David Flaspohler is on an exchange with the Universidad Autónoma de Yucatán, pursuing his ornithology research on how bird communities reflect land use changes, specifically with oil palm expansion for bioenergy. He will be writing several guest blogs during his travels. This piece is a tale of a very old disaster.
During college, I spent the summer of 1983 working for Michigan Ice Services in Kalamazoo, Michigan. You can be forgiven for never imagining that ice, like roof shingles and lampshades, must be made and bagged by someone on an industrial scale to fill supermarket coolers. The ice plant was kept at 25 degrees Fahrenheit, which meant that my fellow cooler-dogs and I worked with full winter garb including coats, hats, gloves, boots, etc. Summers in southwest Michigan are frequently hot and humid, making each work break an abrupt transition from winter to summer.
This memory occurs to me as I emerge from the Cancun airport terminal in January, after departing from Houghton Michigan just eight hours earlier, to face the pleasantly familiar body blow of warmth, humidity, sunlight, and fragrance.
I am here in Merida for two months collaborating with Mexican colleagues to dig into how bioenergy development, and the land use change that accompanies it, impacts ecosystems. I have been working with my graduate student Colin Phifer and other scientists to gather data on bird use of oil palm plantations in southern Mexico. Birds can be good indicators of some forms of human development. For example, when native forest is cut and replaced by agriculture, forest birds, especially habitat specialists, often disappear to be replaced by a few generalist species. The Yucatan hosts almost 550 bird species, some found nowhere else on Earth. So as I raced along Highway 180 from Cancun to Merida and Villahermosa with birds in my head and the Yucatan unfolding before me, it occurred to me with a quality of slow crystallization…
"Nearly every living thing around me from the people hustling across the road to the birds singing in the trees would not exist today if not for a disaster that took place just 25 miles to the north."
Much of the human history of this region was largely unknown to me until I began researching this exchange with colleagues from three Mexican universities, El Colegio de Postgraduados and Universidad Juárez Autónoma in Tabasco, and Universidad Autónoma de Yucatán in Merida, where I am based. Over rich, spicy meals shared in Spanish and English, I learned from colleagues Drs. Amarella Eastmond, Ena Mata Zayas, and her husband Dr. Cesar Jesús Vázquez, of the natural and human history of this branch of southeastern Mexico. However, it is natural history that preoccupies me as I rumble across the peninsula, 900 kilometers from my destination.
Vast time, like vast space, becomes increasingly difficult for humans to comprehend. The rise and fall of Mayan culture spanned about 3,500 years, a nearly graspable epoch. Anthropologists now believe that the ancestors of the Maya crossed the Bering Land Bridge around 15,000 years ago, spilling out over two continents and wrecking havoc on the fauna with their new technologies including language and standardized tools. Dozens of large mammals disappeared from North and South America in the few thousand years after the arrival of Homo sapiens.
It is a truism in biology that species come and species go; to quote David Byrne, “same as it ever was”. Yet in hundreds of millions of years of pre-human history extinctions, there are only five extinction events so depleting to living creatures that they are called mass extinctions. The one that is perhaps best understood began here, just off the northern coast of the Yucatan Peninsula with unimaginable violence. Two geologists discovered the Chicxulub crater in the 1970s while searching for oil. What they found instead was evidence of an ancient, buried crater 110 miles in diameter and up to 12 miles deep. Let me repeat that: 12 miles deep! If that fails to impress you, consider that the deepest mine on the planet goes only 2.4 miles down in South Africa and the deepest borehole is in Russia at 7.6 miles.
It must have been intense to be on our planet when the collision occurred, or in the months and years that followed as the Earth’s climate likely changed. That is an obvious understatement as evidenced by the thousands of extinctions that followed, including most dinosaurs, with one very important exception. One reptile’s misfortune is another’s opportunity. The impact at Chicxulub was the opportunity that a fortunate few had been looking for. In addition to a few small mammals, the survivors included a group of small bipedal dinosaurs called theropods, some already sporting feathers that would have provided insulation, increased their sex appeal, or allowed them to glide to avoid predators or capture prey. To make a 65 million year story short, evidence from hundreds of fossils supports the theropod ancestry of modern birds. The great beneficiaries of Chicxulub were birds and mammals—chickadees and you.
"For in the absence of this slate-clearing cataclysm, the reptiles, including the decedents of T. rex would likely still be wandering the seven continents, pterosaurs would be sailing the coastlines of the planet, and great mosasaurs would be terrorizing the sharks of the oceans."
So it is no exaggeration to say that the birds I have come to Mexico to study, and the humans whose industry so often imperils them owe a great debt to Chicxulub. In fact, a modest monument exists in this Mexican port town bearing skeletal likenesses of dinosaurs. Certainly, human evolution took many improbable turns on the path to us. But if humanity as a species reflected on the pivotal events that bent the arc of evolution in our favor, we might feel such a profound debt to Chicxulub that a monument scaled to this debt would dwarf Notre Dame, the Washington Monument, Angkor Wat, and of course the enduring pyramids of Giza and nearby Chichen Itza.
Of course, 65 million years of evolution could have turned out entirely differently from the way it did with our 10,000 species of birds and 7.4 billion humans. We remain today, for now, like the birds, an evolutionary success story: thanks in part to the grinding reason of evolution, punctuated by an act so audacious, it seemingly could have brought the whole experiment of life on Earth to an end. And yet here we are, the lucky birds and mammals, given an improbable chance to compete with the reptiles by a 6-mile wide hunk of space rock. The soulful minimalist singer Gillian Welch has a song titled: “No one knows my name” with the chorus: “It’s a wonder that I’m in this world at all…It’s a wonder that I’m in this world at all.” That about captures it for me.
Acknowledgements: National Science Foundation, OISE-PIRE program and Kathy Halvorsen.
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