DEEP IN the forest of Tabin wildlife reserve, Borneo, Simon stops and sniffs, comically twitching his nose. He has very youthful features for one not far off my age, not a sign of grey at his temples, skin as smooth and tight as a ten-year-old’s, yet, for one with such a young appearance and equally youthful enthusiasm, he’s very serious about what he does. Simon Ambi is a tracker, a naturalist who knows the forest in this part of Borneo with the same kind of well-trodden familiarity as you or I might have when we visit our local supermarket. Where I see great buttressed trees, a chaos of green, thickets of antlered ferns and palms all bound together with liana and vines, he sees food, drink and sustenance in many forms; he also reads the tracks, trails and signs of the highly secretive rainforest wildlife, but most importantly, right now he seeks building materials with which to construct a mammal trap.
He gets busy. A few silent moments of concentration, some twisting, cutting, holding loose ends between his teeth and, like a children’s party entertainer making animal forms out of balloons, after some minutes Simon produces with some pride, but still a serious expression, a clever basket trap. A bit like a lobster pot, it is designed to catch an animal alive: by placing a funnel over its mouth and trapping the animal in the wicker ribcage beyond it. He baits it with some overripe banana and, using another strip of palm fibre twisted into a rope, ties it on to a horizontal branch at shoulder height. Arboreal lobsters?
‘But why this one?’ I asked. We’d passed many such branches, on very similar-looking trees much closer to the muddy road that we’d left way behind us now. Simon looked at me incredulously through his sensible-framed glasses decorated with beads of sweat and raindrops that had flicked up from the forest vegetation as we hacked our way through it. They slightly distracted me from the deep and seriously dark eyes behind them which were looking at me as if I was from another planet. ‘Smell them.’ Not a question, I didn’t think, more of a statement of the obvious. He looked at me for a sign, perhaps a nod and a smile and a ‘silly me, of course’ kind of statement. But no. ‘Smell, bad smell.’ Nope, still not got it.
Then he started making big sniffing gestures, simultaneously walking around and wafting air towards his face. ‘Smell, smell.’ Then he started working his way along a low branch, nose to it, like a bloodhound. ‘Here, here, smell it.’ I emulated his actions, and there it was, a musty, slightly unpleasant odour, a little like stale urine, an unclean toilet or a baby’s nappy kind of whiff.
This, he informed me, was where a slow loris had passed by. This odour had been so obvious to him as we had walked through the complex tangled matrix of lush forest vegetation that it was what had made us stop and build and set the trap here in the first place.
Slow loris, like many mammals, live in a world of smell, a vaporous world of social-status updates: who’s in a relationship with whom, whether you’re new in town, are single, dominant, male or female – available in oestrus or a tail not worth chasing. It’s an olfaction-based social media and in the dense, verdant tropical vegetation, in the dark of the night, it’s a handy way of getting the message across without drawing the attention of too many predators. It also has a decay factor, a half-life, and so a scent mark has a temporal element; if you are a slow loris you can tell exactly how long ago the message was left. In the same way, I guess, I can tell how long ago my wife left the hallway by how strong her perfume is. Obviously, a slow loris can probably glean an awful lot more from his female’s perfume fug than I can about my wife’s. It’s a neat way of communicating, not strange to the animal kingdom.
What fascinated me was the fact that Simon noticed it at all. After a week or so of walking the forest trails with him, I too was becoming olfactorily aware through his expert tutoring. Every time we passed through an odiferous cloud, he would give it a species name. It might be a macaque, pig, clouded-leopard, moon rat, flowering vine, rafflesia or a fruiting tree, surrounded by a halo of fallen fruits at varying stages of decay. Via his nose, he was extracting clues as to what was around us. Hidden by the blanket of dense vegetation, other life forms were oozing and releasing chemicals into the air. Some by design, others a by-product of a biological process. Even the smell of, say, a rotting carcass, while repulsive to us, performs a purpose. The pungent putrefaction serves as an attractant to nature’s clean-up task force – scavengers of carrion home in on this odour trail: like characters in a Bisto advert, mammals, birds, invertebrates all dive in to feed on, or breed on, this resource.
Whether we’re aware of it or not, we walk through this world of waft all the time. But how many of us retain this knowledge of the niff, like Simon? Simon’s lifetime of sniffing and questioning and re-sniffing enabled him to pass on a wealth of sensory informative short cuts to me. While there was no way I would be able to take on the nuances of his nose craft, I was becoming more tuned in to my nose than I might previously have imagined or thought possible. Training your nasal awareness, it turns out, is surprisingly similar to training any other awareness. You need to start, you need to go out of your way to smell things, to seek the scents, then slowly you start connecting, and when the source of an odourant in an environment is located, the process of linking the perfumed thing with a time and a place and, of course, with input from your other senses makes it stick. If you gain something from the process, then it sticks even faster. It is in Simon’s interest, as a guide, to bag us a slow loris, it’s a priority to him. Putting a visitor ‘on’ an animal experience is how wildlife guides make their money, how they pay their bills and how they put bread on the table. It becomes a priority and not just a hobby; it’s a tool in your sensory toolkit again. Just as it would once have been. An essential way to find food and avoid trouble. Like so many other non-visual senses, it’s one we’ve come to use less. Or so we think. Without doubt, our sense of smell is very useful to us: we use it when we eat, to test food, to make decisions about whether to put something in our mouth, or to detect how clean something is. It has the ability to trigger memories, and it has a role to play in our sex lives too, how we choose mates and as part of our courtship; it also has a role to play in our immune systems, and in our social lives – but despite all this, we don’t seem to be aware of its full potential as a sense, and most of are still convinced that we’re not very good with it.
How do we smell?
Like most of us, including the great Charles Darwin, you probably think your sense of smell is pretty poor. It is probably the least appreciated of the big five. Occasionally, it might make you lean a little more towards a flower, or test whether the milk in the fridge has gone off. It’s a widespread misconception that as a species we’ve not been dealt a very good hand, and therefore our few forays into the vaporous world of olfaction and smell are pretty limited. Common belief is that as we scurried up the phylogenetic tree from a small shrew to where we are today we dropped most of our cards.
Our early ancestors had a pretty good olfactory sense, as it turns out – being primarily nocturnal, these primitive primates would have been immersed in a ripe world of odour, a black-and-white, three-dimensional landscape to which smell gave a colour. These odourants told them all they needed to know about each other and their food; they were living very much like our slow loris today. However, it was thought that as eyes became better developed and our primate ancestors moved out of the shadows and into the daylight, the sense of olfaction was replaced by the gradual ascendance of our eyes and colour vision as the primary method of perception.
It simply wasn’t as useful to us any more. The evolution of bipedalism meant we left the ground below us, or, more importantly, our noses did. Nostrils were lifted away from the surfaces over which our early relatives once scampered, away from the ground that was once a sea of odour trails and clinging odourant clouds. They moved onwards and upwards, leaving what we often consider a primitive and defunct sense of smell behind. This change in locomotion and the evolution of a different exploitation of the habitats available is probably one of the reasons our senses swapped over, but the physical practicality of the limited amount of space for these sensory organs on and in our heads has been given as another. We don’t have enough space in our brain case to pack in all that neurological plumbing and processing power; one sense, it seems, would have to give way to another and that is pretty much what we believe happened.
There are, however, many humans with a fine ‘nose’ who might disagree, many for whom the nose is a very important way of life: the wine testers and sommeliers, cork analysts (yes, they exist), perfumers, food scientists and aromatherapists are all sensory analysts of sorts that put a huge onus on their sense of smell. Are they simply highly sensitive people or is their acute sensory skill one that can be learned and enhanced by a training regime?
The way we tend to access a mammal’s smelling potential is by counting the number of functional olfactory receptor genes or ORs. Recent scientific studies by the University of Tokyo have done just that and the results seem to back up what we think we already know: the best of the smellers also has the most versatile nose. The African elephant has an incredible 1,948 ORs, with mice and rats owning in the region of 1,100. Primates didn’t do so well and generally have a much lower OR count, and while we have around 396, there are other primates with even fewer olfactory receptor genes. It seems that as far as some of our closest cousins are concerned we are actually pretty well endowed in the nose.
Between 2000 and 2003, a series of behavioural studies were published that looked at the bigger picture, not just the genetic evidence. They went beyond the microscopic scrutiny of our genes and took a step back, carefully considering all the factors that influence our sense of smell. They investigated the structures used in the collection and perception of smell such as the shape of the nasal cavity, taste, the brain’s processing powers and language – all of which may combine to give us a better sense of smell and odour perception than previously thought.
It was discovered that if part of the brain of a rat is removed, including 80 per cent of the part that sits just above the nasal sinus called the olfactory bulb, incredibly, it doesn’t appear to affect the animal’s ability to perceive smell. So if the remaining 20 per cent of the olfactory bulb can still work the 1,100 OR genes, without any noticeable decline in performance, this suggests that there is no reason why a human, even with our much lower OR count, can’t perform as well as a rat!
The studies have shown this to be true. We are actually very good at discerning smell and in various tests designed to see just how well we detect specific smells, it has been proved that in some instances our noses are more sensitive than those of both dogs and rats.
This experimental evidence goes a long way to suggest that we’re probably in the realm of being macrosmats – that is, good smellers like dogs, cats and horses, rather than microsmats, which, previously, we were classified as. To me this just reinforces something that I’ve been aware of for some time, namely that we should start to use and trust our noses much more in our everyday explorations of the environment and not just our dinner plates. The nose and its associated internal software is not as shabby as you probably once thought and, with a little consideration, your sniffer could be up to snuff.