by Carl Strang
Winter is a time when we slow down and become introspective. Sitting and staring into the fire, we ponder the big questions. If you have been following this blog, you know that the focus here is science, science that can be done simply in outdoor settings. But we are more than scientists, and science has well defined limitations that need to be understood by everyone who does science or studies its findings. This winter I am using one post per week to develop my own viewpoint and biases, in particular sharing my take on the relationship between science and spirituality. In part this defines for me what these two realms of human experience are all about, and also develops the separate methods used for inquiry in each realm. I plan to place this paragraph in front of each entry in this series, so that those who are interested only in natural history or in scientific practice can skip these posts.
What Are the Senses, Really? (part 2)
Our senses are by no means the only ones that exist. Each kind of animal has its own senses, and its own range of sensitivities. Many mammals hear beyond our hearing range at both the high and low ends. Some insects and birds can see colors in the ultraviolet energy levels, higher than our range. Bats are amazing in that they can reconstruct the 3-dimensional world based on reflected sound. They scream, and the reflections of each ultrasonic (to our ears) scream give them information about nearby objects. It’s a connect-the-dots world view, however, with spaces between the screams. Moths, which are important prey to many bats, can hear, but their high-frequency hearing range does not overlap with ours at all. The only reason moths can hear is that this allows them to detect approaching bats. When a moth hears something, this is bad news, for it is picking up the high-frequency sounds of a bat’s screams. The moth goes into a power dive with an unpredictable course, which sometimes successfully squeezes the moth through the holes in the bat’s connect-the-dots world. In addition, male moths can “smell” with their antennae, but they can smell only one thing: the pheromones released by females of their species. When a moth smells something, this is good news, for he can follow the scent trail to an advertising female.
Stranger yet are senses totally different from ours, for instance the electromagnetic field detectors of certain fish that live in large, muddy tropical rivers. They cannot see, but they can create an electric field which is disturbed by nearby objects with greater or lesser conductivity than the surrounding waters. The fish can interpret this information and do the things necessary for survival.
Ethologists (behavioral biologists) use the term Umwelt to refer to the world as perceived through the limited senses of a particular species. Our Umwelt is dominated by vision, with sound also significant and other senses rounding out the picture. It cannot be regarded as giving us the “true” image of the Universe, any more than does the Umwelt of an electric eel. This is the strange conclusion that science has discovered for us, and it adds to the irony when some scientists so confidently judge what is and is not “real.” One suspects that, when they were children, their monster-under-the-bed sensors didn’t work at all.
Our sensory organs filter the information coming in to them. Organizational cells within the retinas of our eyes exaggerate edges and otherwise edit what we “see.” In a similar way our ears edit the complex combinations of incoming sound vibrations into just a few dominant perceived sounds. Some of the richer but more confusing reality can be measured with instruments, but is left out of what we notice.
Our brain takes this incomplete, edited information and uses it to manufacture a cohesive, sensible model of our surroundings. One example of the brain’s work is its compensation for the blind spot, a small area in the retina of each eye which contains no sensory cells. We do not notice any holes in our visual field because the brain fills them in. Our brain also fabricates a continuity that fills the gaps when we blink.
An important implication of this tendency of the sense organs and brain to sharpen the edges of sounds and sights, to fill in gaps and selectively organize a sensible model of the world, is that we have an exaggerated understanding of the separateness of things. There is more connection, more oneness, to the Universe than we perceive.