If any alien race wanted to eradicate humans but leave all other creatures on earth

No it would be some local problems.

as a portion of the earth it is very minor.

No it would not.

some small areas of the planet would suffer but not worse than the periodic natural disasters. you have a wildly unrealistic idea of the footprint.

A particularly virulent version of smallpox would probably work. It’s human-specific, highly contagious, and some versions are greater than 90% lethal. There may be a need to do some mop-up work for the odd survivor, but that could do it.

The silly humans have actually kept samples of this otherwise extinct virus, more fools them, as the vast majority now have zero immunity. A few have been vaccinated, but only a few.

I’m sure these super-advanced aliens can step in to deal with these items before they become a crisis.

They could do it through a lethal STD. The only people left would be children, who would either die of neglect, or eventually get it, and the asexual, or non-sexually-active, who would eventually die out.

This. It has been posited in Science Fiction. They get us to stop breeding. We slowly die off as a species. Those that survive longer would take of disposing of the bodies of those that didn’t, minimizing the mess.

What about the monogamous? I mean the really monogamous of course. A really large fraction of married couples would survive.

Of course an STD is silly. Sexually transmitted infections are those that are so hard to catch from another person that you need to exchange bodily fluids to get them. Airborne viruses work a lot better.

And of course, if you drop dead in a few days from the infection, you’re not out infecting other people. How long does your lethal STD take to kill people? To spread the infected patients have to live long enough to infect at least one other person before they die.

It’s more than extremely difficult to impossible to eradicate and entire species without effecting any other. Especially a top predator that is extremely adaptable consisting of 7 billion. No matter the disease, our DNA would mutate at some point. It would actually cause more harm to the current life on the planet than good, besides we’ve already had 3 apocalyptic disasters with 99% of everything that has ever lived being extinct. There’s no logical point to ending a species on purpose.

Realistically I don’t believe any Alien of such intelligence to get here would need to do such. They can clone DNA of whatever and place them on another, similar planet…that would be easier. Resources of precious metals are on tons of lifeless planets so there’s no need to do away with us. Also even if they wanted to destroy our planet, a simple giant rock from space, hurled with precision would do the trick.

Also, let’s view things from the other direction. We travel the stars and encounter a planet with belligerent beings. What do you do? Destroy them?..makes sense right. Why not just go away if you don’t like them?, you can travel the entire freaking universe after all

Make 'em drink this:


Relentless sexbots.

The non-drinkers would be enough to keep civilization running while the entire generation of children who were too young to drink grow up and then repopulate the world.

Example: “The Screwfly Solution” by James Tiptree, Jr.

They could appear as representatives of a benevolent civilization, here to share holodeck technology with us.

Stargate SG-1 had an advanced race that took the “helpful” approach. They provided technology, military, and medical assistance to less advanced civilizations. The stinger was in the medical “aid”–their treatments for various things also caused widespread sterility. (And they weren’t above engineering a plague to set the stage for it.) They didn’t necessarily wipe out other races completely–they preferred reducing them to agrarian “client” worlds–but they could have.

Biological warfare both against us and against the crops we depend on for food.

Also turned into a Masters of horrorepisode.

I believe the experts speculate that 90% of the native North American population was wiped out by smallpox shortly after it arrived here, even without the assistance of advanced technology, so it would be a good choice. Add two or three other viruses to make sure the rare immune people get hit with something, then go in and shoot anyone remaining.

However, even if the aliens step in and feed the cows and turn off the nuclear reactors, what do they plan to do with the billions of rotting corpses? That alone would be quite an environmental disaster.

A nuke plant cannot be shut down safely without external electrical power. That’s what happened at Fukushima. No nuke plant today is “walk away safe”. No humans = no electrical grid = every nuke plant on earth melts down. Also every spent fuel pool will catch on fire for the same reason.

Likewise most steel-framed skyscrapers will collapse within 100 years unless they are meticulously maintained. Maybe millions of alien maintenance workers in overalls will steadfastly work to to prevent this, or maybe they wouldn’t care. Whichever their opinion, they had better each have a geiger counter and be careful where they go because wiping out the human race would result in lethal global contamination on a vast scale.

I’d determine the two most potent militaries in the world (say, USA and China), hack into their official government Facebook accounts and threaten each other with nuclear annihilation, and then just sit back and watch humanity do it themselves out of fear and loathing alone.

What stops the aliens from showing up at the power stations and nuke plants to take care of this?

Or maybe they send a workforce to dismantle those building or maybe they start using the buildings themselves, just move in and take over like white people did after the Indian clearances in the southeast in the early 19th Century - the Natives were forced-marched to Oklahoma on the Trail of Tears and white people just simply moved into the houses they left behind and appropriated all their stuff.

In this scenario, lack of humans does not mean lack of intelligent tool-users to maintain the infrastructure.

How about an air or water borne virus that causes no clinical signs other than permanent sterility.

Arthur C. Clarke, in a story published in Playboy (with illustration, if I’m not mistaken, by Gahan Wilson) suggested that, after softening us up with many of the things suggested above – illnesses, city destruction, and the like – the thing that REALLY let the aliens take over was when they captured Switzerland and got hold of the numbered bank accounts. Then they could persuade the important people to do anything.

No, it would not, you have wildly exagerated ideas of the footprint of all this (and indeed of the contamination). It would cause localized contaminations that pass in the eyeblink of time.

This is on the level of those who talk about nuclear weapons blowing up the planet. It is irrational

but perhaps the multi-factor attack of both a small pox or the similar for putting the world health services off and in crisis, with a viral attack for long-term sterility of the male and the female.