Environmental resources per year (R) |
3000 |
Maximum amount of
resources that can be acquired from the environment per year; puts a
limit on population size. Under default parameters, R=3000 means that
population size is about 400-500 individuals. |
Maximum group size (G) |
800 |
Under default parameters, G = 800 means
that all population is a single group. Population size is always less
than 800 due to resource limitation. |
Memory capacity (MC) gene mutation rate |
0.04 |
MC gene mutates with
probability 0.04 when transferred from parent to child. |
MC gene mutation effect Mean, StDev |
0, 0.4 |
Mutation effect is added
to the gene value. If the resulting gene value is out of the permitted
range (in this case, if MC becomes negative), mutation is cancelled and
attempt is repeated. |
All other genes mutation rate |
0 |
MC is the only trait that can evolve
genetically. |
Basic brain volume |
20 |
Minimum possible brain volume. Brain volume of
an individual is 20 when MC gene value is 0. |
Actual brain volume |
20 + MC |
Brain becomes larger by one per each
unit of MC |
Meme categories allowed |
TrE, Useless |
Individuals can invent and
transmit memes for Machiavellian tricks (selfish trait) and memes for
Useless actions (maladaptive trait) |
TrE memes efficiency: mean, StDev |
1, 1.5 |
TrE meme efficiency is
added to the phenotypic trait TrE of the individual. When a TrE meme is
invented, its efficiency is set to normally distributed random value and
remains constant thereafter. If meme efficiency is negative, calculation
is cancelled and attempt is repeated. |
TrE meme size: C, R |
1, 2 |
Meme size is calculated as the sum of meme
efficiency multiplied by C and a random number with zero mean and
standard deviation R. If meme size is negative, calculation is cancelled
and attempt repeated. |
Useless memes efficiency: mean, StDev |
0.2, 0.2 |
Useless meme
efficiency is the probability of performing a useless action per year.
If there is more than one Useless meme in memory, their efficiencies are
summed as probabilities (e.g., p1 +
p2(1-p1)). |
Useless meme size: C, R |
5, 2 |
Coefficients are such that the average
sizes of memes of all categories are equal to 1. |
Useless action cost |
1 |
1 resource is taken from individual for each
useless action |
Probability of forgetting a meme |
0.02 |
Individual forgets each meme
with probability 0.02 per year |
Hunting cost |
2 |
2 resources are taken from individual for
participating in collective hunting |
Resources consumed per year (life supprot) |
3 |
|
Migration chance |
0.001 |
Probabilty of migration of an individual to
another group (per year) |
Probability of death |
Age*0.002 |
This results in average life span of
about 27 years. |
Initial state: population size, resources per individual |
10, 20 |
Simulation starts with 10 individuals each possessing 20
resources |
Initial state: LE, TE |
1, 0 |
By default, the individuals are perfect
learners but incapable teachers. One attempt per year of teaching and
learning is performed by each infividual. If the transferred meme does
not exceed free memory capacity of the learner, learning attempts are
always succesful, whereas teaching attempts have 0.5 success probability
((teacher’s TE) + (1 – teacher’s TE)*(learner’s LE)). |
Initial state: HE, TrE, MC |
10, 0, 0 |
Individuals initially have
hunting efficiency 10 (enough to survive and reproduce under default
conditions), Machiavellian trick efficiency 0 and memory capacity
0. |
Creativity |
0.000266 |
Memes of each category are invented with
probability 0.000133 per individual per year. Two meme categories are
allowed under default conditions, so the total creativity is
0.000266. |