If we consider other hominids, we don't know exactly, but it seems we outcompeted them. If we consider more distant animals, because we converted the entire planet to provide for us much faster than they could evolve to catch up with us.

However, the pressure has to have been exerted before humans outcompeted other hominids. This might seem too obvious, but you can't have an effect preceding its cause.

I think that's the "we just happened to be first" argument. Which could be true, but not very satisfying, because no detail.

We didn't have to be first. Other primates might have picked up the rock before we did, but eventually lost the race. Maybe the fire-cooking, rock-throwing domesticating niche is just that competitive.

So it might be more like "we are the ones that remain", but yeah, either variant is a spin on the old weak anthropic principle, which is never quite satisfying.

And we do seem to have wiped out/outcompeted Neanderthals etc.

> fire-cooking, rock-throwing domesticating niche

Just knowing if that was the evolutionary pressure along the path would be enough for me (even if it could have been another ape or a corvid or whatever - or maybe they are on that path now?)

BTW Matt Ridley has the theory that division of labour (trade enabling specialization) was the gradient.

Just because there's no detail, or it's not satisfying, doesn't mean it's less likely.

> why are we the only intelligent animal on Earth?

The process is not stuck in time. If we disappeared, another ape (or some other animal) might get where we are eventually, through some other path.

I've been inclined to think it has something to do with communication and community-forming tendencies. It seems that a number of other species, including Octopuses and African Grey Parrots, have pretty significant intelligence for animals. Yet their greater intelligence than most other animals doesn't seem to get them a really game-changing advantage over them. Human intelligence, or perhaps communication and organization in combination with them, has given us a series of game-changing advantages in a row, so many that our civilization is utterly dominant over any area where we choose to be.

I believe there is some evidence to suggest that we have not always been the sole intelligent species on the planet.

Notably there is some speculation that Neanderthals were of equal or similar intelligence to early humans

Perhaps arguing semamtics, but Neanderthals (Homo sapiens neanderthalensis https://wikipedia.org/wiki/Neanderthal) were "human": could interbreed, and had Lucy etc as common ancestors.

This article glosses over it but I think the answer is cooking. Cooking took pressure off our digestive system which allowed us to stack it up vertically.

Richard Wrangham wrote a book on this "Catching Fire: How Cooking Made Us Human"

I think that's a trong contender for biggest contributer.

Natural food was was less calorie dense back then. I wonder if we reached a point where we could consume the most calories per pound of our own body weight, and never looked back.

> why didn't all animals in the region become intelligent

Because humans took over that "being intelligent" niche and outcompeted everyone else who tried to capitalize on intelligence.

Speaking in Venture Capitalists language, humans "sucked the oxygen from the room".

> why are we the only intelligent animal on Earth?

Are other animals not intelligent? Are you sure we are intelligent?

I guess that the difference between apes and humans would be minuscule to the outside observer.

if you are interested I have good article for you listing some differences between humans and animals http://staffwww.dcs.shef.ac.uk/people/A.Sharkey/2008-darwin....

You can argue for their intelligence, but they can't argue for yours.