Digit ratio and indicator to personal optimal Testosterone level?

[PAUL-E]

The digit ratio is the ratio of the lengths of different digits or fingers typically measured from the midpoint of bottom crease (where the finger joins the hand) to the tip of the finger.It has been suggested by some scientists that the ratio of two digits in particular, the 2nd (index finger) and 4th (ring finger), is affected by exposure to androgens e.g. testosterone while in the uterus and that this 2D:4D ratio can be considered a crude measure for prenatal androgen exposure, with lower 2D:4D ratios pointing to higher prenatal androgen exposure. The 2D:4D ratio is calculated by dividing the length of the index finger of the right hand by the length of the ring finger of the right hand. A longer index finger will result in a ratio higher than 1, while a longer ring finger will result in a ratio lower than 1.
The 2D:4D digit ratio is sexually dimorphic: while the second digit is typically shorter in both females and males, the difference between the lengths of the two digits is greater in males than in females.
A number of studies have shown a correlation between the 2D:4D digit ratio and various physical and behavioral traits. https://en.wikipedia.org/wiki/Digit_ratio
.



So basically saying the longer the ring finger and shorter the index finger the more exposed to testosterone in the womb. My self my ring finger is long and very close to my middle finger and my index is considerably shorter. I myself seem to need a higher testosterone level to feel better whale others seem to do better with lower levels of testosterone. Considering are brain development is in the womb with hand development I am wondering if there is a correlation between digit ratio and optimal testosterone levels for the individual, kinda like saying your brain is programmed to preform at certain levels if that makes sense.
I know there are a lot of other variables but what do you guys think?

 

[Nelson Vergel]

Researchers have been pretty obsessed with this. My ratio is low . Is that why I am an alpha?




Fetal development of the hand, digits and digit ratio (2D: 4D)

MA Malas, S Dogan, EH Evcil, K Desdicioglu - Early human development, 2006 - Elsevier
OBJECTIVE: The purpose of this study was to investigate growth patterns in human hands,
digits and digit ratio (2D: 4D) during the fetal period. METHODS: The study is carried out on
161 human fetuses (83 males, 78 females) free from external pathology or malformation ...
Cited by 229 Related articles All 9 versions Cite Save


[PDF] from researchgate.net

A longitudinal study of digit ratio (2D: 4D) and other finger ratios in Jamaican children

R Trivers, J Manning, A Jacobson - Hormones and Behavior, 2006 - Elsevier
It has been hypothesised that the ratio between the length of the 2nd and 4th digits (2D: 4D)
is a correlate of prenatal sex steroids, and this relationship is strongest for the right hand.
Furthermore, it has been suggested that 2D: 4D is sexually dimorphic, the dimorphism is ...
Cited by 202 Related articles All 11 versions Cite Save


[PDF] from researchgate.net

Finger length ratio (2D: 4D) correlates with physical aggression in men but not in women

AA Bailey, PL Hurd - Biological psychology, 2005 - Elsevier
Finger length ratio (2D: 4D) is a sexually dimorphic trait. Men have relatively shorter second
digits (index fingers) than fourth digits (ring fingers). Smaller, more masculine, digit ratios are
thought to be associated with either higher prenatal testosterone levels or greater ...
Cited by 284 Related articles All 17 versions Cite Save


[PDF] from researchgate.net

Digit ratio (2D: 4D) and physical fitness in males and females: Evidence for effects of prenatal androgens on sexually selected traits

J Hönekopp, JT Manning, C Müller - Hormones and Behavior, 2006 - Elsevier
It has been suggested that male achievement in sports and athletics is correlated with a
putative measure of prenatal testosterone the 2nd to 4th digit ratio (2D: 4D). It is not known
whether this association also extends to females, or whether the association results from ...
Cited by 163 Related articles All 11 versions Cite Save


Digit ratio (2D: 4D), lateral preferences, and performance in fencing 1

M Voracek, B Reimer, C Ertl… - Perceptual and motor …, 2006 - amsciepub.com
Summary The second to fourth digit ratio (2D: 4D) is a sexually dimorphic trait (men tend to
have lower values than women) and a likely biomarker for the organizational (permanent)
effects of prenatal androgens on the human brain and body. Prenatal testosterone, as ...
Cited by 101 Related articles All 4 versions Cite Save


[PDF] from researchgate.net

Meta‐analysis of digit ratio 2D: 4D shows greater sex difference in the right hand

J Hönekopp, S Watson - American Journal of Human Biology, 2010 - Wiley Online Library
Objectives: Our aims are, first, to describe the sex difference in the length ratio of the second
and fourth digits (2D: 4D), which likely reflects prenatal testosterone levels in humans.
Second, to infer the loss of reliability observed in 2D: 4D based on self-measured finger ...
Cited by 189 Related articles All 8 versions Cite Save


[PDF] from researchgate.net

The effects of sex, ethnicity, and sexual orientation on self-measured digit ratio (2D: 4D)

JT Manning, AJG Churchill, M Peters - Archives of sexual behavior, 2007 - Springer
Abstract We used self-reported direct finger measurements from 255,116 participants in a
BBC Internet survey to investigate the measurement of 2D: 4D ratios and their association
with sex, ethnicity, and sexual orientation. We found significant sex differences such that ...
Cited by 152 Related articles All 9 versions Cite Save

 from elsevierhealth.com[/URL][/B][/B][/B]

[B][B][B][B][URL="http://www.sciencedirect.com/science/article/pii/S037837820400012X"]2nd to 4th [B]digit ratios[/B], fetal testosterone and estradiol[/URL][/B][/B][/B][/B]

[B][B][B]S Lutchmaya, [URL="https://scholar.google.com/citations?user=4GAQ-RUAAAAJ&hl=en&oi=sra"]S Baron-Cohen[/URL], P Raggatt… - Early human …, 2004 - Elsevier[/B][/B][/B]
[B][B][B][B]... indirectly influence the prenatal production of testicular androgen and (b) the development of
the [B]digits [1] and [B]... relate to gonad function [3]. One likely candidate for such a link is the [B]ratio
between the length of the 2nd (the “index” [B]finger) and 4th (the “ring” [B]finger) [B]digit ([B]2D:[B]4D). [B]...[/B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B][/B]
[B][B][B][URL="https://scholar.google.com/scholar?cites=6647825277491724870&as_sdt=5,44&sciodt=0,44&hl=en"]Cited by 630[/URL] [URL="https://scholar.google.com/scholar?q=related:RsLBQd7RQVwJ:scholar.google.com/&hl=en&as_sdt=0,44&as_vis=1"]Related articles[/URL] [URL="https://scholar.google.com/scholar?cluster=6647825277491724870&hl=en&as_sdt=0,44&as_vis=1"]All 13 versions[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Cite[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Save[/URL][/B][/B][/B]


[B][B][B][B][URL="http://onlinelibrary.wiley.com/doi/10.1002/ajhb.20603/full"]Endurance running and [B]digit ratio [/B]([B]2D[/B]: [B]4D[/B]): implications for fetal testosterone effects on running speed and vascular health[/URL][/B][/B][/B][/B]

[B][B][B]JT Manning, L Morris, N Caswell - American Journal of Human …, 2007 - Wiley Online Library[/B][/B][/B]
[B][B][B]Abstract There is anatomical and physiological evidence that endurance running (ER), ie, 
running one or more kilometers using aerobic metabolism, originated early in the evolution 
of Homo, and the consequences of early selection for ER may be important in modern [B]...[/B][/B][/B][/B]
[B][B][B][URL="https://scholar.google.com/scholar?cites=4935428316989075933&as_sdt=5,44&sciodt=0,44&hl=en"]Cited by 131[/URL] [URL="https://scholar.google.com/scholar?q=related:3bGJwOcpfkQJ:scholar.google.com/&hl=en&as_sdt=0,44&as_vis=1"]Related articles[/URL] [URL="https://scholar.google.com/scholar?cluster=4935428316989075933&hl=en&as_sdt=0,44&as_vis=1"]All 3 versions[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Cite[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Save[/URL][/B][/B][/B]


[B][B][B][URL="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2883918/"][HTML] from nih.gov[/URL][/B][/B][/B]

[B][B][B][B][URL="http://link.springer.com/article/10.1007/s10508-007-9271-3"]Spatial ability and prenatal androgens: Meta-analyses of congenital adrenal hyperplasia and[B]digit ratio [/B]([B]2D[/B]: [B]4D[/B]) studies[/URL][/B][/B][/B][/B]

[B][B][B][URL="https://scholar.google.com/citations?user=fZ_ZqrMAAAAJ&hl=en&oi=sra"]DA Puts[/URL], [URL="https://scholar.google.com/citations?user=fEWuQs0AAAAJ&hl=en&oi=sra"]MA McDaniel[/URL], CL Jordan… - Archives of sexual …, 2008 - Springer[/B][/B][/B]
[B][B][B]Abstract Hormonal manipulations indicate that early androgens organize sex differences in 
spatial ability in laboratory rats. In humans, spatial ability is also sexually dimorphic, and 
information about the effects of prenatal androgens on spatial ability can be obtained from [B]...[/B][/B][/B][/B]
[B][B][B][URL="https://scholar.google.com/scholar?cites=4748614734637387675&as_sdt=5,44&sciodt=0,44&hl=en"]Cited by 149[/URL] [URL="https://scholar.google.com/scholar?q=related:m08_IfF35kEJ:scholar.google.com/&hl=en&as_sdt=0,44&as_vis=1"]Related articles[/URL] [URL="https://scholar.google.com/scholar?cluster=4748614734637387675&hl=en&as_sdt=0,44&as_vis=1"]All 17 versions[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Cite[/URL] [URL="https://scholar.google.com/scholar?q=2D:4D+digit+ratio&hl=en&as_sdt=0&as_vis=1&oi=scholart&sa=X&ved=0ahUKEwj1nPvBgJfMAhVBOiYKHYgwCq8QgQMIGzAA#"]Save[/URL][/B][/B][/B]

 

[PAUL-E]

There might be something to it. I tested in the 90th percentile of people for visual/image problems but spelling and grammar could use some work.

 

[James]

mine is low too. It will be interesting to see if others weigh in on this. I suspect most will be low.