House O’Rats

Picture the destiny of some rats that stumble into a grain silo full of wheat.  It’s an unbalanced diet, but there sure is a lot of it, and the rat population explodes, even though they’re not particularly healthy.

Their population increases until there’s just enough grain pouring in to feed them all (barely), at which point the silo is chock-full o’ rats. Now they’re hungry as well as malnourished. Once in a while, typhus or bubonic plague decimates the rats and there’s plenty to eat for a generation or two, until population catches up again. That doesn’t take long, because rats breed like.. rabbits?

The silo is big and contains an obscene number of rats – all potential mutants – and we keep this up for some 400 rat generations. There are lots of new mutations, some of which pay off in the silo. Natural selection in the silo favors traits that work better there, and the rats, they are a changin’. Eventually we see new versions of metabolic genes that fit them better to this restricted diet [like lactose tolerance, or a new and improved ergothioneine transporter]  and new versions of immunological genes that make them more resistant to the plagues made common by the crowding.  With the crowding, the optimal behavior changes, and so the rats acquire different dispositions. They even develop an interesting dominance hierarchy, with rat Kings.

I  mustn’t forget the spigot that spouts ethyl alcohol, CH3CH2OH.  The rats adapt to that too – those that survive.

Not content with our simple selection experiment, we also install complicated mazes with flaming hoops that the rats have to jump through in order to get extra food and mates: we want rats with different brains, and eventually we get them. They’re maze-bright and flaming-hoop-bright. We install treadmills and feed the rats according to their work output, and eventually they produce more work per amount of food eaten.  They’ve maximized efficiency rather than surge power, which was more useful back when they were wild and free.  Not only that, they eventually come to like being on the treadmill, almost as if it’s some sort of race.

There are other silos – one full of rice and another full of maize.  They have different mazes and flaming hoops, built at different times: and there are still wild rats, too, although not as many as in the silos.

But no matter how much they change, they’re still just a bunch of rats.

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28 Responses to House O’Rats

  1. g2-337af867fe9cd20258bdbc586fbefd0d says:

    It is a question of definition. 400 generations in a silo-island may induce speciation, they would hate the look, the smell and the behavior of those so-called “rats” from the other silos and the wild ones, and they may even stop being inter-fertile. But they would still be a bunch of mammals.

    • gcochran9 says:

      Speciation takes considerably longer than that.

      • John Harvey says:

        Between 1937 and 1945 Sockeye Salmon (Oncorhynchus nerka) were introduced into Lake Washington near Seattle. Dr Andrew P. Hendry of the University of Massachusetts began studying them and found that the fish appeared to have evolved into two different groups. One group laid its eggs on a lakeside beach, whilst the others used territories in feeder rivers. What’s more the two groups looked different, had identifiable genetic differences, and were markedly disinclined to interbreed. After only fifty years or as little as thirteen generations they had evolved into two distinct races and were moving steadily towards speciation.

      • g2-337af867fe9cd20258bdbc586fbefd0d says:

        In the wild, yes.

  2. greg kai says:

    Of course they will change, but they will change in exactly the same manner in each silo, no matter on how different the silos are. They will also develop independent and colorful cultures that help them cope with local environment, all different but equally worthy.
    Well, there may be some biological difference, one can not completely rules that out….If some evil biologist find some (because of some hidden agenda featuring a flute and a cliff), it will either be trivial, or provide a set of advantages and disadvantages that exactly balance each other ( and that using any ranking procedure, or course)
    This is all kept in balance between the different silos using a special kind of quantum entanglement called “fairness”, no magic involved….
    Well, anyway, this is a difficult subject interesting for only a small amount of specialist having too much time on their hand, because everybody knows this does not really matter: any rat can become king of his (or any other) silo if he really want to, play nice, is hard working and never gives up.

  3. Kat Ring says:

    Dark stuff, brah.

  4. Neil Ratstrong says:

    Have these rats in the wheat silo by any chance sent a few of their kind to the moon?

    • ziel says:

      I first read this early this morning, pre coffee, on my iPad still in bed. Funny, in that groggy state I actually thought it was about rats.

  5. Anonymous says:

    I wonder what bullets taste like.

  6. dave chamberlin says:

    A dark and disturbing tale, particularly when you read the wiki link to rat kings. I read it twice and the second time I was comforted to see it is listed as a fable. But on further thought I’ll bet it’s true. Picture if you will two rats that chew their way into the top of a barrel of grain. They eat their way down living in the barrel amoungst their own filth. They reproduce so that by the time they reach the bottom of the food supply there are thirty two inbred rats and in their close living conditions their tails have intertwined so completely that they no longer can seperate.

    I once spent an awful night in a corn silo filled with white, and black rats. Only it is not called a corn silo it is called Galesburg Illinois. Their is only one employment opportunity for the white rats since the Maytag factory was shut down and it is gaurding black rats at the huge state prison just outside of town. The town is surrounded by lush corn fields that spread as far as the eye can see but the farmers employ brown rats because they work harder and for less money. In the morning as I ate my breakfast I read their local free newspaper. I played soduku and did the crossword puzzle. Most newspapers have a difficulty rating of 1 on Monday progressing to 5 on Friday for suduku. On the difficulty scale this one was about one third. The crossword looked like something I got in the weekly reader back in the third grade. A good nights sleep in Galesburg is impossible. Because the town can’t afford train gates the frieght trains just blast their horns from one end of the town to the other. My motel parking lot seemed to be the local meeting place for the meth head population. I presume people who stay up all night yelling and fighting in Galesburg are methheads, but I can’t say for sure.

  7. Of course Drosophila are not mammals but it wouldn’t particularly surprise me if a similar sort of laboratory evolution experiment has already been done, perhaps long ago. FWIW, I just added to my desk inbox the Michael Rose UCI lab 2009 review of Drosophila experimental evolution. (Experimental Evolution with Drosophila by Molly K. Burke and Michael R. Rose.) Rose’s emphasis has always been toward caloric restriction though, not abundance.

  8. rightsaidfred says:

    …they’re still just a bunch of rats.

    But some are more equal than others.

    I’m wondering about the effects of self organized behavior. Let’s say the rats are self aware, and the silo is filled by rats on a treadmill. The initial caste of treadmill rats are one percent of the group: for a daily ration, one rat augers enough grain to feed 99 others. But our treadmill is a bit sloppy, and the treadmill class soon learns they can divert the auger to feed just themselves. Thus the political leaders have to continually replace the treadmillers, and ramp up the social controls to keep the treadmillers in line. Soon they start importing some outside rats “to do the work native rats just won’t do.” However, the new rats soon assert political and demographic power, and displace the original rats. Good times are had by all.

  9. The fourth doorman of the apocalypse says:
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  12. RS-prime says:

    I guess this is a pretty large fish (a foot long, in lakes), and the lake is ~1.5 x 12 miles. That means very small pop size, and for that reason alone I find this claim rather credible. It’s worth noting that something (quantitatively) similar could never happen with pops of say 10,000. So you will virtually never actually lay eyes on a living, wild organism in whose population this could take place.

    > Between 1937 and 1945 Sockeye Salmon (Oncorhynchus nerka) were introduced into Lake Washington near Seattle. Dr Andrew P. Hendry of the University of Massachusetts began studying them and found that the fish appeared to have evolved into two different groups. One group laid its eggs on a lakeside beach, whilst the others used territories in feeder rivers. What’s more the two groups looked different, had identifiable genetic differences, and were markedly disinclined to interbreed. After only fifty years or as little as thirteen generations they had evolved into two distinct races and were moving steadily towards speciation.

    • gcochran9 says:

      “could never happen with pops of say 10,000. ”

      Sure it could.

      • RS-prime says:

        So I guess you are saying subspeciation could happen rapidly where N=10,000, but not speciation.

        This calls for a precise def of speciation. I don’t know of a precise and perfect one, but a precise and near-perfect one is to say that it has occurred when there is only a 2% chance of ‘going back’.

        –And that would perhaps (often) be round about the timepoint where 80% of hybrids are below the 20th centile for fitness, with the picture for them monotonically (or very near-monotonically) getting worse — ? Or something like that. At that point there is still little obstacle to introgression of really important alleles, and yet ‘the deal’ is already 98% sealed.

      • RS-prime says:

        > At that point there is still little obstacle to introgression of really important alleles

        Assuming a sympatric or intermittently sympatric scenario I mean.

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