May, 2002. See below for an explanation of the controls and the display.
Every day the animals pair up for the day's activities. (This pairing is not completely random; see the next paragraph.) An altruist spends some of its vitality called "cost", but its partner receives a greater vitality called "benefit". The births that occur in the herd are random, but weighted accoring to vitality. Each animal gets 10 units of vitality during the day, and if it's so lucky to be paired with an altruist, then it gets 10 + benefit. And cost is subtracted from the vitality of each altruist. It is assumed these animals are haploid, and that a child of an altruist is an altruist while the child of a nonaltruist is a nonaltruist.
See details for more information on the daily agenda for the herd.
It turns out that no matter what the parameters are set to, eventually the herd will become either completely selfish or completely altruist. There are several parameters that can be set.
Since the parameter "runs" is set to 100, there will be 100 runs (simulations) in each series. Each simulation continues until the herd is eitherly entirely altruist or entirely selfish. A simulation could take hundreds or thousands of days. For the default settings, there are 10 series, 100 runs in each, hundreds of days for each on average.
The bar graph shows for each of the 10 series just what proportion of the runs became entirely altruist. The first bar shows what proportion of the 100 runs which initially had only one altruist eventually became all altruists. The second bar shows the proportion of the 100 runs becomes entirely altruist when there are 2 altruists initially. And so forth.
The text report gives the results in a form suitable for copying and pasting in a report. It gives more detailed information. First, there's a summary of the parameter settings:
Herd size: 200. Deaths: 5. Altruists: 10. Cost: 10. Benefit: 50.Next comes a table.
initalt sel alt avesel stdsel avealt stdalt 1 96 4 70 102 2256 607 2 85 15 133 146 2274 636 3 83 17 149 165 2153 494 4 82 18 240 255 2296 658 5 72 28 244 196 2273 752 6 58 42 315 323 2274 720 7 53 47 313 308 2374 838 8 62 38 331 274 2231 677 9 53 47 347 196 2242 654 10 49 51 376 229 2236 753There is one row for each series, and the first entry indicates how many altruists are placed in the herd initially. The next two columns indicate the number of herds that became completely selfish and completely altruist, respectively. So, for instance, in the series of 100 runs with 1 initial altruist, 96 became completely selfish, and only 4 became completely altruist (as illustrated in the first bar of the bar graph).
The remaining four columns describe how many days were required to become completely selfish or altruist. The one labelled "avesel" gives, for those herds that became completely selfish, the number of days to reach that state. The next one labelled "stdsel" gives the corresponding standard deviation. Similarly, the columns labelled "avealt" and "stdalt" give the corresponding statistics for those herds that become completely altruist.
The files for this applet are listed here. The Mothstats.html
file is this file you're looking at. The *.java files
are the program source files for the applet. The *.class
files are the compiled files that run when the applet is
running. They're all needed to run the applet. There are
a couple of *.au sound files used by the applet, too.
My way Or The Highway: Introduction
David E. Joyce,
John Kennison,
both of the Department of Mathematics and
Computer Science,
and Nicholas Thompson,
of
the Frances L. Hiatt
School of Psychology.
Clark University
Worcester, MA 01610