Throughout Avatar and its sequel, Avatar: The Way of Water, human Avatars are shown to have five fingers, while the indigenous Na'vi only have four (in addition to other, less immediately obvious biological differences). James Cameron brought audiences back to Pandora in December 2022 with the much-anticipated follow-up. Avatar: The Way of Water picked up over a decade after the first film in narrative as well as release date, showing Jake and Neytiri living happily with their growing family before humanity re-enters their lives. Avatar introduced the idea of remote-piloted Na'vi Avatars — lab-grown bodies designed to allow human scientists to interact with the native Na'vi, and to explore Pandora much more thoroughly.
At first glance, it would be hard to determine which bodies were Avatars and which were Na'vi, as they both share strikingly similar features including their height, coloring, bone structure, and hair, however, there is one major difference between them. While the Na'vi have evolved to have four fingers on each hand, the Avatars have five, just like any other human. This became an important plot point in The Way of Water, as many were still untrusting of Jake because he shared physical features with humanity, who had caused a huge amount of destruction in the previous war.
How Avatars' Biology Works
By 2154, when Avatar takes place, humans have made huge technological advancements, most notably in the fields of genetic engineering and psionics, which has allowed them to create secondary bodies that genetically-matched human pilots can connect to. The Avatar bodies were designed in order for humans to fit in with the indigenous Na'vi of Pandora, so they needed to look like them and share specific characteristics. For this, genetically modified human DNA was mixed with Na'vi genetic material and then grown into a fully-formed body.
The genetic match between the human pilot and the Avatar itself means that the human can literally transfer their consciousness into the Avatar body, and live inside it as if it were their true physical form. This is what allows Jake Sully to integrate so easily into the Omaticaya clan, and eventually, with the help of Eywa, transfer his consciousness permanently into his Avatar. Even so, the human component of the Avatar DNA means that the Avatars are different from the Na'vi, with slight differences in facial structure, smaller eyes, eyebrows — and of course — the difference of them having five fingers, instead of four like the Na'vi.
Why Two Of Jake's Children Have Five Fingers Instead Of Four
Avatar: The Way of Water introduced Jake and Neytiri's children, but while three of them share Jake's characteristic of five fingers, the others have four fingers like their Na'vi ancestors. Kiri, the daughter of Grace Augustine's Avatar, has five fingers as she was born from Grace's Avatar body, and though her father hasn't been revealed, theories range from her sprouting from Grace's communion with Eywa, or an illicit relationship with Norm Spellman, another Avatar. Spider, their other adopted child, is the human son of Quaritch who was abandoned in Hell's Gate at the end of Avatar, so he has retained his five-fingered human trait.
While Jake and Neytiri's oldest and youngest biological children, Neteyam and Tuktirey "Tuk", have four fingers, seemingly taking after their mother, their middle child, Lo'ak, has inherited five fingers. This informs a lot of Lo'ak's feeling as an outcast, but is also interesting to note as it appears that Na'vi DNA could be more dominant. Perhaps the human DNA in the Avatars are the recessive genes, creating yet another bleak statement on humanity delivered in Avatar and Avatar: The Way of Water.
James Cameron Has Teased That New Na'vi Cultures Will Have Different Physiologies
While the Avatar finger certainly stand out, there will be more differences between Na'vi cultures explored in future movies. It has been confirmed that the Avatar sequels will introduce new tribes and cutlures of Pandora, and each new installment will showcase both the environments the new Na'vi cultures live in and how these habitats affect their biology. When discussing the eventual introduction of a nomadic tribe on Pandora, James Cameron stated that "we had to do cultural design and imagining what these different Na’vi adaptations to these different biomes might look like."
While the Na'vi's war with the "Sky People" has been the main focus of the Avatar movies thus far, the promise of new Na'vi tribes is the most exciting aspect of the new movies. Along with the desert-based "windtraders" that Cameron teases, there will also be the more ruthless "Ash People" tribe in Avatar 3 which seems to set the stage for conflict among the Na'vi themselves rather than just the colonizing invaders as in Avatar and Avatar: The Way of Water.
