Parameter Default value Comments
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.