Fun Science - How many megabytes in the human body?

September 27th, 2007

Following on from my post about the incredible progress of computer storage density over the last twenty years, I remembered hearing a ‘popular science’ broadcaster here in Australia equating the gamete transfer during sexual reproduction to data transfer.

I like ‘weird science’ so I thought I’d go back and try and ‘reproduce’ his findings (pun entirely intended) - so - in this post I’m going to explain in ‘digital terms’ (eg megabytes, gigabytes):-

  1. The number of megabytes of ‘data’ exchanged during human reproduction.
  2. The amount of data which the human brain can store (hypothetical).
  3. The amount of data stored in all the cells in the human body.

This post involves some low-level discussion of sexual reproduction. So, if you’re prudish or get offended by this kind of thing, I apologise in advance and please turn away now :)

The amount of ’storage’ in the human brain

We can do similar calculations with the human brain - although these are much less definite - we’re much less certain about how the brain works than we are about how sexual reproduction works.

The average brain has around 100 billion brain cells (neurons) - that’s 100,000,000,000 brain cells (although this is a ‘guesstimate’ based upon other factors).

Human Neuron - like a bit of data?Each neuron is functionally connected to around 1000 neurons (again, a guesstimate). If we assume that neurons have either an ‘on’ or ‘off’ state (digital logic - although, not unsuprisingly, we have reason to believe that brain storage uses analogue voltage ‘levels’ rather than digital logic for storage) we can then assume that each neuron can ‘read or write’ 1000 neurons - essentially 1000 bits or 0.122 kilobytes of data.

Assuming that this ‘data’ ripples through the brain in a steady-state manner, we can assume that the average amount of ’storage capacity’ is hence 100,000,000,000 by 0.122 kilobytes, or 122 million (122,000,000) kilobytes. If we convert that figure to gigabytes, we arrive at the sum of 116.34 Gigabytes of data in digital terms.

Obviously there is a massive fudge factor here - the calculations make alot of very ‘broad’ assumptions - it’s really just a ‘fun’ measure of what our brain capacity would be if it was a digital system.

How many Megabytes in the Human Body

This one’s just too complex for me to consider this early in the morning - but lets have a go (drawing on my limited recollection of genetic biology here).

I’d guess to work it out you’d have to define each ‘base pair’ as a bit of information.

In human DNA there are two common base pairs which consist of the ‘nucleotides’ adenine, thymine, guanine or cytosine. Generally speaking only adenine and thymine pair with each other, as do guanine and cytosine - so the typical DNA base pair can be AT or CG - one of two states - a bit.

The DNA Double Helix, and 'digital' base pairs

The human genome is estimated to contain some 3 billion base pairs - so (again, simplifying) 3 billion bits = 0.35 gigabytes - so each cell in our body encodes roughly a third of a gigabytes of information - that’s a pretty high information density, especially considering that the double helix DNA in our cells is a minute proportion of the cell as a whole (and that the process of cell reproduction produces RNA strands which may be present in a cell as well).

Estimates for the number of cells in the human body range between 10 trillion and 100 trillion (see Sears CL. 2005. A dynamic partnership: Celebrating our gut flora. Anaerobe, Volume 11, Issue 5, October 2005, Pages 247-251).

The generally accepted figure is 100 trillion cells - so, given each cell contains 0.35 GB of data, the (very) approximate amount of data held in human cells is 35 trillion gigabytes, or 34,179,687,500 terabytes of data, or, expressed in megabytes 3.58400 × 1016 megabytes!!

If you add in the information encoded in RNA and the base pairs in the bacteria which live in our body (another 1000 trillion cells) then we’re talking about a hell of alot of data.

The human race would make a truly excellent data center if Google ever runs out of storage space or we get invaded by aliens with a need to store lots of information :-D

The number of Megabytes ‘exchanged’ during human reproduction

The human sperm can be one of three states - x, y or wasted.Each sperm cell in a human male is heterogametic, meaning it contains only one of two sex chromosomes (x or y) - incidentally, the female egg is homogametic - meaning that it only has an x chromosome.

This means the male ‘determines’ the sex of the child, which makes a mockery of Henry the 8th’s annulment of his marriage with Catherine of Aragon on account of the fact that she was ‘incapable of providing a male heir’.

Basically, sperm cells are like bits - they can (in most cases) be only one of two states - x or y, or in digital form, 0 or 1. So, it’s possible to express an ejaculate in megabytes (!?!) - Let’s try.

The average human ejaculate contains around 180 million sperm. So, that’s 180,000,000 bits. If we use google to convert 180 million bits to megabytes, we find that approximately 21.45 megabytes of ‘data’ is transferred during each act of human sexual reproduction in the form of gametes.

Whether this ‘information transfer’ results in anything constructive is up to individual circumstance, but it does raise a number of interesting questions (I’m putting my communications enginner / silly hat on again):-

  • Given that this is ‘bursty’ traffic, what is the peak data transmission rate (in megabits per second)?
  • How does this compare to optical fibre (assuming the subject doesn’t suffer from ‘dark fibre’ problems :-D )?

doc

Have you got any other ‘fun science’ questions you’d like answered? Any comments? You can leve your comments below.

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23 Comments Add your own

  • 1. MD2B  |  October 24th, 2007 at 3:57 pm

    I stumbled upon this from google and I must say I really appreciate your math work here, some very interesting numbers come out. Though to give you another layer of depth, (that you may or may not care about), the DNA is read from each side, not together, meaning that not only is the pairing important, but in which order the pair is in, simply, there are 4 different choices. Which means that the amount of information that the cell holds should double. Then there is also mitochondrial DNA if you just wanna find a big #, but whose counting.

    Anyway, thanks for the info.

  • 2. theDuck  |  October 29th, 2007 at 7:06 pm

    Thanks MD2b - appreciate your informed comments :-D It’s been a long time since I’ve done any genetics (theoretical OR practical)

  • 3. jason  |  November 8th, 2007 at 11:09 am

    Hi, Stumbled upon your site looking for questions to set for my Biochem students. A nice bit of fun science speculation. I would like to point out that while sperm contain a single X or Y chromosome, they also contain one copy of each of the other chromosomes as well, not so much a binary situation. Each sperm contain about 3 billion bases of genetic information.Additionally, while much of this information is redundant (the same from sperm to sperm) each copy ( all 180 million) of each chromosome is subtly different.

    Another smallish point; while the human genome is about 3 billion bases, most cells in our body (apart from things like sperm!) contain 2 different copies of the genome. Again, a lot of this information is redundant, but the difference is still there. So each cell actually contain 6 billion bases.

    jason

  • 4. theDuck  |  February 7th, 2008 at 2:55 pm

    Thanks Jason - again, it’s really cool to have some input from readers on my hypotheticals!

    Keep up the insightful comments folks, and if you’ve got anything else you’d like me to cover, let me know.

    M

  • 5. Shaun  |  February 21st, 2008 at 7:12 pm

    Is AT different from TA, and GC different from CG? I don’t know, but if they’re different each base pair would need 2 bits. Also is there ever a G paired with anything other than C, or is it always G with C and T with A? Thanks.

  • 6. Adam  |  February 28th, 2008 at 2:09 am

    As has been mentioned, there are four options for each of the 3 billion base pairs - each therefore requiring two bits. This gives 6 billion bits which equals 715 megabytes - about a CD’s worth!

  • 7. olivia  |  May 14th, 2008 at 7:37 am

    how many RNA strands are there in the human body?

  • 8. Faun  |  July 17th, 2008 at 2:28 pm

    What are some advantages and disadvantages to sexual reproduction?

  • 9. Joseph  |  September 21st, 2008 at 12:57 am

    I don’t think the calculation on the brain storage is anywhere near correct.
    I don’t have a research article to prove this - but I’ll link 2 videos of some regular people with amazing mental capacities, I would venture to say would fill up much more than 116 gigabytes. (http://de.youtube.com/watch?v=dAfaM_CBvP8)
    (http://de.youtube.com/watch?v=k2T45r5G3kA)

    Also - if you want to get into some very large numbers, do the calculations on the data transfer of a glycome

  • 10. Cole Crawford  |  October 9th, 2008 at 12:00 pm

    It seems very interesting that you come up with only 116gb of data. My laptop that I am typing on now has a hard drive that is 160gb, and I would like to assume that the human is much more advanced than a computer. I truly doubt that you can even begin to estimate the storage capacity of the brain because you would have to have a much better idea of how it stores information than is currently available. The brain does not ‘write’ information like a computer, it is organic and shouldn’t be compared to digital storage capacity.

  • 11. Matt  |  October 10th, 2008 at 11:28 am

    From a computer science point of view, it would be very wasteful to store the three billion bits that make up each cell 100,000,000,000,000 times!

    Considering that the DNA of each cell is the same (save for random mutation and telomerase unwinding based on the age of the cell), it would be much simpler to store the 0.35GiB once, and then use a pointer (let’s be generous and use a 32-bit number) to refer to the original copy instead.

    By doing so, you’ve reduced your original 34,179,687,500 tebibytes to 363 tebibytes ((100000000000000 cells * 32 bits) / 8 bits in a byte / 1024 bytes in a kibibyte / 1024 kibibytes in a mebibyte / 1024 mebibytes in a gibibyte + 0.35 gibibytes for the original data) / 1024 gibibytes in a tebibyte)!

  • 12. steve  |  October 18th, 2008 at 10:29 am

    As far as transfer of data during human reproduction… I think you need to take in to account that almost all of the data are in “lost packets” These do not count int the transfer or exchange.

  • 13. Heinz  |  December 2nd, 2008 at 11:01 pm

    Thank you, Matt, just loved your comment. Interesting thought.

  • 14. jennifer  |  December 23rd, 2008 at 11:16 pm

    what do you mean by gene and IS cancercell naturally in our body or not

  • 15. vakoya  |  February 4th, 2009 at 9:47 am

    i think that yeah that’s what i thing!!!

  • 16. gesundheit  |  March 11th, 2009 at 11:26 pm

    Sehr wertvolle Informationen! Empfehlen!

  • 17. aarsh  |  March 16th, 2009 at 4:07 am

    this stuff is hard to belive, but stranger things have happened. I was amazed that the human body is this complicated and also fun to read about. Anyways thanks for the article and just so you know my family likes this artice too.
    THANKS.

  • 18. aarsh  |  March 16th, 2009 at 4:09 am

    does this information differ with some cancers or the size or the age of the person?

  • 19. Hao  |  April 15th, 2009 at 9:08 am

    100,000,000,000 by 0.122 kilobytes, or 122 million (122,000,000) kilobytes

    100,000,000,000 * 0.122 kb = 12,200,000,000 kb or 12.2 terabytes

    Your discussion of the information density in DNA ignores the information in the machinery. Without the necessary biological environment for producing proteins from DNA, the DNA is functionally meaningless as information. All the data on your computer hard drive is useless without the proper software & operating system to read it and interpret it.

  • 20. Container  |  September 8th, 2009 at 5:17 am

    Yeah, great stuff! I wondered today how much a dna is in mb and googled out this page… Its amazing, that a CD (or so) of bytes can be used so efficiently to store the whole human body information. That is a hell of a good compression if you ask me :) –> Afaik, every cell holds data (in dna) for all possible cells in our body, but each cell only uses small part of the “register” according to its neighbour cells … (this true?)

    And to the fun part of “sexual data transfer”: You should count in, that only a tiny percentage of one’s “data streams” (or “uploads” hehe) even reach the receiver successfully! Man, what a waste of bandwidth! We should use torrents instead :)

  • 21. james barkley  |  September 13th, 2009 at 12:45 pm

    my God!, i thought. and this only after searching out the answer to a question my 12 year old son and i came up with. here’s an interesting tangent. think of the how and to what extent the range of information and processing capacity a divine creator would need to implement a human being and its supportive existance, i.e. universe? hmmm.
    or what would the statistical probability be on the randomness of the human development in a structural sense without one (a divine creator, that is)

  • 22. Paul  |  November 15th, 2010 at 2:09 am

    Great article. You should take into account our flora.

  • 23. Lirik  |  June 2nd, 2011 at 5:11 am

    The human genome actually contains about 681 MB of data, so when you calculated 1 GB you weren’t far off. The other thing is that each sperm contains the full DNA sequence so that’s 681 MB per sperm and with 180 million sperms that turns out to be about 114.161521 petabytes of information in a single “transfer.”

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