A New Look at Animal-Human Experiences
Sentient: How Animals Illuminate the Wonder of Our Senses
Jackie Higgins, 2021
Jackie Higgins' work is another outstanding book regarding the sensory experiences of animals and humans, with a huge amount of surprising information regarding the range of sensory experience and the sensory capacities of various animal species. Higgin's book also has something to say about genetics, e.g., the standard account of the selfishness of genes:
In July 1980, scientists first observed vampire bats regurgitate blood for a young bat not their own. According to Higgins, "These were the first observations in nature of non- family sharing of blood, not only across generations but now also between adults. .. They (scientists) started to notice that the behavior followed elaborate sequences of grooming. The team had already noticed the bats spending inordinate amounts of time licking, scratching and nibbling one another, but now it became apparent that these rituals were being used to encourage sharing. ... In a rare case of altruism in nature, "A bat who has flown home on a full stomach donates life saving blood to another in exchange for being groomed and the likelihood that one day the tables will be turned " (pp. 86-87) Apparently selfish genes may become capable of enlightened self interest when survival of a colony of vampire bats depends on it.
An experiment in which volunteers were blindfolded night and day for five days discovered something surprising about the visual cortex in humans. By day 5, "The act of touch stimulated their visual cortex." "They were seeing with the tip of their finger," said Pascual- Leone, who interpreted his findings as evidence " not merely of exceptional neuroplasticity (of the brain) but of a whole new way of looking at the brain." This scientist argues that "the brain may not be organized into sensory modalities at all. What neuroscientists have called the visual cortex for the past century seems not to be devoted exclusively to the eyes," but (according to this hypothesis) is the "area of the brain best able to discriminate spatial relationships, and ... will use any relevant sensory input," including "from the hair cells of our ears or the mechanoreceptors of our skin." One neuroscientist opines: "You can do so much more with your brain than Mother Nature does with it." (p. 80)
Higgins cites research indicating the touch is the first sense to "ignite" in the human embryo at eight and one half weeks and touch is fundamental to establishing a boundary between self and others. She refers to Francis McGlone's contention that "the roots of our self lie in our skin." ( p. 103) McGlone hypothesizes that when young children experience gentle touch as painful rather than pleasureful and soothing, their ability to emotionally attach to caregivers and develop the capacity for empathy is undermined.
In 2007, scientists in Alaska tracked the flight of a bar tailed godwit from Alaska to New Zealand and beyond, a flight of 18,300 miles. "Her final 11,680 kilometer (7300 mile) leg .. had been done in eight days without stopping." (p. 208) The godwit flew eight days without food, water and "no sleep as we know it." Godwits have hard to believe navigational abilities. How do they do it? Decades of research were required to understand how some birds have compasses oriented to the earth's magnetic field, a sensory capacity that can be disrupted in laboratories by electrical appliances, including computers. Birds can react "to a man made force barely one thousandths of the earth's magnetic field." And "The bird's magnetic compass is a million times more sensitive than any other sensory system known." (p. 214) Experts have engaged in vituperative debates ( seemingly quite common in science where confirmation bias runs amok as in every human investigation). Some scientists believe the compass of birds operates through light sensitive quantum reactions while other scientists (equally well informed) hypothesize that internal compasses in animals depend on the iron mineral magnetite. According to Higgins, " scientists found magnetite crystals in the abdomens of honeybees and the beaks of birds." (p. 216) Other scientists have proposed that birds use both quantum processes in their visual systems and magnetite crystals in their bodies to navigate in the dark.
Some scientists who did earlier research regarding the magnetic sense of birds and other animals were subject to widespread ridicule from scientists inclined to view alleged discoveries of new senses in animals as quack science. I remember in college during the 1960s when behaviorists in the psychology department publicly mocked the idea that humans and other animals have a biological clock that regulates homeostatic processes. Higgins comments: "Nearly all plants and all animals, as well as fungi, algae, and even some bacteria march to the beat of an internal timekeeper. This is a clock so reliable, so accurate .. it possesses the hallmarks of one crafted by human hands .. a body clock gauges natural time the and the passing of a solar day." ( p. 190) Research of biological clocks in animals and plants has flourished while behavioral psychology in its1960s form (Skinner, et al) is deader than a door nail.
The biologist Andreas Keller asserts that "We estimate that humans can discriminate at least trillion olfactory stimuli." Higgins states: "... our sense of smell has been grossly undervalued ... Most auditory scientists would agree that an average human ear can discriminate between hundreds of thousands of audible tones. Most visual scientists would assert an unremarkable human eye can see several million shades of colors. Yet our nose can smell at least a trillion different scents." (p. 138)
It appears that science has only scraped the surface of understanding the senses of animals and human senses. Higgins summarizes: "Science has shown that our eye senses not just space but time. ... Our tongue smells and our nose tastes, as do other bits of our body. Our nose might also detect airborne messages that don't even have a smell. A strange variant of touch exists within our muscles that grants knowledge of where our body is ... Yet these (senses) and more alchemize into sentience." (p. xi)
In her concluding chapter Higgins quotes the neuroscientist David Eagelman: "Our brains are tuned to detect a shockingly small fraction of the surrounding reality. " (p. 249) Humans lack certain senses altogether, for example the electric sense of a platypus which "through tens of thousands of microscopic electric sensors can home in on its prey with preternatural accuracy " (p. 249) Higgins opines: "We remain insensible to aspects of reality because we can only experience what is first sensed," (p.249) a dubious assertion that does not account for feeling, the foundation of central nervous systems, according to Antonio Damasio. Perhaps a better formulation would be "We can only sense what is felt and sensory awareness and feeling combine to generate sentience."
-- Dee Wilson