Well look at you. Aren’t you a masterpiece of biological evolution? You are a big, ambulatory, autonomous human being. You are separate from the insects on the ground, the birds in the air, and the steer in your burger. As a human, you envision yourself as lord of your surroundings, a unique animal risen and separate from other “lower” forms of life. Look at those clothes! And those thumbs! You are a whole and special individual, a single, isolated member of a species that has dominated and partitioned itself off from “nature” through years of rugged conquest and ingenuity. You could be very smug about all of that.
Except you’d be wrong.
You are not alone. While it is no secret that humans share their bodies with a bunch of microscopic, and smallish macroscopic, guests, the scope of their pervasiveness and impact on our lives is not commonly understood. The role of microorganisms and other parasites in the human experience extends far beyond a bit of armpit odor, bad breath, head lice, and dandruff.
In the perspective of a bacterium, the outside of the human body is an endless substrate, strewn with a ridiculous amount of nutrients and minerals, set on a lumbering factory that just churns out more goodies, making human skin an attractive place to settle down and colonize. The inside of humans is even better! It’s warm and moist and if you’re in the right organ system, new nutrients get delivered right to you! Human bodies are to bacteria as a mystical candy house in the woods is to Hansel and Gretel. It is only by the graces of the immune system provided, non-stop, by vigilant human cells that you and I aren’t eaten from inside out…and also from the outside in…by our plentiful tenants.
Powered flight (in the biological world, flight that comes from the mechanical flapping of wings as opposed to passive drifting or gliding) can be found in a wide range of animals on our planet. It is has evolved independently in insects multiple times, leading to a biologically diverse menagerie of colorful blotches on our windshields. While insects are far and away the first creatures to master the air (by a solid 200 million years), and the only invertebrates to do so, they share the skies with the much larger vertebrate fliers like birds, bats, and at one time, the reptilian pterosaurs. Aerial locomotion provides an animal with obvious advantages; ease in avoiding predators, access to new habitats and food sources, and the nullification of the game of Monkey in the Middle. There definitely are interesting correlations concerning the success of flying; it appears as though once evolved, flight is an incredibly successful strategy. Bats account for a fifth of all mammal species, birds have the most species of any land-lubbing vertebrate class, and the class containing insects is more speciose than all other animal groups combined. So it obviously pays to take to the skies, on a numbers and diversity level. That, and flying is quite clearly the most badass way to get around.
And yet, some representatives of these flying lineages drop the practice altogether. One explanation is that they are ungrateful, arrogant pricks who wouldn’t know the value of an honest day’s wingbeat if it bit them in the ass.
“Soaring elegantly through the heavens is sooooo mainstream.”