Reflections on the “Pollen Tsunami” of 2015

In early May national news media warned of a “pollen tsunami” descending on the northeast. In 2014 a “pollen vortex” threatened to follow the polar vortex that brought us such a hard winter. Headlines can be misleading; we tend to forget that this happens every year. It’s still important news, because millions of people suffer from spring allergies or even asthma. Both pollen stations in southern New York were registering counts of 1500 to 2000 grains per cubic meter of air for a few days early this May. Yes, this is very high but it’s also very normal. In years past we’ve seen over 10,000 per cubic meter in one 24-hour period around this time.


Looking south from Fordham University’s pollen monitoring station in Armonk, NY. Manhattan skyline on horizon, 35 miles away.


A Burkard device collects pollen on a rooftop at the Louis Calder Biological Station of Fordham University in Armonk, NY.

Springtime is mating season for trees in the northeast – one reason that I haven’t posted anything here for two months. Although I teach biology at Fordham University, I also do the airborne pollen counts for southern New York State. Fordham’s pollen-monitoring program comprises two counting stations, one in mid-town Manhattan, the other in Armonk, about 30 miles up in the northern suburbs. Some years ago, I found myself in charge of both operations, so the annual blizzard of airborne tree pollen engulfing the Tri-State area in April-May keeps me more than busy.

Allergies have bothered me since I was 16, but they stopped when I traveled to Africa at 19, only to return the following year when I got back to England. It turns out that pollen allergies are not nearly so common in the tropics, but I’ll come to back to that in a moment.

Pollen travels from male to female flowers, where eggs become fertilized. Seeds form and the next generation gets started. Magnolia, cherry and dogwood have pretty flowers with big petals to make themselves attractive to insects who do the work of getting pollen from flower to flower. But oak, elm, birch have adopted a more ancient evolutionary strategy by which they release vast amounts of pollen directly into the air to be carried in the wind. Grasses and many wildflowers like ragweed do the same thing; that way they don’t have to rely on insects that may not always appear at the proper time.

All seed plants make pollen. They have been doing so since long before there were dinosaurs. Wind carries the microscopic pollen grains, even though most miss their target and are wasted. But late in the age of dinosaurs the first flowering plants evolved by getting insects to carry their pollen directly. This grand evolutionary alliance between animals and plants meant that flowering plants didn’t need to spend so much energy and resources on pollen that mostly landed on the ground. In the early days of flowers, the climate was a lot warmer and more stable (there was a lot more greenhouse gas in the atmosphere too). As in the tropics today, insects were abundant and very dependable.

Oaks don't need insects. Clusters of tiny flowers form tassels called catkins release the pollen directly into the air

Oaks don’t need insects to pollinate. Clusters of tiny flowers form tassels called catkins. They release pollen directly into the air. Here red oak catkins are ready to open in Central Park. May 2015

But by the time humans appeared in the Pleistocene Era, the earth got cooler and the climate less stable. The last 2 million years have seen a steady tidal rhythm of ice sheets going back and forth across the higher latitudes. Today, in the temperate regions, trees that flower in the spring cannot count on insects to be around when they are needed. A late frost can come unexpectedly and upset the insect life cycle, but the flowering schedule of trees is more tightly linked to the number of daylight hours. So, many species like oaks, birches and hickories have decided to give up on insects and go back to doing what pines and junipers have always done: make vast clouds of pollen and let the wind distribute it at the proper time.

In fairness to the folks who write news headlines, we did have a long winter, which can delay the beginning of tree season. This can make the flowering times of different tree species overlap more;  and more trouble for people with multiple allergies. But our pollen records didn’t really show that in the end. By the peak in early May it was turning out to be a quite normal spring pollen season in southern New York, a bad time to be here if you have allergies. Yes, weather matters a lot. Rain can wash pollen out of the air for a few hours, but otherwise the order and timing of tree pollen is very predictable. The bad news is it’s been happening since the last ice age and will go on every year unless we have sub-freezing temperatures without a break all the way through into late May. But that would be a different kind of story.

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Unnatural Selection: The Ape Who Tamed Itself

It’s early morning rush hour in the North Bronx in the coldest February since 1934. I’m on the 6 train out of Pelham Bay as we pick up still more passengers at East 177th Street, Parkchester. Ordinarily, we would now switch to the fast track and run express to 125th Street in Harlem.

The 7:05am Number 6 at Pelham Bay

The 7:05am Number 6 at Pelham Bay

But extreme cold last night has frozen the switches, so this train is stuck on the local track until after we go underground at Hunts Point in the South Bronx.
Already packed, our train will take on dozens more people. Bags and coats are getting caught and at each successive stop it takes longer for the doors to close. There’s grumbling as we all get squeezed tighter together. I hear some shoving and shouting down the car. but eventually peace prevails, doors close and the train trundles forward on the elevated icy tracks. No one here is at fault and we grudgingly accept that it’s just going to get worse until we get to Harlem where folks can transfer to the 4 and 5 trains.

And I’m thinking: we are the only primates who can do this. We’ve grown tame when compared to our closest relatives, the other apes. We have an extraordinary tolerance for crowding and stress. You couldn’t pack other primates into confined spaces without one of them getting killed or maimed along the way.

The Long Road to Civilized Behavior

By 80,000 years ago we Homo sapiens were well on our way to self-domestication, or tameness. I’ve remarked in an earlier post that warfare is a recently established institution, less than 10,000 years old. But the in-your-face, bar-room type of explosive violence is different. Though we still get in fights and inflict bodily harm on each other, such behavior has declined over the long time-span since our lineage split from the other great apes. Among our closest living relatives, Chimpanzees get into fights a hundred times more often than we do. Male chimps are responsible for almost all of the violence, which is often fatal.

Bonobos, our other closest relatives are another story entirely but I’ll return to them in another post.

Darwin’s “Domestication Syndrome”

Charles Darwin described the biology of domesticating animals in 1871. He discovered that when animals are bred to get along with people, anatomical changes also occur. Dogs get floppy ears and curly tails. But notice that wolves and coyotes, their undomesticated relatives, don’t have these traits. The anatomical changes over human evolutionary history tell the story of our own domestication. Over time our once prominent brow crests have diminished; we have smaller teeth and shorter faces. Particularly among males, those trends can be traced back through the fossil record for at least a half million years.

From right: our ancestor, Homo heidelbergensis, with large brow crests modern Homo sapiens (Cromagnon), juvenile chimp, adult male chimp. (Note juvenile chimp looks more human than adult. We look like the docile young ape because our development takes longer)

From right: our ancestor, Homo heidelbergensis, with large brow crests, modern Homo sapiens (Cromagnon), juvenile chimp, adult male chimp. (Note juvenile chimp looks more human than adult. We look like the docile young ape because our development takes longer)

Docility of temperament in people and animals is linked to a more drawn out development and childhood, lower levels of stress hormones and testosterone. Between women and men, there is much less anatomical difference (sexual dimorphism) than between male and female chimps or gorillas. But it is men who have come to look more like women than the other way around.

Taming Ourselves

We domesticated animals by deliberate selective breeding for tame behavior and tolerance for being around people. But if we also domesticated ourselves, how could that have happened? There are clues to this among the social practices of hunter/gather people who have continued to exist into the industrial era, and whose ways anthropologists have observed and recorded. Out of the reach of modern legal systems, these tight cooperative social networks cannot tolerate an aggressive, violent male among them. A strong ethic of cooperation and egalitarianism prevails among hunter/gather people, who will collectively shun and socially sanction anyone who attempts to dominate other members of the group. If all non-violent sanctions fail, the group will by agreement kill the offending individual (note this is not the same as capital punishment, a relatively modern institution).

The hundreds of thousands of years of prehistory during which aggressive males were weeded out of the human population have made males more cooperative. Along the way we men have developed a more feminine facial structure partly due to lowered testosterone and stress hormones. (not that masculinity is disappearing exactly… it’s just been getting a facelift on the way to civilization)

Civilization: Homo sapiens boarding the 6 train at Pelham Bay Park

Civilization: Homo sapiens boarding the 6 train at Pelham Bay Park

Our 6 train finally pulls into 125th Street Station below the streets of Manhattan. The doors slide open disgorging a flood of people who hurry across the platform toward a much less crowded 4 train now arriving from the west Bronx. I stay on board the 6 as both trains proceed south toward lower Manhattan. I’m happy to have a seat now, and that more than half a million years of prehistory has made us such a cooperative species.

The Meek Inherit the Earth

As Rome was extending its imperial reach, a prophet living on its eastern periphery declared that the meek shall inherit the earth.
But by that time, they already had.

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The Time Before Warfare Began

Coventry, England 1940. Photo: Wikimedia Commons.

I remember my mother’s story of the bombs exploding over the City of Coventry while she hid below the ground. She can’t remember exactly how long they were confined in the basement of her school–probably 4 days–long enough to run out of drinking water. Her father was in the trenches of the First World War; he was shot and gassed, but sent back to the front each time. I was born during the “post-war” Baby Boom, but would not see my father for another 6 months. As an American citizen, he had been drafted into the war in Korea. If the 20th Century has been the most violent to date, the 21st has seen no peacetime so far.

It can seem as though organized killing has been with us forever, and certainly for longer than there is written history, and I admit that I have wondered if the institution is essential to human nature.

The View from “Deep Time”

Nevertheless, we have been around for a lot longer than written history; 200,000 years in our anatomically modern form; 2.5 million as the genus Homo. And there is no trace of warfare before 10,000 years ago, at a time roughly corresponding to the advent of agriculture. Harvard psychology professor Steven Pinker recently made an elaborate argument that violence has decreased over time. But the evidence from deep time shows rather the opposite: for most of our existence warfare was unknown; the institution only became widespread in the last few thousand years. A related observation is that during our long nomadic hunter-gatherer existence there was no accumulated wealth, consequently no source of inequality.

What Cave Art and Carvings Tell Us

There is little evidence of violence in Paleolithic time, but not because we know too little of our prehistory. In fact a vast body of information on life in the Paleolithic exists in the form of thousands of paintings and carvings that go back more than 30,000 years. Paleontologist and artist Dale Guthrie looks at this body of cultural expression as a scientist, and has discovered that a trove of detailed pre-history is recorded in Paleolithic art. In addition to some renderings we recognize as “cave art,” early people also left us a huge record of detailed observations about their regional environments, ecology and of animal behavior.

Giant Deer (Megaloceros), Lascaux Cave, Dordogne, France. Painted about 17,300 years ago. The line of dots is interpreted as a blood trail from a spear wound. Photo: Wikimedia Commons.

But most importantly, for this question of warfare, Paleolithic art makes an eloquent argument against the long held assumption that war and murder are part of early human life and cultural practices.

Weapons, But Not of War

It was in the Paleolithic that we became the people that we are. Although spears and other hunting weapons feature prominently in cave paintings and other artworks, notably absent are shields, maces, daggers, the type of weapons used exclusively by people engaged in combat. There are no fortified settlements in this long time before the end of the last Ice Age. Among hundreds of Paleolithic skeletons known worldwide, only a few show any sign of violent death.

Warrior with attendants. Note shields and weapons of combat. Edo Court of Benin, Nigeria. Plaque in Metropolitan Museum of Art, NY. Photo: Wikimedia Commons.

Agriculture, Inequality and Institutional Violence

But as we approach the present from 10,000 years ago, signs of organized killing begin to accumulate: depression fractures on skulls, defensive wounds or “parry fractures” on forearms, spear points embedded in bone, mass burials and dismembered skeletons. It is sporadic at first, but intensifies. Fortified settlements were becoming common in Europe by 6500 years ago.

It’s probably not an accident that signs of inequality and stratified societies also accumulate over this same period, elaborate burials and artifacts that display the wealth, prestige and dominant status of an elite. Accumulated and stored wealth present an opportunity for plunder. As archaeologist Brian Ferguson put it, people could no longer walk away from trouble, and so warfare was born.

Finding Humanity in the Stone Age

Neither war nor inequality is an essential feature of modern human culture. We became who we are long before institutional warfare became part of our culture. Perhaps we should to go back to the Stone Age, where we might find people striking similarity to us who can teach us much about our own early humanity.


Ferguson, Brian 2003. The Birth of War, Natural History July/August 2003

Guthrie, Dale 2005. The Nature of Paleolithic Art. Chicago University Press.

Pinker, Steven 2011. The Better Angels of Our Nature. New York. Viking.

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Paleolithic Origins of Science: A Solution to Wallace’s Paradox

We all do science; as ­­we navigate the world around us from day to day we are often unconsciously using the scientific method. Most of the time we don’t see it that way, but doing science could be a key trait of the human mind. It may be that the scientific approach is what has made Homo sapiens who she is.

In school I was taught the textbook version—the scientific method arose in Western Europe with the Age of Enlightenment.  Science’s story begins on foundation of reason and logic first laid down by ancient Greeks, then abandoned for centuries until the early-moderns struck upon the experimental method to make science what we know and practice today.

But that simple story leaves out too much.

Linnean Society of London

Alfred Russel Wallace discovered, with Charles Darwin, the process of natural selection as the engine of evolution. But Wallace also described a paradox in our understanding of our own prehistory that is still with us today. He wondered how modern pre-literate people, and our own recent ancestors, had the brain size and mental capacity of scientists and philosophers of his own day. We tend to think of Paleolithic life as brutal and uncivilized. Such a world would have no place for art, scientific reasoning, or the capacity to imagine how things might play out well into the future; life was limited to satisfying basic needs and dealing with immediate threats.

Both Paul Ehrlich and Al Gore have recently invoked this view of our prehistory to assert that people are biologically ill-suited to make long term plans; that our evolutionary history has not prepared us to foresee that our actions may reshape the world deep into the future. As such, global warming presents us with a unique and unprecedented type of problem.

What actually happened is neither as simple nor as recent. Our capacity for scientific reasoning is probably hundreds of thousands of years old at the least. Over this vast stretch of time, we evolved the mental capacities out of which come cultural practices we depend on today when we do science.

Trackers as the First Scientists?

In The Origins of Science Louis Liebenberg (2013) explains how modern people who track animals are deploying a complex set of practices. To most of us city dwellers it seems mysterious and we tend to think of expert trackers as visionaries who can “read the tracks” on the landscape. But tracking is a focused empirical process. Signs of a deer or an antelope will lead an experienced tracker to construct a detailed scenario about how and when the animal passed over the terrain. Many animals track or stalk other animals and can follow them across all kinds of terrain, usually much better than we can. But when, for instance a dog follows the trail of another animal, it uses an acute sense of smell or other capacities that we humans are notoriously deficient in. Among people, the ability to imagine is used to map out the trail of an animal long after its scent has evaporated, and its physical tracks have disappeared.

Imagined Landscapes, Testing Narratives, and Science

A tracker can imagine events that may have happened but can no longer be seen. Animal signs will often be incomplete and intermittent; and tracking becomes a process of discovery. It is empirical, in that the imagined course of the animal and its physical condition will now be subject to a barrage of real world tests that can quickly destroy one hypothesis so that a new one must be proposed. The human imagination is a sophisticated piece of mental equipment with which we can critically review the past and make forecasts about the future. The entire process is akin to the formulation of a hypothesis in the textbook version of scientific procedure.

Liebenberg is a scientist who spent years learning directly from hunting/gathering people of the Kalahari and decided that their ways were a clue to the prehistoric origins of science. At the same time he saw their way of life being lost as the modern world crowds them out and fences prevent the movement of migratory animals as never before. To counter the loss, Liebenberg helped develop a database whereby Kalahari trackers now upload their observations and activities using a hand-held digital device and software designed for non-literate users. The ancient and current knowledge and expertise is being built into a “modern” science with immediate applications in biological conservation, and is being used to intercept poachers evading more conventional and costly means of law enforcement. Just when the ways of our ancestors are lost, technology can amplify prehistoric skills of following the trails of animals, something evolved over hundreds of millennia of hunting, and paradoxically, may help preserve those very animals.

Paleolithic Clues to a more Human World

At the same time, we can learn much of what makes us unique as humans, and how these rather special mental capacities have evolved over the millions years that we foraged and hunted for a living. There is much to suggest that not only science, but art, language and storytelling are all intimately tied up with our Paleolithic lifestyle.

Pleistocene hunters developed deep understanding of the ways of animals. Paleolithic art is a record of people learning the craft of tracking. Photo: Wikimedia Commons.

The evolution of imagination had interesting side effects; Paleolithic art and musical instruments are tangible evidence of this.

Life in the Paleolithic is not just a window to our past, but it offers glimpses of a humanity obscured in this troubled world. Our long prehistory is not a tale of easy times, yet it holds distinct clues to help us envision a different future from our present, one based on science and stewardship instead of ignorance and exploitation. Alfred Russel Wallace thought that our intellect must have been given us by a higher intelligence, but as Liebenberg explains, it simply evolved because we could not have survived without it. Now the question is, can we apply our scientific imagination to continue to survive.

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