A little Gray Building
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When I look at microscopic images of bugs, I am also reminded of the complexity of all life. We humans tend to have a self-centered perspective that puts us at the pinnacle of nature. We marvel at the complexity of our bodies: what a perfect-seeming pump our heart is, how fascinating that mineral stones in the tubes of our inner ear give us a sense of balance, how staggering it is that our oh-so-complex brains allow us to think and talk and write essays. Seeing bugs magnified is a reminder that they too are exquisitely adapted for the environments that they operate in. They too are made of trillions of cells working together, and they have organs, behaviors, and sometimes even social structures just as complex as ours. A bee can’t write a sonnet. But can you see ultraviolet light or tell your family how to find food by explaining its distance away from home and angle from the sun with a dance? Didn’t think so.
Looking at many bugs is also a good way to notice a deep evolutionary feature shared amongst all bugs, worms, and creatures with backbones: the segmented body plan. Although scientists have understood the basics of evolution by natural selection for over 200 years, it was still a challenge for a long time to explain the mechanistic details of how body plans could change significantly from generation to generation. One of the key breakthroughs towards understanding this process was the discovery of a set of genes called Hox genes in the 1980s. In brief, Hox genes act like master switches, which turn other genes on and off during development. Scientists first figured out how the workings of Hox genes, which guide development of an organism segment by segment, in fruit flies. If we imagine the genes speaking, they might say something like, “This segment is going to be the head – turn on the genes for eye and antennae development. These next three sections make the thorax, turn on the leg-growing genes here,” and so on. One small mutation in the timing or operation of these genes can change how the body segment develops, which might help or hurt the animal in its particular environment. The beneficial changes tend to stick around in the population, as the creatures that have them reproduce more, and thus continues evolution. As animals evolved and branched off from the basic plan for millions of generations, this original segmentation can be hard to see. In humans, you can notice it the repetition of the vertebrae in our spine, our ribs, and our segmented abdominal muscles. It’s easier to see in the segmented muscles of fish or the overlapping sections of a wasp’s abdomen. It’s plain as day when you look at a worm or a centipede.