Page last updated at 11:12 GMT, Monday, 18 January 2010

Feet hold the key to human hand evolution

By Victoria Gill
Science reporter, BBC News

Human and ape hand (SPL)
Scientists simulated the change from an ape-like hand to a human-like hand

Scientists may have solved the mystery of how human hands became nimble enough to make and manipulate stone tools.

The team reports in the journal Evolution that changes in our hands and fingers were a side-effect of changes in the shape of our feet.

This, they say, shows that the capacity to stand and walk on two feet is intrinsically linked to the emergence of stone tool technology.

The scientists used a mathematical model to simulate the changes.

Other researchers, though, have questioned this approach.

Campbell Rolian, a scientist from the University of Calgary in Canada who led the study, said: "This goes back to Darwin's The Descent of Man.

The results are quite exciting
Paul O'Higgins
Hull York Medical School

"[Charles Darwin] was among the first to consider the relationship between stone tool technology and bipedalism.

"His idea was that they were separate events and they happened sequentially - that bipedalism freed the hand to evolve for other purposes.

"What we showed was that the changes in the hand and foot are similar developments... and changes in one would have side-effects manifesting in the other."

Shape-shifting

To study this, Dr Rolian and his colleagues took measurements from the hands and feet of humans and of chimpanzees.

Their aim was to find out how the hands and feet of our more chimp-like ancestors would have evolved.

The researchers' measurements showed a strong correlation between similar parts of the hand and foot. "So, if you have a long big toe, you tend have a long thumb," Dr Rolian explained.

"One reason fingers and toes may be so strongly correlated is that they share a similar genetic and developmental 'blueprint', and small changes to this blueprint can affect the hand and foot in parallel," he said.

With this anatomical data, the researchers were able to create their mathematical simulation of evolutionary change.

Early man using stone tools (SPL)
Human ancestors and early humans crafted stone tools

"We used the mathematical model to simulate the evolutionary pressures on the hands and feet," Dr Rolian explained.

This model essentially adjusted the shape of the hands or the feet, recreating single, small evolutionary changes to see what effect they had.

By simulating this evolutionary shape-shifting, the team found that changes in the feet caused parallel changes in the hands, especially in the relative proportions of the fingers and toes.

These parallel changes or side-effects, said Dr Rolian, may have been an important evolutionary stem that allowed human ancestors, including Neanderthals, to develop the dexterity for stone tool technology.

Robin Crompton, professor of anatomy at the UK's Liverpool University, said the study was very interesting but also raised some questions.

"I am not personally convinced that the foot and hand of chimpanzees are a good model [of human ancestors' hands and feet] - the foot of the lowland gorilla may be more interesting in this respect," he told BBC News.

He pointed out that there was a lot more to the functional shape and biomechanics of the human foot than just its proportions.

Paul O'Higgins, professor of anatomy at the Hull York Medical School, UK, said: "The results are quite exciting and will doubtless spur further testing and additional work."



Print Sponsor


SEE ALSO
Fossil is breakthrough of 2009
17 Dec 09 |  Science & Environment
Fossil finds extend human story
01 Oct 09 |  Science & Environment
Hobbits 'are a separate species'
06 May 09 |  Science & Environment
Human ancestors born big brained
14 Nov 08 |  Science & Environment

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites


FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC navigation

BBC © 2013 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific