By Mary Ellen Hannibal

The café is actually called Bytes, and it’s Paul Ehrlich’s lunchtime hangout. As it abuts Stanford’s Electrical Engineering Department, most of the crowd exudes practical optimism. Not so much Dr.
Ehrlich, Bing Professor of Population Studies and president of the Center for Conservation Biology at Stanford. A persistent mystery concerns his good cheer, pretty much unfailing even as he describes the soon to be scorched earth. A favorite topic: the imminent collapse of industrial civilization.

“We aren’t going to be able to build it all back up again either,” he told me one day.

“Don’t candy coat it Paul.”

“’My plan is to avoid the whole thing by dying,” he said (he is 86). “We’ve already depleted all the precious metals and so forth that are easy to get, close to the surface,” he went on. “So if we want to
remake computers, we aren’t going to be able to get to the necessary materials without electricity for hydraulic drills. Of course all of that will be down.”

Ehrlich has specialized in dire since he first attained popular notoriety in the 1970s, publishing The Population Bomb with his wife Anne Ehrlich. The book propelled him into a limelight that rarely shines on scientists. Back in the day, he appeared on the Johnny Carson Show scores of times. Handsome, hyper-articulate, with a fast hearty laugh, the young Ehrlich was a cross between Carl Sagan and James Bond.

I met Ehrlich about four years ago while researching my book Citizen Scientist: Searching for Heroes and Hope in an Age of Extinction. One of the book’s threads is an investigation into some of the reasons why plants and animals are disappearing at a rate and magnitude equaling that which took out the dinosaurs. One of Ehrlich’s most lasting contributions to science concerns co-evolution. The concept describes how species evolve in relationship with other species – and these relationships are being torn asunder by climate change and habitat loss, leading to accelerated extinctions.

Co-evolution was intuited by Darwin but not proved by him. With botanist Peter Raven, today president emeritus of the Missouri Botanical Garden and an author of the Pope’s encyclical on climate change, Ehrlich comprehensively documented the step-wise process by which species develop traits in tandem.

Working with plants and butterflies, Raven and Ehrlich showed that as plants develop defense mechanisms against predation by butterfly larvae, the butterflies develop ways to survive them.

Raven and Ehrlich were able to quantify the process of co-evolution because for hundreds of years, avid butterfly collectors have documented the relationship between species and their host plants. “People raised butterflies because they wanted perfect specimens. When they figured out the host plant, they sent in a little notice or paper to a journal, and now we have this unparalleled database,” Ehrlich told me.

Similarly large databases have essentially been accumulated by amateur naturalists – citizen scientists – who have also documented birds, weather, and phenology, or the timing of natural events including spring bloom times, also for hundreds of years. Ecological relationships are discernable in the resulting patterns, and so is change over time. Today’s citizen science is turbo-charged by computing power, satellite technology, statistical analysis, and smartphones. Millions of observations made every year by citizen scientists contributing to eBird and iNaturalist (check it out – they’re free!). Right now they are helping to explode our understanding of how nature works, and what we need to do to protect it.

“One of the things were doing with climate change is tearing apart long-evolved co-evolutionary relationships and doing it at a rate which is higher than we have seen over most of history, but not
entirely,” Ehrlich told me. “Things have happened fast before. One of the problems though is that we’re having this extremely rapid evolutionary change for the first time since we’ve had an over- populated, resource-short civilization trying to do it.”

Ehrlich has been among a handful of scientists pointing out that absolute extinction rates are bad enough, but we are confronting an even worse loss of overall biodiversity – we are losing vast numbers of bodies of plants and animals, even those that are not yet in danger of completely blinking out. In just the past 40 years, wild species populations have shrunk in alarming numbers: 39% of marine wildlife and 76% of freshwater wildlife are gone. In 1970, a billion more birds flew over the Earth than do so today.

“We’re going to have to get into triage,” Ehrlich told me.

“Like bringing back the wooly mammoth and the passenger pigeon?” I asked. Stuart Brand, who spearheads an effort called “de-extinction,” was once a student of Ehrlich’s.

“Smart guy,” Ehrlich said. “Completely nuts.”

“They’re pretty far along with some aspects of it,” I said.

“No they’re not. They’re not even started.”

The professor of population biology patiently explained. “If you’re going to reestablish the passenger pigeon, first of all, you’d have to recreate about a million of them because they are predator saturators. They went extinct when there were still many thousands of them left. The way they survived was by having gigantic breeding colonies in random places so that predators could never catch up with them. Additionally, their biggest food sources were acorns from the great forests of northern and eastern North America – most of those are gone now, fragmented, and they don’t produce enough food for passenger pigeons anymore.”

“What are we going to do?”

“You know I never like to give my opinion on anything.”

“That’s why you’re a terrible interview.”

“We have to assign an intrinsic value to nature, show why it’s important to human beings. We can’t avoid the problem of biodiversity loss and just hope we can find some sort of palliative. If people tell themselves we don’t have to worry about extinction because we can bring animals back, that’s moral hazard. The solution to our problems is to rescale society. We have to lower our population and our rate of consumption, particularly among the rich.”

“But our instincts tell us to get more and more, to build our coffers and increase our genetic success.”

“Do you have more than 30 children?”

“Two.”

“The instinct we know is engraved in our DNA tells us to out-reproduce our buddies. So you are fighting your instincts and doing a good job of it, because your physical capacity would be about 30 births. You and millions of other women have suppressed your instincts using pills, condoms, and so on. In ancient
Egypt women used crocodile dung suppositories as contraceptives.”

“How effective was that?”

“I’ve tried to get some graduate students to study this, but they refused.”

“So if it isn’t instinctive, then we aren’t we stopping ourselves from destroying our own world?”

“If I throw a rock at your head, you do a whole series of differential equations in one millionth of a second and duck. You see the rock coming at you against a constant background. Our constant background is changing gradually and we don’t see it. Gradual accumulation of greenhouse gases, nuclear weapons, toxins, population. We aren’t designed to see and respond to the ethereal.”

But today, we have a way to visualize and so confront the ethereal – or at least patterns in nature that are hard to discern in the short time frame. Raven and Ehrlich discerned co-evolution from historical citizen science records of butterflies – other scientists have used the same data to show how butterflies are changing their distributions in response to temperature and precipitation change brought on by greenhouse gas warming. When we see where the butterflies are moving, we can target our conservation efforts to help them adapt. Citizen science is a tool for grappling with change – hopefully, before it hits us in the head.

Mary Ellen Hannibal is a long-time journalist living in San Francisco who has focused on natural history and literature. Her most recent book, Citizen Scientist: Searching for Heroes and Hope in an Age of Extinction, was one of the San Francisco Chronicle’s 2016’s best non-fiction books. She is a recipient of the National Association of Science Writer’s Science and Society Award.