"The Fifth Race" is the sixteenth episode of the second season of Stargate SG-1.


Colonel Jack O'Neill accidentally encounters a machine which downloads an entire Ancient database into his mind, and causes his brain activity to increase. He begins to be unable to speak English but only in a completely new language, Ancient. There is nothing the team can do to prevent the transformation, so O'Neill is forced to go his own way to save himself.


SG-1 visits the planet P3R-272 and find themselves in a room with a circular inscription in the middle. Colonel Jack O'Neill steps over the circle and immediately a device comes out of the wall. Teal'c looks in it but only sees blackness with colored lights. When O'Neill steps up and takes a look, the device grabs his head for a few seconds, then lets go and O'Neill collapses into unconsciousness.

SG-1 travels back to Stargate Command. O'Neill is checked for injury but none is found. While SG-1 is being debriefed by Major General George S. Hammond, O'Neill replaces common words with unknown ones. General Hammond then orders him to stay on base for a while so they can keep him under observation. O'Neill's language condition starts getting worse and soon he is replacing common words with unknown words more frequently ("cruvus" for wrong, "cosars" for knees and "falatus" for ability).

Jack, along with Teal'c, goes to Dr. Daniel Jackson's lab to see if they can find out what is happening to him. Daniel quickly realizes that the language is similar to Latin. A picture of the circular inscription from the planet is on Daniel's computer, which Jack can now read aloud, which he does well where 8 vocabularies can be heard clearly: "nu ani anqui etas hic qua vi deum". They discover that O'Neill is also able to read other writings that Daniel has been working on deciphering. O'Neill then writes a series of complex equations on a chalkboard in half a minute. The equations don't make any sense, even to Captain Samantha Carter.

O'Neill is taken back to Dr. Janet Fraiser for tests and it is discovered that he is using over 90% of his brain capacity at one time compared to 5 to 10% at any given time for a normal human (myth propagated for story purpose). Daniel speculates that the device downloaded an alien language into O'Neill's brain.

Hammond is then called to the Stargate Operations room. They find O'Neill entering a software program into the mainframe computer. Hammond then orders him to stop but O'Neill replies that he can't. Teal'c is then ordered to physically restrain him. When O'Neill's program runs, Carter informs everyone that it added new gate destinations, however they are not from the Abydos cartouche.

Back in Daniel's office, O'Neill (who has lost the ability to speak anything but the alien language) and Daniel are translating the circular inscription, either with or without complete understanding. It reads "We are the Ancients. This is the place of our legacy." Daniel, identifying them as Roman deities, speculates that:

  • the Ancients might have been the original creators of the Stargate
  • the device which grabbed Jack's head was a Repository of knowledge
  • the alien device downloaded that information into Jack's brain (or "visually injected")

Carter, perplexed by the equations, wishes that Jack could explain what the formula is all about; Jack responds by handing her a paper that says 10=8, this is to state that the equations are using base 8 math as opposed to the base 10 commonly used. It turns out to be a revolutionary way of calculating the distance between planets.

Dr. Frasier, after examining O'Neill further, concludes that the information is slowly taking over his brain. Jack can no longer speak English and is in danger of eventually dying.

The SG-1 team, minus O'Neill and Daniel, are sent off on a mission to one of the new gate addresses (P9Q-281) in the hope that there they might find new information to help Jack.

Meanwhile, Jack starts building a device which he himself doesn't know the purpose of. After he completes it, Daniel tells O'Neill that SG-1 is trapped on P9Q-281 because the Dial Home Device (DHD) is stuck mid-dial. SG-1 is in trouble because a second sun has risen up on the planet, which will roast the team alive. Jack draws and writes very detailed instructions on how to fix the DHD, which are then sent through the gate to the team. SG-1 returns home safely but were not able to find anything which could help Jack's problem.

Soon after, the computer dials a gate address and cannot be overridden. Carter informs Hammond that the gate needs more power to activate. Meanwhile, Teal'c and Jackson follow O'Neill to the power room, where he hooks up the device that he made. Carter then tells Hammond at the control room that the Gate has suddenly obtained the amount of power it needed.

The Gate dials on its own, and a wormhole is established at its eighth chevron (instead of the normal seventh). Jack, Daniel and Teal'c then enter the control room and Sam figures out that the gate has dialed outside of the Milky Way galaxy and the seventh chevron is for a distance calculation to that galaxy. Hammond allows O'Neill to go through the gate, but without an GDO for safety precautions.

O'Neill, upon arriving on the other side, makes contact with the Asgard. The Asgard remove the memory of the Ancients from his brain. They explain to him that the information was not meant for him as his brain was not developed enough for it. However, his subconscious mind brought him to Othala, in the galaxy of Ida where he could get help. They have been monitoring Earth for some time and discovered that the humans of Earth have great potential.

The Asgard inform him about the Ancients and how there was an Alliance of Four Great Races (the Ancients, Asgard, Nox, and Furlings), and that O'Neill's race is advancing to become the Fifth Great Race and he had taken the first step. O'Neill is then sent home through the Stargate with none of the Ancient knowledge. He expresses faith in humanity's future, hinting that with regards to "The Meaning Of Life," the Asgard have told him that "we are going to be OK." The program that O'Neill had been writing earlier allowed him to return without an ID device.


Appearances for The Fifth Race




Sentient Species





Notable quotes[]

O'Neill: Well... this was an intergalactic waste of time.
Carter: Well, wait a minute, sir. Where's the power for the lights coming from? What's the point of this place?
Jackson: (shouting at the ceiling) Hello? Hello? I'm Daniel Jackson, we're peaceful explorers from the planet Earth. (O'Neill makes a disbelieving face at him) It's worth a try.
O'Neill: Daniel... how long ya figure we oughta hang out here and scratch our cosmic heads?

Hammond: Colonel, are you sure you're okay?
O'Neill: I am absolutely fine. There is nothing cruvus with me. (everyone looks at him) What?
Jackson: You just said there's nothing "cruvus" with you.
O'Neill: I did not.
Jackson: Yes you did.
O'Neill: No I didn't.
Jackson: Yes you did.
O'Neill: Didn't.
Jackson: Did.
O'Neill: Didn't.
Jackson: Did.
O'Neill: "Cruvus"? What is that?
Jackson: I don't know.

Teal'c: What is the reason for these padded gloves, O'Neill?
O'Neill: So we don't hurt each other. I'll be honest with you, Teal'c. It's so you don't hurt me.
Teal'c: If our purpose is to not cause each other harm, why then are we doing battle?
O'Neill: What can I tell you? It's boxing. It's fun, come on. (begins to bounce around in front of Teal'c) C'mon, Teal'c, you gotta move around a little bit. You gotta dance.
Teal'c: I do not understand, O'Neill. Are we preparing to dance or to do battle?

O'Neill: Alright. What the hell is going on with me?
Jackson: What do you mean?
O'Neill: Well apparently I have lost the falatus to speak properly. That wasn't a joke. I didn't do that on purpose.

Jackson: Well my translation's a little bit vague. I think the circle means "the place of our legacy." Or it could be "a piece of our leg," but the first seems to make more sense.

Hammond: Colonel?
O'Neill: Yes sir?
Hammond: What are you doing?
O'Neill: I don't know, sir. You know me and computers.

Carter: What's it doing?
Tech: Chevron Eight is locked.

Hammond: Colonel! I'm just supposed to let you go?
Jackson: He's already gone, General. I don't think we have much of a choice.

O'Neill: Why did I come here?
Asgard #1: The Ancients moved on from our region of space long ago, but your subconscious mind used their knowledge to find us here, where you could get help.

Asgard #2: Very impressive..

O'Neill: You're the Asgard. Thor's race.
Asgard: You have heard of us?
O'Neill: Nothing but good things.
Asgard: We have studied your race closely.
O'Neill: Ah. What did you learn?
Asgard: That your species has great potential.
O'Neill: Great potential. That's good.

Asgard: Understand this: there was once an alliance of four great races in the galaxy. The Asgard, the Nox—
O'Neill: Met them.
Asgard: The Furlings.
O'Neill: Don't know them.
Asgard: And the Ancients. The builders of the Stargates. This alliance was built over many millennium. Your race has much to prove before we may interact at such a level.

O'Neill: You folks should understand that we're out there. Now. We might not be ready for a lot of this stuff, but we're doing the best we can. We are a very curious race.
Asgard: You have already taken the first steps toward becoming the Fifth Race.


Main Characters

Guest Stars


  • The Ancients are first mentioned in this episode.
  • In the subtitles for the Asgard, the word "Ancients" is spelled with a lowercase "a" but it is spelled with a capital "A" throughout the series later on.
  • In this episode, it is revealed that the Stargate can be used to travel to another galaxy by dialing eight symbols. However, it needs massive amounts of energy to do so, according to Captain Samantha Carter, at least 10 times the energy of a seven chevron address.
  • In the series finale, "Unending", Thor confirms that the Tau'ri have become the Fifth Race.
  • O'Neill later has another Repository of knowledge downloaded into his brain in "Lost City, Part 1." Unlike here, the knowledge remains in his brain for quite some time, forcing O'Neill to go into stasis until Thor can remove it in "New Order, Part 2." Like here, O'Neill is able to do several things with the knowledge, but seems to display a better more conscious control over it as time goes on unlike here when he has no idea what he's doing.
  • Its shown in "Lost City, Part 2" that along with granting knowledge, the Repository apparently grants the powers of the Ancients somehow though O'Neill displays none here. That may be because his condition was more advanced the next time when he displays the Ancient healing power that comes with Near ascension.
  • This episode is the first to feature the "10% of brain capacity" urban legend; it becomes common to Stargate episodes dealing with Ascension, e.g. "Tao of Rodney". Brain function imaging techniques show no large unused portions of the brain in humans or any other known organism. Such an arrangement would be highly inefficient: even the "unused" portions would still consume energy, otherwise those cells would promptly die off, and since the brain accounts for some 20% of the body's energy consumption, if the 10% myth were true then 18% of the body's energy expenditure would go to waste. Such a structure would be naturally selected against.
  • In the Australian and Region 2 releases of the DVD Box set, this episode is switched with "A Matter of Time". This order is also used on the Australian streaming service Stan, and the US streaming releases on Hulu and Amazon Prime Video.
  • Archive footages from this episode appeared in all following clip shows of the series. No different episode appeared in so many clip shows.


  • At the around 7:00 mark, Colonel Jack O'Neill tears the first sheet of paper from the clipboard and puts the clipboard on the table. A drawing identical to one he was just making can clearly be seen on the second sheet of paper (they probably printed multiple copies of the drawing for multiple takes, especially since O'Neill folds the paper twice before leaving the briefing room).

Other languages[]

  • French: La Cinquième Race (The Fifth Race)
  • German: Die fünfte Spezies (The Fifth Species)
  • Italian: La Quinta Razza (The Fifth Race)
  • Spanish: La Quinta Raza (The Fifth Race)
  • Czech: Pátá rasa (The Fifth Race)
  • Hungarian: Az ötödik faj (The Fifth Race)
  • Russian: Пятая раса (The Fifth Race)

Links and navigation[]

v  e
Episodes and Seasons
Season 1 12345678910111213141516171819202122
Season 2 12345678910111213141516171819202122
Season 3 12345678910111213141516171819202122
Season 4 12345678910111213141516171819202122
Season 5 12345678910111213141516171819202122
Season 6 12345678910111213141516171819202122
Season 7 12345678910111213141516171819202122
Season 8 1234567891011121314151617181920
Season 9 1234567891011121314151617181920
Season 10 1234567891011121314151617181920
Season 1 1234567891011121314151617181920
Season 2 1234567891011121314151617181920
Season 3 1234567891011121314151617181920
Season 4 1234567891011121314151617181920
Season 5 1234567891011121314151617181920
Season 1 1234567891011121314151617181920
Season 2 1234567891011121314151617181920
Season 1 12345678910