Ancient teeth hint that right-handedness is nothing new


Ancient teeth hint that right-handedness is nothing new

* 12:27 23 May 2009 by Ewen Callaway
* For similar stories, visit the The Human Brain and Human
Evolution Topic Guides

Ancient bones suggest "lefties" have been coping with a right-handed
world for more than half a million years. A study of Homo
heidelbergensis, an ancestor of Neanderthals, seems to show that the
ancient humans were predominately right-handed.

"Finding that a hominin species as old as Homo heidelbergensis is
already right-handed helps to trace back the chain of modernity
concerning hand laterality," says Marina Mosquera, a
paleoanthropologist at Universitat Rovira i Virgili in Tarragona,
Spain, who was involved in the study.

Humans are the only animal believed to show a strong preference for
performing tasks with one hand or the other. Determining when right-
handedness first evolved could shed light on traits linked to
lateralised brains, such as language and technology, Mosquera says.
Efforts to solve this mystery have looked to ancient human skulls and
marks left on tools.

But these methods may not be reliable. Two-million-year-old tools
carved out of animal bones contain marks that might be indicative of
use by right-handers; however left-handers could have created the same
patterns, she says.

Similarly ancient skulls may have been split into two hemispheres, but
these changes could also reflect language processing, which occurs
predominately in the left brain of both right-handed and left-handed
people, Mosquera says.
'Third hand'

In search of a less ambiguous indicator of handedness, Mosquera's team
looked to teeth, of all things. Ancient humans probably used their
teeth like a third hand, she says, clenching onto meat and other
objects to cut them with stone tools. And in the process, ancient
humans might have grazed their incisors, creating diagonal marks.

To avoid cutting their noses off, ancient humans probably moved their
blade in a downward motion, causing right-handers to make tooth marks
in one direction, left-handers in another. Mosquera's team confirmed
this bias by asking left and right-handed assistants to simulate the
process while wearing mouth guards.

Next, her team analyzed 592 cut marks on 163 teeth found at Sima de
los Huesos cave in northern Spain, which has produced a trove of Homo
heidelbergensis remains. The vast majority of the marks looked to be
made by right-handers, Mosquera's team found.

Indeed, out of the 19 individuals to whom the teeth belonged, 15
appeared to be right-handed and none left-handed. Teeth from four
individuals contained mostly vertical marks and, therefore, could not
be interpreted.

http://www.archaeologynews.org/story.asp?ID=443052&Title=Ancient%20teeth%20hint%20that%20right-handedness%20is%20nothing%20new



Right handedness of Homo heidelbergensis from Sima de los Huesos
(Atapuerca, Spain) 500,000 years agostar, open



References and further reading may be available for this article. To
view references and further reading you must purchase this article.

Marina Lozanoa, Corresponding Author Contact Information, E-mail The
Corresponding Author, Marina Mosqueraa, José María Bermúdez de
Castrob, Juan Luis Arsuagac, d and Eudald Carbonella

aÀrea de Prehistòria, Universitat Rovira i Virgili-IPHES, Plaça
Imperial Tàrraco, 1, 43005 Tarragona, Spain

bCentro Nacional de Investigación sobre Evolución Humana (CENIEH),
Avenida de la Paz 28, 09004 Burgos, Spain

cDepartamento de Paleontología, Facultad de Ciencias Geológicas,
Universidad Complutense de Madrid, 28040 Madrid, Spain

dCentro de Investigación (UCM-ISCIII) de Evolución y Comportamiento
Humanos, calle Sinesio Delgado, 4 (Pabellón 14), 28029 Madrid, Spain

Received 19 May 2008;
accepted 2 March 2009.
Available online 9 May 2009.

Abstract

Handedness is a product of brain specialization, which in turn seems
to be responsible for the higher cognitive capabilities of humans,
such as language and technology. Handedness in living humans is well
established and shows the highest degree of manual specialization.
Studies on hand laterality in nonhuman primates, particularly in
chimpanzees, remain a matter of controversy as results tend to vary
depending on factors such as the tasks performed and the environment
in which the individuals live. Studies in several disciplines have
attempted to determine where in the course of human evolution
handedness established itself, with evidence collected from sources
such as paleoneurological analyses, stone tool flaking,
zooarchaeological studies and dental wear analyses, the last one of
which have proven the most reliable source of information. Here we
report an experimental and paleoanthropological study on hand
laterality of a sample of 28 hominids from Sima de los Huesos
(Atapuerca, Spain), dated at about 500,000 years ago, and compare our
results with dental microwear analysis in other fossil samples such as
that from Krapina (Croatia), as well as modern traditional societies.
Our results indicate that European Middle Pleistocene Homo
heidelbergensis was already as right-handed as modern populations.

Keywords: Hand laterality; Dental microwear; Middle pleistocene; Homo
heidelbergensis; Preneanderthals; Human evolution
Article Outline

1. Introduction
2. Dental microwear
3. The Sima de los Huesos site
4. Material and methods
5. Results
6. Discussion
7. Conclusions
Acknowledgements
References



Thumbnail image

Fig. 1. Geographic setting of the Homo heidelbergensis sites of Sierra
de Atapuerca (Spain) and Krapina (Croatia).

View Within Article


* 12:27 23 May 2009 by Ewen Callaway
* For similar stories, visit the The Human Brain and Human
Evolution Topic Guides

Ancient bones suggest "lefties" have been coping with a right-handed
world for more than half a million years. A study of Homo
heidelbergensis, an ancestor of Neanderthals, seems to show that the
ancient humans were predominately right-handed.

"Finding that a hominin species as old as Homo heidelbergensis is
already right-handed helps to trace back the chain of modernity
concerning hand laterality," says Marina Mosquera, a
paleoanthropologist at Universitat Rovira i Virgili in Tarragona,
Spain, who was involved in the study.

Humans are the only animal believed to show a strong preference for
performing tasks with one hand or the other. Determining when right-
handedness first evolved could shed light on traits linked to
lateralised brains, such as language and technology, Mosquera says.
Efforts to solve this mystery have looked to ancient human skulls and
marks left on tools.

But these methods may not be reliable. Two-million-year-old tools
carved out of animal bones contain marks that might be indicative of
use by right-handers; however left-handers could have created the same
patterns, she says.

Similarly ancient skulls may have been split into two hemispheres, but
these changes could also reflect language processing, which occurs
predominately in the left brain of both right-handed and left-handed
people, Mosquera says.
'Third hand'

In search of a less ambiguous indicator of handedness, Mosquera's team
looked to teeth, of all things. Ancient humans probably used their
teeth like a third hand, she says, clenching onto meat and other
objects to cut them with stone tools. And in the process, ancient
humans might have grazed their incisors, creating diagonal marks.

To avoid cutting their noses off, ancient humans probably moved their
blade in a downward motion, causing right-handers to make tooth marks
in one direction, left-handers in another. Mosquera's team confirmed
this bias by asking left and right-handed assistants to simulate the
process while wearing mouth guards.

Next, her team analyzed 592 cut marks on 163 teeth found at Sima de
los Huesos cave in northern Spain, which has produced a trove of Homo
heidelbergensis remains. The vast majority of the marks looked to be
made by right-handers, Mosquera's team found.

Indeed, out of the 19 individuals to whom the teeth belonged, 15
appeared to be right-handed and none left-handed. Teeth from four
individuals contained mostly vertical marks and, therefore, could not
be interpreted.
'Same old problems'

Travis Pickering, a biological anthropologist at the University of
Wisconsin in Madison, agrees that dental marks are a good way of
determining handedness in ancient humans. "Most hominins, even early
hominins, are going to be bright enough not to bring a blade up to
their noses," he says.

But the new study runs into the same problems as other attempts to
understand ancient human behaviour by analysing marks left on teeth or
tools, Pickering says.

A right-handed lab assistant may create diagonal marks across a tooth
guard while using a stone tool, but cut marks on a 500,000 year-old
tooth could have come from entirely different activities or even
natural wear and tear.

Journal reference: Evolution and Human Behavior (DOI: 10.1016/
j.evolhumbehav.2009.03.001)




http://www.archaeologynews.org/story.asp?ID=443052&Title=Ancient%20teeth%20hint%20that%20right-handedness%20is%20nothing%20new




Right handedness of Homo heidelbergensis from Sima de los Huesos
(Atapuerca, Spain) 500,000 years agostar, open
Purchase the full-text article



References and further reading may be available for this article. To
view references and further reading you must purchase this article.

Marina Lozanoa, Corresponding Author Contact Information, E-mail The
Corresponding Author, Marina Mosqueraa, José María Bermúdez de
Castrob, Juan Luis Arsuagac, d and Eudald Carbonella

aÀrea de Prehistòria, Universitat Rovira i Virgili-IPHES, Plaça
Imperial Tàrraco, 1, 43005 Tarragona, Spain

bCentro Nacional de Investigación sobre Evolución Humana (CENIEH),
Avenida de la Paz 28, 09004 Burgos, Spain

cDepartamento de Paleontología, Facultad de Ciencias Geológicas,
Universidad Complutense de Madrid, 28040 Madrid, Spain

dCentro de Investigación (UCM-ISCIII) de Evolución y Comportamiento
Humanos, calle Sinesio Delgado, 4 (Pabellón 14), 28029 Madrid, Spain

Received 19 May 2008;
accepted 2 March 2009.
Available online 9 May 2009.

Abstract

Handedness is a product of brain specialization, which in turn seems
to be responsible for the higher cognitive capabilities of humans,
such as language and technology. Handedness in living humans is well
established and shows the highest degree of manual specialization.
Studies on hand laterality in nonhuman primates, particularly in
chimpanzees, remain a matter of controversy as results tend to vary
depending on factors such as the tasks performed and the environment
in which the individuals live. Studies in several disciplines have
attempted to determine where in the course of human evolution
handedness established itself, with evidence collected from sources
such as paleoneurological analyses, stone tool flaking,
zooarchaeological studies and dental wear analyses, the last one of
which have proven the most reliable source of information. Here we
report an experimental and paleoanthropological study on hand
laterality of a sample of 28 hominids from Sima de los Huesos
(Atapuerca, Spain), dated at about 500,000 years ago, and compare our
results with dental microwear analysis in other fossil samples such as
that from Krapina (Croatia), as well as modern traditional societies.
Our results indicate that European Middle Pleistocene Homo
heidelbergensis was already as right-handed as modern populations.

Keywords: Hand laterality; Dental microwear; Middle pleistocene; Homo
heidelbergensis; Preneanderthals; Human evolution
Article Outline

1. Introduction
2. Dental microwear
3. The Sima de los Huesos site
4. Material and methods
5. Results
6. Discussion
7. Conclusions
Acknowledgements
References



Thumbnail image

Fig. 1. Geographic setting of the Homo heidelbergensis sites of Sierra
de Atapuerca (Spain) and Krapina (Croatia).

View Within Article




http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6H-4W80GJ1-2&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=85ca3e8836a5cc710f9b91ae6948f34c
.

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