Non-vertical cultural transmission, assortment and the evolution of cooperation.

Dor Cohen,Ohad Lewin-Epstein,Yoav Ram,Marcus W Feldman

doi:10.1098/rspb.2020.3162

Abstract

Cultural evolution of cooperation under vertical and non-vertical cultural transmission is studied, and conditions are found for fixation and coexistence of cooperation and defection. The evolution of cooperation is facilitated by its horizontal transmission and by an association between social interactions and horizontal transmission. The effect of oblique transmission depends on the horizontal transmission bias. Stable polymorphism of cooperation and defection can occur, and when it does, reduced association between social interactions and horizontal transmission evolves, which leads to a decreased frequency of cooperation and lower population mean fitness. The deterministic conditions are compared to outcomes of stochastic simulations of structured populations. Parallels are drawn with Hamilton’s rule incorporating relatedness and assortment.

Highlights

Cooperative behaviour can reduce an individual’s fitness and increase the fitness of its conspecifics or competitors [1]
Our results demonstrate that cultural transmission, when associated with social interactions, can favour the evolution of cooperation even when genetic transmission cannot, partly because it facilitates the generation of assortment [11], and partly because it diminishes the effect of selection
A polymorphism of cooperation and defection can be stable if horizontal transmission is biased in favour of defection (TA < TB) and both c and α are intermediate

Summary

Introduction

Cooperative behaviour can reduce an individual’s fitness and increase the fitness of its conspecifics or competitors [1]. The importance of relatedness to the evolution of cooperation and altruism was demonstrated by Hamilton [9], who showed that an allele which determines cooperative behaviour will increase in frequency if the reproductive cost to the actor that cooperates, c, is less than the benefit to the recipient, b, times the relatedness, r, between the recipient and the actor This condition is known as Hamilton’s rule:. Our results demonstrate that cultural transmission, when associated with social interactions, can favour the evolution of cooperation even when genetic transmission cannot, partly because it facilitates the generation of assortment [11], and partly because it diminishes the effect of selection (owing to non-vertical transmission from non-reproducing individuals [18])

Models

A B A B frequency

Results

Result

Discussion