An Evolutionary Mystery: The Taste and Color of Pollen
No one knows exactly when some of the ancient hunting wasps stopped chasing their meals and opted for veggies. We simply don’t have detailed records of early transitional species. What we do know is that some descendants of the early Crabronidae family of wasps gave up meat in favor of pollen, eventually becoming bees.
By 80 million years ago, we had fully-formed social bees equipped with all the paraphernalia of modern pollen eaters. In fact, a bee preserved in New Jersey Cretaceous amber is a dead ringer for some of today’s stingless honey bees.1 Still, we don’t know when the changes occurred. In the typical way of evolution, the transition was probably a series of chance events that turned into something good for both bees and plants.
But how could it happen? Well, imagine this. Mama wasp goes hunting for food and pounces on a small beetle resting on an inconspicuous green flower. She zaps it with her stinger, then flies the helpless creature home to feed her young. But after she drops the insect in the nest, mama discovers something clinging to her thorax.
She tries to brush it away, but it transfers to her leg. She swipes it with another leg, but it sticks there, too. Like a piece of Velcro, a pollen grain adheres to everything it touches. Vexed, she finally drags her leg across the stunned beetle where it sticks like glue. Relieved to be rid of the thing, she mutters under her breath, “There, kid, eat that too.”
The Bee is Born
Most likely, this scenario — or something like it — played out over and over until pollen became a regular part of the wasp diet. Maybe the offspring thrived on this food, or perhaps the mama wasp flourished because she no longer needed to tussle with so many unfriendly entrées. In any case, pollen most likely became part of the diet before it became the main event. Perhaps, over the millennia, pollen became a greater and greater portion of the menu: Pollen Medley. Pollen Glazed with Nectar. Pollen Primavera with Minced Beetle.
More hairs appeared on the insect’s body to help collect pollen, and later, the hairs became branched. Eventually, the descendants of the Crabronidae sported the complete pollen option — hairy bodies, antenna cleaners, electrostatic charges, pollen brushes, combs, and presses. They foraged in a world where the flowers had also changed. Newly evolved flowers had eye-catching colors, alluring odors, and sweet rewards. Suddenly — geologically speaking — these insects separated from their ancestors and the bee was born.
If some wasps began eating pollen by accident, nutritious pollen must have already been available in the environment. Indeed, a recent finding of a beetle in ancient amber seems to support that idea.2
The fossilized beetle, Cretoparacucujus cycadophilus, was found preserved in amber along with pollen grains that appear to belong to an ancient cycad. Some evolutionary biologists believe that cycads were pollinated by beetles long before flowering plants appeared on Earth, perhaps as early as 250 million years ago.
The researchers reasoned that the preserved beetle was a cycad pollinator based on a number of clues. The proximity of pollen along with the shape of the mandibles, the presence of maxillary palps (mouthparts common in today’s pollinators), and the fact that modern descendants of the beetle still collect cycad pollen, all indicate an established relationship.
Since insects were consuming pollen long before wasps began using it as baby food, pollen was probably already quite nutritious. If beetle pollination was advantageous to cycads, cycad pollen most likely evolved to attract them. From there, the leap to other insect pollinators was almost inevitable.
A Strange Food
No matter how you look at it, pollen is on odd menu item. Pollen contains the male gametes of a plant. Of all the edible plant parts — leaves, stems, flowers, roots, fruits — it’s hard to imagine gametes being a hit. But in fact, pollen is a nutritional powerhouse, responsible for multiple lines of animal life and a complex web of plant/pollinator co-dependencies. A vast number of species eat pollen, and an incredible variety of pollen grains exist to feed them.
The diversity of pollen is even more mind-bending when you consider that many plants are pollinated by wind alone. Wind-borne pollen — the type that makes some folks wheeze and sneeze — is small and light, allowing it to travel for miles on soft currents of air. In comparison, animal-mediated pollen is often large and bulky and crammed with nutrients. While animal-friendly pollen is expensive for a plant to make, it has a much better chance of reaching its target than wind-blown pollen — a perfect example of nature’s economy.
In order to harvest the many types of pollen available to them, bees developed a panoply of pollen-collecting variations. Depending on what kind they collect, some bees have small hairs packed closely together, while others have long hairs spaced farther apart. Honey bees, stingless bees, and bumble bees carry pollen in moistened pellets, while most bees carry it in patches of hair located on their legs, abdomen, or thorax. Some bees swallow it whole and regurgitate it later, and many bees just steal it from other bees. Truly, it’s a zoo out there.
Food that Tastes Good
Living creatures like food that tastes good. In fact, things that have gone bad or are dangerous to eat generally don’t taste all that great. Indeed, their foul taste warns us away. Since bees love nectar, honey, and syrup — all things that taste good to humans too, I assumed pollen must be tasty. So one day, I popped a few bee-collected pollen pellets in my mouth just to see. I cannot stress my discovery enough: Pollen tastes vile.
Afterwards, I heard that some pollen is worse than others, and I probably just tried an unfortunate sample. So I retained an open mind – at least until a few months later, when I was manning a honey booth at a local fair. I was serving little squares of comb honey on crackers when a gentleman at the next table gave me a piece of dark chocolate infused with pollen pellets, a confection he had purchased from another vendor.
Being an aficionado of dark chocolate, I was delighted, even though I was horrified at the price he’d paid. Since I didn’t know him, I especially appreciated the kind gesture. I eagerly peeled back the gold foil and took a bite.
Honestly, I didn’t know it was possible to desecrate a piece of chocolate to that degree. In fact, I didn’t know something could taste that bad without killing you. I immediately