Mental template matching is a potential cultural transmission mechanism for New Caledonian crow tool manufacturing traditions

S A Jelbert,R J Hosking,R D Gray,A H Taylor

doi:10.1038/s41598-018-27405-1

Abstract

Cumulative cultural evolution occurs when social traditions accumulate improvements over time. In humans cumulative cultural evolution is thought to depend on a unique suite of cognitive abilities, including teaching, language and imitation. Tool-making New Caledonian crows show some hallmarks of cumulative culture; but this claim is contentious, in part because these birds do not appear to imitate. One alternative hypothesis is that crows’ tool designs could be culturally transmitted through a process of mental template matching. That is, individuals could use or observe conspecifics’ tools, form a mental template of a particular tool design, and then reproduce this in their own manufacture – a process analogous to birdsong learning. Here, we provide the first evidence supporting this hypothesis, by demonstrating that New Caledonian crows have the cognitive capacity for mental template matching. Using a novel manufacture paradigm, crows were first trained to drop paper into a vending machine to retrieve rewards. They later learnt that only items of a particular size (large or small templates) were rewarded. At test, despite being rewarded at random, and with no physical templates present, crows manufactured items that were more similar in size to previously rewarded, than unrewarded, templates. Our results provide the first evidence that this cognitive ability may underpin the transmission of New Caledonian crows’ natural tool designs.

Highlights

Cultural traditions are common in the animal kingdom[1,2,3], but cumulative cultural evolution is rare[4]
Though subjects are provided with spoken and written instructions as to the goal of the task. This demonstrates that action information is not always necessary for cultural transmission, and that, at least in certain artificial settings, cumulative culture can emerge in humans through emulative social learning processes, focused only on learning from products
One hypothesis is that New Caledonian crow tool designs could be culturally transmitted – without teaching, language or imitation – through a form of end-state emulation, termed mental template matching[24,26]

Summary

Introduction

Cultural traditions are common in the animal kingdom[1,2,3], but cumulative cultural evolution is rare[4]. Though subjects are provided with spoken and written instructions as to the goal of the task This demonstrates that action information is not always necessary for cultural transmission, and that, at least in certain artificial settings, cumulative culture can emerge in humans through emulative social learning processes, focused only on learning from products. Whether New Caledonian crow tool designs are culturally transmitted, and have evolved over time, remains contentious[23] In part this is due to an absence of evidence, in this species, for the types of sophisticated social learning mechanisms thought to be necessary for such behaviour. One hypothesis is that New Caledonian crow tool designs could be culturally transmitted – without teaching, language or imitation – through a form of end-state emulation, termed mental template matching[24,26]. Mental template matching is a specific type of end-state emulation that could potentially allow for cumulative cultural change in the design of material artefacts

Methods

Results

Conclusion