An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization

The sperm whale Physeter macrocephalus (Linnaeus, 1758) is the largest toothed whales and possesses the highest absolute values for brain weight on the planet (together with the killer whale Orcinus orca). Former calculations of the encephalization quotient (EQ), which is used to compare brain size...

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Published in:International Journal of Comparative Psychology
Main Authors: COZZI, BRUNO, MAZZARIOL, SANDRO, Podestà, Michela, ZOTTI, ALESSANDRO, Huggenberger, Stefan
Other Authors: Cozzi, Bruno, Mazzariol, Sandro, Zotti, Alessandro
Format: Article in Journal/Newspaper
Language:English
Published: University of California USA 2016
Subjects:
Online Access:http://hdl.handle.net/11577/3219003
https://doi.org/10.46867/IJCP.2016.29.00.01
http://escholarship.org/uc/item/4jv59569
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spelling ftunivpadovairis:oai:www.research.unipd.it:11577/3219003 2024-02-11T10:05:30+01:00 An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization COZZI, BRUNO MAZZARIOL, SANDRO Podestà, Michela ZOTTI, ALESSANDRO Huggenberger, Stefan Cozzi, Bruno Mazzariol, Sandro Podestà, Michela Zotti, Alessandro Huggenberger, Stefan 2016 ELETTRONICO http://hdl.handle.net/11577/3219003 https://doi.org/10.46867/IJCP.2016.29.00.01 http://escholarship.org/uc/item/4jv59569 eng eng University of California USA volume:29 numberofpages:9 journal:INTERNATIONAL JOURNAL OF COMPARATIVE PSYCHOLOGY http://hdl.handle.net/11577/3219003 doi:10.46867/IJCP.2016.29.00.01 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85090272411 http://escholarship.org/uc/item/4jv59569 info:eu-repo/semantics/openAccess Encephalization Quotient sperm whale brain size sexual dimorphism in the brain social evolution info:eu-repo/semantics/article 2016 ftunivpadovairis https://doi.org/10.46867/IJCP.2016.29.00.01 2024-01-24T17:44:51Z The sperm whale Physeter macrocephalus (Linnaeus, 1758) is the largest toothed whales and possesses the highest absolute values for brain weight on the planet (together with the killer whale Orcinus orca). Former calculations of the encephalization quotient (EQ), which is used to compare brain size of different mammalian species, showed that the sperm whale brain is smaller than expected for its body mass. However, the data reported in the literature and formerly used to calculate the sperm whale EQ suffered from a potential bias due to the tendency to measure mostly larger males of this extreme sexually dimorphic species. Accordingly, we found that the brains of female sperm whales are close to the absolute weight range of the males, but, given the much lower body mass of females, their EQ results more than double of what reported before for the whole species, and is thus nearly into the primate range (female EQ = 1.28, male EQ = 0.56). This sexual dimorphism is unique among mammals. Female sperm whales live in large families in which social interactions and inter-individual communication are essential, while adult males live solitarily. Thus the particular sex-specific behavior of SWs may have led to a maternally-driven social evolution, and eventually contributed to achieve female EQ values (but not male EQs) among the highest ever calculated for mammals with respect to their large body mass. Article in Journal/Newspaper Killer Whale Orca Orcinus orca Physeter macrocephalus Sperm whale toothed whales Killer whale Padua Research Archive (IRIS - Università degli Studi di Padova) International Journal of Comparative Psychology 29
institution Open Polar
collection Padua Research Archive (IRIS - Università degli Studi di Padova)
op_collection_id ftunivpadovairis
language English
topic Encephalization Quotient
sperm whale
brain size
sexual dimorphism in the brain
social evolution
spellingShingle Encephalization Quotient
sperm whale
brain size
sexual dimorphism in the brain
social evolution
COZZI, BRUNO
MAZZARIOL, SANDRO
Podestà, Michela
ZOTTI, ALESSANDRO
Huggenberger, Stefan
An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
topic_facet Encephalization Quotient
sperm whale
brain size
sexual dimorphism in the brain
social evolution
description The sperm whale Physeter macrocephalus (Linnaeus, 1758) is the largest toothed whales and possesses the highest absolute values for brain weight on the planet (together with the killer whale Orcinus orca). Former calculations of the encephalization quotient (EQ), which is used to compare brain size of different mammalian species, showed that the sperm whale brain is smaller than expected for its body mass. However, the data reported in the literature and formerly used to calculate the sperm whale EQ suffered from a potential bias due to the tendency to measure mostly larger males of this extreme sexually dimorphic species. Accordingly, we found that the brains of female sperm whales are close to the absolute weight range of the males, but, given the much lower body mass of females, their EQ results more than double of what reported before for the whole species, and is thus nearly into the primate range (female EQ = 1.28, male EQ = 0.56). This sexual dimorphism is unique among mammals. Female sperm whales live in large families in which social interactions and inter-individual communication are essential, while adult males live solitarily. Thus the particular sex-specific behavior of SWs may have led to a maternally-driven social evolution, and eventually contributed to achieve female EQ values (but not male EQs) among the highest ever calculated for mammals with respect to their large body mass.
author2 Cozzi, Bruno
Mazzariol, Sandro
Podestà, Michela
Zotti, Alessandro
Huggenberger, Stefan
format Article in Journal/Newspaper
author COZZI, BRUNO
MAZZARIOL, SANDRO
Podestà, Michela
ZOTTI, ALESSANDRO
Huggenberger, Stefan
author_facet COZZI, BRUNO
MAZZARIOL, SANDRO
Podestà, Michela
ZOTTI, ALESSANDRO
Huggenberger, Stefan
author_sort COZZI, BRUNO
title An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
title_short An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
title_full An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
title_fullStr An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
title_full_unstemmed An Unparalleled Sexual Dimorphism of Sperm Whale Encephalization
title_sort unparalleled sexual dimorphism of sperm whale encephalization
publisher University of California USA
publishDate 2016
url http://hdl.handle.net/11577/3219003
https://doi.org/10.46867/IJCP.2016.29.00.01
http://escholarship.org/uc/item/4jv59569
genre Killer Whale
Orca
Orcinus orca
Physeter macrocephalus
Sperm whale
toothed whales
Killer whale
genre_facet Killer Whale
Orca
Orcinus orca
Physeter macrocephalus
Sperm whale
toothed whales
Killer whale
op_relation volume:29
numberofpages:9
journal:INTERNATIONAL JOURNAL OF COMPARATIVE PSYCHOLOGY
http://hdl.handle.net/11577/3219003
doi:10.46867/IJCP.2016.29.00.01
info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85090272411
http://escholarship.org/uc/item/4jv59569
op_rights info:eu-repo/semantics/openAccess
op_doi https://doi.org/10.46867/IJCP.2016.29.00.01
container_title International Journal of Comparative Psychology
container_volume 29
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