When you unwrap it, break off a piece and stick it in your mouth, it doesn't remind you of the pyramids, a suspension bridge or a skyscraper; but chocolate, says materials scientist Mark Miodownik, "is one of our greatest engineering creations."
True, it begins with a cocoa bean plucked from a tree. But no one would eat a raw cocoa bean. "It tastes revolting," Miodownik says in his new book, Stuff Matters.
But cut it, leave it, roast it, tinker with it for a couple of centuries (and add sugar) ...
... and cocoa beans can be totally transformed. Chocolate now melts in our mouths, floods our senses with flavor, and might — just might — Miodownik suggests, get us to have fewer babies (and thereby save the planet). Let's start with the bean.
Chocolate bars have a circus trick, an "Oh, my" moment: They're solid when you unwrap them. They make a satisfying snap when you break off a piece. But then, when you put that piece into your mouth, when it's resting on your tongue, it turns liquid. A chocolate bar, Miodownik says, jumps states so quickly, it is, in effect, a paradox: "a solid drink ... made possible by engineering."
The secret ingredient is cocoa butter, stored in the form of large molecules called triglycerides that come with three (thus the "tri") prongs. Inside the chocolate, these fat molecules are jammed together but sensitive to temperature. They can sit very loosely, like this ...
... or more tightly, like this ...
... or ( I'm redrawing this from Mark's book) more richly intermeshed, like this:
The denser the package, the harder the chocolate. So when you break off a piece, it's more interlocked, like the third drawing. If you've left it out on a table in the sun, and it's gotten gooey and melty, it's more like the top drawings.
If the candy company has been careful, your candy bar should not have experienced temperatures higher than 18 degrees Celsius (64 degrees Fahrenheit).
"Now, in your mouth," Mark writes, "they experience higher temperatures for the first time. This is the moment they have been created for. It is their first and last performance. As they warm up and reach the threshold of [your body temperature, 98.6 degrees F], they start to melt. This frees them to move around as a liquid."
Once it starts to flow, says Miodownik, chocolate is soothing and comforting, but it is also exciting and — not to put too fine a point on it — seems to satisfy more than a physical hunger.
Is Chocolate Better Than Kissing?
People (it's no secret) really like chocolate. The signs are everywhere. Chocolate billionaires proliferate on the Forbes list of the richest people in the world (Michele Ferrero of Italy, who makes Nutella, is worth $27 billion; Forrest Mars, Jacqueline Mars and John Mars, who make Milky Ways, Snickers and M&Ms, are collectively worth about $60 billion).
Then there's the science. In 2007, David Lewis, a psychologist now at Mindlab International in Britain, recruited a small number of couples, all in their 20s, attached electrodes to their scalps, monitored their hearts and asked them to suck on pieces of dark chocolate. Which they did.
Next he asked them to kiss. Which they did.
Then he compared the effect on their bodies — kissing versus tasting chocolate. It wasn't a big study (six couples) and it hasn't been repeated as far as I know, and it may have been sponsored by food companies. But his findings, according to a BBC report, were very pronounced:
Both kissing and chocolate raised heart rates. But chocolate's effect was longer lasting and more powerful. The buzz from chocolate, Lewis told the BBC, "in many cases lasted four times as long as the most passionate kiss." Even with its caffeine, sugar and stimulants, "chocolate's power really surprised us," Lewis said.
"The study also found that as the chocolate started melting, all regions of the brain received a boost far more intense and longer lasting than the excitement seen with the kissing," according to the BBC.
Is Chocolate Better Than Sex?
These findings, Mark Miodownik writes, "point to a genuine truth about chocolate: For many, it is better than sex."
He then looks up the countries with the highest consumption of chocolate. Sixteen of the top 20, he notices, are located in Northern Europe. Switzerland is the leader; then there's Ireland, the U.K., Austria, Belgium, Germany.
Just for fun, I looked up the fertility rates in these countries and found that, with two exceptions (Ireland and France), women in chocolate-loving countries happen to have fewer than two babies — that's below the replacement rate. If that continues, these countries will get decidedly smaller.
Is chocolate sometimes a substitute for baby-making? Possibly. Or maybe it's just the cold. Notice, there's no tropical country on the Love-Chocolate List. Chocolate doesn't taste as good when it's warm. Either the candy bars melt on the shelves or get put in the fridge (where they are gobbled before they are ready to melt, spoiling the solid-to-liquid experience.) "This problem may explain, perhaps," Mark writes, "why the Mesoamericans, who first invented chocolate in the tropics, never created a solid bar but consumed it only as a drink."
OK, there are, of course, many other things that affect a country's fertility rate. But still, maybe, just maybe, it would be worthwhile to think about trying this: a worldwide chocolate experiment. We rejigger chocolate one more time, so it is less temperature sensitive. Then we take these new, dark, melt-in-your-mouth bars and make them available to young people all over the world — for free. Wait a generation, and see what happens.
If the world starts to have fewer babies, if the population boom subsides, freeing up resources, allowing for cleaner air, more wild spaces, more butterflies, more panthers, more trees, more beauty, we can then turn together to those little brown bars, and say (just before we swallow), "Thank you, chocolate."