A Death Observed

Virginia died yesterday, a life sown, grown, and ripened in the state that gave her a name. She slipped away gently in the night, her passing unnoticed until she had gone. It’s often like that.

Our neighbor was just one of 154,000 people who passed that day, but the only one whom we knew and loved.  Born to a farming family, she was married twice, widowed once, and bore some private tragedies and hardships that everyone who lives to ninety must expect. Her only child died in infancy; the first marriage was broken by grief; she was a victim of fraudsters; two years ago when her home was laid waste by a hurricane she too was almost snuffed out; and she endured a growing burden of illness at the end, with pain …cameo

Virginia lived the two lives defined by Susan Sontag: a healthy one and the other.  Illness is the night side of life, a more onerous citizenship. She bore it bravely before crossing over the frontier to a shadowy territory, so familiar in name yet so strange in nature. Like other partings, it left me wondering how she could have flown so far and so quickly when she was so vividly amongst us the day before.

Can biologists say anything worth a whistle about that most mysterious of journeys? Not much! Ours is the science of life, and it’s not our job to turn the coin to read the other side. And those who study the opposite pole of the lifespan, like me, are least qualified; we are a happy bunch, watching embryos negotiate uncertainties until they emerge triumphant and hopeful of a full span ahead of them.  Writing this post was a way of working through uneasy thoughts, casting back to memories of lost parents and friends, certainly not expecting Virginia’s passing to be revelatory, only assured that empty feelings will be filled later by the business of living.

***

Death is either an instant or an eternity; I can’t decide between them.  But because it is not in time it is outside the realm of science, beyond the reach of the scientific method.  Talk about thanascience and I will tell you it’s nonscience.

Thanatos was a Greek daemon, a sort of nature spirit or custodian of the departed who served the Gods with his brother Hypnos (Sleep). He was (is) the dreaded leveler. Achilles, who knew a thing or two, advised Odysseus: Death comes alike to the idle man and to him that works much. While he mercifully bears away fallen warriors from the battlefield, Thanatos knows no justice, taking Virginia’s son, Skippy, after a medical error long before he came back to release her from pain and frailty.

Last week I passed a ramp on the I-64 outside Charlottesville where I remembered years ago the traffic was slowing to pass an accident. A highway patrolman and another driver stood beside a bulging yellow tarp spread beside a motorbike on its side. No one had yet picked up the shoe from the middle of the lane. The shoe, the shoe … that’s the thing I most remember every time I pass that point. Perhaps the poignancy of its emptiness is why I can’t forget it. How much harder it is to accept an untimely death than when time’s arrow has had its full flight before coming to ground. What then is aging?

Death_Sleep
Death & Sleep carry a warrior. @Trustees of British Museum

In his speech, All the world’s a stage, Jaques catalogued seven stages of life, ending with sans teeth … sans everything. Then the fool declared … from hour to hour, we rot and rot; and thereby hangs a tale (As You Like It).

Biologists protest his picture of aging. Healthy bodies don’t rot away gradually with the years, and death doesn’t have commerce with life by trading time for vitality, though statisticians might argue.  Aging is a slippery subject, still full of secrets.  We have discovered many chronometers inside cells, but a master timepiece showing how far we have traveled, how far to go, is still elusive – if one exists at all. To measure biological aging we fall back on insurance actuaries and government statistics whose data show the annual risk of dying increases at a compound rate of interest, called the force of mortality. We are not gradually dying from the moment of birth, as Jaques would have it, but the probability starts climbing after childhood.

The math predicts our chances of dying double every seven years, a prime number that was laden with mystical significance in the past. As people live longer on average nowadays, sailing past the old prescription of three score years and ten ought to fill us with more gratitude than rage against the closing of the light. We push towards the limits set by biology and genetics, and bioengineering may well succeed in helping future generations to pass Madame Calment’s record of 122 years.

It is awesome that life forces inside cells triumph for long over the Second Law of Thermodynamics which commits all non-living matter to decomposition and heat death.  Life succeeds against the odds but aging is neither its price nor is it ubiquitous: some animals and trees have indeterminate lifespans, are exempt from the signs and statistics of age, although none is immortal, all eventually fall to accidents or ‘Acts of God’.  Death is the tipping point on a gradient when vitality can no longer sustain life: and then the fall is precipitous.

While Thanatos bides his time, his junior agents are busy pruning the body, mostly for benign or even beneficial ends.  Cell death is happening everywhere all the time, and is often executed by a genetic program called apoptosis, meaning falling leaves, a Greek expression coined by my former colleagues in Edinburgh.  Trees continue to live after shedding their leaves in fall. In our bodies, healthy cells are sacrificed to make more a perfect form, like trimming surplus cells to create digits from the club hand of an embryo, and removing unhealthy cells, including cancer, if not always with enough gusto.  That kind of death we can celebrate.

But when he snatches a pretty bird with a red claw from our feeder it grieves us, yet the hawk and its chicks would starve on a diet of nuts and berries.  His work is paradoxical, taking one so another can thrive, keeping the wheel of life turning. Yet what is wise in nature seems so cruel when it strikes home, and prematurely. Isaiah may have reassured his followers, All will be well, but can he comfort us?

***

When the seventh seal was opened in the Book of Revelation, there was silence in heaven. The late Ingmar Bergman created an agonizing existential silence in his 1957 black and white movie, The Seventh Seal. Antonius Block, a Swedish knight returning from the Crusades to his homeland ravaged by the Black Death meets Death dressed as a hooded monk. As they play chess on the beach, his early hopes of winning are dashed, and after he knocks the pieces over Thanatos remembers every place on the board.

When a subject is too much to bear we laugh it off. In Death Knocks, Woody Allen’s hilarious parody of The Seal, Nat Ackerman in a New York apartment receives a surprise visitor in a black cape carrying a broken scythe over his shoulder.

Nat: “You look a bit like me.”

Death: “Who should I look like? I’m your death.”

Nat protests that he had come too soon, while still enjoying rude health. Then he challenges him to a game of gin rummy, winning a Pyrrhic victory.

As in Markus Zusak’s book set in Nazi Germany, The Book Thief, Death in all these stories is like his Greek forerunner, not the master of the house, more like a janitor with a solemn duty which he carries out efficiently without knowing or even asking the reason why.

Biology too, if just in this regard, is barren soil, offering only an endless dark night of the soul. Apart from religious belief, the humanities is the other spirit struggling for meaning, even if in honest moments it admits no more than to circle back to where it began. In his last big poem, Four Quartets, T.S. Eliot wrestles for words at the borderline of time and eternity, traveling from a mysterious revelation in the rose garden at Burnt Norton to East Coker where the heavy feet of rustic villagers clump nuptial dances, and he finally stands by the cornfield  nourished by his ancestors underground. People take what they will from literature, and from science too for that matter, but for a biologist these metaphors ring truer than, say, the mysticism of William Blake for their familiar organic-ness and earthy order. At the center of a turning wheel of life Eliot observes stillness, a peace like Dante and Hindu traditions observed long ago.

When we lit candles as a memorial for Virginia, my thoughts wandered to a memory of tramping through swampland where I once saw a dancing blue light, the will-o’-the-wisp, eerily emanating from the stinking bog of decaying biological matter. It wasn’t a hostile flicker, nothing like the devilish faerie light of Milton’s Paradise Lost drawing travelers to their doom, and I knew it was only a manifestation of the carbon cycle. But I liked the metaphor of the burning bog, almost Old Testament-like, gently drawing you closer until the animation suddenly vanished.

Next Post: Costs of Knowledge

Cardinal robes

As winter marches towards spring, two male northern cardinals have set up territories in our yard, keeping an eye on their mates but not getting along with each other.  They watch, emblazoned against a blue sky, from a favorite perch in bare trees. Catching sight of each other they ‘see red’, puffing up scarlet robes which get more brilliant as the breeding season approaches.

Why does red stand above all others, sometimes a sign of menace, sometimes a symbol of courage, and often expressing the power of joy and passion?

Cardinal
Cardinal in our yard

Red brake lights, red stop lights, red London buses, red light district, red planet, Redcoats, Red Army, red flags, cardinal bishops, Coca-Cola … the list goes on.  A color so intense it seems to sear the back our brain, where circuits originating in the red cone receptors of the retina are processed in the visual cortex. Would red convey a smaller emotional charge if blood was blue or fire green?

There’s nothing in a color beyond a wavelength – apart from how the brain perceives it. Hot peppers come in green as well as red, and red letter days and red herrings are fairly benign! Most mammals lack the red cone, seeing gray instead, but they are capable of as much passion as any primate or bird that has full color vision.  Bulls charge at a waving ‘gray’ flag.

To ask how a bird gets as hot as a cardinal is like asking for a Just So story – How the leopard got his spots … How the camel got his hump? Well, it’s the diet, dum-dum, because everyone knows, “We are what we eat.”  And looking around the yard, there is ostensible evidence everywhere.  Holly and Nandina bushes tempt hungry birds with dangling crimson berries.  But wait, biologists seldom answer a simple question with a straightforward story. Most of the intensity in these berries is from anthocyanin pigments which are not absorbed intact into the bloodstream. If berries are not wholly responsible, perhaps birds get their color from something else in their diet – like insects.  Errh … not the cactus juice-sucking insects that gave us cochineal for the pantry and for dyeing the tunics of Redcoat officers.

Most old sayings become threadbare in the light of research, and with a few exceptions there is no simple relationship between what we eat and how we look because of the rumbling process of metabolism going on inside.  Otherwise some of us would look like … well, I leave that to your imagination.

Nandina
Nandina

What then lends cardinals their color – and to so many wonders in nature, from fall leaves to appetizing vegetables?  Bugs Bunny would say that carrots are a good place to begin nibbling:

“Oh, carrots are divine, you get a dozen for a dime …”

Nearly two hundred years ago, a German student, one Heinrich Wickenroder, extracted from carrot juice a “yellow fatty oil with carotin” which dissolved in ether but not in water.  He won praise from his professors who thought it might fend off gut parasites, which were rampant in those days and still all too common in domesticated animals and wildlife.  Over time, his discovery expanded into a family of related molecules from plants, called carotenoids, including lycopene, lutein, and beta-carotene, which is the precursor of vitamin A. If I was asked to score my favorite molecules, carotenoids would be in the top ten beside DNA and chlorophyll.

Carotenoids are needed for photosynthesis, so they are almost ubiquitous in the plant kingdom, from whence we satisfy our own needs.  They prevent blindness, promote fertility, inhibit cancer, block oxidation, boost immunity, and make dandies of our avian friends in the yard.  I love the biological symmetry: carotenoids make plumage conspicuous in birds and give the power of vision so their mates and rivals recognize it and we can enjoy it (in fact, vitamin A is only responsible for the rod cells). Because we can’t make these virtuous molecules in our bodies but have to absorb them from our diet, the food police keep heaping more fruit and veg on our plates.

Northern cardinals obtain their supply from an omnivorous diet of berries, seeds, and insects, while American goldfinches subsist on strictly vegetarian fare.  When Cornell ornithologists reduced red carotenoids in the diet, cardinals grew pale, and goldfinches turned orange when yellow carotenoids were deficient. But changing diets didn’t go as far as switching their colors because the gut is wise to the vagaries of nature (and researchers) by converting one type of molecule to another.  It’s obvious that diet alone can’t explain everything because female cardinals eating the same food are so much drabber than males.  It takes testosterone to make a male hot.

Red grouse are hardly that.  A game bird looking like a large cardinal in the open heather would soon end in a vixen’s den or on a Scottish table. But the males have a small red comb, a token that performs the same service as the cardinal’s feathers.  Since grouse are plagued by roundworms and ticks, ornithologists wondered whether treating the males with anti-helminthic drugs could improve their breeding performance as well as their overall health. They did.  After ridding them of parasites, the birds absorbed more vitamins from their food which, in turn, increased the color intensity of their combs.  The little red flag on their heads was more attractive to the hens, who thought they would make healthier partners.  Female cardinals get the same message. They can’t be hoodwinked by a frail male because carotenoids painting the breasts of males bursting with blushing pride make honest birds of them.

Next Post: A Death Observed

A Dog’s Dinner

Banana Joe stole the show!

No, not the LA radio presenter, I mean the affenpinscher from Attleboro who won Best in Show last week at the Westminster Dog Show in NYC.

I’m not a pooch person, prefer big mushy dogs, but Joe the affenpischer who looks like a cross between a toy and a monkey is easy to love. And a monkey dog he is (ein Affe, a monkey). Like monkeys, Joe and our Golden enjoy a banana, which is not so surprising if you consider it is a perfectly natural food for their cousins – wolf packs in Minnesota and Alaska.  Erhh!

We changed their dietary preferences after the first wolf cub was adopted by a human family.  I ought to pause to correct myself because dogs can’t express preferences any more than I could as a London schoolboy. It is only a slight exaggeration to say that we were served Dickensian gruel for school lunch. I remember peering through the kitchen window at the cooks watching over steaming vats of bubble and squeak made from yesterday’s left-overs and stirring custard thick as tar but not so smooth. It was ‘Hobson’s choice’, or, in other words, no choice at all, just as it has always been for our dogs.

Until the food industry realized there was a canine market, most dogs had to make-do with human left-overs, living hopefully for a bone flung their way with a morsel of meat on it.  As members of the Order Carnivora, their ancestors enjoyed a high protein diet before they were domesticated around 10,000 years ago (some put it earlier). Neolithic people were then switching from hunting and gathering to agriculture, growing various cereal crops in the Old World, sweet potato, corn and beans in the New, and – yes – bananas in New Guinea.  Growing-their-own enabled them to form settlements with greater food security, and afterwards their diet became much richer in starch. So did the dogs’.

A new study of whole genome resequencing shows what an impact this change had on canine genetics. There are not as many genetic differences between dogs and wolves as you might think from their manner and appearance, but significant differences were found between genes involved in brain function and the digestion of starchy and fatty foods.  It seems that a genetic bottleneck occurred in the early prehistory of domestication. Animals with gene variants that favored compliant behavior and efficient starch digestion squeezed through, and those survivors became the founders of modern dogs. The wild-type wolf genes disappeared because dogs lacking genes that were better adapted to the new life were either kicked out for bad behavior or didn’t thrive on the new diet. Lying at your fireside is an example of how we sculpt the evolution of species.

Lilah
Lilah’s turn

Now to sweeter talk. Sweet is one of our five senses of tastes, but long before we celebrated it by inventing confectionary it was probably beneficial for distinguishing between good and bad food. Since wolves will occasionally eat vegetable matter it’s not surprising that they share the same sweet taste receptor gene, Tas1r2, as ourselves, and dogs inherited it from them.  Other mammals can taste sweetness too – raccoons and of course bears – but not all. Cats can’t taste it because their Tas1r2 is pseudogenized (meaning it doesn’t function), and likewise in sea lions, otters, dolphins, and hyenas.  Since they are flesh-eaters that swallow their food whole there’s no time for tasting and therefore no point in having a sweet taste receptor. But biologists who love to tell a commonsense story are often embarrassed by an ugly fact that threatens a beautiful theory. We might expect a species that sips its food to have a well-developed sense of taste, but apparently vampire bats don’t have a sweet tooth in their heads.

Now back to bananas and Banana. Our dog, Lilah, has a more discerning palate than her owner because she turns her nose up at green bananas which are just full of starch but she will happily chomp on yellow ones in which much of the starch has been converted to sugar.  We throw away overripe bananas but, given the chance, she will gorge on them knowing they have the most sugar.  The French clearly know their bananas too because their grocery stores have premium prices on fruit with brown skins.  Belle banane.

Banana Joe deserved a better reward. He was taken to a swanky Manhattan restaurant where he was served filet mignon to celebrate victory. I expect he was glad to leave starch behind for a day if only to prove he is still a card-carrying carnivore.

Next Post: Cardinal robes