Human Population Through the Looking Glass

I can’t avoid this topic forever, not under the headline Peace with Nature. It is the intractable, controversial matter of the teeming numbers of human beings. How many more of us can the Earth sustain in this Anthropocene?

Only the most pig-headed science denier can dismiss environmental challenges that threaten our future, even our survival. Among the obvious are food insecurity and infectious diseases, soil erosion and desertification, air and water pollution, fossil fuels and global warming, animal and plant extinctions. It’s hard to dwell on them for long because our responses at best are puny against the tide. Besides, pessimism is not an attractive outlook.

Much can be blamed on world overpopulation. We are doubling every 49 years and will soon reach 8 billion. That is ratcheting up the impact of our insatiable appetites for consumption, which are reflected in an obsessive drive to constantly expand economies (as if no ceiling exists).

If everyone consumed resources like a medieval peasant, we would be far behind the curve. Billions of us still live that way, though never by choice. Wealth is not distributed in a bell-shaped curve. Raising prosperity for everyone to, say, an American level is unattainable on this finite planet: for some to be rich, many must stay relatively or absolutely poor. If this present state is manifestly unjust (who can deny it?), would a smaller population shrink the gap in wealth?

Population control is the hottest of hot potatoes. The liberty of choosing to have children and how many is a cherished human right. Woe betide the institution that coerces people into contraception or mandates sterilization.

Sanjay Gandhi tried during the 1975 ‘Emergency’ in India. The son of a prime minister led an aggressive program of shoddy vasectomies and tubal surgeries for mostly poor subjects in exchange for trivial incentives or were forced to comply. People pushed the policy back and his family became a tragic story. An authoritarian government succeeded in curbing growth of the Chinese population by limiting families to one child after 1979, but that policy relaxed too.  A distorted age pyramid had huge socio-economic implications and many girl babies were ‘missing’ before birth. Fortunately, family planning methods are freely accessible in many countries, although not enough. Private decisions in bedrooms have a bigger effect on birth rates than any government diktat or contraceptive.

As a young reader of Silent Spring and The Population Bomb, ecology and population created a frothy amalgam in my head. At that more idealistic age, I believed that the pair together with nuclear weapons made a triumvirate that threatened civilization. I then leaned into a career in reproduction research, hoping to help discover new contraceptive targets. To disable the sperm or egg before fertilization seemed (still seems) preferable to hormones for blocking ovulation or the more elusive goal of knocking out spermatogenesis. I became a Population Council (NY) research fellow, but drifted to profertility technologies, like my mentor Robert Edwards who pioneered fertility treatment with  IVF.

This is no small irony since I still fret about the ‘population problem’, although my original fear of human numbers and hopes for a technological fix were naive.  Family sizes in the West started to shrink at the end of the Victorian period when bumper crops of kids were grown. This shift occurred in tandem with declining infant mortality, revealing that people had the know-how to make reproductive choices before highly efficient contraceptives were developed after WWII. Men have traditionally called the shots at home but as women gained more authority and education, they chose smaller families, or started later, or remained childless. A trend that began in the West continues to spread globally.

The population anxiety of fifty years ago when the UN and grant agencies plowed money into research and fertility services has switched from fear of too many babies to too few for replacing people who die. Some countries, notably Japan, will have half the population by the end of the century, with huge social implications. They now try to hoist birth rates above the replacement threshold of 2.1 by offering incentives like free childcare services, and will welcome more immigration to offset population decline.

And yet the world population continues to climb while other countries catch up with the demographic shift. A recent paper in the Lancet offers a more optimistic forecast than the United Nations’ official projection. Instead of peaking at 10.9 billion by 2100, it reckons there will be only 9.7 billion of us in 2064. This small mercy doesn’t quash concerns about overpopulation, and there are no quick remedies, barring a global catastrophe. But sometime next century I believe new institutions will guide us through a painful and dangerous demographic transition to a much smaller population and more stable than ever in history.

That kind of flourishing worldwide requires peace between people and with nature. A more equitable society rolling over the lottery of being born rich or poor can offer a peace dividend and deliver environmental justice. A smaller population should draw from Earth’s limited bounty more sustainably with a lower impact on the environment. It will avoid impoverishing posterity and generational injustice.

Technology has been called a bane for conservation, but it also helps to live more gently with nature. But it can’t do the heavy lifting of giving 8-10 billion people a fairer share of prosperity. With a smaller population there is more to go round, but how much smaller for everyone to have a generous slice of pie that doesn’t cost the earth?

Ballpark averages of rich versus poor populations (or nominal GDPs per capita) show a 5-to 10-fold difference in wealth. Hence, for sustainability the world population should be no greater than a tenth of the present, about one billion or close to the number alive in the year 1800.

Maybe this speculation is pie in the sky. Optimism is in short supply and we are blind sighted by the narrow window of our own experience. But each successive generation experiences the world differently and sometime in the future people may look back aghast, wondering how their ancestors living in our time managed to muddle through. I think we will, just as people did in pandemics and wars of the past, because humans are experts at surviving and Earth is our only home. Gaia will be relieved when a post-Anthropocene era emerges with human numbers and appetites she can comfortably support.

Next Post: About Nostalgia

 

 

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Don’t Write Off the Bat

It was a perfect evening for a spin in the Batmobile with a team of three amateur chiroptologists. The air was warm and still when the sun went down.

After leaving the carpark, we were overtaken by every vehicle along the Colonial Parkway as we crawled at 15 mph, hugging the kerb. Fortunately, the traffic was light. It was too dark to see if the faces passing us were puzzled by the tall aerial sticking out of our sunroof or if they guessed what we were up to from the sticker on our trunk illuminated in their headlights: Bat Monitoring – Pass Safely.

Although I rarely hear bats nowadays, I love to watch their silhouettes against the last glow of a darkening sky. Their acrobatic flights look sheer joy, although I know they are to satisfy voracious appetites, twisting and turning to skim the air of mosquitoes, moths and lumbering beetles.  After years of wondering what species lived here, I now had an opportunity to find out.

The passenger sitting beside the driver held the aerial with one hand and used the other to control the tracker pad of a laptop perched in front. I watched over her shoulder as she loaded the SonoBat software.

SonoBat

All set in the Batmobile

We hadn’t gone far along the tree-lined parkway when the computer chirped. It was our first hit. A chirogram on the screen (like a sonogram) showed regular pulses as a bat called for echolocation to detect prey and avoid obstacles. A machine-learning algorithm identified the species, saved data to a spreadsheet and could mark ambiguous results, if necessary. The passenger in the seat beside me backed up results by writing on a notepad. We had detected a Red bat, named for its red fur. It was impossible to see it or any others through impenetrable night.

This was my first time for a bat positively identified while flying free in the wild. Soon, there was another chirping, then another, often in a different tone and frequency. After two hours on the road we gathered 125 recordings, mostly ascertained. The total number of individuals was, however, unknown, and we probably had duplicates because bats of a given species have the same voice. But we were more confident that seven species flew close enough to detect that night, including the Big-eared, Big brown, and Silver bat. I never knew we had so many.

chirogram fromSonoBat

Chirogram of Red bat

The software program identified calls by referencing a library of thousands of recordings of species from across the continent.  We mostly detected Red bats, a common and widespread species. The Seminole bat has a similar chirogram, but being near the northern limit of its range it was unlikely to be mistaken for the closely related species.

When I joined the survey one night last year, bats were getting more attention from conservationists and there was growing public interest in their dwindling populations from loss of habitat to human development, Insectageddon threatening their food supply, and the toll from white-nose syndrome.  They haven’t lost friends who always cared about them. But people who were indifferent before or harbored superstitions can find a better excuse for fearing them than the old myth that bats get caught in young girls’ hair.

Evidence is growing that the COVID-19 virus originated in bats before it infected humans, perhaps via an intermediate host. The species and country of origin are still unclear. Bats harbor coronaviruses to which they evolved enviable tolerance from long association and robust immunity. They have orthologs of our ACE-2 protein, a molecule with a physiologic role and widely distributed on our cells that offers the virus a gateway for infecting us by binding its spike protein.

To persecute bats as suspects of this or other zoonoses (certainly they can carry the rabies virus, like any other mammal) is no more justified than putting people in jail for spreading disease before they understood the menace or knew they were infected. Solutions to our problem lie not with the animal but in our connected world and with global travel.

Bats flying at night

Thanks to Ruth Rios on Unsplash

Bats are fascinating creatures in the web of life. They cling to familiar habitats and if left alone they help us as insect-eaters and providers of pollination services.

When contact distancing is revoked after the pandemic, I hope to board the Batmobile again to watch pulses on the glowing screen that spark imagination about the peregrinations of bats outside in the night.

Next Post: On Human Population

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Virginia is for Oyster Lovers

“Why then the world’s mine oyster, which I with sword will open.” Thus, Shakespeare gave us a new idiom in the Merry Wives of Windsor repeated ever since, and Oscar Wilde wielded it with customary wit: “The world was my oyster, but I took the wrong fork.”

It means a person expects to avoid adversity and find opportunity, like the discovery of a precious pearl. But if you asked an oyster it wouldn’t sound optimistic. Our excessive love kills them, and few cared about the relentless harvest until recently. In the poem recited by Tweedledee and Tweedledum, Alice felt sorry for oysters as the Walrus and Carpenter gobbled them on the beach.

Had we been aboard the shallop steered by the first English explorers of the Chesapeake Bay in Shakespeare’s day we would have been gobsmacked by an abundance of oysters, some as large as dinner plates and forming reefs grown close to the surface.  In 1701, a foreign visitor wrote in astonishment: “whole banks … ships must avoid them … four times as large (as English oysters) … I often cut them in two to put them in my mouth.”

The Bay was drastically impoverished by dredging its bed barren in the 19th century Oyster Rush.  The local economy collapsed and watermen switched to crabbing to make a living. The crash drastically impacted other fauna and flora since the remaining 2% of original numbers now took a year to filter the entire Bay which used to be achieved in a week. It is a classic example of the folly of free-for-all harvesting of a seemingly inexhaustible natural resource. Oyster beds are now making a slow recovery against a tide of agricultural effluent and disease, but helped by volunteers for the Chesapeake Bay Foundation and less harvesting pressure as oysters are cultured commercially.

If they are on your menu today, imagine the same shells on your plate again. The suggestion is ridiculous, but the point is that some restaurants in our region recycle shells for building wild oyster beds and embedding in artificial reefs. At one time, they were used as lime for mortar and roads, but when that became redundant they were dumped in landfills, so the recycling program is positive in every way.

oysters in Chesapeake Bay

Oysters shells curing in the sun

Shells are trucked to a depot in Maryland or the Virginia Institute of Marine Science beside the York River. A volunteer tips them on a hopper for conveyance through a tumble washer and bagging to cure in the sun for a year, eliminating the last traces of condiments from your meal. The happy, hot and sweaty team beside the river is, alas, not reassembling this year because of the coronavirus contagion.

oysters in Chesapeake Bay

Oyster gardening

Cured shells are loaded in tanks of brackish water to which larvae (‘spat’) are introduced from external suppliers. The spat can attach to hard surfaces like stone or concrete, but they prefer old shells, like the reefs of old. Young oysters are then dropped in sanctuary areas of the Bay or its creeks and rivers or oyster gardeners raise them for a year in cages where they grow faster and are protected before reaching their final destination. The goal is to deposit 10 billion oysters by 2025, an effort requiring over 21,000 hours of volunteer time.

oysters in Chesapeake Bay

Oyster lovers beside the York River

Not only will future diners and watermen benefit but the whole ecosystem. It is a story of a keystone species. In purifying 50 gallons of water a day, each oyster reduces dissolved nitrogen and phosphorus and, hence, the risk of dead zones from algal blooms. Their colonies provide important habitat for fish and crabs too. The early explorers adopted the Algonquin name for Chesapeake, meaning great shellfish bay,  and perhaps one day it will be apt again.

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The Sound of Noise & Silence

Among many things we will remember after the coronavirus pandemic, the world was quieter than normal. When I compared a busy avenue-street intersection in Manhattan before and during the lockdown, I found a 6 decibel (dB) difference, four-fold in amplitude. (The vast range of sound detected by the human ear needs the logarithmic scale.) A lower density of traffic on the ground, underground and overhead was mostly responsible, with contributions from building work, human voices, and so on. In suburbia, it is weed whackers, chainsaws, and trucks that make most of the racket, and sometimes neighbors too! You can check out a noise map for your region and community here.

Human ear and listeningI can’t think of any virtues for noise, though we don’t agree on the main offenders. Objections are sometimes muted by vested interests. Noise is in the ear of the beholder. Sounds that some heads perceive as musical turn others in disdain or even pain. I remember marveling at the virtuosity of nightingales singing through the night in Languedoc. The volume can reach 95 dB, above the threshold of harm for human hearing.

… That thou, light-winged Dryad of the trees

In some melodious plot

Of beechen green, and shadows numberless,

Singest of summer in full-throated ease …

John Keats: Ode to a Nightingale

Music is mostly regarded as the antithesis of noise, but commonly causes hearing loss. Rock music at concerts and through headphones, for instance, but players of classical music are also at risk, especially French horn players, and when did you see them wearing ear protection? A trombone and trumpet can even register around 110 dB.

The world gets ever noisier, affecting mental well-being and wildlife. The background soundscape can swamp bird song and amphibian calls needed for wooing mates and defending territories, and sound from shipping and industry is conducted faster and farther through water, harming marine life. Even national parks can be noisy. I registered 65 dB at a car park in Yellowstone and had to hike far from human activity to find a nadir of 30 dB, equivalent to a soft whisper from signing leaves and boughs in still air.

We may seek quiet places for peace, but, please, not too quiet. Plunging below 30 dB is strange and uncomfortable, though few people experience it. When I sat in an anechoic chamber in a lab the ringing in my ears was unpleasant, like so much static (tinnitus). Exploring a labyrinthine cave was probably as silent as outer space, but I never noticed discomfort one day deep underground because I was lost and focused on finding a way out! Just as our brains can blot out noise, they can filter out silence too.

While noise irritates, silence is fascinating, even when it makes us feel uncomfortable. When John Cage’s enigmatic 4’33” composition was performed in 1952, the audience heard the soloist close the piano keyboard for the 3 movements. That’s all, except it wasn’t strict silence—someone coughed and there was a ripple as another suppressed a giggle. Some people interviewed afterwards said they felt insulted or cheated, whereas others said it made them watch and listen more intently than usual. I never heard this composition live, although I often listen in solitude or helped by watching dogs teach alertness to everything around, even when they seem to be dozing. May a quieter planet continue to reign after the pandemic.

 

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About Giant Eggs & Double Yolks

This week’s gift from a neighbor’s chicken coop included one extra-large egg. After hard-boiling and cracking open we found a double yolk, which some say is a good omen on our wedding anniversary. The following conversation over a meal would be unlikely in most homes, but perfectly natural in ours.

“Have you ever seen a giant human egg?” I asked my wife, Lucinda Veeck. I have only had a few hundred eggs under my microscope, but Lucinda has examined tens of thousands over a long career in her IVF lab.

Chicken egg with double yolkShe said it happened once. It was obviously immature because there were two nuclei in a cell enclosed by a membranous ‘box’ (the ‘zona pellucida’). A normal egg contains one nucleus and it vanishes shortly before ripening at ovulation by ejecting a surplus set of chromosomes in a cytoplasmic bleb. This elimination is so a fertilizing sperm can add a matched set to restore the pair.

Now here’s the thing. Her giant egg was not a microscopic version of the cooked egg. If a hen bird ovulates two yolky eggs simultaneously, which happens occasionally, they are quickly bathed in albumen, then enclosed in a common membrane and a shell during their journey down the oviduct, a process that takes about 24 hours to laying. As the nuclei are in separate yolks, the outcome is a normal genetic makeup with two chicks hatching from the same egg, although the cramped space affects their viability . The closest parallel is when non-identical human twins are conceived after a double ovulation.

But the nuclei in Lucinda’s giant shared the same cell, so their DNA would be inherited together. Had it been mature for fertilization the embryo would likely have three sets of chromosomes (two female and one male), called digynic triploidy, and fail to develop.

We explored explanations for its origin. If you have seen densely packed eggs in biopsies of young human ovaries you might wonder how they manage to grow independently instead of being swayed by neighbors, like people jostled in a football crowd. Sometimes they lose autonomy. I have seen two or more eggs combined inside follicles of every species examined, up to 14 in dog ovaries, although some looked unhealthy from the competition.

When boxed inside their own membrane eggs can’t fuse to make giant eggs. They have unique genetic makeups, just like eggs from separate follicles that go forward to make non-identical twins. But what happens when they coexist in a ‘box’ and don’t fuse to form a single cell?

Lucinda saw an example five days after an IVF procedure. It was a double embryo at the blastocyst stage with about 64 cells each. If separated for implanting in the womb, it seemed likely they could make non-identical twins, but if they had originated from a fertilized egg that had split instead of from two separate eggs they would make identical twins. It’s possible that they could unite (or reunite) to make a singleton pregnancy, and, if originating from two fertilized eggs, the baby would inherit mixed genetic lineages, a known condition called chimerism.

In the interests of being (somewhat) intelligible, I avoided more abstruse explanations and outcomes. With so many ways that development can go awry, it is a marvel that we turn out well, or mostly, and I am thankful for my genesis otherwise you wouldn’t be reading this post. I usually avoid writing technical stuff, but correspondence is welcome from readers who like to crack eggs.

Next Post: The Sound of Noise & Silence

Posted in Animalia, Assisted reproductive technology, Fertility, Nature | Tagged , ,