford on the “successful extraction and amplification of DNA from human bones between 300 and 5,500 years of age.”15 Reminiscing on the impact of this research at the time, another interviewee and pioneer in this research referred to the findings and their subsequent publication as a “watershed” moment. It provided evidence that some DNA could, and in this case did, survive in paleontological and archeological material including bones, not just skins and tissues. “Twenty-five years ago,” the interviewee said, “people had no idea whether DNA survived in bone, and if it did what to do with it or how to get it out in the first place” (Interviewee 11). This study, the first of its kind, elicited excitement. It generated a good deal of skepticism too.
Despite publication in a top-tier journal such as Nature, some scientists found it hard to believe the results. In 1990, the controversy over the preservation and extraction of DNA from old bones came to a head when Pääbo directly confronted Hagelberg at the Biomolecular Palaeontology Community Meeting at the University of Glasgow.16 “Svante Pääbo, very famously at the meeting, stood up and said, ‘Of course, you can’t get DNA from bone!’ ” recalled a researcher. And that was “just before Erika Hagelberg stood up and said, ‘Here’s my results on DNA from bone’ ” (Interviewee 9). Another scientist recounted a similar situation: “Svante had . . . some very public fights with her in conferences . . . saying it was all shit.” According to this scientist, “Svante stood up and said, ‘This is shit! It’s full of shit! Where are your controls? You haven’t got any! And the sequences you have are rubbish!’ ” In the end, “it was a big shouting match” (Interviewee 32), and “she [Hagelberg] felt very much as if he [Pääbo] was trying to undermine her work at the time” (Interviewee 9).
The fight over DNA from old bones came down to concerns about contamination. With human scientists working on human remains, it would be difficult, if not seemingly impossible, to detect modern contamination via the traditional sequence comparison. In fact, this controversy over contamination, specifically as it related to the study of ancient humans, would impact the young field for years to come. Importantly, it was not just the controversy itself at the time but the retelling of it to fellow colleagues and later students that served to establish and reinforce a specific narrative of the early days of the field. “For a long time,” said a younger practitioner in the field, “ancient DNA [research] was about, ‘What is possible?’ ‘Is it possible—in the very early days—to get DNA from bone?’ ” Although not present at the conference where Pääbo confronted Hagelberg, this scientist did recall the retelling of it: “I wasn’t there at the time,” they said, “but I heard the story that at one of the first ancient DNA meetings Svante Pääbo said you will never be able to get ancient DNA from bone” (Interviewee 15). These disagreements were far from superficial. As researchers continued to test the limits of this new field, the issue of contamination would continue to define, even drive, the development of the field.
Sure enough, some researchers tested the limits to see just how far back in time DNA could survive. In 1990, for example, Edward Golenberg at the University of California, Riverside, and fellow colleagues reported the recovery of the oldest DNA to date: 17–20-million-year-old DNA from a fossil Magnolia leaf recovered from the Clarkia deposit in northern Idaho.17 The research findings, published in Nature, marked the recovery of the oldest DNA to date. An article in the Washington Post noted, “Scientists for the first time have read the genetic code of an organism that died between 17 million to 20 million years ago, achieving a record-breaking glimpse into the past based on new techniques that could soon be used on other ancient plants and animals.”18 The New York Times ran a report, “Genetic Code Found in 17-Million-Year-Old Leaf,” quoting a scientist who called it a “fantastic breakthrough” and the NSF, which claimed it was an “unprecedented achievement.”19 New Scientist devoted an entire six pages to the discovery of “The Oldest DNA in the World,” which “has left molecular palaeontologists with more questions than answers.”20 Indeed, some researchers had serious questions about the authenticity of the multimillion-year-old DNA.
Pääbo and Wilson, for example, were wary of the results, noting that the recovery of such DNA “seems to surpass our wildest dreams.”21 They were suspicious of Golenberg and colleagues’ results mainly because the sequences he claimed to have recovered were too long. At 790 base pairs, this sequence surpassed Pääbo’s suggested threshold of 150–500 base pairs, which would be more characteristic of old DNA. In a separate study, Pääbo, Wilson, and Arend Sidow—a colleague from the University of Munich—set out to replicate the results. They did, in fact, recover evidence of DNA. However, the DNA was not plant DNA but bacterial in origin. Unable to replicate Golenberg’s results, and in light of the fact that they determined their own extractions to be bacterial in origin, Pääbo and colleagues suggested that more extensive work be conducted to demonstrate the veracity of claims around multimillion-year-old DNA.22
In 1991, Pääbo and Golenberg came face to face at the Biomolecular Palaeontology Discussion Meeting at the Royal Society in London, both giving presentations on their separate findings of the Clarkia deposit.23 Martin Jones, an archeologist at Cambridge University and another early researcher in the search for DNA from fossils, documented the tension in the room as the two young researchers presented their conflicting conclusions. As Martin recalled, Golenberg went first and in a “slightly nervous presentation” discussed the need for “care and control” but stood by his results of having obtained ancient and authentic DNA from a fossil leaf. Pääbo went next, explaining that in his own work on samples taken from the same site they had not recovered plant DNA but bacterial DNA. According to Martin, “The inference was that Golenberg’s result arose from contamination.”24 Indeed, contamination was an ever present concern: one step forward was almost always accompanied by two steps back.
The growing funding and awareness of ancient DNA research, as well as the availability of PCR, invited more scientists to join the search for ancient DNA. This increased competition brought about bolder claims of long-term DNA preservation in a variety of material, high-impact scientific publications, and high-profile media attention. It also brought about more accusations of contamination. “Up until the Magnolia publication,” wrote Martin, “the front runner in the race for ancient DNA was emerging as Svante Pääbo.” However, as other scientists joined the hunt, often testing the limits as they did so, Pääbo found his role in the field shifting. According to Martin, “He was no longer simply the bright young star of the field, but was getting used to a new role as traffic policeman in a convoy moving with rather too much momentum for its own safety.”25 Ancient DNA research was evolving into a new field of scientific inquiry but one colored by controversy. For the skeptics, extraordinary claims required extraordinary evidence.
SCIENCE AND FICTION COLLIDE
In July 1991, the University of Nottingham in England hosted a conference called “Ancient DNA: The Recovery and Analysis of DNA Sequences from Archaeological Material and Museum Specimens.”26 It was the first official international meeting of its kind. Richard Thomas—formerly at the University of California, Berkeley—had recently relocated to London as director of the DNA Laboratory at the British Museum of Natural History and was responsible for organizing the event. The conference’s objective was to bring together an international and multidisciplinary group of practitioners interested in ancient DNA research to share results, compare research, and discuss potential protocols as well as problems.
The two-day conference—sponsored by the British Museum of Natural History along with NERC and Cetus Corporation—featured nearly thirty-five presentations by researchers from the United States, United Kingdom, Netherlands, Germany, Italy, Israel, Denmark, Sweden, France, Spain, and South Africa. Overall, the meeting involved senior and junior researchers alike from different disciplines ranging from archeology, paleontology, and geology to molecular biology, genetics, and forensic science.27 Some of the researchers demonstrated the use of ancient DNA to trace the evolution and domestication of plants, while others tested hypotheses about the evolutionary relationships of extinct and endangered animals. Others focused on human evolutionary history, namely the sexing of skeletons for kinship. According to one interviewee, an early leader in this research area, “Everyone was really excited. It was a completely unmapped field—getting DNA from dead things. No one had ever done it before.” Still, the enthusiasm for the new field was not entirely unbridled. While there was “a lot of really ambitious speculation,” there was also “a lot of realism about what could be done and what couldn’t be done” (Interviewee 4). Indeed, researchers recognized that not every specimen was going to yield DNA, and if it did, it would be degraded or damaged, and difficult to determine its authenticity.
The public had quite a different view. In November 1990, nearly six months before this meeting, Michael Crichton’s science-fiction novel Jurassic Park was published.28 The book—whose plot was based on scientists’ recovery of dinosaur DNA from amber-preserved insects—was an immediate success, and after being translated into multiple languages from Chinese and Japanese to Hungarian, it became an international best-seller. There was also much excitement and anticipation around turning the book into a Hollywood movie. Crichton was an already famous author whose novels had been made into highly successful movies. According to Don Shay and Jody Duncan, authors of The Making of Jurassic Park, Crichton sent his manuscript to his publisher, Alfred A. Knopf, in May 1990. In no time at all, major movie producers from Twentieth Century Fox and Warner Brothers to Universal Pictures were jockeying for the chance to make the film. However, as Shay and Duncan noted, Crichton had privately promised Steven Spielberg the film rights, an agreement that reportedly transpired when Crichton and Spielberg worked together on a screenplay, ER, which Crichton had written and Spielberg was at the time crafting into a medical drama television series. Nonetheless, intense bidding ensued. In the end, the film rights went to Universal and the job of producing and directing went to Spielberg.29 With such an award-winning director in charge, Jurassic Park was a highly anticipated blockbuster.
The enormous popularity of Jurassic Park was partly a result of its scientific and technological plausibility.30 After mulling over the Jurassic Park story line for nearly a decade, Crichton settled on a science-fiction thriller about genetically engineered dinosaurs brought back to life from DNA preserved in the gut of a mosquito trapped in ancient amber. Jurassic Park was a world-class dinosaur theme park as well as a cutting-edge scientific experiment gone wrong. In his book, Crichton utilized current DNA technology and research on cellular and molecular preservation in fossils to make the story convincing.
Specifically, Crichton used the work of George Poinar and Roberta Hess at Berkeley as the novel’s premise. Poinar and Hess, advocates for the search for molecules from fossils since the early 1980s, had since teamed up with Allan Wilson and Russell Higuchi to try to recover DNA from amber insects.31 Although Poinar and Hess’s research was influential, it was the quagga research by Wilson and Higuchi, as well as the early mummy study by Pääbo, that made Jurassic Park so plausible to the public. “Genetic material had already been extracted from Egyptian mummies, and from the hide of a quagga, a zebra-like African animal that had become extinct in the 1880s,” explained Crichton in his book. “By 1985, it seemed possible that quagga DNA might be reconstituted, and a new animal grown. If so, it would be the first creature brought back from extinction solely by reconstruction of its DNA. If that was possible, what else was possible? The mastodon? The saber-toothed tiger? The dodo? Or even a dinosaur?”32 This research, and the speculation about bringing extinct creatures back to life associated with it, was the backdrop for International Genetics Incorporated, the fictional bioengineering company in Crichton’s story, and their remarkably successful efforts to clone full-size dinosaurs.
In June 1991, just before the Nottingham conference that July, the science section of the New York Times made note of the upcoming meeting, advertising it alongside a recipe for bringing dinosaurs back to life. The report—“Scientists Study Ancient DNA for Glimpses of Past Worlds”—was written by the well-known science reporter Malcolm W. Browne. “Will it one day become possible to breed a living dinosaur from genes preserved in fossils?” he asked. “Although most scientists regard such an idea as unrealistic, a few have begun to conclude that it can no longer be dismissed out of hand.” In a step-by-step illustration, Browne outlined a “Recipe for a Dinosaur.” The first step: “Find a bead of amber that contains a blood-sucking insect from the age of the dinosaurs.” Next, “extract genetic material from blood cells of a bitten dinosaur, and amplify DNA with the PCR technique.” Then, “process and inject into embryo of an alligator.” Last but not least, “wait until it hatches.” Browne credited this “recipe for a dinosaur” to George Poinar, citing it as the inspiration for “the basis of the best-selling science-fiction novel ‘Jurassic Park.’ ” “Obviously, we couldn’t reconstruct an extinct animal today, even if we had all its DNA,” Poinar said in an interview with Browne. “However, my belief is that there are dinosaur cells inside biting flies trapped in amber of Cretaceous age and older. It’s just a matter of finding the dinosaur DNA and getting it out.”33
Although the first official and international ancient DNA conference put the practice on the map for a professional audience, Jurassic Park and the New York Times story put the science in the media spotlight. In the “Research News Series” for Science, Jeremy Cherfas covered the conference, highlighting the fact that the meeting attracted more attention than anticipated. According to Cherfas, Thomas, one of the conference organizers, had hoped for a “quiet” and “technical” meeting, “but that was before the science section of The New York Times published a fanciful ‘recipe’ for recreating a dinosaur from ancient DNA.” “We were inundated by people,” Cherfas reported Thomas saying. “We were stunned and amazed by the reaction from the press. We had to spend a fair amount of our time telling them, ‘No, we are not going to reconstruct the dinosaur.’ ” “However much scientists may protest that it cannot be done,” Cherfas wrote, “the public and the popular press clearly expect ancient DNA to create Jurassic Park for real.”34
FOUNDING A NEW FIELD
By 1991, a scientific community had come together under the name of “ancient DNA research” and started to communicate professionally about their expectations for what appeared to be a new research field. Reporting for Science, Cherfas interviewed Thomas, who noted that earlier meetings on ancient DNA research had been “controversial” as “scientists disputed the validity of their techniques.” As far as Thomas was concerned, the University of Nottingham conference was different: “There, he [Thomas] says, with considerable satisfaction, people at long last talked openly about the problems they had with their samples.” Indeed, the community appeared to be moving toward more open, honest, and collegial discussions of the potential, as well as pitfalls, of the search for DNA from fossil specimens. According to Cherfas, for the conference attendants, the take-home message of the meeting was clear: “They found they had created a new field.”35
In addition to the conference, the ancient DNA community was interested in taking other measures to establish and expand on the work being done. At this conference in particular, several attendants considered the idea of forming a research journal dedicated to the search for DNA from fossils. Ultimately, they decided against it for the time being, reasoning the field might be too premature to provide sufficient content and ensure long-term success. Instead, they settled for a newsletter to better connect researchers both professionally and personally.36 Robert Wayne, an evolutionary biologist at the Zoological Society of London, and Alan Cooper, a graduate student at the University of Wellington in New Zealand who had just started working at Berkeley with Wilson and Pääbo, accepted the “dubious honor” of becoming the newsletter’s first editors.37
In a letter dated April 1992, Wayne and Cooper introduced the first Ancient DNA Newsletter. The newsletter included up-to-date summaries of research projects, study outcomes, and practical lab tips. There was even a question-and-answer section—“Dr Russ’ Problem Corner”—where scientists could share their technical lab troubles with Higuchi, the molecular biologist guru, and receive a response in the following issue. At the same time, the newsletter was more than just business. The “Personals” of each newsletter included “general gossip,” from write-ups of special events and restaurant reviews to short research statements with the “intent of building bridges between laboratories with common interests.”38 To help fund the newsletter’s continued production and aid the success of the new field, researchers could buy their very own “Ancient DNA” shirt featuring the Ancient DNA Newsletter logo, a Tyrannosaurus rex holding a pipette in one hand and a double helix in the other.39
Specifically, this newsletter was a space for scientists to construct a culture of professional and philosophical values around the practice. This was especially important because the search for ancient DNA brought together scientists from disparate disciplines, from archeology and anthropology to botany, paleontology, molecular biology, and forensic science. Researchers had diverse motivations for joining the search, as well as their own unique sets of research methods, questions, and traditions. “It was a way of really standardizing the techniques and information and methods that were going on in the field,” recalled one researcher. “And it was pretty important at the time in terms of solidifying the field as an entity rather than people just using ancient DNA for quite different things” (Interviewee 32). In light of their disciplinary differences, this early community of ancient DNA researchers had a common interest in reliably extracting, sequencing, and analyzing DNA from long-dead organisms. Ancient DNA and the pursuit of it was their common ground, their boundary object, and the newsletter was a means that scientists used to consolidate their various educations, experiences, and trainings toward the pursuit of this shared goal.
Cover of Ancient DNA Newsletter (April 1992), illustrated by the biologist and paleontologist Blaire Van Valkenburgh. (Courtesy of Blaire Van Valkenburgh)
The first ancient DNA conference and subsequent newsletter, as well as earlier funding efforts and high-profile scientific publications, were fundamental to the emergence of ancient DNA research as a new field. At the same time, the media played a real role in its formation too. The media helped bring attention to a marginal, rather speculative idea, and in doing so invited both professional and popular interest in its potential as a revolutionary approach to studying evolutionary history. Specifically, Crichton’s best-selling book and movie in the making corresponded with some of the field’s initial funding efforts, publications, and conferences. The New York Times’s explicit connection between the first ancient DNA conference and Crichton’s Jurassic Park positioned the new field and its practitioners in the media spotlight. For the public, Jurassic Park gave life to the rather abstract concept of extracting DNA from long-dead creatures.
For the majority of scientists, however, the goal was not to bring dinosaurs, or any other extinct creature, back to life. Higuchi and Pääbo, for example, discussed species resurrection with media reporters only to reinforce the point that it would be impossible, impractical, and even unethical. In his Science report, Cherfas speculated about resurrecting a woolly mammoth based on the fact that Wilson’s lab had earlier recovered some small sequences of DNA. Cherfas asked Higuchi his thoughts on the topic: “The amount of mammoth DNA is enough that in theory a dedicated graduate student could reassemble the entire mitochondrial genome,” Higuchi said. “So we could have elephants walking around carrying mammoth mitochondrial DNA sequences.” According to him, however, there was problem with this: “It would make absolutely no difference. They’d still be elephants.”40
Pääbo also argued that such a project would be far from worthwhile. In a different media article, he told reporter Malcolm Browne, “It’s theoretically possible to isolate the gene for a certain character, and introduce it into another species, if you thought that was worthwhile, which I do not.” As far as he was concerned, he objected to species resurrection for practical and philosophical reasons: “You could find the gene for the typical quagga color pattern, for example, and introduce it into a zebra.” However, “you would end up with something that looked like a quagga, but in reality it would just be a zebra that looked like a quagga.”41 Regardless of whether scientists were actually attempting to bring dinosaurs back to life, and despite their efforts to brush the prospect aside, the idea of resurrection and its connection to the search for DNA from fossils, especially as embodied by Jurassic Park, generated attention and activity around what was an otherwise novel research practice.
Even as scientists rejected the conclusions or implications of the Jurassic Park narrative, as well as media reporters’ mentions of it, they drew on its popularity to bolster their own work. “The ‘clone-me-a-dinosaur’ faction,” recalled one researcher, “people are obviously going to get excited about that . . ., and there were a few of us, I think, at the time that were happy to piggyback off that interest to get funding and so on” (Interviewee 24). Indeed, researchers were aware of the news values around their practice and some catered to it for the pragmatic purpose of creating awareness, which would hopefully bring more resources such as publications, collaborations, funding, and status. The connection between the science of ancient DNA research and the science fiction of Jurassic Park made this easy to do. Indeed, this connection between the two would become increasingly important as the field continued to evolve over the next few years.
Overall, the conference and the momentum it engendered seemed to be a success. It was an eventful and exciting time for the growing community, but also a somber time with the early and sudden passing of one of its founding members. Wilson, a pioneer in molecular evolution and an early player in this research, was diagnosed with leukemia and had been undergoing treatment. “Allan’s lab . . ., it’s the birthplace of ancient DNA,” said a former student and colleague. “That lab was incredibly creative. You could come up with any hare-brained idea. Allan . . . encouraged it actually. . . . The crazier you were the more he encouraged you” (Interviewee 18). Wilson, unable to attend the conference, was not forgotten. According to another early researcher, the conference attendants took the time to make him a get-well card that they all signed (Interviewee 30). He died just two weeks later.
THE ROLE OF SPECTACLE
By the early 1990s, a small but growing group of researchers became interested in testing the limits regarding the theoretical preservation and potential extraction of DNA from museum specimens, human remains, and fossil material. Crucially, scientists’ pursuit of this goal was chiefly facilitated by the innovation of PCR. With PCR, they were able to more easily extract and sequence the small amounts of degraded DNA from ancient and extinct organisms. As PCR’s utility became apparent, they explored a variety of samples from ancient muscle and skin to even partially fossilized bone. Researchers were also interested in understanding more about what types of environments might yield DNA at both a higher quantity and quality. They investigated the likelihood of recovering DNA from specimens thousands to millions of years old. Meanwhile, some scientists sought to use ancient DNA sequences to investigate the properties of and processes that contribute to DNA degradation in hopes of finding observable or generalizable patterns. In all of this, the early community of ancient DNA researchers were testing the limits of DNA preservation and of a new field they had recently created.
The first ancient DNA conference at the University of Nottingham and subsequent founding of the community newsletter were landmark events that both aided in and signified the establishment of a new field. Additionally, the fact that some of the earliest experiments were funded by prestigious agencies and initiatives such as the United Kingdom’s NERC Special Topic in Biomolecular Paleontology, and were published in top-tier journals from Nature to Science, demonstrated to the broader scientific community, as well as the public, that ancient DNA research was a promising endeavor in its own right. Indeed, these activities, achieved through the actions of the individuals who initiated them, denoted a move toward disciplinary development. As historians, sociologists, and other scholars have shown, the establishment of conferences, journals, newsletters, funding opportunities, employment opportunities, student training, and publications are all classic indicators of discipline formation.42
However, as the search for DNA from fossils developed into a discipline, it did so under the influence of intense press and public interest, particularly as this new line of research coincided with the publication of Jurassic Park, accelerating the attention that the field and its practitioners received. In testing the theoretical limits of DNA preservation, along with the technological limits of PCR, the early community of ancient DNA researchers showcased the discipline’s potential as a way to study evolutionary history. As they did so, ancient DNA researchers realized the opportunity to harness the media attention that often accompanied the search for DNA from fossils, using it to their professional and personal advantage. In fact, doing so seemed expedient, even necessary. The discipline was a young one, and scientists had yet to prove its worth. It seemed that any publicity was good publicity.
For practitioners, opportunities for media attention were easy to come by. The recovery and reporting of DNA from fossils became a sort of spectacle that captured the imaginations of both professional and public audiences. While most spectacles are visual or audible phenomena, science can, and often does, take on other forms of show.43 Ancient DNA, for example, was far from a sensory phenomenon. Rather, the act of procuring DNA from ancient and extinct species was a curiosity because doing so defied expectations of how long DNA could last and how it might be used in research. For some, ancient DNA was a way to directly study the past. For others, it was a way to bring extinct species back to life. Indeed, the very prospect of seeing a resurrected dinosaur, mammoth, or other creature was a grandiose spectacle.
Although practitioners had made strides toward the founding of a field, the recovery of DNA from fossils was still more of an anomaly than a predictable research outcome. Indeed, the preservation of DNA in some fossils did not guarantee the preservation of DNA in all fossils. At this point, researchers also realized that even if they were able to consistently extract DNA from old material, they would have to address the problem of contamination. PCR was extremely sensitive, with a tendency toward amplifying contaminating DNA sequences as opposed to the ancient DNA sequences of interest. As early as 1989, Pääbo, Higuchi, and Wilson had suggested a short list of steps to take in the lab to circumvent contamination and to project a level of realism about the field’s potential among its challenges.
In light of this, some scientists felt the need to counter, or at least control, the growing enthusiasm for ancient DNA research. It was important to scientists to maintain some sort of power over the direction of the discipline because a lot was at stake, namely their credibility. Consequently, practitioners found various ways to balance the science of ancient DNA research with the spectacle and speculation that seemed to follow it. They very much realized the importance of doing so in a practice that from its beginning held such a strong public appeal. Interestingly, the spectacle of extracting ancient sequences from some of the world’s oldest organisms, and the press and public attention associated with it, would simultaneously help and hinder the growth of ancient DNA research as scientists tried to transform it from a curious phenomenon into a credible practice. As the discipline developed, and as scientists continued to test its limits, a handful of practitioners would make more deliberate and influential attempts to build boundaries around the practice, especially in response to contamination concerns and increasing media coverage.