I’m weird. I like weird things. For example, I study a very weird aspect of animal behavior that lured me in with its unending intrigue and infinite mysteries. Physiological extremes. Hibernation is one of the most extreme examples physiology gone haywire. And I love it. My interest in weird physiology has been growing ever since my sophomore year in college when, in my animal physiology class, we had to pick any topic concerning physiology for a term paper. At the time, I thought I was destined to study marine mammals. The topic I chose? Diving physiology of Weddell seals. Diving physiology is insanely cool. These air-breathing animals are able to spend hours underwater searching for food at depths that would, no doubt, burst lungs and explode brains in unadapted species. They achieve these feats through oxygen compartmentalization, manipulating the body into prioritizing oxygen flow to only the most critical tissues. This is accomplished via vasoconstriction, where blood that normally flows to the peripheral tissues, limbs and such, is instead shunted to the core to keep the essential organs, like the heart, lungs, and brain, working at peak performance. This allows seals to out-swim their prey when the eatin’ is good. Now do you understand my love of extreme physiology? Maybe it’s not so weird after all.
Searching for the perfect graduate program, I stumbled upon my advisor’s web page and links to the Duke Lemur Center’s site. It was there that I discovered that there exists a genus of lemur that hibernates. Hibernates! A primate! The genera in question? The dwarf lemurs that reside on the beautiful island of Madagascar, and are ONLY found there.
Okay, this behavior is weird for two reasons. One, I’ve mentioned previously, that when you dissect, is not all that strange: hibernation occurring on Madagascar. Madagascar is often times synonymous with tropical. In reality, due to its latitude some parts of the country are classified as sub-tropical. A minute, but important difference. And, as you already know, some parts of the country can be downright freezing! The latitude of our field site is 19 degrees S. For comparison, North Carolina sits at roughly 36 degrees N. In addition, the altitude where we call our temporary home, and is home to the population of dwarf lemurs we study is about 1600-1700 m. Higher altitude, colder temps. So let me back up. Madagascar does not necessarily always experience warm climate regimes. Trust me on this one. This is coupled with the fact that many tropical and sub-tropical mammals utilize a hypometabolic state (i.e. a pronounced depression in metabolism, characteristic of hibernating animals) to evade energetic demands posed by their environments. These demands could be resources related (extreme drought, for example) or temperature related. Bats, tenrecs, and African shrews are some of the many examples of warm-adapted animals that are capable of reversibly depressing their metabolism when needed.
The second, and I think most, perplexing phenomenon regarding dwarf lemur hibernation is that they are primates. Other primates? Chimpanzees, gorillas, and humans to name a few, ummmm, well-known examples. Do any of these species hibernate? Nope. It is believed that hibernation and the corresponding physiological changes are manifested due to changes in gene expression. Humans and lemurs are, at the genetic level, roughly 95% identical (give or take a few percentage points. Bear with me. It’s hard to fact check at a remote field site with limited Internet access). So, a little lesson in logic using “if/then” statements. If humans and lemurs are genetically similar, and hibernation is primarily governed by genes and how/when they are turned off and on, then why can’t humans and other primates hibernate? What makes a dwarf lemur so unique, genetically and physiologically speaking, that allows them to hibernate? As far as we know, they are the only primates that can exhibit such a state where heart rate drops from 180 beats per minute to 4 beats per minute, breathing rate is so depressed that an animal can go 21 minutes between breaths (Seriously. We just documented this for the first time last night), and animals appear to be brain dead. Whoa. Mind blown. I’m on the quest to uncover answers to these mysteries.
Rigorous scientific research on animal behavior isn’t always the most kind endeavor. We dig up lemurs hibernating snugly in their underground burrows. But, in our defense, our intentions are good. I swear! The more we know about a particular animal’s physiology and natural behaviors, the better position we are in to preserve them. This is especially relevant as lemurs, as a group, were just given the unfortunate distinction as being the most endangered mammal in the world. Before I move on, I need to make a few more introductions to the team. We had a few late arrivals and an early one, whom I’ve failed to introduce due to weird circumstantial timing. The early arrival was Bobby and Elley’s second son, Sam, our premier motorcycle battery obtainer. Next up, Andrew, an extraordinary sleep researcher, who is a savant at reading thoroughly confusing EEG records, and Kathrin, one of the most creative people I know who is currently crocheting a dwarf lemur stuffed animal and teaches our daily watercolor class. Also, she is my science idol, first documenting the unique metabolic profiles of hibernating dwarf lemurs. Now that the whole team was present and accounted for, we got to complete the exciting task of revealing our lemurs from their underground burials. Remember as a child playing feverishly in your sandbox? Well, uncovering lemurs is a lot like digging in a giant sandbox, except it’s not sand. It’s spongy, root-laden peat soil. And it’s not exactly a sandbox. It’s the Malagasy rainforest. To do this, we use the expertise of our awesome Malagasy guides, Renee, Jules, and Parfait. Standard operating procedure: Locate lemur via radio tracking. Start digging (with hands, please. Not shovels. We wouldn’t want to dig up any half lemurs). End protocol.
Usually this process doesn’t take very long, as the animals situate themselves no deeper than the length of sub sandwiches Sam can consume in one bus ride: Approximately a foot and a half. Every time I see this happen, (digging up a lemur, not watching Sam stuff his face with subs) the movie title “Bringing up Baby” comes crashing into my mind. This is weird because a.) I have never even seen this movie, nor do I even know what the plot is, and b.) I’m not even sure of the actors portraying the main characters. Also, c.) is this even a movie title?
And now for a little story: We had gone out to the forest after a delicious lunch of rice and beans (Mmmmm…) to uncover two of our lemurs. First one dug up? Check. The second one? A bit more problematic. The little problem “child” was Ramily, an adult male, who is now called “Ravioli” by those in our camp who have a hard time remembering names. Ramily’s uncovering started out just like any other standard lemur revealing. He was located. Renee and Jules started digging…and digging…and digging. 120 cubic feet of displaced soil and 50 minutes later, we finally “brought up baby”. Just kidding. We didn’t. We actually never found him. It was reminiscent the “Great Jules Incident of 2012”. A similar situation occurred with Jules, our star hibernator of last July’s field season. He was found a little while later.
We did eventually locate the elusive Ramily 2 days later, about 4 feet from where we were actually digging. He never aroused all the while we were tossing dirt around him and stepping on the actual spot where he was hiding. I wonder what he would do if a predator found his hibernacula?
It’s a jungle out there.