St Andrews Research Repository

St Andrews University Home
View Item 
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  •   St Andrews Research Repository
  • University of St Andrews Research
  • University of St Andrews Research
  • University of St Andrews Research
  • View Item
  • Login
JavaScript is disabled for your browser. Some features of this site may not work without it.

Causes and consequences of tool shape variation in New Caledonian crows

Thumbnail
View/Open
Sugasawa_2017_CB_ToolShapeVariation_AAM.pdf (1.187Mb)
Date
18/12/2017
Author
Sugasawa, Shoko
Klump, Barbara Christina
St Clair, James J. H.
Rutz, Christian
Keywords
Acheulean
Artifact
Chimpanzee
Construction behavior
Cumulative culture
Extractive foraging
Hook
New Caledonian crow
Tool manufacture
Tool use
QH301 Biology
QL Zoology
BF Psychology
NDAS
BDC
R2C
Metadata
Show full item record
Altmetrics Handle Statistics
Altmetrics DOI Statistics
Abstract
Hominins have been making tools for over three million years [1], yet the earliest known hooked tools appeared as recently as 90,000 years ago [2]. Hook innovation is likely to have boosted our ancestors’ hunting and fishing efficiency [3], marking a major transition in human technological evolution. The New Caledonian crow is the only non-human animal known to craft hooks in the wild [4 ; 5]. Crows manufacture hooked stick tools in a multi-stage process, involving the detachment of a branch from suitable vegetation; “sculpting” of a terminal hook from the nodal joint; and often additional adjustments, such as length trimming, shaft bending, and bark stripping [4; 6 ; 7]. Although tools made by a given population share key design features [4; 6 ; 8], they vary appreciably in overall shape and hook dimensions. Using wild-caught, temporarily captive crows, we experimentally investigated causes and consequences of variation in hook-tool morphology. We found that bird age, manufacture method, and raw-material properties influenced tool morphology, and that hook geometry in turn affected crows’ foraging efficiency. Specifically, hook depth varied with both detachment technique and plant rigidity, and deeper hooks enabled faster prey extraction in the provided tasks. Older crows manufactured tools of distinctive shape, with pronounced shaft curvature and hooks of intermediate depth. Future work should explore the interactive effects of extrinsic and intrinsic factors on tool production and deployment. Our study provides a quantitative assessment of the drivers and functional significance of tool shape variation in a non-human animal, affording valuable comparative insights into early hominin tool crafting [9].
Citation
Sugasawa , S , Klump , B C , St Clair , J J H & Rutz , C 2017 , ' Causes and consequences of tool shape variation in New Caledonian crows ' , Current Biology , vol. 27 , no. 24 , e4 , pp. 3885-3890 . https://doi.org/10.1016/j.cub.2017.11.028
Publication
Current Biology
Status
Peer reviewed
DOI
https://doi.org/10.1016/j.cub.2017.11.028
ISSN
0960-9822
Type
Journal article
Rights
© 2017 Elsevier Ltd. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.cub.2017.11.028
Description
This study was funded through a BBSRC David Phillips Fellowship (BB/G023913/2; C.R.), studentships from JASSO (S.S.; L12126010025) and BBSRC/University of St Andrews (B.C.K.), and a JSPS overseas research fellowship (S.S.; H28/1018).
Collections
  • University of St Andrews Research
URI
http://hdl.handle.net/10023/16640

Items in the St Andrews Research Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

Advanced Search

Browse

All of RepositoryCommunities & CollectionsBy Issue DateNamesTitlesSubjectsClassificationTypeFunderThis CollectionBy Issue DateNamesTitlesSubjectsClassificationTypeFunder

My Account

Login

Open Access

To find out how you can benefit from open access to research, see our library web pages and Open Access blog. For open access help contact: openaccess@st-andrews.ac.uk.

Accessibility

Read our Accessibility statement.

How to submit research papers

The full text of research papers can be submitted to the repository via Pure, the University's research information system. For help see our guide: How to deposit in Pure.

Electronic thesis deposit

Help with deposit.

Repository help

For repository help contact: Digital-Repository@st-andrews.ac.uk.

Give Feedback

Cookie policy

This site may use cookies. Please see Terms and Conditions.

Usage statistics

COUNTER-compliant statistics on downloads from the repository are available from the IRUS-UK Service. Contact us for information.

© University of St Andrews Library

University of St Andrews is a charity registered in Scotland, No SC013532.

  • Facebook
  • Twitter