Nothing gets a good conversation flowing better than fire. People start trading stories around a campfire faster than one can light it. Field biologists are particularly susceptible to the primeval charm of the amber glow. Crouching among these veterans of the forests and the seas, one can’t help but admire the courage apparent in their field tales. Close encounters with the fanged kind, near misses with animals twice their height, and great escapes in remote lands seem to be a routine part of their remarkable lives. But what remains unsaid, unspoken is the ‘f’ word, the word that one learns to live with but never mentions in the annals of field biology: fear.
Fear is as integral to sentient beings as it is to the lives of the biologists that study them. Deer form groups, turtles hatch en masse, monkeys shriek from canopies – all to outmanoeuvre predators on the prowl. Such are the stakes that, even when besieged by sleep, animals must stay a step ahead of flicking tongues and blunted canines. Steven Lima and his colleagues described the all-powerful influence of predators on sleep behaviour in a seminal paper, titled ‘Sleeping under the risk of predation’, in 2005. A decade later, five hundred Bay Island lizards confessed their strategy to this author. In the tropical evergreen forests of the Andaman archipelago, these diurnal lizards had a few cards up their sleeve even at night.
After a day of perching on tree trunks, with their chitinous food on the forest floor and escape route towards the canopy, the lizards retreat to their sleeping sites. Much like humans, they remain immobile – their bellies down and limbs stretched out. During these hours, they have an increased arousal stimulus, a phrase alarm clocks around the world know all too well. But even in their slumber, fear is writ large. They perch almost exclusively on thin, young plants, their distaste for old trees at night apparent in their selection. To err on the side of caution, they often face the approach path of potential slithering guests: they face the petiole when on leaves, the trunks when on branches, and the ground when on the trunk.
Larger individuals sleep higher than smaller ones, probably in an attempt to distance themselves from the forest floor. This composite of sleeping choices must render many attempts at their lives ineffective. Large snakes would rather be helpless at the prospect of climbing seemingly unstable and flimsy young plants. Those that do make the climb alert the sleeping lizards with inadvertent tremors of the tree and meet with the cautious stare of an awakened lizard, ready to jump to the ground and disappear into the night.
Such evading strategies are not the domain of a few lizards but prevalent across the animal kingdom. When ducks detect a lurking predator – or a predator-model placed by intrusive scientists – literally keep an eye on the threat, and shut the other one. What is remarkable is that the hemisphere of the brain connected to the glaring eye remains active while the other hemisphere snoozes, enabling vigilance and siesta at the same time. ‘Uni-hemispheric sleep’ would be the dream solution to the sleeping woes of every time-starved professional in the world.
Living in the ecologically sanitised environments that make up modern housing, where even cockroaches barely cling to life, urban humans have forgotten that sleeping is synonymous with vulnerability. Out in the wild, an innocuous snore may give one away and an unsure tug at the blanket can be met with a startled krait snuggling for warmth. A night in a tropical forest can remind us of the hazards of sleep, walking to use the washroom at the middle of the night or of paying more attention to glowing smartphones than the trail ahead.
The anti-predatory shenanigans of the Bay Island lizards, with a smaller brain-to-body ratio than humans, taught me to establish security protocols of my own. This personalised ‘field researcher’s guide to survival’ (or paranoia, depending on one’s point of view) included thorough checks every time I put on my shoes, stretched my legs under the table and even when I touched the light switch to assess any breach of my living space. My headlamp and mosquito net were my best friends when it came to increasing my chances of survival, although they were not of much emotional support. A working hypothesis I was able to come to was an inverse correlation between the level of inebriation and the number of close encounters. And so, I am content with my modest contribution to ecology.
Thankfully, much better men, women and others have served ecology well, whether it by working in tiger country or in the laboratory. But take them out of their comfort zones, where predators to avoid are unfamiliar, and every one of them gets uncomfortable. Walking through the territories of big cats was routine for one such scientist I had the good fortune to work with. The trails, with fresh and ominous pug marks and scat, and the occasional scratch on a tree, didn’t daunt him. But when we moved to the wet evergreen forests of the Western Ghats, the man was faster than a tiger – all in an attempt to avoid leeches. Others are more subtle in their approach. A geneticist, when faced with the prospect of a long trek and possible encounters with elephants, found a certain acute injury in his femur, most likely a hitherto undocumented genetic mutation.
Science – in settings familiar and otherwise – draws us closer to our fears and teaches us to be smart about them. Even when removed from the stressors of modern living, a life in the wild is never too far from a ‘fight or flight’ response.
Nitya Mohanty is a PhD student at Stellenbosch University, South Africa.