Presentation Information
[C15-02]Can oblique teaching evolve under a life-schedule trade-off?
*Tsuyoshi Shimodaira1,2, Hisashi Ohtsuki1 (1. The Graduate University for Advanced Studies (Japan), 2. RIKEN (Japan))
Keywords:
teaching,cumulative culture,cultural evolution,life-schedule
Teaching is a common altruistic behavior in humans and thought to be one of the keys that makes it possible for humans to accumulate culture. Cultural inheritance is unique compared to the genetic inheritance in that cultural traits are transmitted not only vertically (from parent) but also obliquely (from other individuals in the parental generation). However, the evolution of oblique teaching is not obvious because teachers have to obtain more benefit than the altruistic cost.
In this study, we examine the effect of kinship on the evolution of oblique teaching. If there is a certain degree of relatedness between the teacher and the learner, it is possible that teaching cost is offset by indirect fitness through kin selection, leading to evolution of teaching.
We assume two life stages: learning stage and mature stage. Learning stage is further divided into social learning (SL) and individual learning (IL) stages as in this order, and one can improve the skill level. At the SL stage, one chooses a role model from the previous generation, and one’s skill level improves according to the efficiency which depends on the baseline and the amount of investment into teaching by the role model. One’s parent is selected as a role model with probability q, otherwise the one with relatedness r is selected. At the IL stage, one’s skell level improves at a constant rate.
At the mature stage, one invests its effort into reproduction and teaching. The product of the length of time and the proportion of each behavior represents the amount of investment. The fitness is defined as the product of the skill level and the amount of investment into reproduction. Investment into teaching does not contribute to one’s fitness, but it increases the social learning efficiency of the individual in the next generation who chose the focal individual as a role model.
We analyzed this model, obtained evolutionarily stable strategies, called ESS, and examined what degree of relatedness is needed for the evolution of oblique teaching. We have found that a certain degree of relatedness extends the parameter space where teaching evolves and that it contributes to the accumulation of culture. In terms of the trade-off in life-schedule, if the probability q that one chooses own parent as a role model is high, teaching is favored and investments into individual learning and reproduction decrease. As the probability q and relatedness r decrease, investments into social learning and teaching decrease.
In this study, we examine the effect of kinship on the evolution of oblique teaching. If there is a certain degree of relatedness between the teacher and the learner, it is possible that teaching cost is offset by indirect fitness through kin selection, leading to evolution of teaching.
We assume two life stages: learning stage and mature stage. Learning stage is further divided into social learning (SL) and individual learning (IL) stages as in this order, and one can improve the skill level. At the SL stage, one chooses a role model from the previous generation, and one’s skill level improves according to the efficiency which depends on the baseline and the amount of investment into teaching by the role model. One’s parent is selected as a role model with probability q, otherwise the one with relatedness r is selected. At the IL stage, one’s skell level improves at a constant rate.
At the mature stage, one invests its effort into reproduction and teaching. The product of the length of time and the proportion of each behavior represents the amount of investment. The fitness is defined as the product of the skill level and the amount of investment into reproduction. Investment into teaching does not contribute to one’s fitness, but it increases the social learning efficiency of the individual in the next generation who chose the focal individual as a role model.
We analyzed this model, obtained evolutionarily stable strategies, called ESS, and examined what degree of relatedness is needed for the evolution of oblique teaching. We have found that a certain degree of relatedness extends the parameter space where teaching evolves and that it contributes to the accumulation of culture. In terms of the trade-off in life-schedule, if the probability q that one chooses own parent as a role model is high, teaching is favored and investments into individual learning and reproduction decrease. As the probability q and relatedness r decrease, investments into social learning and teaching decrease.