Last night, I headed down to the beautiful Bell House in the Gowanus section of Brooklyn for the latest Secret Science Club lecture, featuring evolutionary biologist Dr Evon Hekkala of Fordham University.
Dr Hekkala started her lecture with a brief autobiography. She had a personal statement, "doing" is better than "believing"- the process of scientific inquiry is what is important, not reliance on authorities. She then chronicled her rambling career, as she became disenchanted with the graphic design she studied as an undergrad, then progressed to a study of evolutionary theory, with a desire to study lemurs. Her study of lemurs was derailed when she discovered that the residents of the villages she visited had eaten the lemurs in the vicinity, but she came to the realization that one can't tell someone whose child's belly is distended with malnutrition to refrain from eating bushmeat. She was determined to return to Madagascar, and changed the focus of her studies to the native crocodiles. When she returned to Madagascar, she had to act as a courier for a team of researchers who had run low on funds. In a plot worthy of a "James Bond" movie, she detailed getting a transfer to her bank account, purchasing bundles of travelers' checks, then cashing them in Madagascar, where the exchange rate was so lopsided that she had to hire porters to help her carry the cash.
Dr Hekkala then gave a quick overview of the crocodiles. There are 12 recognized species of extant true crocodiles, genus Crocodylus (compared to two species of extant alligators). Crocodiles have been hunted for their skins, which can be made into a fine leather. They also face danger from wetlands development , chemicals which interfere with the development of their endocrine systems, and, perhaps most alarmingly, from global climate change, which can determine which gender hatchlings will develop in the nest.
Most of Dr Hekkala's work with crocodiles involved the East African "Nile" crocodile Crocodylus niloticus, which inhabits various ecological niches in Madagascar, including karst caverns and "sacred" lakes, such as Lake Ravelobe. Again, her work comes across as an action film (and was immortalized in a "National Geographic" documentary, Man-Eaters of Madagascar- in the space of a year, nine humans were killed by the crocodiles of Lake Ravelobe. Traditionally, the humans in the area coexisted peacefully with the crocodiles- women could wade into the waters of the lake with cans of worms on their heads while they fished. Unraveling the mystery of the crocodile attacks, Dr Hekkala determined that the lake was being fished by persons unfamiliar with the area, and runoff from slaughterhouse located upstream from the lake caused the crocodiles to become more aggressive (I am reminded of a case in Brazil where sewage runoff attracted aggressive sharks) while water management efforts by the government caused the level of the lake to rise and destroy crocodile nests and the lack of younger crocodiles (crocodiles are cannibals) removed an important food source from the lake. As an aside, I have been looking for Man-Eaters of Madagascar on the web, but have not been able to find the video, much to my chagrin. It really sounds like it has the makings of a great action/mystery flick.
Dr Hekkala then proceeded to discuss her efforts to collect DNA from crocodiles, both living and dead, and to sequence their genomes. Again, she was confronted by a mystery- ever since Herodotus wrote his histories, the crocodiles of the Nile were divided into aggressive, dangerous monsters and more docile crocodiles sacred to the ancient Egyptians, who often mummified them. The mummies were often wrapped in documents, and the possibility that such mummies were used as fuel would represent a tragic loss.
In 1807, the French naturalist Étienne Geoffroy Saint-Hilaire noticed differences in the skulls of the "sacred" crocodiles and the larger Nile crocodiles. Sadly, the two types of crocodiles were lumped together as C. niloticus and Saint-Hilaire's proposed species name Crocodylys suchus went largely forgotten. In her study of the DNA of various crocodile mummies and preserved specimens from museums around the globe, Dr Hekkala was able to determine that the crocodiles of the Nile belong to two distinct, distantly related species. Crocodilus niloticus is actually more closely related to the New World crocodiles than it is to the "rediscovered" C. suchus. Yet another instance of "sleuthing" on Dr Hekkala's part- is her career better than a movie, or what?
Dr Hekkala, no stranger to preserved crocodiles, then went into a brief digression into the tradition of scholars and apothecaries hanging crocodiles in their shops. In a case of truth being stranger than fiction, it turns out that crocodile blood has antibiotic properties... maybe those old quacks were onto something after all!
In the Q&A, some bastard in the audience asked Dr Hekkala about the contrast between the diversity and cosmopolitan (in the tropics and subtropics) distribution of the true crocodiles vs the relatively limited ranges of the two extant alligator species. Why are the crocs so much more successful? While Dr Hekkala didn't have a direct answer for this question, she noted that the alligators and crocodiles diverged about 65 million years ago, in the Cretaceous period, so alligators and crocodiles, despite superficial similarities, are about as closely related as bats and humans. The Nile crocodile, far from being "primitive", is about as old as humanity.
All told, this was another incredible Secret Science Club lecture... it hit the sweet spot between adventure narrative and hard science, and Dr Hekkala came across as a supergenius action star. She totally knocked it out of the park.
On an unrelated note, I met an old friend, handsome Johnny C., native of Ireland, but long-time Brooklyn resident, at the Bell House for the lecture. He coaches soccer for the same program I coach judo for- I had a big blond 'fro when I first met Johnny C. It was good to be able to hoist a few pints with an old friend and, more importantly, to win another convert over to the ways of the Secret Science Club.