Thursday, November 23, 2017

Half-Lives and Other Genetic Mysteries

So I found out something recently. I think the official C3 genetics kit has been lying to us this whole time.

If you've ever messed around in the genetics kit, chances are you have at some point come across the massive Half-Life gene. This single gene is responsible for determining the rates at which every single chemical in a creature's bloodstream degrades. By selecting a chemical and moving the half-life slider bar, you can determine how long it takes for a chemical to drop to half its original value. Lower values result in a faster degradation, while higher values are slower. If you watch the bottom bar of your genetics kit window, you will see what that time is estimated to be, from 50 milliseconds at 0, to 148.8 years at 255.

But while I was looking at the half-life of the Life chemical in an average ChiChi, 99, I noticed the genetics kit claims that half life only amounted to 15 minutes. And well, that just doesn't make sense.

The "die of old age" receptor kicks in when Life drops to 0.02. And we already know that tends to happen around the 5h39m mark. But if the half-life chemical is really 15 minutes, that would mean:

15 minutes after birth Life would be 0.5
15 more minutes later, or 30 minutes after birth Life would be 0.25
45 minutes after birth Life would be 0.125
60 minutes after birth Life would be 0.0625
75 minutes after birth Life would be 0.03125
and 90 minutes after birth Life would be 0.015625, which is below the 0.02 mark at which a ChiChi dies of old age. And we all know norns live a lot longer than that! What's going on here?

I wrote up a script to output some information about a Creature's life chemical to the debug log, and this is what I found:

Contrary to what the Genetics kit tells us, the half-life of 99 seems to actually be closer to an hour.

I was curious as to how this scaled, so I set Life to have a half-life of 88, or what the genetics kit considers to be five minutes.

And it was actually more like twenty.

I did several more tests with different values (and different chemicals too, just to be certain this wasn't something with Life specifically) and came to the same conclusion. The half-life time specified in the genetics kit is actually only about 1/4th the actual half-life.

But why? Such a vast difference seems like kind of a big oversight, doesn't it? Well, I'm not certain exactly why, but I have a theory. As I continued to run more tests to learn more about half-lives, I wrote a script that output the amount of a chemical every tick. And that's when I noticed it.

See the pattern? It appears that the engine only processes chemical degradation in creatures once every four ticks. So it would make sense to consider that the C3 genetics kit was developed during a time when that was not the case. If the chemicals did indeed degrade each tick, then the times specified in the kit would match up! It seems possible to me that the process rate was changed sometime after the genetics kit was developed and no one ever thought to update it.

Before I wrap this up, I have one more bit of information to share. While I was testing different half-lives I noticed that despite what the genetics kit claimed, any chemical with a half-life setting greater than 171 never degraded. Ever. All chemicals with half-life settings between 172 and 255 stayed the same and only lowered if they were used up through other chemical reactions. Why is 172 the magic number? I honestly have no idea. Ultimately this information probably has no practical use, since a half-life of 172 would take real-time months to degrade anyway and norns generally don't live that long, but it's still quite an interesting mystery to me.

Anyway, I hope the results of these experiments have left you a little more informed about half-lives. If anyone else has done similar experiments, I'd be interested to see if you got the same results or discovered anything that might be contrary to these findings!


  1. Thanks for this! I was wondering why when I was messing with the immune system that half lives seemed arbitrary. I was sitting around tweaking things and I was so confused why something that was supposed to be happening every quarter of a second was happening only once a second!

    1. I'm glad you found the information useful! It really is kind of a strange bug, but at least we kind of have an idea of what's actually going on now :P

  2. I wonder if this bug holds true in the C1 and C2 Genetics Kits?

  3. But what does it all MEAN, Watson?!

    No srsly this is fascinating and I'm so impressed with how smart you are!!! Well done!!!

    (found this article through the Rock Paper Shotgun article)

    <3 Merboy

  4. In C1, I once spent several months tending to norns edited to have the longest possible half-life for the life chemical, and one of them did become a child (though I had a lot of trouble keeping them alive - C1 norns were pretty fragile!).