Question: if you put an extra heart in somebody would it function differently and have a faster or slower heart beat than the other.

Thomas Biggans answered on 22 Jun 2016:

What I’d love for it to do is make that person into a time lord like the Doctor but unfortunately I don’t think that would be the case.

To start off I’m not exactly sure how you would plug it into the rest of their body but let’s assume you put it alongside their original heart so in essence they’ve doubled the amount of blood that can be pumped around because they’ve now got two hearts. However all the other organs would have to be able to cope with this, they might need their lungs to be double the size so they can breath in enough oxygen, all the arteries and veins which are the tubes that carry the blood around the body would have to be bigger and stronger to be able to carry around more blood without bursting open.

Assuming we figured out a way to put it in and everything else would manage, I think the second heart would work together with the first heart beating at the same rate because we’d probably have to connect it to the same nerves as the first heart so it would receive the same signals so their brain wouldn’t know it had two hearts it would just control them both exactly the same. But when they’re doing sports or something that requires a higher heart rate the brain would learn that it only needs half the heart rate because the work is being split between the two hearts so they’re not working as hard which means that might last longer leading to a longer life. There’s also the possibility that if one of the hearts stopped working properly the other heart would take over to avoid any damage to the other organs.

So in summary I think the second heart would function exactly the same as the original heart and both of them would beat together at a slower heart rate.