As a child, Kristofer Helgen was captivated by mammals. "I loved how beautiful and different they could be," he recalls. "From bats to whales to dogs, it's one coherent group, but there's so much difference in form and biology." Helgen was consumed by the seemingly simple question of how many kinds of mammals roam the planet. "It seemed like something you should be able to look up in a book, and I tried to do that my whole childhood. I kept lists of the mammals I found out about, but it was only as I started working in museums"--beginning as an undergraduate at Harvard University’s Museum of Comparative Zoology--"that I found out that there is no place to go to for that information. We're so far from a good answer."
Now a curator of mammals at the Smithsonian Institution’s National Museum of Natural History  in Washington, D.C., Helgen is doing his part to remedy that. Traipsing through rainforests and scouring museum collections, Helgen has discovered about 100 mammal species previously unknown to science and formally described about a quarter of those in peer-reviewed publications. He's still keeping lists: Among his varied responsibilities is the editorship of Mammal Species of the World, the standard reference for mammalian taxonomy. Other responsibilities include untangling the biogeography of remote areas of New Guinea, collaborating with conservation biologists in the service of conservation planning, and helping prepare museum exhibits.
With this feature, Science Careers celebrates Darwin's birthday with two articles on scientists working in natural history museums. Please read the companion piece from Kate Travis, Keeping Order , about Erica McAlister, curator of bugs at the Natural History Museum in London, and check out our Resources page . Our colleagues at Science magazine have a special online Darwin birthday section  as well.
Helgen’s path from child fanatic to revered specialist typifies that of museum scientists--and mirrors Charles Darwin's own trajectory. If you substitute dinosaurs for mammals, it's the same story for Peter Makovicky, a dinosaur paleontologist at the Field Museum  in Chicago, Illinois. At age 3, Makovicky curated a formidable collection of dinosaur models. When he was 4, a family visit to the Natural History Museum in London made a lasting impression. He recalls the museum's enormous Diplodocus cast, its long neck stretching down the middle of the hall; the wall-mounted Tyrannosaurus rex in its incorrect tripod pose; and the armored glyptodont--an extinct armadillo relative--with its bathtub-sized shell. To Makovicky's young mind, they were all "very cool." He finds them no less cool today.
The role of natural history museums has evolved over the centuries. From the curio cabinets of medieval Europe, they grew to be understood, during the Victorian era, as priceless--if incomplete--repositories of knowledge about the natural world. Today, the museums house billions of natural history specimens: vertebrate fossils, marine mammals, dried botanical samples. Like the organisms they document, the repositories themselves continue to evolve and grow. The American Museum of Natural History (AMNH) in New York City, for example, adds about 90,000 specimens to its collections each year.
Robert Cook, director of both the Harvard University Herbaria , which houses more than 5 million dried botanical specimens, and the university's Arnold Arboretum  in Boston, says such collections are priceless because "they don't just teach us about the real world--they are the real world. Each specimen documents that a living plant of a particular species existed at a known place on a precise date in time." Many of the specimens in his care are "type specimens," the original samples from the plant that were first used to identify a species. "These resources are immensely valuable to the whole world, and we have an obligation to preserve them on behalf of the whole world."
Matthew Lamanna, a dinosaur paleontologist at the Carnegie Museum of Natural History  in Pittsburgh, Pennsylvania, says it was the museum's rich collections that lured him there. "When they offered me the position, it took me about 15 seconds to say yes," says Lamanna, whose research focuses on dinosaurs that populated the southern continents. "In the basement of this museum, I have a huge collection of dinosaur bones that have been collected over the last 100 years. That's a huge resource for a dinosaur paleontologist." Unlike university paleontologists, who have to travel to museums to compare their finds with important reference collections, "I can just go to my basement," Lamanna says.
Museums have a second distinguishing asset: scientists with such deep, specialized expertise that if they see something they haven't seen before, it's likely to be new to science. "Compared with a university system, where there tends to be more focus on procuring outside funding and teaching classes, we're allowed the luxury of being specialists, and people pride themselves on that," says Susan Perkins, a microbiologist at AMNH  who studies malarial parasites. "It's the kind of environment that welcomes scientists who are interested in, say, a single subfamily of beetle or a person who is known among colleagues not as a marine biologist but as 'the leech guy.' Those kinds of specialists have more or less disappeared from universities. I would say we're almost human relics."
Museum scientists--whose work depends on public support both at the gate and in the form of philanthropy and government funding--have recognized the need to connect their scholarly pursuits with their institutions' public mission. "Museum science has had to learn to translate itself better to the public," Perkins says. "Rather than just being institutions to house, study, and display collections, we are more and more finding ourselves taking on the important role of educating students and the public about the importance of science."
Many scientists relish the opportunity to participate in public outreach by planning exhibits, developing education programs, leading tours, and supervising educational travel. "I was shaped by dinosaur books and exhibits when I was a kid, and it's a cool feeling to know I have the opportunity to share my own work with the public and to serve as a conduit for the best science in my field," says Lamanna, who recently helped oversee a $36 million refurbishing of the museum's dinosaur exhibit, Dinosaurs in Their Time.
Through adjunct positions, museum scientists are also well-placed to teach classical taxonomic and comparative techniques to undergraduates and graduate students and to teach courses in subjects that are the traditional province of natural historians, such as ornithology, entomology, or mammalogy. AMNH has pushed its teaching mission further to the fore, this year launching a standalone Ph.D. program in comparative biology, the first of its kind.
As molecular techniques have come to dominate the life sciences, museums have sometimes struggled to prove their relevance to modern scholarship. "Because we're smaller and don't have huge undergraduate bodies, we tend to be viewed differently than other academic institutions," says Makovicky. "We have to work to remind people that we're doing work that is just as valuable."
Ironically, molecular techniques' very success has helped museums reassert their relevance, especially in biodiversity research. "There was a period when science was developing some of the molecular tools we use today but developing them on model systems in the lab," Makovicky observes. Now that those tools have matured to the point that scientists can extract DNA from even the most fragile specimens, he says, it's been possible to import the methods back into the museum world. "The scientific community has recognized that it's in our collections that the data for the big questions about biodiversity lies."
Museum scientists have begun to also embrace the opportunity to apply their work to real-world problems. "Like many museum scientists, my passion is fueled by a mix of basic and applied interests," says Helgen, who collaborates regularly with conservation biologists to analyze patterns of species distribution to facilitate conservation modeling. "I’m not a taxonomist who is going to be comfortable spending the rest of my life just characterizing organisms. I'm interested in contextualizing the biodiversity I see and making sure that that information is being applied toward conservation questions. I was drawn to the field of biology because of a simple curiosity about mammals, but I've decided to make it my life's work because the questions are sustaining."
Siri Carpenter is a writer in Madison, Wisconsin.