The iconic movie Jurassic Park has provided us with quite a number of quotable lines:
"I hate it when I'm always right."
"That is one big pile of shit."
"See? Nobody cares."
"Hold onto your butts."
But as someone who has studied (and taught) evolution for decades, none of them has stuck in my mind like Ian Malcolm's pronouncement, "Life... uh... finds a way."
This short sentence sums up something really profound; however the Earth's ecosystems are damaged, they always bounce back. Even after the catastrophic Permian-Triassic Extinction -- which by some estimates wiped out 90% of the existing taxa on Earth -- there was a recovery and rediversification.
Note that I'm not saying that means it was a good thing. The end Permian extinction event was, it is believed, caused by an unimaginably huge series of volcanic eruptions, followed by a major spike in the carbon dioxide content of the atmosphere -- leading to a jump in the global temperature and catastrophic oceanic anoxia.
So yeah. "Life survived" doesn't mean it'd have been a fun event to live through. But it should give us hope that the damage humans can do to the Earth as a whole is, in the grand scheme of things, short-lived.
As an encouraging example of this, take a recent study out of the University of Florida on snail kites. These birds, related to hawks and falcons, are serious food specialists; they eat only one species of snail, found in salt marshes like the Everglades (and also parts of Central America; I first saw snail kites in Belize). When things are stable, being a specialist is a good thing -- you pretty much corner the market on a particular resource, like the South American hummingbird species whose bills are shaped to fit one and only one species of flower. The snail kite's food finickiness is this same sort of thing, and as long as the Everglades was undamaged and had an abundant supplies of snails, all was well.
But when the environment is rapidly changing, either through human effects or because of natural events, being a specialist is seriously precarious. When a new species of snail -- the island apple snail -- was introduced to the Everglades, its larger size and voracious appetite outcompeted the native snails, and the snail kites were in trouble because their bills weren't large and heavy enough to tackle the bigger prey.
Snail kites were already on the Endangered Species List, given that the Everglades has been massively damaged by human activity. This, it seemed, might be the death blow to the Florida population of this striking bird.
But... life, uh, finds a way.
The snail kite, in a near-perfect reenactment of the bill diversification in Darwin's finches in the Galapagos, had a variety of bill sizes. Genetic diversity, despite their extreme specialization. Before the introduction of the island apple snail, bill size probably didn't make much difference, positive or negative, to the individual birds. But now, large bills were a serious advantage. The birds with the biggest bills could tackle the larger snail species -- meaning they had a copious food source that their smaller-billed cousins couldn't utilize.
And in the thirteen years since the introduction of the island apple snail, the average bill size has gone up dramatically -- and the overall population is rebounding."Beak size had been increasing every year since the invasion of the snail from about 2007,” said Robert Fletcher, who co-authored the study. "At first, we thought the birds were learning how to handle snails better or perhaps learning to forage on the smaller, younger individual snails... We found that beak size had a large amount of genetic variance and that more variance happened post-invasion of the island apple snail. This indicates that genetic variations may spur rapid evolution under environmental change."
Many of us were riveted to the screen last week watching the successful landing of the Mars Rover Perseverance, and it brought to mind the potential for sending a human team to investigate the Red Planet. The obstacles to overcome are huge; the four-odd-year voyage there and back, requiring a means for producing food, and purifying air and water, that has to be damn near failsafe.
Consider what befell the unfortunate astronaut Mark Watney in the book and movie The Martian, and you'll get an idea of what the crew could face.
Physicist and writer Kate Greene was among a group of people who agreed to participate in a simulation of the experience, not of getting to Mars but of being there. In a geodesic dome on the slopes of Mauna Loa in Hawaii, Greene and her crewmates stayed for four months in isolation -- dealing with all the problems Martian visitors would run into, not only the aforementioned problems with food, water, and air, but the isolation. (Let's just say that over that time she got to know the other people in the simulation really well.)
In Once Upon a Time I Lived on Mars: Space, Exploration, and Life on Earth, Greene recounts her experience in the simulation, and tells us what the first manned mission to Mars might really be like. It makes for wonderful reading -- especially for people like me, who are just fine staying here in comfort on Earth, but are really curious about the experience of living on another world.
If you're an astronomy buff, or just like a great book about someone's real and extraordinary experiences, pick up a copy of Once Upon a Time I Lived on Mars. You won't regret it.
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