Brains take a ton of energy to keep ticking, and human brains are proportionally huge. Therefore, humans need to consume a lot energy through their diets. For Last Word on Nothing, Heather Pringle explains that one food, maybe more than any other, could have allowed for our ancestor’s ever-expanding craniums. Starting 2.5 million years ago, she says,

ur hominin ancestors may have dined extensively for the first time on energy-rich honey, a food that may have fueled the evolution of our large, metabolically costly brains. The earliest member of our genus, Homo, emerged some 1.5 to 2 million years ago, equipped with brains significantly larger than their predecessors. Moreover, they possessed smaller molars, suggesting that they were dining on an easily consumed food. Honey.

As a modern analogue, Pringle points to the hunter-gatherer society of the Hadza people, a culture in eastern Africa that “prize honey above all else in their diet.” This preference for honey has lead the Hadza hunters to develop a symbiotic relationship with a local bird species know as the greater honeyguide. Pringle says,

The bird dines almost entirely on beeswax and bee larvae, but it needs help to crack open hives. So the honeyguide calls to both honey badgers and Hadza hunters. When human hunters whistle back, the bird gradually leads the men by call-and-response song to the nearest colony.

The Hazda’s preference for honey may have stemmed from the same drive as some of our earliest ancestors: honey is energy dense and can even provide protein and fat on top of its abundant sugars.

But if it’s true that honey is one of the pillars that brought us so far as a species, that lends extra gravity to the recent epidemic ravaging honeybee populations known as colony collapse disorder. Potentially caused by a combination of pesticides, food stress and parasites, colony collapse disorder is wiping out bee populations across the western world. The disorder has so far had a profound effect on honey production, with 2011 being “one of the lowest crops in recorded history of honey production.”

More from Smithsonian.com:

Humans: The Honey Hunters

Honey Bees Still Struggling

North American Bumblebees on the Decline