Doctor Who season 10 episode 2 (or series 10 installment 2, if you prefer the UK nomenclature), Smile: in one scene, a smiley-robot (or Vardy interface) puts out some food for The Doctor and Bill. The interesting part is that it puts two blue cubes on one plate, but only one blue cube on the other. Bill initially suspects the future is still sexist, but The Doctor surmises that the robot has been confused by his two hearts.

The problem is, that's not the first interaction between the robots and the Doctor. A few scenes beforehand, they're handed little smiley-badges, and they each get just one. If the Doctor's two heartbeats make him "count twice", then shouldn't he have been issued two smiley badges?

And for that matter, why are there only two plates? Clearly, the robots are counting people, not heartbeats. So why the unequal distribution of food cubes?

  • 1
    This is an excellent question.
    – Mikasa
    Apr 27, 2017 at 21:22
  • 1
    What if the first robot recognized number of mood-emitting biomasses?
    – DonFusili
    Apr 28, 2017 at 5:58
  • 2
    Just a small FYI...we don't typically use "instalment" in that sense here in the U.K. We use series/episode.
    – Andy
    Apr 30, 2017 at 9:15

5 Answers 5


I just had an inspired thought (for some meaning of "inspired", anyway): I think the Vardy-interface is interpreting the doctor's two heartbeats as a pregnant human.

This handily matches all the premises and explains the outcomes: the robots are preparing the planet for humans, not time-lords, so they have no reason to have any special programming related to time-lord physiology. Hence, when presented with a phenomenon that looks unusual, they go with the explanation that matches human physiology. In humans, what does two heartbeats in one body signify? Pregnancy, obviously. So they only issue one badge, since an unborn baby's happiness is not exactly separable from its mother's; but they issue extra food rations (on one plate), because, well, "eating for two".1

1 Yes, yes, I know, that's a myth - pregnant women don't actually need twice as many calories as non-pregnant women. No fair messing up my lovely theory with pesky facts.

  • 14
    Correct me if I am wrong, but I was under the impression that pregnant women do need more calories and nutrients, (and especially specific nutrients) than non-pregnant women? Not double, but more. Was the cube supposed to be the entire day's fare?
    – sharur
    Apr 28, 2017 at 0:18
  • 20
    @sharur: the additional calorie requirements of pregnancy tend to be... disappointing, especially if you were imagining finally being allowed to eat all you want. Third trimester, we're talking maybe an additional 400-500 calories per day. (Earlier in pregnancy, it's even less.) But "eating for 1.2" just doesn't have the same ring to it.
    – Martha
    Apr 28, 2017 at 4:05
  • 2
    As usual with such matters, it's not a simple answer. ncbi.nlm.nih.gov/books/NBK235247 Apr 28, 2017 at 8:32
  • 2
    @KCWong the range of efficiency of nutrient extraction in a human body is large so although measurements are based on the mother's needs (the placenta uses quite a bit in the early stages too) this doesn't necessarily account for input. This is a fascinating topic, especially when you realise that there's a reasonable recent hypothesis that the limit to gestation is metabolic, i.e. when the mother can no longer provide for the foetus to grow while carrying it internally.
    – Chris H
    Apr 28, 2017 at 8:34
  • 3
    Thanks Martha, GeoffAtkins and Chris H. I understand it's a difficult subject to research... I've read about researchers following up on the development of children whose pregnant mothers were affected by the effects of 9-11 and getting isolated in a snow storm for weeks. The researchers describe those as rare opportunities, as such experiments would be otherwise inhumane.
    – KC Wong
    Apr 28, 2017 at 9:24

Warning! Low quality answer incoming! (But series-appropriate IMHO, having seen a Christmas Special or two: "How does Santa fit all those presents in his sleigh?" / "It's bigger on the inside")

For the smiley stickers, the robot that issues those is probably counting faces rather than heartbeats. (No rule that says they all scan for the same thing, is there?)

For the two cubes on one tray rather than two cubes on two trays; in addition to counting heartbeats, the system probably also recognizes proximity of the heartbeats to one another - it probably figured the Doctor was a pair of Siamese twins or something, so two cubes on one tray.

  • 8
    Alternatively, the system could be doing an analysis of caloric needs, and serving size is adjusted appropriately. Men generally, per the health organization data I've seen, are recommended higher caloric amounts. This would be even higher if the man in question had two hearts (and the more complex cardiovascular system this implies).
    – sharur
    Apr 27, 2017 at 21:15
  • 11
    True enough. After all, the Doctor is just guessing that that's why he got two food cubes.
    – Steve-O
    Apr 27, 2017 at 21:18
  • @Steve-O Does he ever guess wrong?
    – Shane
    Apr 28, 2017 at 17:00
  • 1
    @Shane can't really answer that without definitive evidence of the correct answer to every guess he's ever made.... I'm not invested in the show enough to go find that. =P
    – Steve-O
    Apr 28, 2017 at 17:58
  • 2
    I did notice / it was noticeable how many "wrong" guesses the Doctor made in this episode. Without getting into spoilers, it seemed he came to one conclusion, it was mistaken, picked a course of action, realized it was a mistake -- far more than usual. It seems he might be making more mistakes in his old age?
    – michael
    Apr 29, 2017 at 9:13
  1. The smiley indicates the emotional state of the person. The Doctor has only one emotional state, like normal humans.
  2. Hearts are used to push nutrients through the body. If you have two, it's a reasonable assumption that you need double the nutrition and calories
  3. If your goal in life is the happiness of your people, feeding them more is always a good bet (see the cruise ship industry). If I don't know more about you than a simple physical scan, I'm going to err on the side of feeding you too much, rather than too little

I think the Vardy-interface is discriminating, but not by sex but by worth. Not because he's a man, but because he has two hearts.

Machines that fulfill important roles have redundant critical systems, so a human with two hearts might be deemed as more critical, and thus, more important by the machines. That would deserve double the ratio in a non egalitarian society.

Another explanation involving double the calories but a single smiley face and plate would be that, from the machines perspective, such 'active' redundancy (two hearts) increases resource consumption by some function, but a safe assumption is usually directly linear. So double systems = double cubes.

  • This seems highly unlikely. There is no reason (that I know of) to think that a human with redundant hears are move valuable than any human with only one heart. In fact, people with redundant hearts often have a lot of problems because of it and cost more to keep around (i.e. less valuable).
    – Clearer
    Apr 28, 2017 at 11:32
  • 2
    @Clearer "Machines that fulfill important roles have redundant critical systems, so a human with two hearts might be deemed as more critical" It doesn't make sense to us, but we aren't sentient robots.
    – Shane
    Apr 28, 2017 at 17:02
  • 1
    @Clearer true,but if one heart fails it is minor inconvenience so to a robot that might signify that the human cannot ever go offline, signifying it might be an important leader or genius who cannot ever risk death. Of course, double hearts are never good but that doesn't mean the robot couldn't determine a successful and healthy individual with two hearts and therefore make the appropriate conclusion.
    – user64742
    Apr 28, 2017 at 23:20
  • @Clearer You are right, for humans, it does not measure worth, and it's not even a biological advantage. But those machines didn't have perfect information, or not even slight knowdeledge of modern "timelord with human companion" ettiquette (or they would've put the same amount of food on both plates). So the question revolves around where did the machines reasoning fail, or what wrongful assumptions did they make. Mine's a theory as any.
    – Oxy
    May 2, 2017 at 9:09
  • 1
    @Clearer Sentient meat. terrybisson.com/page6/page6.html
    – Shane
    May 2, 2017 at 14:26

They guessed he may be two conjoined identical twins

  • 1
    Can you provide any sources for your answer?
    – Edlothiad
    Apr 29, 2017 at 16:27
  • Do any of these answers have a “source”? This answer is simply a low quality duplication of an idea posted in a prior answer. The correct flag is VLQ.
    – JDługosz
    Apr 30, 2017 at 7:16
  • 1
    Wouldn't conjoined twins also need 2 emotion badges? May 1, 2017 at 17:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.