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Thats true, but I just wanted to point out that humans are actually one of the best species on Earth at distance running

http://www.slate.com/articles/sports/sports_nut/2012/06/long...

We are extremely good at throwing things with precision as well.

The combination of unusual tricep structure (also found in cats and the extinct great sloth), remarkably mobile shoulder structure (inherited from our primate ancestors) and grippy hands (thumbs!) gives us remarkable downward thrusting power useful for smashing, grabbing and throwing.

One of the earliest inventions, the spear-thrower, enhanced that ability even more, giving us the ability to kill big game from a distance with near impunity. (It works by increasing the lever arm. Think of a lacrosse stick.)

http://en.wikipedia.org/wiki/Spear-thrower

My professor once told us that we were thinking of Australopithecines, a recent hominid, all wrong.

While we thought of early human ancestors as less intelligent versions of ourselves, the correct analogy was to a modern Velociraptor: fast to the point of running animals to death, fiercely intelligent, and with unparalleled group coordination.

Arguably the last of the giant dinosaurs was the Moa, a bird with claws that could eviscerate a human with a single swipe, and our species wiped them out as a prey animal.

We are a terrifyingly effective species.

I agree with pretty much anything you said, but I disagree on humans being poor runners. We are amongst (if not THE) most endurant runners on the planet. Humans have been known to defeat horses in long races [1]. As for running on the heel, this is more of a modern shod runner curse than a natural instinct or predisposition.

[1] http://en.wikipedia.org/wiki/Man_versus_Horse_Marathon#Winne... (might be anecdotic, but still somehow revealing)

That's what happens when you're a biped

Paradoxically, this skill only becomes really apparent when humans act in the role of hunters. As prey, it's more likely a sneaky tiger will spring forth from the jungle and run us down for dinner.

But yep, we can actually run other animals to death.

Humans are terrifying unbalanced creatures.

"Humans have no natural predators. Zero."

As a group yes. As individuals - no. Go in alone somewhere where other big predators like wolves, bears or whatnot and hold your ground for a few weeks. I bet that unless you build some kind of fortress for yourself to sleep at night, not even firearms will help you in the long run.

"Even with stone-aged levels of technology we spread to every corner of the world, in every known climate and ecology, in large numbers, and thrived."

Actually, we've managed to thrive only in the places where there was enough air (no underwater humans), water (not many thriving communities in the deserts), food (which was a hard limit for the level of development, famine was a regular regressing factor), warmth (no people in Antarctica), and other such useful things. In this regard we are no different than other animals.

> we're capable of wiping out every living thing that inhabits the surface of a world.

Oh come on now, dont flatter yourself so much.

No, humans cant wipe out all living things that inhabig the surface of the world.

I think you might need to look into what the Russian and USA nuclear arsenal might do if used evenly across the world. If this does not convince you let me introduce you to the cobalt bomb [1].

1. http://en.m.wikipedia.org/wiki/Cobalt_bomb

I laugh I your General direction: http://en.m.wikipedia.org/wiki/Waterbear note there is a lot of surface area on the planet. A 1MT nuke per sqare mile would come fairly close but not quite get to where you suggest and we don't have close to that many nukes.

I have to say I love Tardigrades, but without a food source they are not going to survive. Nuclear winter is not too conducive for moss growth.

More seriously I suspect that short of a massive high altitude cobalt bomb detonation that some small life will survive on the surface even if all the current nuclear weapon were used.

Well they can go without food for 9+ years so that's more of a long term problem. As to nuclear winter they already live in Antarctica so there food source can also survive fairly harsh conditions, and it only takes one (or 2 depending on species).

Not that we have a lot of spare planets lying around but IMO it would be an interesting experement. Also, there is a fairly interesting ecosystem living inside the chernobil building which just goes to show how hardy some things are. http://en.m.wikipedia.org/wiki/Radiotrophic_fungus Gama radiation as food... Yea that's a thing.

A cobalt bomb will keep the background radiation level on the surface lethal for nearly 100 years.

There is no way we can yet destroy all life on earth - microbial life is too tough for that, but we could destroy all macroscopic life on the surface.

Excluding caves. Also, rain drastically reduces how long radiation stays in an area. And again cobalt produces Gama radiation which some things use as food.

Even if we take 1985 levels of nuclear warheads - the maximum, I believe USSR had 40 000 back then, and fuck it, lets say for even numbers, 100 000 nuclear warheads.

Land-surace is about 150 square million km. Take 1.2Mt the biggest yield in US arsenal currently. That would require around 270 000 nuclear warheads to cover every square km. We dont have that many and never had.

Also that wouldnt even scratch the oceans.

And the cobalt bomb, it hasnt been built, and anyway wouldnt work its not a doomsday device.

There are also way too many caves and cave systems with ecology in them which would be largely unaffected by civilized weapons.

Sure, the earth wouldnt look like it does today, but life would still prevail - and civilization isnt really that powerful to exterminate all life.

"...to cover every square km. We dont have that many..."

One does not have to rake every piece of soil in order to wipe out the entire life. The oceans would get the radioactive lavement of the soil and cycle that back on the land over and over though radioactive rains. This affects especially the bottom layer of the food chain, which cause chain's partial (if not total) collapse. In the end there is the possible nuclear winter that may render almost the entire planet inhabitable for all life forms. (Spores, bacteria, algae or other microscopic life forms may resist in hibernation to thrive again someday, but that is not called "living" through the event.) The reality is that there wasn't in our planet history any extinction event that involved nuclear contamination of every available living habitat (among other hostile-to-life effects), and speculating about it and about if it would or not be destructive enough, feels to me a little bit like playing with madness here.

Yep, we sure can. Don't underestimate our lunacy.

"We" arent that powerful, the best we could do is exterminate our selves, but life would continue, and adapt.

We sure are. We can blacken the sun, wipe away the ozone layer, irradiate and poison the earth, freeze the oceans, we can drill down to nearly the mantle, introduce plagues that can ravage continents and over time, we can fracture the earth's ecosystems so badly that a meteor strike will look like a pebble drop.

Every living thing on the planet will die as a result.

If we dedicated ourselves to wiping out the biosphere, I'm sure we could. But the current nuclear arsenal wouldn't cut it.

At best we could destroy civilization, but probably not even humanity.

> The only thing that is dangerous to humans is other humans.

And microbes. And other parasites.