Rio Constantino

In the early 1980’s, paleontologist Stephen Jay Gould released a book called “Wonderful Life”, about the Burgess Shale nestled high in the Canadian Rockies. The Burgess is a priceless deposit of thousands of tiny fossil animals, all dating back more than five hundred million years to just after the Cambrian Explosion, the origin of multicellular life. These strange organisms, identified, misidentified, and reinterpreted by dozens of scientists since their discovery in the 1910’s, are invaluable for what they say about the nature of evolution itself.

Yet the surreal and extinct fauna of the Burgess Shale also pose a problem. “How,” Gould asks, “should scientists operate when they must try to explain the results of history, those inordinately complex events that can occur but once in detailed glory?”

“Historical explanations differ from conventional scientific explanations in many ways… We do not attempt to interpret the complex events of narrative by reducing them to simple consequences of natural law; historical events do not, of course, violate any general principles of matter and motion, but their occurrence lies in a realm of contingent detail. (The law of gravity tells us how an apple falls, but not why that apple fell at that moment, and why Newton happened to be sitting there, ripe for inspiration).”

In high school, the scientific method is usually taught as an experimental setup: predict and repeat under controlled conditions. You make a hypothesis: monggo beans will only grow in sunlight. You get some seeds, divide them into two groups, and plant them in two different places: one in the sunlit garden, the other in a dusty cabinet. Give them the same soil and water for a month, and voila! The garden seeds have grown healthily, while the poor beans in the cabinet have gone the way of the dinosaurs.

However, a paleontologist cannot just rewind the clock, add extra appendages to a trilobite, unpause, predict an outcome, and observe what happens as evolution’s tape proceeds yet again. Neither can a climatologist, investigating some distant ice age, enter a frozen epoch themselves, or a cosmologist, researching the origin of the universe, hop back in time to just after the Big Bang.

The monggo bean experiment teaches us to verify hypotheses by their ability to reliably predict outcomes in strictly controlled laboratory environments. However, nature is not always so cooperative. There’s no way of controlling the past, and it is absurd to make predictions about events which have already happened. The procedures taught by high school laboratories falter when dealing with the unrepeatable, uncontrollable products of history. What other approaches are available instead?
Like all other elements, oxygen atoms exist in the form of several isotopes different in weight and neutron number. Snow, as frozen H2O, contains oxygen. During colder eras, for reasons related to water’s poleward cycles of evaporation and condensation, the snow laid down in the Antarctic has more of the lighter oxygen isotope, 16O, than the heavier 18O. As successive seasons of snow are laid down and pushed ever deeper into the ice, past temperatures are recorded in the ratio of lighter and heavier oxygen isotopes contained by the layers of ice in a glacier. By comparing these ratios to those found in modern oceans, scientists can infer the Earth’s ancient temperature record.
In the end, what defines science is not any particular method, or experimental setup, but testability. And when it comes to history, any hypothesis is tested by its ability to coordinate independent observations into a cohesive whole. Reflecting about how evolution, as a theory, was first established, Gould writes:

“We know that evolution must underlie the order of life because no other explanation can coordinate the disparate data of embryology, biogeography, the fossil record, vestigial organs, taxonomic relationships, and so on.”

A single ice core, by itself, does not tell the whole story. In an interesting confluence of marine biology and climate, the shells of long dead marine microorganisms, foraminiferans, tell a story about past climes. Foraminiferan shells are built of calcium carbonate, CaCO3. Calcium carbonate contains oxygen. Over eons, vast amounts of dying foraminiferans fall and build up layers of sediment at the ocean floor. Like ice cores, foraminiferan shells take up different oxygen isotope ratios depending on the surrounding temperature.

What other primary sources are there? Trees accumulate new layers of wood as they grow. Every year, as a tree grows wider and wider, the layers of wood it adds are distinct. They differ based on the climatic conditions during the year a layer was added, and together describe the different temperatures, rainfall, and sunlight a tree experienced as it grew.

All these far-flung data points, when combined with modern measurements of surface temperatures over the last hundred or so years, show a pattern: while the Earth’s temperatures may have fluctuated over eons, going from hot to cold over timespans lasting hundreds of thousands of years, never have temperatures spiked so rapidly, so alarmingly fast, than in the decades after the industrial revolution.

The Antarctic ice also preserves more than just oxygen isotope ratios. As snow falls, it also traps greenhouse gases, like CO2. Research into these trapped gas bubbles, when put alongside historical temperature records, tells another familiar story: hotter temperatures strongly correlate with increases in greenhouse gas concentrations.

In his telling of the Burgess Shale, Gould takes pains to emphasize one point: that evolutionary history, complex as it is, cannot be reduced to a single, deterministic law of survival of the fittest. There are so many strange and different Burgess animals, from stout Opabinia to the aptly named Hallucigenia, smooth-skinned Amiswia to fierce Anomalocaris. Yet of these, so few survived to yield the familiar lineages, insects and more, we know in the present. Most of the anatomical forms preserved in the Burgess Shale never appeared again.

Were Hallucigania and the rest simply unfit? Gould, and the other scientists whose work built the basis of his book, didn’t think so. There’s no evidence to say any of the Burgess organisms were more fit than the others. Instead, Gould spies a possible explanation in contingency, in the many connected coincidences, twists and turns of blind chance and dumb luck, that make up history.

After all, before their extinction, dinosaurs were the dominant animals on Earth. Mammals were just tiny furballs scraping by in the background. Who could have predicted a giant space rock would wipe out almost all forms of large terrestrial life, and pave the way for tiny mammals to claim the foreground? From there, after so many other twists and turns, arose what may be the most game-changing contingent detail of all: consciousness.

Science and history are inextricable. Atmospheric CO2 only began building up in earnest in the late 1800’s, when British coal engines spawned the fossil fuel industry. Fossil fuels don’t burn themselves, it’s capitalists who do, and it’s up to the rest of us to make sure fossils stay right where they belong: underground.

The century-long accumulation of CO2 also begs another question. Ice cores have been around since the middle of the 20th century; tree rings, the middle of the 19th century. In 1896, Svante Arrhenius, of acids and bases fame, quantified the relationship between increasing CO2 concentrations and rising global temperature. The warning signs were there. The fossil fuel industry continued scaling up its emissions anyway. Who controls research publication and funding, science education and popularization? Who gets to speak science, and define what science is? Who, ultimately, is science for?

We need an understanding of science as history, as a discipline which deals with not just mute matter but, increasingly, the consequences of human action and choice. The sooner we do, the better equipped we will be to deal with our current crisis.