We Will Not Have Appendixes in the Future

""Hello, I am a useless pinky toe. Someday, you will be born without me.""

- Barbara, Phil of the Future

What better way to show the passage of time in Time Travel stories than by having humans lack appendixes and other vestigial organs? Progress!

Never mind that it takes millions of years for significant evolution like that to occur and the fact animals like whales and snakes (specifically snakes like boas, pythons, and slender blind snakes) have had vestigial leg bones for so long that it's unlikely that humans would shrug off their own vestigial organs anytime within a hundred thousand years.

Evolution is a result of natural selection, and there isn't much evolutionary pressure against having an appendix. If something is truly vestigial, there is little advantage in getting rid of it so evolution will be particularly slow in getting rid of vestigial organs, if it gets rid of them at all. Whenever a feature becomes useless to an animal it does tend to slowly disappear since genetic mutations that lead to its degeneration are not weeded out by natural selection. There is also the issue of the resources, minor as they presumably are, that the animal uses to grow these useless features; there is therefore some benefit to losing these vestiges, but there's not much in it.

Of course, this trope can easily be justified through genetic modification - the appendix didn't naturally evolve away, humans simply altered their own genome to weed out the junk.

A note on the appendix itself: The appendix has historically been thought a useless, vestigial or even dangerously self-destructive organ, but Science Marches On - it's still considered vestigial, but not necessarily useless. In the last few years scientists have begun to suspect that it is actually important to the body, as a reservoir of the "good bacteria" species that populate the colon and are necessary for digestion. When the colon's population is thrown out of whack by infection, diarrhea, or the like, the bacteria "hiding" in the appendix can recolonize it and return the necessary balance. There are also suggestions that this reservoir is used in training the immune system of babies and young children. It's still a lot easier to live without one than it is to live without any of your other organs, but it does seem to serve at least a non-vital purpose. This is what we would expected from evolution; if you have something useless hanging around, it can be repurposed. Moreover a smaller appendix might more easily become infected, putting up a barrier to it's fading away and selecting for a larger apendix.

Incidentally, shouldn't the plural of appendix be appendices?

Do not confuse with We Will Not Use an Index In The Future. Also see We Will Have Perfect Health in The Future and Evolutionary Levels.

Comic Books

 * The Legion of Super-Heroes would have us believe that in 1,000 years humans will grow an extra heart. Forgot the fact that an extra pump in our chest would cause more problems than it would solve.
 * European comic boy genius Olivier Delabranche invents a two-person scooter out of his school bag but then sleeps through class and dreams in class that human laziness will cause evolution to phase out toes... then feet, legs, hands why not? Until humans are big brains on wheels. When he wakes up, he smashes the scooter with a rock, repeating over and over "I don't want to be a brain on wheels!"

Literature

 * Isaac Asimov seems to be fond of this trope, though his uses of it generally do not have the quality of You Fail Biology Forever as usual.
 * He employed this trope in A Pebble in the Sky where Imperial officials realize the main character is a time traveler by the fact he has wisdom teeth and an unusually large appendix. Justified by the fact, which would increase mutation rates vastly. How much time passed between the "present" in A Pebble in the Sky (1950s) and the Empire is disputed in the Robots/Empire/Foundation fanbase.
 * This is actually a plot point in Asimov's The End of Eternity, when two of the main characters, both time travelers, who were born three million years apart notice that the only difference between them is the lack of wisdom teeth and the lack of appendix in the one from the later time. They (perhaps hastily) draw the conclusion that Eternity was trying to prevent human evolution.
 * While it is not employed in Part 3 of The Gods Themselves, the eugenics-conscious moon government wants to use genetic engineering to get rid of various organs they consider unnecessary, like molars (the artificial food of the Moon requires little chewing).
 * The interesting thing about this trope in Asimov's works is that he is a biochemist; where, exactly, this trope pops up is purely a property of Science Marches On.
 * The genetic manipulation side is handled fairly well in Schismatrix. The Shapers are engineered to not only go without appendices, but also to not need any of the bacteria humans currently need to digest food properly, allowing Shaper habitats to be free of any non-engineered nasties. Unfortunately for them, not everybody has this advantage; Shapers going from the aseptic environment to a bacterial one tend to get diarrhea, nausea and horrible rashes. Non-Shapers living in their habitats have to agree to get their intestines pumped and eat regular doses of foul-tasting yoghurt full of digestive enzymes to make up for it.
 * This is exhibited by the children in Nicole Luiken's Violet Eyes.
 * H.G. Wells designed the Martians in War of the Worlds by turning this trope Up to Eleven: he started from a humanoid body plan, then stripped off everything -- limbs, digestive tracts, sexual reproduction -- that he thought mechanization and/or medical technology could potentially make obsolete. All that he left them was a giant head, a few tendrils for pushing buttons, and the ability to breathe. Instead of eating, they drain captured aliens and humans of blood and inject it into their bodies.
 * The futuristic anatomical doll in the short story "Mimsy Were The Borogroves" lacked an appendix, and a distinguishable large intestine for that matter. It also had at least one entirely new organ system, suggesting changes were engineered rather than evolved.
 * The Wind Whales of Ishmael features a race of four toed future people.
 * The Hive Series by TJ Bass features a race of Nebish - four feet tall, four toes, pink blood due to lack of hemoglobin...
 * In the Doctor Who New Adventures spin-off novels, the companions Chris Cwej and Roz Forrester have no appendices. They're from the 30th Century.
 * In Mikhail Akhmanov and Christopher Gilmore's Captain French, or the Quest for Paradise, the titular protagonist has 2000 years (subjective time) or 20,000 years (objective time) over his new wife, who is only in her 50s (but looks 20 thanks to the omnipresent cure for aging). The first thing he does after taking her onboard his ship is to have her examined by the ship's Auto Doc. The doc revealed something horrible to French - she still has an appendix. Angry at the carelessness of her home planet's religious fanatics, he has the Auto Doc remove the "offending organ" despite the fact that it there was nothing wrong with it.
 * The Lunar people of I, Weapon have engineered away belly-buttons and bodily hair because neither is considered important in the colony. Pregnancies are handled via test tubes and body hair clogs the air filters.

Live Action TV

 * This trope was facetiously employed in Phil of the Future when Phil ran into a problem: he would have to be seen barefoot to stamp tomatoes in a farm on a class trip, but in his time, no one has pinky toes. To quote Phil's mother "They won't lose their pinky toes for another 70 years." Ironically, pinky toes are actually used for balance.
 * In The Big Bang Theory, Sheldon argues that his pinky toes and lateral incisors are smaller than average, indicating that he is a more advanced form of humanity, a "homo novus", and thus is too evolved to learn how to drive. Leonard would beg to differ, but doesn't bother.

Tabletop Games

 * In GURPS: Transhuman Space No Appendix is an advantage that the Alpha genetic upgrade and Zisudra parahuman have, both templates are intended to be an "ideal" human.

Western Animation

 * Parodied in Dr. Katz Professional Therapist: when Ben is due to have his wisdom teeth removed, Laura mentions she never had them, which her dentist attributed to her being "more evolved". They end up getting into an argument over the veracity of the statement.
 * Also parodied in The Simpsons, where a news report says that scientists predict people will evolve an additional finger in the future. Characters on the show, of course, have only three fingers and a thumb on each hand.
 * In the episode "Lady Bouvier's Lover," Homer is worried that Abe marrying Marge's mother would make him and Marge brother and sister, and as a result turn the kids into "...horrible freaks with pink skin, no overbites, and five fingers on each hand!"
 * For those who never seen this episode, right after Homer says this, the camera points at the kids, who instead of being drawn in the Simpsons style, are drawn "horrifically" normal.

Real Life

 * Some people are now born without their wisdom teeth
 * On the opposite end, some people don't need to get them pulled.