From the Natural History Museum in London to the Muséum National d’Histoire Naturelle in Paris to the American Museum of Natural History in New York City, pretty much every major city has a science museum that houses collections of animals, plants, and fossils from around the world. The tragedy of the fire that devastated the Museu Nacional in Brazil in September of this year was felt by researchers around the world who understood the value of 20 million specimens housed within its walls. You see, museums aren’t just a fun place to take the kids on a rainy Saturday (though they are great for this). Museums house millions upon millions of specimens hidden behind the walls, in the basement, and pretty much every nook and cranny that isn’t open to the public. These specimens date back decades, and sometimes centuries, allowing researchers to reach into a time machine to answer questions about the history (and future) of life on Earth.
Museum specimens have played a key role in helping us understand how environmental pollutants impact animal populations. In 1968 Joseph Hickey and Daniel Anderson published a paper in Science that examined ~1700 eggs from museum collections. These eggs were collected between 1885 and 1967 and showed a significant decrease in the thickness of the shell during this period. Hickey and Anderson linked this decreased egg shell thickness to the introduction of the pesticide DDT. Their study played a large role in getting DDT banned from the United States. More recently Shane DuBay and Carl Fuldner examined ~1300 bird specimens collected between the 1880s and 2015 and used photometric reflectance to measure ambient concentrations of black carbon on feathers from the same species of birds collected in the same region decades apart. DuBay and Fuldner found that black carbon levels peaked during the early 1900s and dropped midcentury when fuel began to transition away from coal and burning coal became more efficient.
Today there are countless evolutionary questions that can be answered with museum collections. By comparing the past to the present we can detect how animal diets have changed as cities have become more densely populated with humans (which corresponds with an increase in anthropogenic food waste). We can determine the genetic diversity of a population as a city expands and habitat fragmentation increases. We can look for phenotypic shifts among historic and contemporary populations. We can find the specific genes that are under selection in urban environments. And we can answer hundreds of other questions.
However, the frustration that I’ve come across in my own research is that museums don’t often collect common species, especially when those species are in the very city where the museum is located. I recently used VertNet to find out how many pigeons from were located in US-based collections. VertNet is a database that aggregates the digital records of museums, so instead of going to each individual museum website and searching for your focal taxa, you can search through hundreds of museum records at once. After screening the 4273 records of Columba livia specimens I found just 19(!) from NYC with collection dates ranging from 1922 to 1996. Unfortunately, these 19 specimens (12 of which are tissue samples collected near AMNH in Fall 1981) are not a large enough sample size to accurately compare with present day populations.
As technology advances, questions that scientists have never dreamed of asking will be testable – but we need to continue to add to our collections and, yes, even the common urban species are important! Collections are essential to our understanding of how life has evolved in cities and I’m excited to see how contemporary and future scientists use this wealth of information to answer questions about the evolution of life in cities. On Twitter, check out #CollectionsAreEssential & #CollectingIsEssential to find out more about how scientists are using collections.
Are you planning on using museum collections in your urban evolution research? Let us know in the comments below, or reach out to us on Facebook or Twitter.
Great post! I’ve run into problems too when trying to use museum specimens for urban research. Either the species are undersampled in cities or the location information is too imprecise to be sure the animal was from the city and not a rural suburb. GPS units are so cheap now (there’s even phone apps that work great) there is no excuse for modern specimens to not have GPS data, and yet many don’t. There are so many questions we could answer if only the museum record of urban animals was better!