Scientists simulated the change of the primate hand into the human 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.

“[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.

“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.”

The evolution of hand & foot.

Is the mystery about the evolution of the human hand solved?

What did Charles Darwin say about hands & feet?

Scientists from Canada may have solved the mystery of how human hands became nimble enough to make and manipulate stone tools – it may be a side-effect of evolutionary changes in our feet!

A BBC report describes that the discussion continues – for other scientists now question the mathematical model which was used to simulate the changes between the hands & feet of chimpanzees and humans. Campbell Rolian, a scientist from the University of Calgary described:

“This goes back to Darwin’s The Descent of Man. “[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.”

“So, if you have a long big toe, you tend have a long thumb.”

“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. We used the mathematical model to simulate the evolutionary pressures on the hands and feet.”

SUGGESTION FOR FURTHER READING:
The evolution of the human hand!
Five major differences between the primate hand & the human hand!
Primate hands: finger length linked with social behavior!
Beagle report: Charles Darwin had the long pointer finger
The six digit man – hand satire from the Bill Gates Medical Center!

The primate foot & the human foot.
The primate foot & the human foot.

Zhao Liang has very large hands - about twice as long as the hand of his doctor!

The large hand of Zhao Liang – unofficially he was measured as the tallest man in the world!

In april (2009) Mister Zhao Liang from China entered the Tianjin hospital for an operation to relieve pain from an old muscle tendon injury on his left foot. His height caused a stir among hospital staff who urged him to get measured properly in order to establish a new Guinness World Record! Zhao Liang’s length was measured at 2.46m (8.07 ft. tall), making him 10cm (3.9 inches) taller than Bao Xishun, the current tallest man, who is 2.36m (7.9ft).

Rather remarkable, contrary to many other rather exceptionally long people in the world, Zhao Liang’s remarkable body seize is not caused by a medical problem. Zhao Liang’s parents are of a more usual height:

- his father measuring 1.8m (5.9 ft.) – which is quite long, for the average length for chinese men is 1.73m;
- and his mother measures 1.68m (5.5 ft.).

Though the seize of his hands may not be as large as the hands of Leonid Stadnyk from Ukraine (who appears to have the largest ‘normal’ male hands in the world) and Duangjai Samaksamarn from Thailand (who appears to have the largest ‘abnormal’ females hands in the world), the hand of Zhao Liang look very impressive compared to the hand of one of the doctors of the Tianjin hospital – see the photo above.

Nevertheless, Zhao Liang’s mother is quite a bit concerned about the health of her son:

“He [Zhao Liang] has a big appetite and can easily eat eight hamburger-sized steamed buns and three dishes for dinner. But I am so worried about his marriage, job and his health that my hair has turned white.”

READ MORE ABOUT LARGE HANDS:

Leonid Stadnyk has the largest hand in the world!
Lee Redmond had the largest fingernails in the world!
The large hand of Zhao Liang: World’s Tallest Man?
The hands of the 3 tallest men in the world!

The hand-foot syndrome includes: a chronic inflammation of the palms, and possibly: missing fingerprints!

The ‘hand-foot syndrome’ can be understood as a side effect of a chemotherapy – especially the cancer drug Capecitabine (Xeloda) is notorious for the side-effects related to the ‘hand-foot syndrome’.

Last month (may, 2009) a letter from a doctor, published in the magazine ‘Annals of Oncology’, became hot news because his client – a 62-year old cancer patient from Singapore – was held for four hours by immigration officials in the United States because they could not detect his fingerprints! The doctor of the patient had to declare that his patient’s fingerprints disappeared because of a cancer-drug he had been taking for over years. A disappearing fingerprint is one of the typical but rare features of the ‘hand-foot syndrome’.

The major symptoms of the hand-foot syndrome include: feelings of tingling or burning, redness, flaking, swelling, small blisters, and small sores on the palms of the hands or soles of the feet.
Especially the ‘flaking’ aspect which can result in breaking or peeling of the skin, may result sometimes in the vanishing of the fingerprints.

WHAT DRUGS MAY CAUSE THE ‘HAND-FOOT SYNDROME’?

The following chemotherapy drugs (usually used to treat cancer) have been reported to cause hand-foot syndrome in some patients:

>> Capecitabine (Xeloda)
>> Cytarabine (Cytosar-U)
>> Floxuridine (FUDR)
>> Fluorouracil (5-FU)
>> Idarubicin (Idamycin)
>> Liposomal doxorubicin (Doxil)

INTERESTING SUGGESTIONS RELATED TO HANDS & CANCER:

Why a cancer patient may have no fingerprints: the hand-foot syndrome!
Can palm reading pick up ovarian cancer?
Raynaud’s syndrome – another painful hand disorder
Paraesthesia: feels like having pins and needles in the fingers
Research: dermatoglyphs & gastric cancer (Croatia, 2003)