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 ‘Vitruvian Man’ - Leonardo da Vinci‘s famous drawing from the year 1487 - can be described as one of the earliest sources presenting guidelines for hand anthropometry. Today, plays hand anthropometry a considerable role in the fields of design, ergonomics, and even architecture! An update presenting data from e.g. the NASA and the US army.

The drawing, which is in pen and ink on paper, depicts a male figure in two superimposed positions with his arms and legs apart and simultaneously inscribed in a circle and square. The drawing and text are sometimes called the Canon of Proportions or, less often, Proportions of Man.

Interestingly, Leonardo’s comments for the proportions of th e ‘Vitruvian Man‘ includes a few passage where the hands and fingers are mentioned, quote:

“For the human body is so designed by nature that the face, from the chin to the top of the forehead and the lowest roots of the hair, is a tenth part of the whole height; the open hand from the wrist to the tip of the middle finger is just the same; the head from the chin to the crown is an eighth, and with the neck and shoulder from the top of the breast to the lowest roots of the hair is a sixth; from the middle of the breast to the summit of the crown is a fourth. If we take the height of the face itself, the distance from the bottom of the chin to the under side of the nostrils is one third of it; the nose from the under side of the nostrils to a line between the eyebrows is the same; from there to the lowest roots of the hair is also a third, comprising the forehead. The length of the foot is one sixth of the height of the body; of the forearm, one fourth; and the breadth of the breast is also one fourth. The other members, too, have their own symmetrical proportions, and it was by employing them that the famous painters and sculptors of antiquity attained to great and endless renown. Similarly, in the members of a temple there ought to be the greatest harmony in the symmetrical relations of the different parts to the general magnitude of the whole. Then again, in the human body the central point is naturally the navel. For if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centred at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom. And just as the human body yields a circular outline, so too a square figure may be found from it. For if we measure the distance from the soles of the feet to the top of the head, and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of plane surfaces which are perfectly square.”
 

'Study of arms and hands' - another drawing by Leonardo da Vinci.

 Leonardo da Vinci’s comment about the proportion of the average hand was quite right, but the field of anthropometry has later developed more precise methods in order to describe the most important individual variations concerning the human body. Various sources of anthropometric hand data indicate the average hand length is close to 11% of body height (usually slightly smaller). Leonardo’s ‘Study of arms and hands’ is another of his drawings.

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ANTHROPOMETRY TODAY:

Today, anthropometry plays an important role in industrial design, clothing design, ergonomics and architecture where statistical data about the distribution of body dimensions in the population are used to optimize products.


DATA FROM THE NASA & US ARMY:

In the last decade of the 20 century reports became available developed by the NASA & the US army – which include data for at least 20 characteristics of the human hand shape, including e.g. hand length, hand breadth & finger length. The data in the picture above represents static human physical characteristics of the adult hand, presented in 2000 by the Department of Defense Human Factors Engineering Technical Advisory Group.

The picture below presents at the bottom some average data based on German, UK & American populations – which provide useful ‘points of reference’ in the perspective of biometry & Multi-Perspective Palm Reading.


Finally, regarding Leonardo da Vinci it might be interesting to notice here that in 2008 a report was published describing characteristics of his fingerprint:

http://www.handresearch.com/news/leonardo-da-vinci-fingerprint.htm

Marfan syndrome can be understood as a connective tissue disorder – which relates to the tissue that strengthens the body. The syndrome is usually featured with a tall, slender body with long limbs & extremely long, thin fingers & toes. The most serious complications are the defects of the heart valves and the aorta, which could lead to an aortic rupture (due to too much stress on the aorta), which is usually fatal. But many people who have this disorder are not aware of it! This is partly because Marfan syndrome typically becomes manifest only after the age of 5. But there are many hand signs that have a highly reliable diagnostic value!

Marfan syndrome is featured with many typical hand characteristics, however a combination of two specific hands signs related to a long hand shape (hand signs) & hand motorics (joint hypermobility) is often enough to identify the disorder.

The Steinberg sign & Walker-Murdoch sign.

THE STEINBERG SIGN (a):

This test is used for the clinical evaluation of Marfan patients.

Procedure:
Instruct the patient to fold his thumb into the closed fist. This test is positive if the thumb tip extends from palm of hand (see figure a).

THE WALKER-MURDOCH SIGN (b):

This test is used for the evaluation of patients with Marfan syndrome.

Procedure:
Instruct the patient to grip his wrist with his opposite hand. If thumb and fifth finger of the hand overlap with each other, this represents a positive Walker-Murdoch sign (see figure b).


JOINT HYPERMOBILITY

How to check if a person has hypermobility? You can check this easily by doing the 5 tests that are included in the so-called ‘Beighton score‘: see figure 1.

A ‘Beighton score’ of 4 or above usually indicates hypermobility.

And if a person has the Sternberg sign + Walker-Murdoch sign + hypermobility, the chances are above 90% that the person has Marfan syndrome.

The presence of other related hand markers such as: skin quality (hyperextensiblity), a simian crease, extra digital transverse creases, or a high positioned axial triradius provide other significant hand signs which are indicative for a person to have a medical test for Marfan syndrome.

A typical 'Marfan' hand gesture!

The 15 fingers + 16 toes of a Chinese boy!

Last year (2010) another report was made about an unnamed 6-year-old Chinese boy who had 16 toes and 15 fingers.

The boy had unprecented 31 digits, which included 15 fingers and 16 toes! But I am not sure that it would have been recognized as a world record because obviously in the fingers there is ‘syndactly’ involved, which implicates that not all fingers would have been counted – just like in the case of Heramb Ashok Kumthekar:

Anyway, the Chinese boy’s family did not go to apply for a Guinness World Record, rather sent him to Shengjing Hospital affiliated with China Medical University in Shenyang recently to undergo a surgery to remove the extras because he suffered from the inconvenience in the daily life and also being ridiculed from peers of the same age at his school. So appearantly the parents made a very sensible decision.

Participate in the discussion about these RECORD fingers & toes:
http://www.modernhandreadingforum.com/t605-girl-from-myanmar-burma-has-12-fingers-14-toes-a-brand-new-guinness-world-record

 Almost two years ago, we reported the case of Heramb Ashok Kumthekar, a Marketing student from India who has 12 fingers + 14 toes. While the current ‘polydactyly‘ Guinness World Record of having 25 fingers & toes is still in the hands of a boy named Devendra Harne & a girl named Pranamya Menaria – who are both living in India, Kumthekar’s case was not officially recognized because some of his fingers were webbed (syndactyly). But earlier this week a new case of 26 fingers & toes was reported in Myanmar (former Burma).

YANGON, Myanmar — A 16-month-old girl has been recognized as the world record holder for total fingers and toes – 26!

Le Yati Min was born with 12 fingers and 14 toes. Her family has already coined and copyrighted the phrase, “Give me a high-six!” in both Burmese and English.

A neighbor and friend of the family spoke to reporters outside the girl’s small wooden home, “She already counts higher than all the other kids. She got lucky, I guess. We’re just waiting to see what she can do with a typewriter. We’re guessing she’ll be up to 90 or 100 words per minute by the time she’s five, I mean, six.”

Her mother, Phyo Min Min Soe, also told reporters that Le has not been bothered by the extra digits and has “a good grip on things.”

A neighbor and friend of the family spoke to reporters outside the girl’s small wooden home, “She already counts higher than all the other kids. She got lucky, I guess. We’re just waiting to see what she can do with a typewriter. We’re guessing she’ll be up to 90 or 100 words per minute by the time she’s five, I mean, six.”

Her mother, Phyo Min Min Soe, also told reporters that Le has not been bothered by the extra digits and has “a good grip on things.”

The pink handfish - a.k.a. brachionichthys

- TRIBUTE: THE EVOLUTION OF THE HAND -

A few weeks ago (may 2010) Australian researchers Daniel Gledhill & Peter Last from the CSIRO Wealth reported to have discovered 9 new species of the ‘handfish’, in a research that highlights an urgent need to better understand and protect the diversity of life in Australia’s oceans. But the major unanswered question is: ‘two of the handfish fins look like hands, but are they?’

Mr Gledhill described the Handfish as follows:

“Handfishes are small, often strikingly patterned or colourful, sedentary fish that tend to ‘walk’ on the seabed on hand-like fins, rather than swim. Fifty million-years ago, they ‘walked’ the world’s oceans, but now they exist only off eastern and southern Australia“.

One of the newly named species, the Pink Handfish, is known from only four specimens and was last recorded off the Tasman Peninsula in 1999.

Interestingly, if we take a look at some features of red handfish one can notice that it actually isn’t walking with the hands… but with the feet! (See the photos below)

The red handfish - a.k.a. brachionichthys politus!

And in the perspective of evolution it might actually make sense that the hands of the handfish appear to have 4 digits, and the feet have more digits – though 6 digits is really rather remarkable.

Why are 6 digits remarkable?

First of all, the 4-digit hand combined with a 6-digit foot reminds us to a typical characteristics of… amphibians, they are usually featured with 4 digits on the front limbs and 5 digits on the hind limbs!

However, while an amphibian usually spends his live some time on land and some time in the water – there is another rather funny ‘creature’ that has likewise hand- (4 digits) and foot characteristics (5 digits), named: the axolotl – a tiger salamander complex that is living in the waters of Mexico. The difference with the salamander is that the axolotl only lives in the water, just like the handfish!

The axolotl - belonging to the tiger salamander complex!

Most vertebrates have 5 digit limbs!

One should also be aware that most vertibrates (including: mammals, birds, reptiles, amphibians, and various fishes) have 5 digits on each limb. So, from the perspective of evolution it is not a coincidence that us human have 5 finger and 5 toes!

However, in this perspective it is rather remarkable that the handfish appears to have a 6 digit fin!

Would you like to shake hands with a handfish?

Evolution animation: from fish to human!

SUGGESTION FOR FURTHER READING:
The mystery of the five fingers!
Five things that your 5 fingers can tell you!
The difference between the human hand & the hands of primates!

Evolution: from fish to human!

12 Fingers & 14 toes: a new Guinness World Record?Last year various sources around the world reported that Heramb Ashok Kumthekar, a 22 year old marketing student from Pune was born with 12 fingers and 14 toes. The current Guinness World Record holder for having the most fingers and toes in the world is an Indian young boy named Devendra Harne: he has only 12 fingers and 13 toes. However, the student from Pune is not able to claim a new record.

Heramb’s extra digits are caused by the medical condition called ‘polydactly‘, which translates from the Greek for “many fingers”. However, even though his hands have separate bones, technically some of his fingers are attached – this condition is called ‘syndactyly‘.Heramb Ashok Kumthekar says:

“I am happy about it because I have something that others don’t have. I never had a problem with it and after I get publicity I will be famous because of it.”
The congenital condition of having extra fingers occurs in one in every 500 births. Famous holders of extra digits include the beheaded ex-wife of Henry VIII, Anne Boleyn (who was rumoured to have an extra finger on her left hand), the Bollywood superstar Hrithik Roshan (one of Indian cinema’s rising stars has one extra digit on each hand), and recently the new James Bond Girl Gemma Arterton admitted that she was born with 6 fingers on each hand (an extra pinky finger).

 

Heramb Ashok Kumthekar has 14 toes.