Assassin's Creed - How much data can our DNA store?
Greetings my good humans and welcome to another edition of the newsletter “The Science in Video Games”. This is the third edition of the newsletter, which means that you have already read about Disco Elysium and Hollow Knight right? Riiiight? Of course, you have because you are an incredible person.
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So, on to our main story for this newsletter which is the Animus from Assassin’s Creed, the open-world action-adventure stealth video game franchise published by Ubisoft. I believe that this game needs less of an introduction as the franchise is worth 311 million dollars [source] but we will go through some of the basics since today we will be talking about the Animus, a vital part of the game.
The Animus is a virtual reality machine that taps into the user’s “genetic memory” and allows it to project it onto a screen and create an immersive environment. Kinda like the modern virtual reality machines, we can have at our homes, sans the “genetic memory” part. We will talk about it later in this article.
In fact, when it comes to in-game lore, the Animus has controls similar to a gaming console [source]. However, initially, the controls were different but the users had a very hard time adapting to them and Abstergo (the company that developed the Animus) changed them to match gaming consoles.
As you were allowed to view and interact with the memories of your ancestors, the game introduced the mechanic of synchronization which basically meant that if you deviated significantly from the events of the past, the user would lose focus of it and won’t be able to play anymore. While I’m sure there are more lore-specific insights that we could analyze here(after all there is a whole wiki about Assassin’s Creed), I think these simple facts will be enough, for now, to start analyzing a couple of stuff in the real world.
First of all, is “genetic memory” a real thing? Even if it is, and we have the lives of our ancestors “saved” in our DNA could we read it? And then, how much disk space would a whole life take in order to be saved in the DNA?
Let’s start with the bad news first shall we? Genetic memory? Cool concept but not an actual thing. At least not in the way Assassin’s Creed is using them. In psychology, genetic memory is theorized as a “phenomenon in which certain kinds of memories could be inherited, being present at birth in the absence of any associated sensory experience” [source]. Psychologists use this notion and conduct different studies in order to understand transgenerational trauma. Transgenerational trauma is the psychological and physiological effects that trauma has on people of subsequent generations of the initial person that experienced the trauma. Transgenerational trauma can be experienced by individuals, families, and even communities, meaning that the symptoms of the trauma can manifest and cause distress at any of these levels [source]. There have been studies trying to understand the pathways for the transmission of transgenerational trauma. Most of them have to do with the relationship parents have with their children [source, source]. Some of them talk about an epigenetic transmission of trauma [source]. Epigenetics is the study of how your behaviors and environment can change the way your genes work. These changes are not permanent changes in your DNA sequences, however, they might affect the way your body reads a sequence [source]. In our case, these changes don’t matter since we’re looking for more permanent changes in our DNA.
As far as this writer knows, and can research, there is no evidence that supports that we inherit specific episodic memories of our ancestors that are somehow encoded in our DNA. Episodic memories are memories of everyday events that can be consciously recollected [source]. However, there are other types of memories that can be inherited. For example, procedural memory has been shown that it can be inherited.[source, source] Babies don’t need to learn how to suck for instance.
Lastly, we have semantic memory, which is a type of conscious long-term memory for meaning, understanding, and other facts of the world. For example, Lefteris asks science, is a science podcast (you should listen to it if you haven’t!). Now there have been discussions in the field of psychology and linguistics about these types of memories. Carl Jung was talking about the collective unconscious, which was a type of genetic memory that is shared amongst individuals with common ancestors [source]. Then we have linguist Noam Chomsky, that has argued about how we as humans are somehow genetically encoded with universal grammar, a basic understanding of how language works [source].
But let’s see what exactly happens in our brains when it comes to storing and recalling memories. Memories are stored in your brain over time in the form of neural networks. The semantic memories are stored in the neocortex, with researchers believing that the storing of memories in the neocortex happens as we sleep [source]. Additionally, there is the concept called long-term potentiation, in which the brain deposits specific proteins along synapses that will make future communication of memories easier [source]. Yet still, we don’t have evidence that these memories are somehow encoded in the human genome that could later be passed on or stored for future generations.
So far a real-life Animus seems a pretty far-fetched idea. For the sake of argument though, in the case in the future, we found out that we could actually pass on specific memories of our ancestors in our DNA I am going to go through some calculations here. Because believe it or not, data can be stored in DNA. Specifically, DNA can store up to 215 petabytes of data in a single gram (that’s 215 with 15 zeroes after it) [source]. This is not just a theoretical number that some science fiction writers came up with. In 2012, George Church, a synthetic biologist at Harvard Medical School in Boston, created a system that used chemically synthesized DNA to store a book he co-authored [source]. The benefit of using DNA to store data is that while our hard drives store data in 1s and 0s, DNA has 4 building blocks, adenine (A), cytosine (C), guanine (G), and thymine (T) to encode the data. Reading the data is a bit more complicated with a sequencer and a computer reassembling the DNA fragments to read back the data, but who knows, maybe Abstergo has worked on a technology to make this work easier and more portable. There were other works in more recent years that managed to increase the encoding efficiency however, reading and writing data is relatively slow, and the cost was prohibitive, especially for commercial, or large-scale applications [source].
We have now seen that we can store and read a lot of data in DNA but let’s see now see if that’s going to be enough. Just so that we understand some orders of magnitude, all the digital data right now in the world is 64 zettabytes ( that’s 64 with 21 zeroes after it)[source]. Then again, we don’t really need all the digital data in the world just the data of a couple of lifetimes in order to have a working Animus.
For that, we need to figure out 2 things.
How much data in bytes does a person experience in a lifetime?
How many grams of DNA do we have in our bodies, to see if there is enough space?
Answering the first question is a bit tricky. As we have said, people process experiences very differently so it will be hard to know how many bytes of storage love, hate, or sadness take. However, let’s follow the logic of the game, and assume that we’re holding the episodic memories of our ancestors in our DNA. We would be able to recall them and interact with them as if we were watching a high-definition video. Assuming 4K UHD (3840 x 2160) resolution which is mostly used in the film industry, a frame rate of 30 fps, and some generalized compressions we can consider an average size of 6GB per minute of video.[source]
So now with that, we need to see how many years of experience we are recording. That calculation gets a bit complicated because we need to consider average life expectancies over different periods. In 2019 the average life expectancy globally was 73.4 years.[source] But what was the average life expectancy thousands of years ago? While it is generally accepted that life expectancy has increased over the years there are some outliers. There is an Assassin’s Creed game that is set in ancient Greece, and according to a study, there was at least a group of people, that had an average lifespan of 71.3 years (talking about a creaking door eh?).[source] At the same time, the average lifespan in ancient Egypt was 22.5 years.[source] My point is, that it’s hard for us to know exactly how many years per lifetime we can expect to record. So, for the sake of simplification, I’m going to get an average of 50 years per generation to make some calculations easier. Apologies if that’s too simplistic. So with that, we can now say that a lifetime’s worth of 4k video recordings will be around 157,680,000 GB of data. Oof, that’s a lot, but still manageable I think. With this, we can record 1.3 lifetimes worth of data in a single gram of DNA.
Let’s now go to the second question, what is the total mass of DNA in our bodies? And I would have loved just to cite a source and tell you that the weight of human DNA in our bodies is X grams then multiply that by the number of GB that can be stored in 1 gram and here is your answer, but of course, life isn’t that simple. So for that, I am forced to do the one thing that the internet hates the most… MATH!
Earlier we talked about the building blocks of DNA, the nucleotides named Adenine, Guanine, Cytosine, and Thymine. Each nucleotide is composed of one of these four bases, plus a sugar called deoxyribose and a phosphate group. So if we want to find out the molecular weight of each of those four units we’ll have to consider all of these elements. Hence we have
2'-deoxyadenosine 5′-monophosphate
2′-deoxythymidine 5′-monophosphate
2'-deoxyguanosine 5′-monophosphate
2′-deoxycytidine 5′-monophosphate
Each of those basic components creates pairs and then coil around each other to form the familiar double helix we’ve seen in biology class. Since we don’t know the exact configuration of pairs in our body, we can get an average molecular weight of each unit at 326 g/mol [source]. Since DNA is double-stranded we double that to get ~650 g/mol (trying to simplify things a bit).
Now that’s out of the way we need to see how many of those base pairs we have per cell. Thankfully we have a direct answer for that so no complicated math is required. One copy of the human genome has around 3 billion base pairs of DNA [source]. That will give us around 6.5pico-grams of DNA per cell.
Now we just need to know the total number of human cells in our body and voila we’re done. But a quick internet search made me want to cry because I saw numbers vary in the number of TRILLIONS of cells. That’s not only because human sizes vary but because it’s apparently quite hard to count trillions of cells (who would have thought?). The reference that I decided to go by is the National Library of Medicine and a 2016 paper that estimates the number of human cells to be 30 trillion [souce]. This would bring the total weight of DNA to a whopping 195 grams. By all means, these calculations might be wrong so if you have a better idea please let me know.
Finally, we can have our answer. Since in a single gram of DNA we can record 1.3 lifetimes worth of video then our whole DNA could hold data from… ***drumroll please***
265 lifetimes!
Even if my math is a little off, with the average of 50 years per lifetime we’re talking more than 13 thousand years' worth of data. So in theory, if we actually did hold memories of our ancestors (we probably don’t), there is more than enough space for Abstergo to do whatever it wants.
Big thank you to Francesca Mandino and Irene Velidaki for their help and the references they provided for this work
Have you played Assassin’s Creed? Did you like it? Are you looking forward to the next installment of the game? Let me know in the comments below. Also, did you ever play a game and wondered what would it take to bring the events of the game into real life? Let me know in the comments below as well! And of course, don’t forget to share this article on your social media! [=