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By now, the warnings on meat consumption are pretty clear.

The United States’ over-indulgence in meat is not only bad news for our health, but also for our planet, not to mention the animals themselves. A new study out last week put it even more bluntly: if we ate less meat and more fruits and vegetables, we could save millions of lives thanks largely to the reduction in greenhouse gas emissions associated with livestock production.

Of course, none of this is particularly breaking news. We’ve known about many of these risks for some time. And though our overall level of meat consumption has leveled off in recent years, we’re still eating more meat than almost anywhere else in the world. At the same time, global demand for meat is on the rise. And no one seems to know why.

Science journalist, travel writer and vegetarian Marta Zaraska’s quest to find out is at the heart of her new book, Meathooked: The History and Science of Our 2.5-Million-Year Obsession With Meat. In it, the France-based writer offers a historical and psychological context for mankind’s love affair with all-things-flesh that should prove surprising and occasionally disturbing to even the most informed of carnivores.

So what is it? Why can’t we put the burger down already? The Huffington Post recently interviewed Zaraska to learn more.

What was the biggest surprise, to you personally, that you uncovered while researching this book? You traveled to countries including the Netherlands, India and Benin to get at the heart of this.

There were so many it's really hard to pinpoint just one. I was definitely surprised by how big a role meat played in human evolution -- to the point that scientists say that it has actually "made us human.” But I was also surprised to discover how many myths surround meat-eating, and also protein consumption, and how far back into the past these myths go.

Our belief that we need protein from meat to function -- and yes, that's a myth -- goes back to the 19th century, when a few German scientists did a few not particularly scientific studies (the standards were very different back then) and made people believe that without tons of meat in our diets our bodies would fail. One of these scientists, for example, Carl von Voit, calculated how much protein soldiers, laborers, or prisoners consume each day and from this inferred that the resulting number represented how much their bodies actually need. Imagine that today you'd calculate how many sugary drinks kids have per day, and from that infer that they need tons of sugar to grow well!

Credit: Roberto A Sanchez via Getty Images Eating meat has typically been associated with masculinity, wealth and power. This makes it tougher to resist.

Of all the factors you identify in the book as contributing to our current level of meat consumption -- brain chemistry, industry marketing, government subsidies, cultural traditions to name a few -- which of them do you think is having the most influence? Or is more about the sum of all these factors?

It's definitely the sum, but if I were to pinpoint one, I'd say it's the symbolism of meat. Over the centuries meat came to symbolize wealth, power over nature, power over other nations, masculinity. Without that symbolism it would have been much harder for the meat industry to sell meat to us, to convince us that we need it and to convince governments to continue pumping subsidies into the livestock industry.

It is true that some of us have genetic make up that might make it more difficult to give up meat — one study identified, for example, that serotonin receptor genes 5-HT may be involved in how much some of us like beef, but such influences are very small compared to how much we believe in the symbolism of meat.

As a struggling vegetarian myself, I found myself relating quite a bit to the way you approached this topic. I was very struck by the statistics you reported on how many people who identify as vegetarian still eat meat -- why do you think this strikes us as such a “failure” when we've still cut back considerably compared to more regular carnivores?

It's due to our human psychology. For many people, eating meat creates cognitive dissonance -- an unpleasant feeling that arises when we hold two incompatible beliefs at the same time: "I love animals" and "I love meat." One way to deal with this dissonance is what psychologists call "perceived behavioral change" -- you basically try to convince yourself and others that you no longer eat meat (you've changed your behavior) so there is no longer a conflict between your beliefs and behavior. And you eat meat when no one sees you.

On the other hand, people also like to see such "failures" in others -- once again, also because it helps them deal with their own cognitive dissonance when others are imperfect, too.

It seems this sort of absolutist framing of meat-eating is a big part of why so many of us still eat way too much of it -- how do we move away from that? It seems like ideas like being a reducetarian are promising.

I think that strict labels are not the way to go. It's easier for most people to reduce meat consumption than to jump head first into vegetarianism or veganism. Hearing that you may never ever eat meat again is scary. But saying that you will mostly not eat meat, but may still go for the Thanksgiving turkey and it's OK, makes it all easier. And think about it: What is better for the planet, if 100 people go vegan, or if 100,000 reduce their intakes by 5 percent?

What's more, usually once people learn that vegetarian meals can be delicious, once they learn how to prepare them, they often reduce even more, and then more -- but you have to start somewhere.

Credit: Charlie Riedel/Associated Press While dramatic animal-welfare videos can help encourage people to eat less meat, gradual reductions are probably more effective than going 100-percent vegan.

Are there lessons here for a more effective approach to encouraging people to eat less meat? What can someone do at a personal level?

There are several possible approaches here. For example, one of the most effective ones is watching one of those disturbing videos of factory farming --such as "If slaughterhouses had glass walls" narrated by Paul McCartney -- even if you just want to go veg for health reasons, and not for ethical reasons. Watching something like this can lead to what psychologists call a "conversion experience." And people who go vegetarian for ethical reasons have it easier to stay on the diet because they actually develop a physical disgust to meat, something that usually doesn't happen with health or environmental vegetarians.

But that's not the only way, of course. Reducing gradually is also a good method, and there are many tricks known to psychologists you can use to make it easier. I describe many in my book. For example, watching other people eat foods with pleasure makes us start liking these foods much more, and if it's all done during festivities these effects are even more powerful. So try eating new vegetarian meals not by yourself alone at home, but with others who enjoy such foods, and make it a party!

If readers only take away one thing from reading this book, what do you hope it will be?

That although we must reduce meat consumption for health and environmental reasons, if we don't understand the reasons why we love and crave meat so much in the first place, this task will be an uphill struggle. Knowing why humanity doesn't want to give up meat, what keeps us so hooked, will make it easier to draft strategies to change the current trends -- both on individual and societal levels.

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