Why We Haven’t Had a Female Doctor Before Now

INT. TARDIS
The 13th DOCTOR enters the Console Room. She is eager to start a new adventure. Her male companions, GAVIN and JIM are waiting for her.

GAVIN: Are you OK, Doctor? You look tired.

DOCTOR: I’m fine. I just haven’t put my makeup on yet.

JIM: You don’t need to wear makeup, Doc. I think girls are way prettier when they’re natural.

DOCTOR: I’ll take that under advisement. Now! We are currently orbiting the planet Xygggha, which-

JIM: When you think about it, makeup is kind of false advertising.

GAVIN: Yeah, like padded bras.

The Doctor rolls her eyes.

DOCTOR: As I was saying, Xygggha is dangerously close to falling to the Cybermen. Think of it, an entire planet of civilizations, gone. But we can stop it from happening.

GAVIN: How do you know?

DOCTOR: Know what?

GAVIN: How do you know the planet doesn’t want to be controlled by the Cybermen?

JIM: Yeah, how hard could they really be fighting back?

DOCTOR: Are you suggesting Xygggha wants to be overrun with Cybermen?

GAVIN: Well what evidence do you have that they don’t?

DOCTOR: I’ve seen millions of lifeforms eradicated by Cybermen. Their consciousness wiped out and replaced with a soulless machine. If you’ve heard the scream when it happens…

JIM: But that’s just your experience.

GAVIN: Where’s the data?

DOCTOR: I’VE TRAVELLED ALL OVER SPACE AND TIME! I AM THE ULTIMATE LONGITUDINAL STUDY!

JIM: Whoa, calm down!

GAVIN: No need to get so emotional.

JIM: (whispered to Gavin) Someone’s on their space-period.

DOCTOR: Gallifreyan biology doesn’t work that way.

JIM: Actually, I went to college for veterinary science, so I think I know what I’m talking about.