Some very interesting information on sugar in this months National Geographic! Now I know why I love fruit! 🙂
In the Beginning Was the Fruit
If sugar is so bad for us, why do we crave it? The short answer is that an injection of sugar into the bloodstream stimulates the same pleasure centers of the brain that respond to heroin and cocaine. All tasty foods do this to some extent—that’s why they’re tasty!—but sugar has a sharply pronounced effect. In this sense it is literally an addictive drug.
This raises the question, however, of why our brains would evolve to respond pleasurably to a potentially toxic compound. The answer, Johnson told me, lies deep in our simian past, when a craving for fructose would be just the thing our ancestors needed to survive.
I paraphrase Johnson in a voice borrowed from the fables, for what are even the best theories, if not the old stories told again in the language of science? Some 22 million years ago, so far back it might as well be the beginning, apes filled the canopy of the African rain forest. They survived on the fruit of the trees, sweet with natural sugar, which they ate year-round—a summer without end.
One day, perhaps five million years later, a cold wind blew through this Eden. The seas receded, the ice caps expanded. A spit of land emerged from the tides, a bridge that a few adventurous apes followed out of Africa. Nomads, wanderers, they settled in the rain forests that blanketed Eurasia. But the cooling continued, replacing tropical groves of fruit with deciduous forests, where the leaves flame in autumn, then die. A time of famine followed. The woods filled with starving apes. “At some point a mutation occurred in one of those apes,” Johnson explained. It made that ape a wildly efficient processor of fructose. Even small amounts were stored as fat, a huge survival advantage in months when winter lay upon the land and food was scarce.
Then one day that ape, with its mutant gene and healthy craving for rare, precious fruit sugar, returned to its home in Africa and begot the apes we see today, including the one that has spread its sugar-loving progeny across the globe. “The mutation was such a powerful survival factor that only animals that had it survived,” Johnson said, “so today all apes have that mutation, including humans. It got our ancestors through the lean years. But when sugar hit the West in a big way, we had a big problem. Our world is flooded with fructose, but our bodies have evolved to get by on very, very little of it.”
It’s a great irony: The very thing that saved us could kill us in the end.