MAY 23, 2013

Research reports point out:
Thumb + Radial Fingers correlate with Introvert & Internalizing Behavior!


The long opposable thumb is recognized to represent a symbol for the evolution of the superior human brain. Can the thumb also serve as a marker for individual behavior?

The answer appears to be 'yes', because most finger length studies (e.g. various 2D:4D digit ratio studies) point out that both the thumb and radial hand show correlations with tendencies towards introversion & internalizing behavior, while the ulnar side of the hand shows a reversed tendency towards extaversion & externalizing behavior.

The fundamental explanation for these relationships can be found in anatomic structure in terms of nerves and dermatomes; the thumb & radial side of the hand is connected through higher located cervical nerves (in the spinal column) with the brain - which implicates that the ulnar side of the hand is in the spinal nerve system located more close to spinal nerve systems that regulate the heart and the other internal organs. This shows in a nutshell why your thumb is more closely connected with your brains, and why in terms of behavior your thumb is connected with your 'inner world'!
Hand dermatomes correlates with behavior.

Hand dermatomes correlate with behavior.

The continuation of this article summarizes various biological facts & behavior related research results which together point out how the radial side of the hand correlates with behavior that can be associated with the brain, and how the ulnar side of the hand can be associated with behavior associated with the heart (ring finger) & the sexual organs (pinky finger).




Thumb is positioned towards the central axis of the body.

Thumb is located closest to the central axis of the body, and the 'opposable' thumb has a certain rotation which reflects a natural tendency to be faced towards the inner palm and the other fingers.
THE THUMB, EVOLUTION & THE CENTRAL AXIS OF THE BODY!

The thumb is the only digit that can fully be 'protected' by other digits, because the thumb is the most proximal located digit of the hand. But in order to understand the nature of the thumb properly it is also important to be aware that of all fingers & toes the thumb and the big toe are located closest to the central axis of the body (see picture on the left).

Symbolically this represents how the thumb can be associated to represent your inner core - which sometimes may require some protection from the other fingers in order to survive.

Also, it is important to be aware that both the thumb and the big toe (= digit 1 of the hand & foot) only have 2 phalanges (3 bones), while all other digits have 3 phalanges (4 bones): see picture below.

By the way, this is actually a rather typical characteristic in the perspective of evolution, Even the so-called 'Seymouria' (a reptile-like labyrinthodont from the early Permian of North America and Europe approximately 280 to 270 million years ago) was featured with only 3 thumb bones, while the other digits had 4 or more bones. Just like in many many amphibeans, reptiles & prosimian primates, in the Seymouria digit 4 was the longest of all digits and it was featured with even up to 6 bones (see picture below).

This illustrates how the long opposable thumb became recognized to represent a symbol for the superior human brain, while the ring finger (4th digit) became recognized to represent a symbol of a more primitive 'masculine' nature - which also got associated with the hormone testosterone. Since the 80's various studies have pointed out that individual differences in extraversion & aggression are likely to be mediated through testosterone; and thus this explains why the fundamental relationship between the ring finger and extraversion + aggression.

Human hand bone structure.

Human hand bone structure.

Seymouria hand bone structure.

Seymouria hand bone structure.



HAND NERVE SYSTEMS POINT OUT:
THUMB, INDEX FINGER & MIDDLE FINGER REPRESENT THE 'RADIAL SIDE' OF THE HAND


The hand nerve system displays whether the individual fingers belong to the radial- or ulnar side of the hand.

Combining the so-called 'dermatomes' and the 'cutaneous innervation' together shows that the 'radial side' of the hand includes dermatomes C6 & C7 (see left picture below), which basically represent the largest part of the radial- & median nerve system (see right picture below); this perspective implicates that thumb + index finger + middle finger (plus the accessory palmar zones) can be recognized to represent the 'radial side' of the hand.

The 'ulnar side' of the hand includes dermatome C8, which basically is represented by the ulnar nerve system (+ a small part of median- and radial nerve system that is found in the radial side of the ring finger); this implicates that the pinky + ring finger (plus the accessory palmar zones) together can be recognized to represent the 'ulnar side' of the hand.

Hand & upper limb dermatomes: spinal nerve connections.

Hand & upper limb dermatomes: spinal nerve connections.

Hand & upper limb dermatomes: cutaneous innervation.

Hand & upper limb nerves: cutaneous innervation.

The picture below displays how the thumb & radial side of the hand is connected through higher located cervical nerves (in the spinal column) with the brain. This also implicates that the ulnar side of the hand is in the spinal nerve system located more close to lower located spinal nerve systems which involve the regulation of e.g. the heart and the sexual organs.

Hand dermatomes & spinal nerve connection.
Hand dermatomes & the spinal nerve connection.



FINGER LENGTH RATIOS TEND TO CORRELATE DIFFERENTLY
WITH INTERNALIZING & EXTERNALIZING BEHAVIOR!


In the 21th century finger lengt ratios became a popular tool to study the biological causes of normal & psychiatric behavior. Especially the so-called 2D:4D digit ratio became a commonly used measure, scientists also have started using other finger length ratios (though the thumb is only rarely included because it's length is more difficult to define compared to the length of the other fingers - which is usually measured from the proximal crease to the tip of the finger).

Though inconsistent results have been reported, there is a clear tendency in the results reported inside scientific publications which suggest:

- Dominant radial fingers (= higher 2D:4D digit ratios and/or higher 3D:5D digit ratios) get associated with introversion and/or more internalizing problems that correlate negative with testosterone (these may result in self harm due to an overcontrol of emotions, examples may vary from temporary tendencies toward: social withdrawal, feelings of worthlessness or inferiority, dependency; to more permanent behavior patterns related to anxiety, depression, eating disorders, schizophrenia, substance abuse, etc.).

- Dominant ulnar fingers (= lower 2D:4D digit ratios and/or lower 3D:5D digit ratios) get associated with extraversion and/or more externalizing problems that correlate positive with testosterone (these may result in the harm of others due to an undercontrol of emotions, examples may vary from temporary tendencies toward: difficulties with interpersonal relationships and rule breaking as well as displays of irritability and belligerence; to more permanent behavior patterns related to ADHD, aggression, autistic spectrum disorders, conduct problems, etc.).


2D:4D digit ratio & androgen receptors.
2D:4D digit ratio & androgen receptors.
An earlier report this year about a Dutch student population revealed that long middle fingers (finger length) & long index fingers (high 2D:4D digit ratio) were observed significantly more often among 'introverts'; while long ring fingers (low 2D:4D digit ratio) were more often observed among 'extraverts'. Further investigations later also confirmed that long thumbs were more often observed in 'introverts' than in 'extraverts'.



THE FIELD OF HAND READING / PALMISTRY:
THE THUMB GETS ASSOCIATED TO REPRESENT THE SO-CALLED 'I-SIDE'!


In the field of hand reading the meaning of the thumb has been disputed, though it appears that even today few authors are aware of this.

I-side versus You-side.

I-side versus You-side.

Some early authors (including the American author William G. Benham) had associated the thumb to represent how the individual tends to manifest in the so-called 'outer world'.

However, in the 1st half of the 20 century authors (including the German author Ernst Issberner-Haldane) began to associate the radial side of the hand to represent the so-called 'I-side' or 'Ego' of a person, and the ulnar side got associated to represent the so-called 'You-side' - which appears to make sense in the perspective of the fact that the pinky finger had for decades been associated with interpersonal communication via the 'outer world' - resulting in that the thumb became associated to represent the so-called 'inner world'.

This specific approach (or a likewise approach) was later adopted by e.g. quite some prominent West-European authors in the UK & The Netherlands: see picture on the left.

Inner world versus outer world according G.S. Birla (2000).

Inner world versus outer world according G.S. Birla (Vedic Palmistry, 2000).

In the work of Canadian author G.S. Birla it became apparent that the so-called nadi-concept (NOTICE: 'nadis' can be translated as nerves!) used in Vedic philosophy confirms that the radial side of the hand gets associated with the so-called 'inner world' [IDA] and the ulnar side gets associated with the so-called 'outer world' [PINGALA].

NOTICE: The Kundalini Yoga nadis 'IDA' (female energy: cool & incoming) and 'PINGALA' (male energy: hot & outgoing) are recognized to represent a likewise polarity-principle as the so-called complementary 'YIN' (female principle: passive, shaded & reflective) and 'YANG' (male principle: active, bright & shining) of the Chinese philosophy. It is also interesting to notice that in 5 Element Chirology the index- and middle finger (radial fingers) get associated with in respective the YIN-elements 'Water' and 'Earth', while the ring finger and pinky (ulnar fingers) get associated with in respective the YANG-elements 'Fire' and 'Air'. Not to forget that in Christian philosophy the thumb also got associated with a person's soul - which also appears to confirm that the thumb is more likely to have a stronger connection with a person's 'inner world'.

This demonstrates how according the major principles used in the 3 great world philosophies the thumb tends to get associated with the inner nature of man - which perfectly makes sense in the perspective of the fact that in the anatomic perspective the thumb can be recognized to represent: 1) the most proximal located digit, and 2) the only digit that can be described to have a natural position that is directed towards the central axis of the body.





- CONCLUSION -

Despite that in the early days of hand reading some authors associated the thumb with the 'outer world', there is actually plenty of fundamental evidence (based on hard science & eastern philosophies) available which points out that the thumb is much more likely to reveal info related to a person's 'inner world'. This is e.g. illustrated by the fact that finger lenght studies point out that overdevelopment in the radial fingers usually get associated with behavioral tendencies towards 'introversion' and/or 'internalizing behavior'.

The anatomy of the thumb appears to provide additional evidence for this relationship.

Finally, it is interesting to notice that in some branches of Indian predictive palmistry a person's destiny is identified via just the thumb. Parallel to this idea in the field of Western hand reading the 3 phalanges of the thumb usually get associated with the threesome 'willing [will] - thinking [logic] - feeling [passion]', which in Rudolf Steiner's Anthroposophy philosophy got recognized to represent the human soul functions that provide the basis of all human behavior.

NOTICE: The 'mind map' below only serves as an illustration for the huge diversity
that is found inside the international hand reading literature.

Mind map for the hand.


THUMBS & FINGERS NEWS - 2D:4D DIGIT RATIO NEWS

HAND READING NEWS




Martijn van Mensvoort - Hand Research

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