地点、人格与海马体

“Often the places we grow up in… influence how we perceive and conceptualize the world, give us metaphors to live by, and shape the purpose that drives us.” “Place and a mind may interpenetrate till the nature of both is altered,” the Scottish mountaineer and poet Nan Shepherd wrote in her lyrical love letter to her native Highlands, echoing an ancient intuition about how our formative physical landscapes shape our landscapes of thought and feeling. The word “genius” in the modern sense, after all, originates in the Latin phrase genius loci — “the spirit of a place.” I find myself thinking about Shepherd as I return to the Bulgarian mountains of my own childhood, trekking the same paths with my mother that I once trudged with tiny feet beside her, astonished at the flood of long-ago feelings rushing in with each step, astonished too at how effortlessly I navigate these routes I have not walked in decades. The psychological, neurocognitive, and geophysical underpinnings of these astonishments are what M.R. O’Connor explores in Wayfinding: The Science and Mystery of How Humans Navigate the World (public library) — a layered inquiry into the science and cultural poetics of how we orient in space and selfhood, illuminating the stunning interpenetration of the two. “View of Nature in Ascending Regions” by Levi Walter Yaggy from Geographical Portfolio — Comprising Physical, Political, Geological, and Astronomical Geography, 1893. (Available as a print, as a face mask, and as stationery cards.) In a passage evocative of Rebecca Solnit’s memorable observation that “never to get lost is not to live,” O’Connor takes the telescopic perspective of evolutionary time to consider the cognitive handicap beneath this existential gift: Life on earth has created millions of Ulyssean species undertaking epic journeys at scales both large and small. Getting lost is a uniquely human problem. Many animals are incredible navigators, capable of undertaking journeys that far eclipse our individual abilities. The greatest migration on earth belongs to the Arctic tern, a four-ounce argonaut that travels each year from Greenland to Antarctica and back again, a distance of some forty-four thousand miles. Flying with the wind, the tern’s return itinerary is a globe-trotter’s fantasy, circumnavigating Africa and South America. […] One of the devices that an animal needs to navigate is a “clock” — an internal mechanism for measuring or keeping time. The daily mass migration of zooplankton in the world’s oceans requires them to know when dawn and dusk are approaching. It would seem this is a simple response to light stimuli, but deep-sea zooplankton, which live at depths below where light penetrates, also migrate in accordance with the length of day at different latitudes. Even slightly more complex migrations can demand multiple clocks. Perhaps the most astonishing internal clock belongs to the bioluminescent Bermuda fireworm, which swarms the tropical waters precisely fifty-seven minutes after sunset on each third evening after the full Moon in the summer. Such a feat suggests that this tiny marine organism, with a fraction of a fraction of the cognitive capacity of a human, is internally equipped with three different timekeeping devises: a regular twenty-four-hour diurnal clock, a lunar clock with a 27.3-day cycle, and an interval timer to tick out the exact minutes past sunset. Discus chronologicus — a German depiction of time from the early 1720s, included in Cartographies of Time. (Available as a print and as a wall clock.) O’Connor marvels at the staggering evolutionary array of timekeeping devices that allows migratory species to keep partaking of the dance of life: Animals that complete annual migrations or multiyear migrations have to possess a yearly clock, one that is finely attuned to the lengths of days and nights and their changes across each season. In all, evolution seems to have produced annual clocks, lunar clocks, tidal clocks, circadian clocks, and, perhaps for those that migrate under cover of darkness, a sidereal clock — which measures the time it takes a star to appear to travel around the earth. Besides their intricate internal timekeeping mechanisms, many nonhuman animals are endowed with equally intricate space-mapping mechanisms. Each migration season, humpback whales travel more than ten thousand miles far from land to return to the precise place where they were born. There are bird species — European pied flycatchers, blackcaps, and indigo buntings among them — that appear to orient by the pole star in their nocturnal flight; there are insect species — ants and bees among them — that perform triumphs of trigonometry with their light-sensitive photoreceptors, calculating spatial distances by polarized light to find the most direct route home after a winding pathway of foraging. With their mere milligram-brains of one million neurons — a grain of sand to the Mont Blanc of our eighty-six billion — and 20/2000 vision that renders them blind by human standards, honeybees make hundreds of foraging trips per day, meandering many miles from home, then compute the “beeline” back. African ball-rolling dung beetles, Namibian desert spiders, and southern cricket frogs use the stars of the Milky Way as their compass, just like some of the most courageous members of our own species once used the constellations to find their way to freedom from the moral cowardice of tyranny: To ensure they were moving northward, migrants on the Underground Railroad were instructed to keep the river on one side and “follow The Drinking Gourd” — an African name for Ursa Major, or The Big Dipper. “Planetary System, Eclipse of the Sun, the Moon, the Zodiacal Light, Meteoric Shower” by Levi Walter Yaggy from Geographical Portfolio — Comprising Physical, Political, Geological, and Astronomical Geography, 1887. (Available as a print, as a face mask, and as stationery cards.) Like all reality-radicalizing discoveries that defy the limiting creaturely intuitions we call common sense, the notion that animals might use magnetism for navigation was long derided as something more akin to spiritualism than to science. Humphry Davy — the greatest chemist of the Golden Age of chemistry, charismatic pioneer of the scientific lecture as popular entertainment — was keenly interested in the mystery of animal magnetism. A century after him, Nikola Tesla — a dazzling mind epochs ahead of his time in myriad ways, whose legacy shapes so much of our daily lives and whose name is now the measuring unit of magnetic fields — stood a chance of cracking the mystery, given with his twin passions for pigeons and magnetism, but the opprobrium of the scientific establishment was too impenetrable and the technology was not yet there. It wasn’t until 1958 that a young German graduate student — Wolfgang Wiltschko — was tasked with disproving animal magnetic navigation once and for all. Instead, he ended up proving it: In the then-dubious experiment he was asked to replicate, the birds he let loose in a space with no light source could, just like in the original experiment performed by a fellow student, still orient effortlessly. O’Connor writes: The notion that animals have a bio-compass that can “read” the earth’s geomagnetic field has now emerged as the most promising explanation of animal navigation. In addition to those marathon migratory species, nearly every animal that has been tested thus far demonstrates a capacity to orient to the geomagnetic field. Carp floating in tubs at fish markets in Prague spontaneously align themselves in a north-south axis. So do newts at rest, and dogs when they crouch to relieve themselves. Horses, cattle, and deer orient their bodies north-south while grazing, but not if they are under power lines, which disrupt the magnetic field. Red foxes almost always pounce on mice from the northeast. These organisms must all have some kind of organelle that functions as a magneto-receptor, t