Human skull study causes evolutionary headache

Dec 20, 2011

Scientists studying a unique collection of human skulls have shown that changes to the skull shape thought to have occurred independently through separate evolutionary events may have actually precipitated each other.

Researchers at the Universities of Manchester and Barcelona examined 390 skulls from the Austrian town of Hallstatt and found evidence that the human skull is highly integrated, meaning variation in one part of the skull is linked to changes throughout the skull.

The Austrian skulls are part of a famous collection kept in the Hallstatt ossuary; local tradition dictates that the remains of the town's dead are buried but later exhumed to make space for future . The skulls are also decorated with and, crucially, bear the name of the deceased. The Barcelona team made measurements of the skulls and collected genealogical data from the church's records of births, marriages and deaths, allowing them to investigate the of .

The team tested whether certain parts of the skull – the face, the cranial base and the skull vault or brain case – changed independently, as anthropologists have always believed, or were in some way linked. The scientists simulated the shift of the foramen magnum (where the spinal cord enters the skull) associated with upright walking; the retraction of the face, thought to be linked to language development and perhaps chewing; and the expansion and rounding of the top of the skull, associated with brain expansion. They found that, rather than being separate evolutionary events, changes in one part of the brain would facilitate and even drive changes in the other parts.

"We found that genetic variation in the skull is highly integrated, so if selection were to favour a shape change in a particular part of the skull, there would be a response involving changes throughout the skull," said Dr Chris Klingenberg, in Manchester's Faculty of Life Sciences

"We were able to use the genetic information to simulate what would happen if selection were to favour particular shape changes in the skull. As those changes, we used the key features that are derived in humans, by comparison with our ancestors: the shift of the foramen magnum associated with the transition to bipedal posture, the retraction of the face, the flexion of the cranial base, and, finally, the expansion of the braincase.

"As much as possible, we simulated each of these changes as a localised shape change limited to a small region of the skull. For each of the simulations, we obtained a predicted response that included not only the change we selected for, but also all the others. All those features of the skull tended to change as a whole package. This means that, in evolutionary history, any of the changes may have facilitated the evolution of the others."

Lead author Dr Neus Martínez-Abadías, from the University of Barcelona's, added: "This study has important implications for inferences on human evolution and suggests the need for a reinterpretation of the evolutionary scenarios of the in modern humans."

Explore further: Seeing dinosaur feathers in a new light

More information: Martínez-Abadías, N.; Esparza, M.; Sjövold, T.; González-José, R.; Santos, M.; Hernàndez, M.; Klingenberg, C.P. "Pervasive genetic integration directs the evolution of human skull shape". Evolution, November 2011, DOI: 10.1111/j.1558-5646.2011.01496.x

Related Stories

Handsome by Chance

Aug 02, 2007

Chance, not natural selection, best explains why the modern human skull looks so different from that of its Neanderthal relative, according to a new study led by Tim Weaver, assistant professor of anthropology at UC Davis.

'Survival of the cutest' proves Darwin right

Jan 20, 2010

Domestic dogs have followed their own evolutionary path, twisting Darwin's directive "survival of the fittest" to their own needs -- and have proved him right in the process, according to a new study by biologists Chris Klingenberg, ...

Dinosaur skull changed shape during growth

Mar 31, 2010

The skull of a juvenile sauropod dinosaur, rediscovered in the collections of Pittsburgh's Carnegie Museum of Natural History, illustrates that some sauropod species went through drastic changes in skull shape ...

Evolution of skull and mandible shape in cats

Jul 30, 2008

In a new study published in the online-open access journal PLoS ONE, Per Christiansen at the Zoological Museum in Copenhagen, Denmark, reports the finding that the evolution of skull and mandible shape in sabercats and mo ...

Skull survey could improve vehicle safety

Jan 22, 2008

Women's skulls are thicker than men's, but they both shrink slowly after we reach adulthood. That's the conclusion of a new imaging study of 3000 people published in the Inderscience International Journal of Vehicle Safety. The de ...

700-year-old murder discovered

Jan 24, 2006

It took 700 years and the creation of computers, but the mystery of the Bocksten Man -- Sweden's oldest human skeleton -- has been solved: he was killed.

Recommended for you

Seeing dinosaur feathers in a new light

22 hours ago

Why were dinosaurs covered in a cloak of feathers long before the early bird species Archaeopteryx first attempted flight? Researchers from the University of Bonn and the University of Göttingen attempt ...

Mexico archaeologists explore Teotihuacan tunnel (Update)

Oct 29, 2014

A yearslong exploration of a tunnel sealed almost 2,000 years ago at the ancient city of Teotihuacan yielded thousands of relics and the discovery of three chambers that could hold more important finds, Mexican ...

Peruvian dig reveals sacrificial mystery

Oct 29, 2014

Tulane University physical anthropologist John Verano has spent summers in Peru for the last 30 years, digging for ancient bones and solving their secrets. But his most recent work focuses on a unique archeological ...

Phaistos Disk may be prayer to mother goddess

Oct 27, 2014

Ancient writing systems and their meanings absorb scientists who dedicate years of work to deciphering and sorting through arguments to determine the true meaning and purpose of writings. The latest news ...

User comments : 3

Adjust slider to filter visible comments by rank

Display comments: newest first

gunslingor1
not rated yet Dec 20, 2011
Nothing surprising to me in this story, life is adaptable. It's like anything really, like guitar for example. you Learn guitar, your body doesn't strengthen one finger at a time, then increase eye hand coordination, then so and so.... All these things occur in parallel. Even if you practiced really stringently to strength only one finger, you'd be strengthening the entire hand, improving accuracy and coordination all at once. Very similar here.

This study has zero effect on evolutionary theory.
JVK
1 / 5 (1) Dec 20, 2011
See also: http://www.physor...als.html

If the changes in the skull are driven by changes in the size of the olfactory bulbs, they present an even bigger challenge to those who think we are primarily visual creatures. Changes driven by the evolution of our olfactory acuity and specificity also rule out domain-specific modules, which never made scientific sense to me anyway -- even in theory.
jmhoward
1 / 5 (1) Dec 31, 2011
It is my hypothesis that human evolution resulted from selection for
testosterone: "Androgens in Human Evolution," Rivista di Biologia / Biology Forum 2001; 94: 345-362. (If your library does not subscribe to "Rivista ... ," you may read this at:
http://www.anthro...tion.htm . If you do not want to bother to visit this website, please, at least, note the chart from "General and Comparative Endocrinology" of 2003 which directly supports my explanation of human evolution. You may see the chart by going to the link above.)

My work concerning the effects of testosterone on human evolution may explain why "All those features of the skull tended to change as a whole package." ...including consequential changes in the body.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.