Unnatural Selection

During my son’s newborn assessment years ago, the pediatrician turned my rosy baby around in his hands like an experienced fruit vendor with a melon. “Look,” he said, as he placed the baby down on his side. “My favorite anomaly.”

Favorite anomaly? Anomaly, anomaly, anomaly. I couldn’t remember what it meant, and certainly not in relation to my baby boy. Atypical? Abnormal? That couldn’t be right. A mother wants a pediatrician to say it is the most normal baby he has even seen in the history of babies.

He tugged on my son’s ear. “There,” he said, “a gill.”

Dear god. A gill. It was only a small pinprick, as if he’d been born with a pierced ear, but this evolutionary tic was too high up on the ear rim for me to pass him off as a very hip baby. To make matters worse, in my family, the distinctive marker of infant beauty is related to how small and flat the ears are, so everyone looks at them first. I kept a tight little cap on him for months.

Scoot on up to the winter of 2013. Super Storm Sandy. Flooding. Powerful ocean surges. One extreme weather event after another, and the Atlantic succeeds in changing the coastline yet again. Adapting to drastic change may mean more than just picking up one’s shell and moving inland, for when a landscape changes, so do we. For most of the past 150 years, since Darwin first laid out the ground rules for natural selection, scientists assumed that humans had stopped evolving. They believed that with technology, medical advances, and culture, humans had become immune to evolutionary pressures. But no. Like all other living things on Earth, humans undergo genetic changes in response to conditions around them, passing beneficial adaptations down to their offspring. We are not exempt from the laws of nature. And the more extreme the pressures, the faster we will latch on to any mutation that might give an extra edge to our survival.

Here’s a happy thought: In the Paleocene-Eocene Thermal Maximum, 55 million years ago, carbon dioxide, probably from volcano spew, entered the atmosphere causing catastrophic fallout. Ocean acidification wiped out many sea creatures or encouraged them to seek their fortunes on land. It was during this time of mass extinction that opportunistic species, like primates, came into their own. With food sources scarce, we were flexible eaters, and none too picky about the neighborhoods we moved into either. Up a tree or in a cave, we made do. If we had to lose a tail, stand upright, or develop opposable thumbs, we did it and never looked back. We changed and we will change again. Of course, if environmental pressures get too extreme, we might not be the same homo sapiens in a few thousand years. We might, in fact, be so different we could not even cross-fertilize with today’s model. Still, there would likely be some version of ‘us.’

Here’s an unhappy thought: Ocean acidification is increasing at ten times the rate that it was during the Paleocene-Eocene Thermal Maximum. Ten times. Global warming is a related environmental pressure, caused by our machines expelling carbon emissions into the atmosphere, like a million teeny volcanoes. In the name of expediency, it might be quicker and wiser this time to change our habits rather than leaving our fate to evolution. In many ways, scientists were right about humans having the capacity to outwit natural selection. Culture (such as emission laws) and technology (such as new ways of controlling emissions) can help us adapt before going extinct or evolving into something too weird to contemplate. But will we? Political change can be as slow as evolution, and in the game of life, Mother Nature bats last.

Whales once walked the earth, then returned to the sea. Maybe we will too, if there is a living ocean for us to return to. Where I once thought of my son’s gill as a throwback, I now think of it as nature keeping her options open, hoarding old DNA in case we need it again. In the face of rising waters, having a gill or two in one’s genetic back pocket is going to start looking like a pretty good plan to withstand widespread ecocide. And if we have some acid-tolerance code leftover from the days of monster volcanoes, well then. We’re good to go.