And that’s where babies come from.

But what about worms? If you cut one in half it becomes two worms.

Well first of all, you should never cut a worm, or any other living creature, in half. You wouldn’t like it if someone gave you a cut just to show their friends that it would go away in a few days would you?

No not really. But it is kinda cool that it goes away on its own.

Indeed. But that was a good question. Most animals that we know of have a male and a female, even plants have male and female parts. But there are other animals, and other forms of life, that don’t have a male and a female, and there are even species that can switch between them!

Ew. That’s weird.

Really weird, and really cool. In fact, on Eden, the planet we’re headed to, there was an alien species that could even switch its sex based on how long since it woke up!

They’re not there any more? What happened to them?

Well now that’s quite the story. A few decades ago, long before you were born, we sent probes out to Eden. They found a more dense and vibrant ecosystem of plants than we’d ever seen. Millions upon millions of species idyllically cohabitating. But we only found two species of large animal. Or at least so we thought. You see, Eden is tidally locked. Do you know what that means?

I don’t think so.

Well, Earth’s moon is tidally locked. It doesn’t spin around the Earth like the Earth spins around the Sun, so the same face of the moon always faces towards the Earth, and the other side always faces away from it. Eden is the same way, so all the plant life is on the Bright Side, and the Dark Side has nothing but rocks and some ice. Also, Eden’s orbit is longer than Earth’s, and unusually elliptical, which means it’s more of an oval shape than a circle. Anyway, on the Bright Side of Eden, we found a species that was able to vary its traits drastically depending on where it was on the planet, or rather, what plants there were near where it lived. However, no matter where we found variants of this species, they always shared the same fundamental physiology. On the Dark Side, the probe discovered regular collections of uniformly shaped rocks. When it drilled into them though, it found out that the rock was actually a shell for a living thing inside!

Like a turtle!

Exactly. Except that these creatures didn’t seem to move at all. We thought maybe they fed off the heat from inside of Eden, since we only found them in the warmer spots around the cold Dark Side of Eden. The only other thing is how strange Eden’s Ring was.

Eden’s Ring?

Yes, the circle all around the planet, where the Bright side meets the Dark side. It was overflowing with insects.

Insects?

Alien insects of course. Oh! And there was the strange eating habits of the animals. They seemed to be extremely energy efficient, as they only ate the occasional leaf, flower, or branch. The ones that lived near Eden’s Ring didn’t seem to like any of the insects, and squashed them if they got too close. There were A LOT of insects in the Ring. We figured perhaps some flooding that would be likely to occur during the solstices along Eden’s elliptical orbit was what regularly kept their populations in check. Well, we eventually sent the first scientists down to Eden. We chose a spot between the Ring and the majority of the Bright Side, a sort of Dead Ring occupied mostly by plants that fed off the corpses of insects that strayed too close to the Bright Side species. It didn’t take long after inflating the habitat for us to learn that the claws the Bright Sides use to climb and hold onto trees were very, very sharp. Deadly sharp. Not only did they attack the habitat, they attacked everyone who managed to make it into a space suit in time as well. There weren’t enough hard power suits for everyone.

They should’ve had a power suit for everybody on the team.

Well that would’ve been one solution, yes, but by the time they realized that may have been a good idea, it was too late to do anything about it. The surviving members of the team aborted the mission, while making sure to take a few specimens with them, alive or dead. The United Earth rethought its approach to colonizing Eden. We would need to wipe out the Bright Sides. The next decade or so was spent methodically commiting alien genocide. Because Eden’s tidally locked, the plant life on the Bright Side constantly evolves at a rapid pace, so it didn’t take long for us to study the effects of eliminating a population of Bright Sides from a specific patch of the planet. The plant life on that patch evolved, survived, and continued to flourish, so we slowly phased out the remainder of the population of Bright Sides from that face of Eden. This all happened within a half an Eden Year.

Half a revolution around its ecliptical orbit.

Elliptical, but that’s right. When the first probe landed, it was not long after a solstice, which on a tidally locked planet, is when the solar intensity is going through its highest rate of change. But not long after we got rid of the last of the Bright Sides, Eden reached its other solstice. And that’s when the Dark Sides woke up. They shed their shells, walking like zombies to the nearest point on the Ring. They waited for what would be several Earth days, just moseying about, warming up. Eventually they began eating the insects. They ate a lot of them. A LOT. After eating its fill of the insects, each of the Dark Sides went to its own patch of the planet, too sluggish it seemed from having just gorged itself to care about any of the initial colonists that had recently landed and set up shop. The Dark Sides then started to change themselves from gray, naked creatures into more diversified lifeforms. But they all still shared the same fundamental physiology! They were the other sex of the Bright Sides! Once the colonists realized the same species that had so violently attacked the first humans to set foot on Eden were back, the United Earth decided to abort its colonization of Eden. It had lost men to it, then commited genocide on it and nearly lost even more men to it.

If the United Earth isn’t colonizing Eden anymore, why are we on our way to it?

Our family is going to Eden to bring back the other half of the Species. CRISPR, biological 3D printing, and the specimens we collected from the aborted mission, as well as cryogenic freezing if our efforts take more than one Species generation, should be enough to eventually reinitiate some mating between Bright Sides and what will initially be artificial Dark Sides. But repopulation will take time. With how long one Eden Year is, it may take several generations of our family, but we won’t be leaving Eden until its Species population is back where we found it. You may die on Eden with it as your home, or you may leave it one day as one of the great things you’ll accomplish in interstellar space.

Humans can still die?

Many of them are still dying, yes, but at some point not far from now, we won’t have to say goodbye to loved ones forever anymore. And that reminds me, we speculated that the reason the Bright Side sex was so unrelentingly hostile to us was because if we managed to escape them and make it to the dark side, we would be a threat to the stationary and relatively defenseless Dark Side sex. The Bright Sides were probably just trying to protect their partners.

That makes sense.

After those events on Eden though, the United Earth decided that if it couldn’t learn to peacefully live alongside all the lifeforms of a planet on their own terms, then perhaps humanity wasn’t yet ready to be allowed a new home. It’s like when your younger sister was born, you wouldn’t like it if we said you weren’t allowed to live in the same habitat as her, would you?

Well, that would mean that maybe sh–

Oh shush!