As children we are taught never to eat the red berries. Walking through the forest is a tempting odyssey of the unknown. As little hands trace the vibrant green leaves and red berries, our eyes see the slight difference in shape, but our minds don’t understand why one red berry is okay and the other a danger beyond description. Why is it that a handful of blueberries bring nothing but smiles and the occasionally puckered lip, while nightshade, a deep purple look-alike to the unobservant eye, will be toxic? The key to this question lies where all answers inevitably find their origins. Our answer can be found through a compilation of thousands of years of plant evolution, and although it involves mammals, we really aren’t the central characters in this story - as we often forget.
It all begins with seed dispersal. What are we without procreation? Extinct, that’s what we are. Plants, in all their intricate defense mechanisms, know this well. If the main focus is seed dispersal, one may question why fruiting plants would be poisonous to a possible seed carrier. I thought on this for a while, then while picturing the way a bear slowly lumbers through the forest, I decided to do some research. Bear feces is usually produced all at once in a place near to the last. Bears may eat many seeds, however if it is biodiversity and wide seed dispersal that lead plants to thrive, then bears make for terrible hosts. The same goes for humans and most other mammals. We are far less mobile then birds.
Birds are prime seed-dispersal candidates. Research has found birds to be much more capable of digesting fruits, some of which would be toxic to humans. A prime example of birds’ immunity to things that damage, or even kills mammals such as us, is their insensitivity to capsaicin, the pungent chili-like flavour. Birds are extraordinarily fast and can disperse seeds whilst still in flight. It is no wonder, over both of our long and separate evolutionary journeys, that birds have developed a more symbiotic relationship with fruiting plants.
In this line of reasoning it would follow that plants with thorns near to the ground or with irritants on their leaves, are also attempting to avoid ingestion by mammals. For birds can feed and hover above while we bipeds and quadrupeds must suffer the indignity of feeding upon the dirt.
So as it turns out evolution isn’t based upon our needs as a species, which can be an initially disappointing, but ultimately beautiful conclusion. The ecosystems around us arose through so much more “design” then we like to think, and the exceptional feats of plant life are sorely underappreciated. While the child in me will always desires to nibble on a bunch of wild red holly for curiosity’s sake, I am reassured to know that, as a mammal, it would taste pretty terrible.