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Profitable Wonders. By James Le Fanu

Blog | By James Le Fanu | Jul 04, 2024

Warbler, Charles J. Sharp.

The five senses, sight, hearing, touch, taste and smell, are by definition ‘sensitive’ - sharp enough to hear a pin drop or glimpse the flickering light of a distant fire at night. And comprehensive enough to perceive the physical world, with all the nuanced detail of its several million colour 'values', the even greater number of notes of the musical repertoire, tens of thousands of combinations of odours and that subtlety of touch that can discern the difference between a puff of wind and a single molecule of water.

The sensitivity of the senses enriches our lives with wonder and beauty while generating that constant stream of reliable information on which our daily existence depends. The world is as we perceive it to be. Or so it might seem were it not that observing the uncanny attributes and behaviours of our fellow creatures would suggest their sensory awareness can be yet more vivid than our own, with privileged access to dimensions of reality beyond our experience.

Thus while the sensitivity of human smell can detect odours in the minuscule concentrations of a millionth of a gram, this, as we all know, is a trivial achievement compared with the olfactory prowess of our canine companions. The brain of a bloodhound may be just a tenth the size of our own but its million times more sensitive nose can identify a lightly fingered glass slide left in the open air for several days.

And if that is impressive it is no more so than the ability of salmon to smell their way back upwards to a spawning ground they left several years earlier, or for the male emperor moth to be attracted in vast numbers by the scent of a female over a distance of several miles.

Or again, the superlative vision of a falcon circling high in the sky eclipses, by far, that of our own, detecting scurrying movements on the ground below with the acuity of the eight- fold magnification of a pair of binoculars. Owls can see in virtually complete darkness, locating their prey in a dim light equivalent to that produced by a candle a thousand feet away. while insects, and bees in particular, are guided to the nectary of flowers by a target of ultraviolet pigmentation of their petals that is invisible to humans.

It is possible (just) to imagine what these instances of heightened awareness must mean to their possessors for they are essentially markedly enhanced versions of our own senses. By contrast, the 'sixth sense' in its diverse forms of sensitivity to magnetic and electric fields, the ultrasonic and infra-red and much else besides, might seem to verge on the supernatural.

The best demonstrated 'sixth sense', sensitivity to the magnetic fields created by the flow of molten material in the earth's core, is a well-established navigating mechanism by which migrating birds determine their altitude and orientation. It has, however, been found to be ubiquitous in the animal kingdom, deployed by bees, sharks, sea turtles, bats, moles and even mice. And termites, too, where their sensitivity to magnetic fields accounts for their habit of building their homes with the long axis lying north to south. Their broad sides thus face east and west, catching the weak morning and evening sun, thus mitigating the profound fall in temperature of the cold desert nights.

Further, the diverse forms of the sixth sense, it would appear, work in synergy with each other. By itself, ‘magnetoception’ (as it is known) is insufficient to explain fully how migrating birds traverse the featureless ocean at night, which would suggest that some other mechanism must also be involved. In a series of remarkable experiments in a planetarium in the early 1960s, German ornithologist Franz Sauer demonstrated how the lesser whitethroat species of warbler, which migrates alone for several thousand miles from central Europe to Southern Africa, is guided by the position of the stars. The warbler, he was able to show, responded to changes in longitude and latitude (simulated by shifting the declination of the stars in the dome of the planetarium) by constantly reorienting itself towards its destination. This ability to relate the canopy of the sky to the geography of the earth in time and season is, he noted, ‘little short of miraculous'.

The implications of the sixth sense for our understanding of the natural world are prodigious. When the humble warbler is capable of celestial navigation it is only reasonable to speculate how many of those mysterious, seemingly telepathic, powers of animals-the synchronous movements of flocks of birds, premonitions of earthquakes or even pets' well-recognised anticipation of their owners' return-might similarly be due to forms of sensory awareness beyond our knowing.