7 comments, sorted by Click to highlight new comments since: Today at 7:35 AM
New Comment

Genetic algorithms are an old and classic staple of LW. [1]

Genetic algorithms (as used in optimization problems) traditionally assume "full connectivity", that is any two candidates can mate. In other words, population network is assumed to be complete and potential mate is randomly sampled from the population.

Aymeric Vié has a paper out showing (numerical experiments) that some less dense but low average shortest path length network structures appear to result in better optimization results: https://doi.org/10.1145/3449726.3463134

Maybe this isn't news for you, but it is for me! Maybe it is not news to anyone familiar with mathematical evolutionary theory?

This might be relevant for any metaphors or thought experiments where you wish to invoke GAs.

[1] https://www.lesswrong.com/search?terms=genetic%20algorithms

I have a small intuition pump I am working on, and thought maybe others would find it interesting.

Consider a habitat (say, a Petri dish) that in any given moment has maximum carrying capacity for supporting 100 000 units of life (say, cells), and two alternative scenarios.

Scenario A. Initial population of 2 cells grows exponentially, one cell dying but producing two descendants each generation. After the 16th generation, the habitat overflows, and all cells die in overpopulation. The population experienced a total of 262 142 units of flourishing.

Scenario B. More or less stable population of x cells (x << 100 000 units, say, approximately 20) continues for n generations, for total of x * n units of flourishing until the habitat meets its natural demise after n generations.

For some reason or other, I find the scenario B much more appealing even for relatively small numbers of n. For example, while n=100 000 (2 000 000 units of total flourishing) would be obviously better for utilitarian who cares about total equal sum of flourishing units (utilitons), I personally find already meager n=100 (x*n = 2000) sounding better than A. 

Maybe this is just because of me assuming that because n=100 is possible, also larger n sounds possible. Or maybe I am utiliton-blind and just think 100 > 17. Or maybe something else.

Background. In a recent discussion with $people, I tried to argue why I find a long term existence of a limited human population much more important than mere potential size of total experienced human flourishing or something more abstract. I have not tried to "figure in" more details, but somethings I have thought about adding in, is various probabilistic scenarios / uncertainty about total carrying capacity. No, I have not read (/remember reading) previous relevant LW posts, if you can think of something useful / relevant, please link it! 

Is this a closed environment, that supports 100000 cell-generations?  In that case, the 15th generation and predecessors will have eaten 65535 units of food, so the 16th generation will only be partial - either 65536 cells that live about half their normal span, or more likely, a bunch will eat each other, to collapse to a much smaller number that lasts a few more generations. 

Regardless, it's worth exploring where your intuition flips - would 1 cell that repeats for 100K generations be preferable?  50K for 2 generations?  For myself, I'm mostly indifferent in the case of individual cells.  For beings with culture, there's a lot of value in existing during a growth phase, which I don't know how to model.  And thinking beings (if such a thing existed), when there are sufficient numbers and knowledge about the impending limits, can work to increase the limits, and to decrease the per-unit usage.  

Related: https://www.lesswrong.com/tag/shut-up-and-multiply .

>Is this a closed environment, that supports 100000 cell-generations?

Good question! No. I was envisioning it as a system where a constant population of 100 000 would be viable. (RA pipettes in a constant amount of nutritional fluid every day or something).  Now that you asked the question, it might make more sense to investigate this assumption more.

Notably, in either population regime, a randomly chosen individual will have an expected ~n/2 total descendants. However, this only favors Scenario B by a factor of about 6x as opposed to the 131x more lifetimes in Scenario A.

I'm going to assume we're talking about people here. I think the relevant difference for me is the value of having many generations of accumulated culture vs. the value of having many other people alive along with you.

Eventually, yes, it is related to arguments concerning people. But I was curious about what aesthetics remain after I try to abstract away the messy details. 

New to LessWrong?