In "Fantastic Beasts and Where to Find Them", the main character (Newton Scamander) meets a muggle (Jacob Kowalski) who is bitten by a Murtlap.

Thats definitely the Murtlap. You must be particularly susceptible.

Then Newt says:

See, you're a Muggle. So our physiologies are subtly different.

How do muggles and wizards differ? If the only difference is exposition to magical creatures then muggle borns should also have different physiologies. What about Squibs, do they share the same physiology as wizards or muggles?


2 Answers 2


In the world of Harry Potter, magic manifests itself in physical beings. This is the subtle difference that Scamander is referring to.

Wizards for example are susceptible to magical ailments such as Dragon Pox, which simply doesn't exist in any Muggle medical dictionary. Likewise Muggles are much more prone to injury or death from physical harm - even as young children wizards often find themselves unknowingly 'magicking' themselves out of dangerous (but non-magical) situations. Neville for example was dropped out of a window by his great uncle, and bounced around the garden. Harry, when chased by Dudley and his bullies, somehow found himself on the roof of his school, out of harm's way. Remember also Hagrid's outrage at the very idea that Lily and James Potter could have been killed in a car crash.

So this magic running through the veins of witches and wizards gives them subtle differences in their physiology, making them more resilient to some things while more vulnerable to others.

As a side note, this helps explain why so many magical people live for so long - the kinds of accidents that might harm a Muggle just aren't as dangerous to them.

  • 1
    According to this page, the reason Muggles don't get Dragon Pox and other wizarding illnesses is because the Statute of Secrecy prevents muggles from coming into contact with the diseases, not because they are immune.
    – Laurel
    Mar 25, 2018 at 17:55
  • 3
    @Laurel That seems an odd explanation - there are plenty of instances where we see magical people in contact with the Muggle populace; the entrances to the Ministry of Magic, St Mungo's and Platform 9¾ are all in the middle of Muggle London, for a start.
    – Cooper
    Apr 9, 2018 at 16:13
  • I did like how one fanfic dealt with dragon pox; it postulated that dragon pox and chicken pox are caused by the same microbe, but you only get dragon pox if you catch it from a witch or wizard, otherwise you get chicken pox. JKR's subsequent work deep-sixed that theory.
    – EvilSnack
    Oct 21, 2021 at 16:47

According to one Wizarding theory, Muggles and Wizards are entirely different species.

Hambledon Quince
1936 - present
Author of controversial theory that wizards originate from Mars, Muggles from mushrooms.
Wizards of the Month section of J.K. Rowling's old website

Of course, bear in mind that this is a controversial theory in the Wizarding World, and it likely hasn't been proven.

  • 8
    In muggle science, that wouldn't pass muster, because if they were different species they wouldn't be able to produce viable offspring.
    – ConMan
    Nov 28, 2016 at 22:30
  • 4
    @ConMan not necessarily, as we see things like Mules and Ligers in the real world. Because they're different species, it doesn't necessarily mean that cross-breeding won't produce viable offspring.
    – CBredlow
    Nov 28, 2016 at 23:24
  • 4
    Although in most cases (I stand corrected about ligers, having checked the Wikipedia article), said offspring are not viable in the sense that they themselves cannot produce further offspring.
    – ConMan
    Nov 28, 2016 at 23:30
  • 12
    The thing is, in-universe, this theory was probably manufactured to support pureblood supremacist ideologies. It’s probably meant to be a parody of (among other things) eugenics theories.
    – Adamant
    Dec 7, 2016 at 8:33
  • 4
    @CBredlow the whole definition of "species" is build around groups of animals that can breed with other groups but only within group. In reality, species is just a way to communicate with other people about specific groups of animals. However, although the thing with muggles is quite funny (in fact, animals and fungi are sister groups), if trully wizards originated from mars and muggles from mushrooms, they would be too distantly related for this to work.
    – Colombo
    Jan 16, 2017 at 22:46

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