I'd think a tail is an advantage whether on two or four legs as it assists with balance, although there is always the possibility of specific environmental conditions. It's likely that most precursor species did have tails, while the closest living species to humans also lack tails, so it would have been lost in a common ancestor at a point of divergence.

I agree with HumanNoMore; maybe genetic engineering can solve this in the future :)

But genetic engineering doesn't work (easily) on pre-existing creatures. :(

Not to mention expenses...

There are quite many neat things in the world, but they are not affordable for most.

@Clarke: I know; genetic engineering would need to be implemented in vitro for a macroscopic effect. To get the same effect later in life would require a combination of genetic engineering and surgery.

@Aquaplant: That is somewhat true. Genetic engineering coupled with surgery could get to be on the order of $100,000.

It's possible - it just won't cause a tail by itself without EXTREME modification (re-engineering the entire metabolism - lost limbs don't grow back, and the ability to regrow tails is limited to certain reptiles on Earth), but it could easily assist in the implantation of a synthetic biological one to assist in it taking.

Pandora itself as a planet is certainly more functional and beautiful than Earth, but we as a species obviously have much more technological advancement than na'vi ;)

Only a fool or a rather crafty individual goes anywhere without a decent set of useful tools. Seeing as we are not all MacGyvers, we tend to need convenient things to get stuff done, but one must also take into consideration that many of the things we need to get done are quite redundant, but it's all a rather huge mess of things that I'd rather not delve into right now.

I completely disagree. I think it's probably easier for me to address each of those separately:

Antibiotics: Why couldn't we have antibiotics on Pandora? In fact, why couldn't we make antibiotics on Pandora, given the right lab equipment and raw materials? The answer is that there is no reason why we could not do so; antibiotics are completely portable to an alien world.

Physicians: Again, why couldn't we have physicians on Pandora? Hey, I myself want to go through med school, and I see no reason why if Pandora was found to exist I couldn't go practice medicine there.

Air conditioning: Why would you need air conditioning with all that water to cool you down?

Hot showers: That's just silly - that is not a necessity. There's no reason why you can't bathe in a stream.

Flush toilets: I'll give you this one; this would be hard to give up. I wouldn't like living without them, but I could get over it.

Concrete sidewalks: Why would you need concrete?

The Internet: With some development, the Internet could be ported to space, though there would be massive delays. There is already a protocol in the making that doesn't deteriorate over such massive distances called InterPlaNet. You can read more here.

I'm not pretending; I would fit there given the conditions mentioned above.

I couldn't agree more - take my example of the redundancy of hot showers mentioned above in the situation of living on Pandora, for example.

I think the implication is that the Na'vi don't have the technology to do any of that, and to have the technology, you need the infrastructure, and ATM, that infrastructure would get Eywa very annoyed. :P

I wouldn't mind not having flush toilets at all. What I would mind most would be no toilet paper. I mean Taking a dump in the woods and wiping with leaves might be funny the first time or two. But I was at a point where it was happening everyday. And it is not fun. There aren't that many leaves within arms reach. Your feet go numb after squatting for awhile. Leaves tend to rip much easier than toilet paper, and they're not nearly as smooth. However, it would appear Pandora has more, bigger, thicker, and fleshier leaves than Earth, so perhaps it wouldn't be as bad as it is here.

IIRC Eywa develops antibiotics and the like, so the Na'vi never really get sick. Or that might be from 880. Not quite sure, but if it is I assume it would be almost the same for the Na'vi. As for doctors, they seem hardy (CFC bones and the like), plus because of the denser air/lower gravity, there's not really as much of a fall risk. Maybe being hurt from hunting? I'm sure the Na'vi have natural medicines, and if they are hurt beyond help, they just accept it as Eywa's way.

Everything else about AC/showers/other creature comforts, I agree.

However, that's for those who want to be full-blown Na'vi. For Avatars I can see using medicines and doctors to keep the body in shape while the drivers learn to use it, and to maybe compensate for any "incompatibilities" with the environment that may arise.

As for humans, I'm sure all that stuff could be put into Hell's Gate, if it's not already there.

I suppose that's true - I wonder if Eywa would mind a few small, unnoticeable thing like a couple underground wires, so long as nothing was damaged or disturbed.

Very true, but I bet you're right - Pandoran leaves would be better.

Antibiotics, yes. In fact, a lot of the antibiotics from modern medicine are derived from plants. But what about antivirals? It's really, really hard to kill a virus, and if it mutates, any previous immunity is gone. I'd think that would require artificial treatment...

I suppose that's true, but what if it was an accident that wasn't part of Eywa's plan? Or what's to say that modern medicine isn't part of her plan? That's definitely food for thought...

That's very, very true, and something I think is really important to note. All I would add to that statement is that it could also apply to those who became permanent Na'vi but did not want to integrate entirely. Science and medicine are very much needed, especially because procedures to make people Na'vi would not be perfect and would require alterations/responses to side effects.

That really depends on what the procedure entails. If it constitutes, "grow an Avatar, mind-transfer the owner over," than I can't really see how that would require post-op care.