We humans love food to death — literally.

From mammoths to passenger pigeons, we have driven our favorite meals to extinction through overhunting and habitat destruction. And globally, our tendency to overharvest just a narrow range of crops has limited the variety of foods we eat.

"When it comes to fruits and vegetables, we have access to only a fraction of the diversity that existed a century ago," says Lenore Newman in her forthcoming book, Lost Feast: Culinary Extinction and the Future of Food (out Oct. 8). She is the Canada research chair in food security and environment at the University of the Fraser Valley, in British Columbia.

In her book, Newman explores how human activity has limited our food options and still threatens what we are able to put on our plates.

"I think the important lesson that I took away from writing this book was realizing that things can — and do — go extinct even if we really love them," Newman told NPR. Silphium, a plant that was critical to Roman and Egyptian culinary society, is one of many examples of foods we loved that are now considered extinct. The stalk of the silphium plant was used to flavor food, and its leaves were fed to sheep and cattle to improve the flavor of their meat. Newman says the extinction of silphium taught us that loving a food is not enough to keep it in existence: "We actually have to fight to be conscientious, especially as we have a bigger impact on the planet," she says. "We need to be a little more thoughtful about how we eat."

NPR spoke to Newman about the foods we've already lost, the future of meat production and the changes we need to make to preserve our current culinary variety.

This interview has been edited for brevity and clarity.

NPR: In the book, you write that we have lost 90 to 95% of vegetable cultivars and 80 to 90% of fruit cultivars. How did this happen?

It sounds a lot worse than it is because we're always making new ones. Before we moved food around the world the way we do now, every region would grow as many varieties as it could to extend the season of common foods. For example, you'd grow early apples and you'd have a big bunch of apples; then you'd have some late apples right into the very end of the year. When we started shipping foods from regions in other climates, we stopped growing some of the varieties that might have been great but didn't produce quite as much or didn't ship as well. So we went from a seasonal approach to global trade. And in some ways, there's nothing wrong with that, other than it meant we focused on durability rather than flavor. We're seeing a bit of a return to try to bring some of those varieties back, because they do have neat flavor and culinary profiles. But a lot of them are gone for good, and there's no way to bring them back. So that's a big loss.

You write that we eat only a tiny fraction of the 300,000 plants available. Is it possible to expand our current culinary variety?

It totally is. There are people around the world, known as fruit hunters and plant hunters, that go out looking for interesting wild varieties or varieties that haven't really been cultivated. But taking a plant from wild variety to the store is a very difficult process. It takes a long time [and] there's a lot left to discover. The Amazon rainforest is a great example. Each square meter of that rain rainforest has more species than some northern forests do. We don't know what those species are. We've never documented them. So, in theory, we should be bringing new foods into the system. But if we destroy all of our wild biodiversity, we are going to be stuck with what we have.

One of my favorite parts of the book was the "extinction dinners" you prepared with your friends to re-create meals of the past. What was your favorite meal, and what was the idea behind it?

When I started writing the book, I faced a certain amount of depression about the topic of extinction. And all my friends were like, "How are you going to make that a little more bearable for you and the reader?" And we came up with the idea of these dinners. I think my favorite was comparing the different [plant-based] hamburgers. [Eating less meat is one way to reduce our environmental footprint. Veggie burgers and the Beyond Burger — a plant-based burger that mimics the look and flavor of beef — are some of the current alternatives to meat.] We cooked the Beyond Burger, and one of my favorite moments was my vegan friends saying that the Beyond Burger was too real.

The [dinner] we had in Hawaii [which consisted of invasive species that arrived to the island, including wild boar, guava, papaya, pineapple and macadamia nuts] was also fun, because the whole team put it together and it was a great way to kind of ground us and to discuss extinction and these heavy topics of species loss. It was a great way to remember that food is about community and it's about coming together and sharing.

You write about passenger pigeons and how they used to be a common dish at restaurants. They were sold in food markets in the 1770s, but by the mid-1890s the birds were extinct in the wild. How did people adapt to their disappearance?

The passenger pigeon is the one that kind of keeps me up at night, because it was one of the most common birds and it played this oversized role in the food system. In Colonial times it was turned into pie. It was baked. It was roasted. It was made into stew. Basically, anything you do to a chicken is what we did to them. [Because of their] sheer volume, they were incredibly cheap. You could go to the big markets in the big city and pick them up for just pennies. You could literally throw a net over a hundred birds and have dinner. For that wealth to be lost in such a short time shows the power of the industrial food system to liquidate a wild food. And the chicken moved in to fill that gap. Before the end of the passenger pigeon, chickens really were kept in small numbers, and farmers would sell their eggs and they would eat the odd bird. On the Eastern seaboard of the U.S., farmers started producing chicken en masse because North Americans wanted a bird in their food system, and a lot of these wild birds were gone. And so, the chicken kind of moved in as everyone's favorite bird. It is by far the most numerous animal that we grow for food, because it's a bit like the passenger pigeon. It's incredibly versatile.

What lessons can we learn from the extinction of the passenger pigeon that we can apply to other flocking species, such as fish?

I think that [the extinction of the passenger pigeon] says a lot about the future of fish because they're the only thing that's kind of equivalent. I look at our fish docks, and I think that if we're going to see a repeat of that kind of extinction, it might be in something like tuna or cod. I really hope we don't, but the scale of the passenger pigeon extinction is the one in the book that really haunted me. And it's right on the cover because it's hard to get out of your head, once you read about it. We probably can't harvest wild fish in any kind of large-scale way and expect them not to go extinct. We've already driven a number of lake and river fish to extinction, and I think we have to move to on-land fish farming. It's one of the areas that cellular agriculture might have a big potential, where we grow fish in the lab instead.

In the book, you talk about how some scientists are studying how to resurrect species we have lost, including passenger pigeons and mammoths. Do you think that's something we should seriously consider, or should we focus on preserving what we currently have?

I don't think it should be our top priority, because it's one thing to say, "Let's bring back bananas," for example, and another to have an intact ecosystem for a sustainable group of mammals to live in. I don't think there's [any] harm in it, but people have to realize that it's not a solution. We can't let everything go extinct and then think we'll pop it back, because nature doesn't work that way. So as excited as I am at the thought that we might have Tasmanian tigers wandering around again, it's a bit romantic. It's a bit technologically optimistic, and it's not a solution to the bigger problem ... that we're losing massive numbers of species.

What changes need to be made in our current food system to sustain a growing population?

The absolute best thing people can do is to eat more plant-based foods. You don't have to go vegan, but shifting to a more plant-based diet is healthier. Most of the cropland we are cultivating is for growing animal feed to create the huge amounts of meat and dairy that we need. So going plant based is almost inevitable as the population grows. We need to figure out how to grow things without fossil fuels in the long run. And that involves going back to basics, like older varieties and local production. I think [plant-based burgers] are probably the future of meat. And the main reason for that is the plant-based burger can just keep getting better and better. I only recently got to try the Impossible Burger [a plant-based burger that looks and tastes like real meat], because they don't have it up here in Canada yet. And I found it so real; I couldn't quite tell it apart. The cow, when you dig into numbers, it's just a problem. It's much larger than any other animal that we grow for food. Currently, the world's cows graze an area larger than the continental U.S. And if we look at a world where more and more people are eating more and more meat, it's just not sustainable to scale it up. So I think we're going to see shifts in the meat sector. Growing corn and grain to feed cows — I think we're going to see that phased out. And people will be eating other alternatives, whether they're plant based or [meat] grown in the lab, if that technology moves forward.

Luisa Torres was this summer's AAAS Mass Media fellow on NPR's science desk. She's on Twitter: @luisatorresduq.

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