Cold Finger

The last time we had a really cold snap like last week I dug up something unexpected in my backyard. It was not as exciting as a human skeleton, but nonetheless interesting. 

I was digging frozen turf with a sharp spade to prepare a flower bed. It was like cutting ice cream cake into slices. My hands blanched without gloves, but was better working in the cold than waiting for the thaw to turn the ground to mud.

I noticed a strange object after turning over a slice of turf.  It was the size of a hen’s egg, but as hard as a stone. Brushing off ice, it looked buffish with a yellowish stripe, and a long “process” extended from the “body.” When more ice and caked clay were removed I found another long process and two short ones attached to the corners of the body.  A French scientist would have guessed sooner they were frog’s legs.

It was a frozen wood frog, which is well-named Lithobates sylvaticus (meaning a stone that walks in the woods). Tidewater Virginia is as far south as you are likely to encounter this species, whose range extends above the frigid Arctic Circle. How this cold-blooded creature survives freezing is still an enigma, and most animals can’t.

My students in Edinburgh learned about the effects of freezing by some simple experiments with red blood cells. They diluted blood in a test-tube of isotonic salt solution, which turned pink and turbid. After freezing and thawing, the solution became so transparent that print could be read through the tube.  Before freezing, blood cells are still packed with hemoglobin which scatters light and makes the tubes look cloudy. After freezing their membranes have been perforated, which allows hemoglobin to escape and leaves the cells like transparent bags.  To confirm the theory, the tubes were spun in a centrifuge. The unfrozen cells formed a red pellet at the bottom overlaid with colorless liquid showing the cells were still intact, whereas the frozen tube was uniformly pink from dissolved hemoglobin.

Lastly, the students added glycerol at the start of the experiment, which completely prevented freezing damage.

The protective effects of glycerol were discovered by accident in Audrey Smith’s lab over

Audrey Smith (1915-1981)
Audrey Smith (1915-1981)

sixty years ago. It was one of those beautiful errors to warm a scientist’s heart.  Colleagues who remembered working with her told me that Audrey was a delightfully dotty Englishwoman who took her beloved Labradors everywhere, even opening her lab doors so they could join her at work.

Glycerol was the first of a bunch of substances that now preserve a long list of cells and tissues—blood, semen, eggs, embryos, stem cells, heart valves, skin, et cetera. They work in several ways—not simply by lowering the freezing point like car radiator fluid. When they bind water molecules or substitute for water the number and size of ice crystals that do harm inside cells are reduced. Audrey’s research team also showed they reduce the risks of cells pickling in their own brine, because salt reaches harmful concentrations when water starts to freeze.

Unlike amphibians, mammals and birds tightly regulate their body temperature, and those adapted to cold climates are protected with extra insulation and a counter-current blood supply reduces heat loss through cold feet, like penguins. Some species can turn down their internal thermostat—squirrels hibernate and bears become torpid—but none can survive whole body freezing. Hibernators wake up when temperatures fall dangerously low and start to shiver and stoke their metabolic fires.

Nakedness is a great adaptation for hot climates but no good in the Arctic. Humans generate heat by shivering and conserve it by reducing blood circulation in the skin, but for migration to the Far North more clothing and changes in behavior were needed. People with Raynaud’s phenomenon have an exaggerated vasoconstriction to chilling of their fingers and toes (penguin feet).  I do. Their digits blanch and become painful at temperatures that don’t affect others, and turning blue is a frostbite warning.

Raynaud’s can be ameliorated by drugs that reduce vasoconstriction, but in one of my more eccentric projects I tested if a herbal remedy could keep my digits warm. It was a fire water of concentrated ginger and peppers, and barely drinkable. But somehow I managed to gulp it down every day for six weeks followed by six weeks off before repeating the cycles throughout the Scottish winter. I weighed my fingernail clippings at the end of each week to the nearest milligram. If the herbal was improving my cold sensitivity I theorized that my nails would grow faster on treatment from a better blood supply to the nail bed.  There was absolutely no difference, but warming pads for hands and feet worked!

Frozen storage brings to mind episodes of Doctor Who traveling through time and space and coming back from the Planet of the Dead. And that reminds me about Cryonics in which whole bodies of legally-dead people (sometimes just their heads) are frozen in the hope that in the distant future biomedical science will restore them to consciousness. It’s a good business while customers are stiff in liquid nitrogen containers and cannot complain about the service, but I think it’s better to invest in the living.

Frozen frogs are not dead, but almost. In fact they are not completely frozen, even if three-quarters of their body water is iced-up. There is glycerol in the body, but it is not responsible for cold survival. Before hibernating, stores of liver glycogen are converted into glucose, which is another molecule that helps in cryopreservation. More importantly, ice forms in their body cavities rather than inside organs and cells, both of which shrink from partial dehydration and become supercooled. Their hearts slow and finally stop without fibrillating as ours do by only a few degrees of hypothermia.

I can’t be sure if the frog in our backyard really was alive or had frozen to death. Warming it would have given me an answer, but it might not have survived the rest of the winter without a food supply or possibly had insufficient energy reserves for  successful hibernation.  Besides, there is a You Tube video of frogs waking up to satisfy my curiosity. So I quickly returned the stone to frozen ground.

Next Post: Scavengers

Shifting Baselines

Captain John Smith
Monument to Captain John Smith, Jamestown, Virginia

In 1608 Captain John Smith led a crew of fourteen to explore the Chesapeake Bay in a shallop brought over from England in the hold of the Susan Constant.  Leaning over the side of the small craft they could see nearly four fathoms down through clear water. The bed of the estuary was encrusted with oyster reefs, enough to completely filter the bay every week, and some of the shells were large enough to serve a hearty meal. In his journal, Smith recorded, “the oysters lay as thick as stones … (there are) more sturgeon than could be devoured by dog or man … (and plenty of) grampus, porpoise, seals, stingrays, brits (?), mullets, white salmon (striped bass/ rockfish), trouts, soles, and three sorts of perch.”

The sailors must have been in awe of the bald cypress trees lining the shore like a curtain behind which a mysterious forest stretched to the horizon. The canopy was taller than any cathedral they knew in Europe, and was home to unfamiliar birds and game animals. Native people never went hungry where there was so much good fishing and hunting, and they grew corn, beans, and squash in the clearings. Smith noted the country was “very goodly.”

He never found the gold he came for, nor did he realize that the real wealth lay under his boat. It wouldn’t be harvested until the Oyster Rush in the 19th Century, which made shellfish a rarity. When they were still plentiful, their shells accumulated in the sediments leaving a record of when the Bay still teemed with life.

Fishermen and commercial watermen plowing the bay today are content with their normal catch of seafood because its original abundance stretches our imagination, if we think of it at all. We define what is normal not from the deep past, which is barely-known, but from our own experience and stories passed down by elders—“You should have seen the catches in my day, boy!” The pristine state of the Chesapeake Bay and its watershed predate human memory, and explorers like Captain Smith have left scanty records, if any. But does it really matter what the Bay looked like, because in a fast-moving world our attention is fastened on managing a man-made present and future? History is bunk, isn’t it?

Daniel Pauly disagrees. He has a theory that each generation makes its own mental map of what is normal, and consequently it can have lower expectations of richness and diversity in the environment than the previous generation if that has already deteriorated. Progressive generational myopia is called “shifting baselines,” and as a marine biologist Pauly had ocean fisheries in mind, although the concept applies generally in conservation biology and social science. To remind me of the concept I have a list of favorite shifting baselines, starting with shifting waistlines:

  • A Gallup Survey showed that Americans weigh 20 lb more than they did two decades ago, which many people thought was “just right” or normal.
  • House finches can be seen most days in Eastern Virginia, but that would not be normal for previous generations of birders.
  • Thin topsoil in my yard is normal, although I now know that a farm exhausted the land years ago when it was much richer.
  • Since average Americans watch live TV for 34 hours a week I presume they are satisfied with normal programs, though old curmudgeons who remember the hey-days of TV excoriate them.
  • Slow journeys to work in congested cities are not frustrating to everyone as we might expect because new residents accept lengthy commutes as normal.

You will have many more examples of your own, but I must get back to my theme.

There is no doubt that we have been poor stewards by polluting and overfishing the oceans. As consumers we feel the scarcity in our pockets from spiraling prices of tuna, cod, and anchovy, etc. That such a wonderful food is becoming only affordable in the rich world is a tragedy, and governments have been slow to protect collapsing fisheries, perhaps because conservation science has been blinded by the wrong baselines. Maybe a better knowledge of the original state of the environment can help to protect oceanic health and stabilize harvests because everything in a living ecosystem is linked with something else, like a spider’s web which is sensitive to changes in tension anywhere in its orb.

All things are connected.

Whatever befalls the earth

Befalls the sons of earth.

Man did not weave the web of life,

He is merely a strand in it.

Chief Seattle (1780-1866)

Chief Seattle
Chief Seattle

The wisdom of an old Native American chief who lived close to nature chimes with modern ecology. But how can we discover what stable and healthy environments looked like before they were exploited—from poring over the logs of old explorers, fishermen and whalers, or dredging up sub-fossil remains like oyster shells? The baselines that Captain Smith knew have been lost and there are precious few pristine places anymore to serve as models.

It was not however the sea but the land that alerted me to one of my own shifting baselines. I knew that most of our eastern forests are secondary or tertiary growths that have been rapidly regenerating since farming and logging started to decline here. But my error was to assume they were in the process of becoming facsimiles of the virgin forest and would again harbor the same native species with huge tree boles and towering canopies, as if we had never trammeled the land. And I thought the few remaining stands of uncut forest and reforested land protected by the Wilderness Act were pristine.

When President Lyndon Johnson signed the Act into law in 1964 he said something that used to strike a chord in me: “If future generations are to remember us with gratitude rather than contempt, we must leave them a glimpse of the world as it was in the beginning…” (emphasis added). I wish it could true, but regret I have been naïve.

I see many native trees and shrubs on my hikes that have seeded naturally—oaks, maples, hemlocks, et cetera. I fooled myself that the mixture is normal. I thought that wildness guaranteed the forest is the same as it was in the beginning, but in fact it is coming back differently. Some species that used to be dominant are now absent and replaced by foreign species. Suppression of natural wildfires (a well-meaning forestry policy) encourages the succession of fire-resistant species by others, and firebreaks create more edges where different species thrive. A history of logging and poor farming practices has often exhausted or eroded the soil, and dams and mills have altered floodplains and sediments which, in turn, alter the vegetation that grows there.

The American chestnut tree was my biggest blind spot. The tree used to inspire country folk to dub it “king of the forest,” but it is completely eliminated by blight (American Chestnut: the Life, Death, and Rebirth of a Perfect Tree by Susan Freinkel). There is now a host of introduced diseases and insect borers working their way through our pines, oak, hemlock, ash, and dogwood, and they are very hard to control. Sometimes alien species out-compete the native flora because grazing beasts and insects in their new country find them unappetizing.

George Washington
George Washington by Gilbert Stuart

If we could resurrect Captain Smith from his London grave he would tell us tales of a primeval forest he knew that is very different today. We have inklings of it from archives of the colonial era when land surveyors like a young man called George Washington were drawing plats in Virginia’s western frontier for farmers, lumbermen, and land speculators. “Witness” trees that were used as boundary markers on plats give a rare glimpse of species that grew there over two centuries ago.

land plat
A land survey plat by George Washington

And in the North-East and Appalachia sub-fossil records show that giant beech, hemlock, and spruce of the old-growth forests are now substantially replaced by maples in regenerating forests. This difference may not seem unwelcome because maples are ornamental natives, but they are less productive for supporting animal communities and the farm animals that used to run in the forest. The most productive species of all, the oak family, has declined across the range.

Gaudineer Scenic Area in West Virginia. A tiny fragment of uncut, old-growth Appalachian forest

I know that it is no good fawning over the old forests, whatever they were actually like, because they will never come back. Looking back at their green light is unlikely to make a difference, and it is futile to “beat on, boats against the current, borne back ceaselessly into the past (The Great Gatsby). The land passed a tipping point of no return a long time ago when drivers of change were first released into the environment, and they continue to mold it. These changes may even accelerate with global warming.

But if the land is slipping further away from its original state, we can be more optimistic about oceans according to marine biologists. Some of them say the tide of ocean poverty can still be turned by careful management, and the Chesapeake Bay is improving, if agonizingly slowly. For eons, the Bay danced only to nature’s tune, rolling with the seasons, and generations of Native Americans who had little impact on it therefore shared a mental baseline for what they thought was normal for its waters and in the surrounding forest. Only when European colonists arrived with technologies for rapidly extracting resources was there much change, and after four centuries of exploitation Captain Smith would find the Bay strange and much diminished.

I was musing that we condemn people responsible for war, prejudice, and human bondage but rarely blame those who have spoiled the environment by industrialization, mining, overfishing, clear-cutting, and draining, eroding and poisoning land. I wondered if we excuse the pioneers because they struggled to survive in hostile territory and perhaps felt a God-given right to subdue it? Or was it because as their power of exploitation grew they didn’t realize the sea and land have limited abilities to recover? Or do we forgive them because we have benefited from their excesses. Perhaps it is a bit of all of them, but those who don’t know better can’t be held responsible for error.

I then wondered if the excuse is wearing thin on current generations and if we will be judged more harshly than we judged the past. We are no longer ignorant of our impact and are leaving plenty of evidence of our own stewardship. If future generations live in a more impoverished world than ours they will not be so blinded by shifting baselines and would justly hold us in contempt, just as President Johnson warned.

Next Post: Scavengers and Decomposers


Few people are star-struck these days—unless you mean a movie- or rock-star. How could they be when the nightly spectacle is veiled by light pollution?

That expression might strike you as perverse, even as a non sequitur, for isn’t “light” good and “pollution” bad?  In the Bible, people who walked in darkness were the bad guys (them), while the good were in the light (us). In the Land of Mordor, the Dark Lord sat “where the Shadows lie”, far from Bilbo sunning himself at Bag End. Sadly, real human misery is still caused by labeling people as either dark or light.

Since incandescent bulbs were first turned on well over a century ago, darkness is being progressively banished around the world. Hardly anyone wants to go back to when lives were dictated by the dark hours, and our ancestors had to pore over a candle to read, sometimes burning the house down! But lighting is not quite the black and white matter it seems, although it is an uphill struggle to explain.

Something precious that fed the human spirit for eons has been extinguished by universal lighting—a pristine night sky. Few people mourn the loss. Gazing from your window, yard, or a local park in urban North America, Europe, and Japan, you can only see a tiny fraction of the stars and planets that were visible to naked eyes in the past. Two-thirds of Americans now live in places where our own galaxy, the Milky Way, cannot be seen because of sky-glow and air pollution, and the fraction grows as more and more lights go on around the globe. Does it really matter?

Isn’t it another dimension in which we are becoming spiritually disconnected from nature? Richard Louv was thinking of life on our planet when he coined the expression, “nature deficit disorder”, in Last Child in the Woods, and I wonder if we are also impoverished by missing the experience of seeing the wild sky except through the lens of electronic media and science. The philosopher, Immanuel Kant, said, “Two things fill the mind with ever new and increasing admiration and awe … the starry heavens above me and the moral law within me.”

Stars were heavily used as metaphors by writers of the Bible and Quran, but are more familiar today as expressions in conversation and literature than as heavenly bodies in plain sight: how often do you hear star-turn, starlit, star-dust, stardom, star-crossed, Star-Trek, Star-Spangled Banner, etc? Until recently, voyagers used celestial navigation to reach their destination, but a star (read supernova/ comet/ conjunction of planets) can no longer lead the Magi to the manger if it was, say, in Brooklyn.

Detail of Nativity Window. Trinity Church, Boston. Edward Byrne-Jones
Detail of Nativity Window. Trinity Church, Boston. Edward Byrne-Jones

In the past, a night sky studded with stars and planets was familiar to everyone, and those who could interpret mystical meaning in the constellations were hoisted up to become sages. Ever since the Babylonians, people have consulted astrological charts to predict their fate, and farmers and gardeners used the lunar calendar. I read that I should plant onions under a waxing moon and they, like me, are under the sign of Libra.

The brightness of the night sky is reckoned by astronomers on the Bortle scale up to a maximum of 9. Metropolitan corridors, like Washington DC to New York, register 8 to 9, and small developed countries, including England and the Netherlands, are high on the scale even in rural areas. Our small town of Williamsburg in Virginia is 4-5, and most of our National Parks have significant light pollution from the glow of distant cities. National observatories were created in the early Twentieth Century for optical astronomy in dark regions of California, but have had to be moved to mountaintops in Hawaii and Chile.

A perfectly dark sky is hard to find anywhere in eastern North America now, but there is a dark spot rated 1 or 2 on the scale in West Virginia where we have a home in the Monongahela National Forest. The night sky there owes its continuing virginity to a low population density and the fact that most homes and highways are not ablaze with lights. The only places I remember with more dazzling starlight were in New Guinea and Africa, which is still a dark continent and something to celebrate.

If you sat on our deck in West Virginia for half-an-hour after night settles in the forest your eyes would be fully dark-adapted and able to see the faintest celestial glimmers. I recommend sitting inclined on a bank to avoid getting a stiff neck for viewing the azimuth. I’m told that at least 15,000 stars are visible in the Milky Way, plus planets, and other stars and galaxies at distances that defy comprehension. You don’t have to pay or be an astronomer to enjoy this show, although binoculars or, better still, a telescope enrich the spectacle.

Even on moonless nights, there is enough starlight to pick your way along a forest trail or across a meadow, but when clouds are too dense to be pierced by stars or a ghostly moon, it is so dark that you cannot even see your hands or feet. That is Pitch-dark.

The blackouts in European cities during bombing campaigns in World War II and the widespread power outages in north-eastern USA and Canada in 1965 and 2003 were urban lessons in what darkness means. When I lived in a West Yorkshire village the residents refused to allow the council to install street lighting. The main street was pretty dark, but still about 4 on the scale. It is likely, if somewhat exaggerated, that outside lighting helps to deter crime, but the villagers were adamant even during the years when the Yorkshire Ripper prowled the district.

Most people probably won’t object to a darker sky, and some might welcome it. Since thirty percent of outdoor lights point upwards, more directed lighting would reduce sky-glow, save money, and have other benefits. Migrating wildlife is disoriented by nightlights, and perhaps plant growth and even human health are affected. There is increasing evidence that our sleep rhythms are affected by excessive light, although most of it is admittedly from indoor lamps and glaring TV screens and computer monitors, which I am using as I write.

Not many people talk about light pollution though I am not alone because an International Dark-Sky Association exists with chapters in sixteen countries. Perhaps more widespread use of directed lighting will help to reverse sky-glow in future, and janitors will turn off lights in skyscrapers after work. But I doubt that we will ever again hear someone banging on our door like the A.R.P. wardens during the Blitz in London, “Put that light out!”

Next Post: Nose to Proboscis