Turns Out Our Ancestors Were Sweet Enough to Evolve Bigger Brains

For years, the story went like this: early humans got smart because they started eating meat. Chowing down on animal protein and fat gave our ancestors the necessary brain-fueling calories. But what if that's not the whole, ahem, sweet truth?

New research suggests that long before we started deep-frying everything, our hominin ancestors were probably gorging on honey and ripe fruit. And all that natural sugar might have been just as crucial for evolving those big, beautiful brains we're still using to scroll through articles about ancient diets. Which, if you think about it, is a delicious irony.

The Brain's Insatiable Sweet Tooth

Our brains are basically energy black holes. They make up just two percent of an adult's body weight but hog a whopping 20 percent of our resting energy. For a five-year-old, it's an even more absurd 66 percent. All that processing power runs on glucose, which comes from carbohydrates.

Now, getting glucose today is easy. Toast, pasta, a candy bar — no problem. But for early hominins, especially as their brains started ballooning from a mere 300 grams to an impressive 1,500 grams, finding enough fuel was a serious challenge. Meat offers protein and fat, sure, but not a ton of carbs. And cooking starchy plants like wild yams to unlock their glucose came later. So, where did all that early brain power come from?

According to Jennie Brand-Miller, a human nutrition scientist, and her team, it was likely sugar. They modeled hominin diets over four million years, from chimp-like ancestors to modern Homo sapiens foragers. Their findings suggest the earliest hominins might have gotten over 65 percent of their energy from natural sugars in fruits and other sweet treats.

A Parallel Evolution, Sweet and Savory

This isn't to say meat was irrelevant. Not at all. As Brand-Miller puts it, these are "parallel stories." Animal products provided vital nutrients, but the quick, potent energy hit from natural sugars likely played a huge, unsung role in fueling our evolving gray matter.

Once our ancestors figured out fire and started cooking starchy tubers and grains, those became new glucose powerhouses. But before that culinary revolution, sugar was king. It explains a lot, doesn't it, about why a spoonful of sugar still makes the world go 'round — and why your brain still lights up at the sight of a donut. Because apparently, evolution designed us that way.

Of course, figuring out ancient diets involves a bit of informed guesswork. There's still a lively debate about when exactly cooking became widespread enough to impact brain growth. But the idea that our deep-seated craving for sweetness is actually an evolutionary superpower? That's a thought worth savoring.