I decided to make a post about this for no other reason than to have it addressed, as I find it very interesting. Discussion welcomed and encouraged.
There are two given explanations for how the avatars in the Avatar universe are created in the first place, both of which pretty starkly contradict each other.
- The first is the one we hear and see used in the film and most other canon material. "They grow them from human DNA mixed with the DNA of the natives". This explanation presumes that scientists literally mix the DNA of humans with the DNA of Na'vi to create a hybrid creature - and thusly avatars are most commonly referred to as "hybrids". Some genetic manipulation is involved in the process but this method asserts that avatars have a percentage of human DNA and genes in them.
- The other comes from Pandorapedia's page on the AVTR program and the Dark Dreamer Project. This explanation describes the process of creating avatars as running the genes of the human driver through a "translation table" that converts them to a closest match to a Na'vi gene. This creates a sort of "resonance" and "footprint" of the human DNA, but there is no actual human DNA carried by the avatar by the end of it. This would make the avatars not hybrids, but more aptly a subspecies of genetically modified Na'vi. The reason this is done is because the Na'vi do not even have DNA or RNA, they encode their genetic information in a different process from humans which facilitates the need for a more complex way of 'combining' the genes, in order for the avatar to be a close enough match to the driver for linking to be successful.
Now, which is the correct explanation? People seem to prefer the first as it is what's most commonly described in canon material. However, this explanation comes with many scientific questions and issues which the Dark Dreamer Project theory seeks to remedy.
- Humans cannot even reproduce (combine DNA) with our closest living relative, chimpanzees. The concept of combining DNA with an alien seems quite farfetched, especially since we don't see that many other weird animal hybrids existing in the Avatar universe. One can argue that the technology of humans has progressed far enough to make this possible, but it still begs the question of how.
- Great, so scientifically speaking, the first explanation seems less likely. But that still doesn't explain why, if the Dark Dreamer explanation is the correct one, why descriptions of avatars in-universe seldom match it. One can argue that Jake is not scientifically minded or knowledgeable, so his explanation of avatars and how they work is simply his way of conceptualizing the process, and in turn it's easier for audiences to understand put like this. But even within the Activist Survival Guide the process is described this way even though the ASG is meant to be an in-universe document.
- If avatars are truly human/Na'vi hybrids, how do they reproduce with Na'vi successfully? As we observe here on Earth, hybrids generally possess fertility issues, much of the time even being completely sterile, yet Jake Sully and Neytiri successfully produced not one but three children together (presumably).
- This was not actually known in 2009, but identical twins (such as Jake and Tom Sully) do not actually have identical genomes. They have very similar genomes, but there are differences nonetheless, which would mean that - if avatars did carry human genomes - Jake would not be a viable match because he still has a different genome. However, if the Pandorapedia explanation is to be believed, then all that's needed for a successful linking is a resonance of the genome, a 'close enough' template of the human driver. This would presumably allow identical twins to link with each other's avatars as their resonant genetic footprint is similar enough to one another.
- This also makes sense in the context of the Pandora: The World of Avatar theme park. During the Flight of Passage preshow, riders are matched to premade avatars that resemble their genetic information just enough to allow for linking to occur and removes the need for lengthy genetic sequencing and gestation of individual avatars for individual people. It should be noted, though, that much of the park lore is... well, for the park. It has no other basis in canon and you're just expected to suspend your disbelief for a while for the sake of immersion and fun. Obviously, there are probably not magical lanterns in the Avatar universe that make the air of Mo'ara breathable, and the Alpha Centauri Expeditions probably does not, within the metanarrative, actually sell things like Na'vi ears and tails to guests, as general examples. So take this point with a big grain of salt.
However, the Dark Dreamer project/Pandorapedia explanation presents issues of its own.
- If it's true that the avatars are really just Na'vi with human-ish features, then they are, as stated, not their own species and they are not hybrids, they are more fittingly a subspecies or subgroup of Na'vi.
- This explanation only appears on Pandorapedia. The film, ASG, and other sources of canon material never address it, which might mean that it's outdated and might eventually be removed from PP and/or retconned out of existence.
- There's probably more, feel free to comment.
I think the truth might lay somewhere in the middle but in all fairness it's difficult to conceptualize and describe a scientific process that doesn't even exist and is years ahead of our current advancements.