The top three biggest threats to humanity....

[Jackalope]

1. Clowns
2. Mimes
3. Elvis impersonators

[BrianSoddingBoru4]

1. Clowns
2. Mimes
3. Elvis impersonators

Three for one, then. Well done...

Boru

[lifesagift]

I suppose the OP begs the question.. "what is meant by humanity".. if it's the human race, then it is climate change, ebola's big cousin or a meteorite..

But if we mean humanity as general normality (as is what I was getting at probably), then it has to be Islam.. Russia may well be flexing it's muscles, and that nutter in charge of N korea is executing everyone he sees fit...

But Islam is driving a large number of people to do incredibly vile things, on a huge scale... in the name of a book.

And that vile mentality is embedded in every aspect of all our live, albeit in a dormant state... we have to realise that there is the potential for a suicide bomber in your town right now...

I accept that many muslims are peaceful, but I'm realistic about what that book decrees!!!!

[Losty]

Are you seriously suggesting that Islam is worse than Ebola lollies!?

[raincrow]

there are threats and accelerators of threats. Some threats could be less imperative had it not for the "accelerators" coming in to play. Just as an example to illustrate my point, accelerators are for example the far right's inability to accept that anthropomorphic global climate change is nearing criticality. If deniers hadn't been pushing back and scaring people away from the messengers (scientists) with misrepresentations and lies, creating a wall of obfuscation for the uninformed to hide in, there would be a carbon tax by now and we would be entering into agreements with the rest of the world (exc. Australia maybe) to limit or begin to reverse GCC. So what's the larger danger here, climate change or right wing nut jobs? Sure Climate change may be what kills us but for the sake of argument, the right insured that it would happen. Given I don't blame the gun for killing someone, I blame the killer-- I must cast an eye on the deniers following that logic and say they are one of the most serious threats, not climate change. As is the case with ISIS. Who caused ISIS to form. Whence came the seeds of their discontent? The foreign policy of white people over the last 70 or so years? Who is more dangerous?

[vorlon13]

And what if the (putative) 3 top threats are subtle and/or bizarre ??

Like an auto-catalytic prion is put in the ocean and it kills ALL the fish ?

[Anomalocaris]

And what if the (putative) 3 top threats are subtle and/or bizarre ??

Like an auto-catalytic prion is put in the ocean and it kills ALL the fish ?

"Put in the ocean" as in artificial?

That might be lumped together with nuclear war as unaccountable technological disaster.

[fojo]

The human race, antibiotics(failure of), and religion. So the human race for all three. And Keanu Reeves films as boru says. Although dangerous liaisons manages to remain a good film despite his best attempts to act it out of existence

[The Grand Nudger]

Thirst.
Starvation.
Stagnation.

(I know, I know, basic shit. No crazy engineered diseases, no nuclear catasrophes......but the first two are -already- a problem for us and the third has always been and will likely remain so. I don't think the rules have really changed all that much for us since -ever-...so those would be my top three from the dawn of man until the present, and into the future.)