The Genetics and Evolution of Magic
Exploring
- How humans became magical
- Our evolutionary relationship with fellow magical creatures.
- The genes responsible for being magical and how they are inherited
- The existence of squibs and and unusual explanation for Muggleborns.
Magic will always be magic and the beauty is that it does not follow the laws of science or logic. It is something wild, unexplained and unknowable, but given this blog is all about semantics: I say to hell with beauty, let's douse Magic in science and see what strange hybrid ideas are produced!
The Origins of Magic
The most basic fact we know about Magic in the Harry Potter universe is that it is inherited. It is not an acquired skill like being able to ride a bike; it is most definitely a genetic trait. Therefore somewhere in the human genome sits one or more genes that make people magical.
In the Harry Potter universe humans are not the only wielders of magic. In fact there are many species sentient or otherwise, who have the ability to access and in some cases consciously control magic. However, their magic appears to be innate and of the wandless variety. Wands, it appears, are a very human necessity.
Humans can perform wandless magic too; Harry blew up his aunt, Dumbledore summons food to the tables at the Great Hall and Voldemort possesses people. Wandless magic is possible but it is definitely not something that is common or easy to perform. In fact you may need to be a very powerful wizard/witch in order to manage it.
This shows us that humans are not innately magical beings. We do not channel magic in the same natural way as House-elves do; Dobby could throw Lucius Malfoy across the room with a snap of his fingers. In fact the vast majority of the human species are not magical in anyway. They cannot perceive all beings of the magical realm, nor can they channel any magic.
Thus it is less likely that magic first arose as a spontaneous mutation, and more likely that the genetic material which gives people the ability to channel magic is not innately part of the human genome at all but introduced from another source. This means that unlike other magical creatures we have not evolved with magic, it is in effect an intruder into our evolutionary story.
There are two possible ways in which this can occur: through cross-breeding with innately magical begins or by infection (yes you read that correctly).
By definition different species cannot cross-breed and produce fertile offspring. However Fleur Delacour is proof that humans and veela can produce fertile offspring. Thus veela and humans may not be so different genetically that they can be classed as two different species. This interbreeding is not a far fetch fantasy notion, even as recently as 20,000 years ago there were at least two distinct sub-species of humans on Earth and there is now evidence that Neanderthals and Homo Sapiens did interbreed. The Neanderthals never truly went extinct they live in the DNA of many modern humans.
The veela decedents have some of the magical attributes of their non-human ancestors, subject to some dilution - for example Fleur is stunningly beautiful. Thus it is logical that at many points in human history there has been free exchange of genetic material between humans and other humanoid magical creatures through interbreeding.
The genes that confer magic may not be typical coding genes (i.e. genes that provide information for the production of a protein). Most evolution steps take place in genes that don't code for anything useful but instead control how other genes work through mysterious ways that scientists don't fully understand yet.
It may be that what the human race needed was a change in how the genes we already had performed their function.
The other form of genetic transfer is by viruses. Certain types of viruses can inject their own DNA strands into the host cell’s chromosome thereby adding to the genetic material inside the host. This is unlikely to make much of a difference to the host in the long term as a virus can rarely affect every cell in the body. However should the extra DNA end up in a gamete (or sex cell) that is then fertilised, the DNA would end up in all the cells of the resulting baby and if that extra DNA just happens to confer the ability to channel magic - you get a spontaneously magical baby.
Perhaps some of the muggleborns really don't have a distant wizard ancestor but were spontaneous magical babies.
An Evolutionary Advantage?
Having Magic appears to be a wonderful thing and it positively increases your lifespan by the order of the decades. You don’t have to be an evolutionary biologist to wonder why there aren’t more wizards and witches wandering
around. In fact, why hasn’t the entire human race become magical yet given the survival advantage?
In my first essay - Wizards, an endangered species, I have pointed out that using JK Rowling’s own figures: magic is rarer in humans than many genetic diseases.
Therefore the evolution of magic may confer a whole host of disadvantages as well. The most obvious disadvantage being that as a magical person you evidently attract the attentions of other magical races (some of which are definitely not friendly). You also end up being in close contact with and contracting disease from magical creatures.
However I would say that these disadvantages are just scratching the surface of the real problem with magic. We must remember that in order for genes to propagate people have to reproduce. Although wizards live longer than muggles, there is no evidence that they remain fertile for longer. In fact given how rare magic is, I suspect that the magical mutation may have decreased overall fertility. The books vary in terms of depicting family size, but we only have a very small sample size and we have to take into consideration war and inbreeding both of which would affect fertility.
Magic won’t be the first time that the human race has acquired new genetic material that was detrimental to our function. For
example: there is a distinct possibility that genes which give us autoimmune diseases came from our interbreeding with Neanderthals. As we acquired this alien genetic material recently rather than evolved with it, we have no defences against it.
I propose that magical genes have a detrimental effect on the very early stages of the developing human embryo. Most known miscarriages before 12 weeks are due to a genetic abnormality, and most miscarriages are unknown because they happen so early on they pass for a slightly late period. Perhaps the genes which confer magic, also have the unwarranted side effect of preventing the fertilized egg from growing in the womb.
Explaining Magic with Mice
Now we must address the age old question of how is magic inherited? And is there a particular gene or genes that will make one wizard more powerful than another?
We inherit genes from both our parents thus, with the exception of the genes of the sex chromosomes in men, we all have two copies of every gene. Mendel discovered that some genes were dominant: i.e. if you had just one copy of this gene you will display the trait that this gene codes for, and other genes were recessive: i.e. you need two copies of this gene in order to display the trait.
JK Rowling has said that the magical gene is “dominant and resilient”. If only one gene codes for magic then we will not be able to explain the phenomenon of the muggle-born because all wizards/witches would have to have at least one parent who had the dominant magic gene - and therefore one parent has be magical.
However if there were two genes that code for magic, Mendelian genetics can explain in the simplest terms how magic is inherited and why there are both muggle-borns and squibs.
In order for this to work: the Magical trait has to be encoded by two separate genes, each with their own active magical and inactive non-magical forms or alleles. As there is no indication that wizards have more genes than muggles (more DNA than normal usually results in disabling genetic syndromes), muggles must also possess a version of these genes that is inactive i.e: does not make them Magic.
All wizards/Witches must have at least one A and one B but inactive forms (alleles) of the magical genes (a and b) are always circulating within the wizarding population because no one has started genetically testing and actively eliminating any magical people with recessive magical alleles. Thus the recessive alleles will never spontaneously disappear from the Magical population. In the unlucky event that a child inherits two recessive copies of both magical gene: they become a squib. The more recessive alleles the parents have, the more likely they are to produce squibs.
In the diagram below the brown mice are magical, the white mice and the black mice are non-magical. You can see that if both parents are magical but have the minimum number of magical alleles they produce an interesting array of different genetic combinations, only some of which are magical.
These parents have a 7/16 chance of producing a squib and a 9/16 chance of producing a magical child.
Of course there are multiple layers of gene expression control and this is merely the most simple explanation.
Where did all the Squibs Go?
In Harry Potter universe squibs are considered rare and this should not be the case if for many families the chances of producing a squib are almost 50%.
It may be possible that squibs are rarely seen in wizarding world because they choose to live their lives amongst muggles instead, thus taking with them single copies of the dominant magical alleles. A muggle-born is therefore the offspring of two non-magical people each with one dominant copy of a Magical gene. It is most likely that somewhere in the muggle-born’s family tree there are squibs and even further back there wizards.
The other possibility to consider is that: fertilized eggs with certain genetic combinations might be less likely to survive than others. For example if the genetic combinations of all the white mice in the diagram above conferred some kind of fatal problem with embryo development - children with these genetic combinations would never be born. Instead the embryos would miss carry and thus with one stroke, the chances of actually producing a squib have been reduced by over 50%.
However given the state which we find the magical gene pool at the beginning of the Harry potter series, I believe there is a much darker reason why squibs are rarer than they should be.
In fact we can use the genetics of magical inheritance to explain not just why squibs are rare but also the entire notion of pureblood supremacy why the ancient pureblood families have inbred themselves to the point of degeneracy
To be continued in: The Noble and Most Inbred House of Black.