AKA, DC Has Too Much Time on Her Hands. :P
Exploring the effects of three reproductive genes.
Inspired by NimhsLab's edited norns over in the downloads section, I sat down and spent a slightly embarrassing amount of time testing out different combinations with the aim of getting a 5-minute pregnancy and similar cooldown to use on shorter-lived breeds.
After ending up with more data than I really needed, I wanted to share it with the community in case someone finds it useful. So...
Note: All numerical values assume you're using the official Genetics Kit.
The recovery time after laying eggs depends on the half-life of progesterone. The default half-life is 50.
Some approximate cooldowns, using the default laying stimulus:
Half-life 55: 5 minutes.
Half-life 60: 8 minutes.
Half-life 65: 14 minutes.
Half-life 70: 21 minutes.
With longer half-lives, you might want to change the laying stimulus ("Laid egg (invol1)", gene #409 in a typical ChiChi norn) to remove more progesterone.
The length of pregnancy is mainly determined by the gene "Progesterone - Emitter". In a standard Chichi, this is gene #203.
To get noticeable results, you have to slow down the emitter, but slow it down too much and it can't keep up with a fast half-life. Therefore you have to change the two together, but this creates a problem when cross-breeding them with regular norns: if a daughter inherits only the longer half-life, no problem. She'll just take more time before she resumes her cycle after laying, which isn't necessarily a bad thing. However, if she only inherits the slowed-down emitter, it can't keep up with the default half-life! This norn will be unable to bring a pregnancy to term without handish assistance.
I found that with the speedy default half-life of 50, even changing the sample rate to two ticks (the default fires every tick) resulted in stuck pregnancies.
There are two ways to slow down the emitter: increase the sample rate, or decrease the gain. There isn't much room to decrease the gain, as the default is only .012 per tick, about three clicks from 0 on the genetics kit's slider. When I was testing, I focused on changing the sample rate and half-life.
(note: I say "increase" the sample rate, but keep in mind that higher numbers mean it fires more slowly!)
The sample rate seems to make more of a difference to the actual length than the half-life. The half-life puts a sort of cap on the sample rate, after which if you make it any slower it can't inject progesterone faster than it decays.
Of course, if you increased the gain, you could get away with a slower sample rate; but you're also injecting more progesterone every time it fires, so the actual duration may not be any slower.
Changing only the half-life and sample rate, these are the "cap" times I obtained:
Half-life 55: 3 minutes @ sample rate 2.
Half-life 60: 3 minutes @ sample rate 3.
Half-life 65: 16 minutes @ sample rate 6, although for the last couple minutes I thought this was another stuck one! (A sample rate of 5 nets a 5-minute pregnancy.)
Half-life 70: I might not have tested all the way to the cap, but you get 7 minutes @ sample rate 7.
Half-Life 3: The world may never know.
As you probably realized, a noticeably longer pregnancy will necessarily come with a longer recovery time because you changed the half-life.
One more thing... The receptor "Lay egg (invol1)", #202 in a typical Chichi, determines the amount of progesterone required to trigger laying. Specifically, you want to look at the threshold, which in a standard Norn is .875.
Treehugger and Bondi Norns have a higher threshold, which in theory should make their pregnancies take longer. In practice, it makes a difference of less than a minute because of the fast emitter.
Basically, you can fine-tune by changing this receptor, but for more significant increases change the emitter.
On the bright side- emitter changes should rarely result in stuck pregnancies. (although a cross between the HL6/sample 6 example above and a Bondi or Treehugger might have problems!)
For the curious, Nimh's norns I linked earlier have a half-life of 70, sample rate of 6, and gain of .008; with this emitter, a norn experiences about a 12-minute pregnancy. It's 10 minutes in the actual uploaded Norns, because their "lay egg" receptor has a lower threshold at .855.
* To increase the cooldown after pregnancy, increase the half-life of progesterone.
* To increase the length of pregnancy, slow down the sample rate of the progesterone emitter.
* You can fine-tune by altering the threshold of the "lay egg" receptor.
* Norns with lengthened pregnancies don't hybridize well with regular norns.
* "Progesterone", "pregnancy" and "emitter" hardly look like words anymore.
You may also want to slow down the rate at which they become homesick duing pregnancy, controlled by #200 "Go home to lay eggs - Emitter" in a typical Chichi. I didn't test this; I'm just making a note of it.
Updated by Malkin on 9/8/2013 - move this to development.
I did a quick experiment to see how well the longest pregnancy, the 16 minute one, hybridizes, and I was pleasantly surprised. I spliced a Norn with the longer pregnancy, with a regular Norn and tested the offspring for a stuck pregnancy plus how long the pregnancy was. Out of 28 2nd gen Norns: 6 had a stuck pregnancy, 16 successfully laid their egg and out of that 7 had a long pregnancy and 9 had a short pregnancy. 1 Norn successfully laid an egg, but I don't know how long the pregnancy was. 5 of them died from a disease I noticed a bit to late.
I will admit that I wasn't very careful while testing them, so take my results with a grain of salt.
Thank you for writing the article I never
bothered had the time to write!
Awww crud, I forgot to close the (green) tag at the end. Oh well, it looks fine.
Glad you like it, Malkin!
edit: Thought I'd categorized it in development in the first place, too. I'm so on the ball today.
Fantastic, it's great to see such a detailled resource on how each part of the pregnancy can be altered.