How did life on Earth begin?
There are two main theories:
1. Some combination of chemicals happened to create something resembling a living thing enough that over time we got cells and life on Earth as we know it.
2. Life started elsewhere and came to Earth on an asteroid by way of some microscopic life.
What? Are scientists really taking that second theory seriously?
Yep! It’s a theory called “panspermia”.
Why? What’s there to back it up?
I’m sure there’s plenty more I’m missing, but one of the main evidences to back this up is tardigrades.
You may have heard of them before - they’re also known as waterbears or moss piglets, and they’re they’re these teeny tiny critters that basically just waddle around on moss drinking water (there’s a few that are carnivorous and eat other tardigrades, though).
Looks-wise it seems to me like Mother Nature couldn’t decide between “horrifying” and “adorable” and ended up settling halfway between the two.
This is, of course, if you put them under a microscope so you can see them properly. When I say they’re tiny, I mean tiny.
Like, the average tardigrade is 0.116 mm smaller than a side of an average grain of table salt (which is 0.3 mm).
^ The tiny specks? That’s them.
So why are the tiny fat waddly things possible evidence of life starting elsewhere?
Though they don’t look particularly impressive, these minuscule weirdos happen to be the toughest, bamfiest bamfs you’re ever likely to see.
Cockroaches and naked mole rats ain’t got nothin’ on these little dudes (and that’s saying something!).
What makes them such bamfs?
1. If there’s no water to be had, they’re totally fine with dehydrating into teeny little raisins until conditions are favourable again (at which point they pop back up and go about business as usual like nothing ever happened).
The longest a dehydrated tardigrade is known to be able to survive is ten years.
Well, if you count leg movement as “survival” then they can survive for at least 120 years.
Survival or not, getting shriveled up from being 85% water to 3% water and still being able to move at all after 120 years sounds pretty darn impressive to me.
2. They’re fine with 1,000 times more radiation than pretty much any other animal can withstand.
3. They can survive up to 5,000 Gy of gamma radiation (which is considered by scientists to be medium-lethal dosage).
4. They can survive for days at −200 °C; and some have been known to withstand cold up ‘til −272 °C. That’s -1.16 degrees away from ABSOLUTE ZERO.
5. They can survive temperatures of up to 151 °C for a few minutes. That’s higher than the temperature for boiling water.
6. They can survive pressure 1,200 times higher than atmospheric pressure, some species being able to withstand pressures of up to 6,000 atmospheres - practically 6,000 times higher than the deepest part of the Mariana Trench (which is the deepest place on Earth). That means they can survive pressures 6,000 higher than we actually have on Earth. (Why????!!!!)
7. They’re the first (and only) known animal able to survive in the vacuum of space. Scientists took a bunch of them up to the space station and chucked them out the airlock (I’m assuming in some form of container so they didn’t float away). When they brought the tardigrades back inside they popped back up and went about business as usual like nothing ever happened.
8. They can survive in the vacuum of open space combined with unfiltered solar radiation for at least 10 days. They might actually be fine with even longer, but that’s how long the scientists and tardigrades were on the space station for the FOTON-M3 mission (the tardigrade study was nicknamed TardIS - Tardigrades In Space - ‘cause what kind of biologist-astronaut would you be if you weren’t a big Doctor Who nerd?).
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