|This is the talk page for discussing improvements to the Handedness article.|
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|The content of Left-handedness was merged into Handedness on 22 May 2012. That page now redirects here. For the contribution history and old versions of the redirected page, please see ; for the discussion at that location, see its talk page.|
- Moved to Talk:Laterality#From Talk:Handedness.23Shared material with left-handed. Please go there to continue merger discussion.
- The removed material spans 10:25, 25 Jan 2005 to 03:12, 11 February 2006, and was moved from here at 10:27, 11 March 2006.
Proposed merger 
- Moved to Talk:Laterality#Merger proposal. Please go there to continue merger discussion.
- The removed material spans 02:55, 11 February 2006 to 10:16, 11 March 2006, and was moved from here at 2006-03-11 10:27:30
Presidents, Presidential Candidates and Handedness
Completely removed this sentence because it was completely wrong: "After Clinton's term, his left-handed Vice President Al Gore lost to right-handed George W. Bush, who four years later prevailed over John Kerry and John Edwards, both left-handed."
For some reason, there is section exclusively on US Presidents on a article that discusses a universal human charasteristic. I suggest removing that section and creating a see also-link to the article mentioned in that section. Wikikrax (talk) 08:49, 13 December 2013 (UTC)
This section is quite inappropriate to a scientifically slanted article. I agree that it should be deleted. Furthermore, it can't possibly be of interest to any but Americans, and how many of them? — Preceding unsigned comment added by Impregnable (talk • contribs) 00:03, 3 January 2014 (UTC)
Sun direction and earth rotational evolutionary pressure
"That given the disadvantage of hunting or facing an opponent against the sun, a tiny effect from Correlis might suade preference to be "right" over hundreds of thousands or millions of years."
Where does this piece of info come from? I'd like to see an explanation of why this makes sense. The sun will be to a left-handers back in the AM, and to the right-handers back in the PM, so it seems like this is total nonsense? 184.108.40.206 (talk) 03:15, 18 October 2013 (UTC)
- Hi, I don't quite follow the logic of the retort. The original paragraph indicates a thrower facing south so both left and right-handers would have the sun in front of them. Can you please let me know in the retort statement when the sun is to the back of a different handed thrower? Here's my permutation list: both right and left-handers have the same opportunity to face the sun in the AM, and conversely the PM. In the North-South orientation, the sun would always be to the back of the thrower aiming north. Conversely, the south is the opposite. At one of the 45 degree sun angle situations, ie. S-E, both the right-hander and left-hander throwing 90 degrees south would have the sun in their eyes. Northern-direction throwers won't. Sure, the east-west has a small component advantage, but it's negated by equal opportunity hunting before or after noon. I would focus on the direction where there is asymmetry between right and left with respect to the sun.
- Focus on the north-south direction. Don't get trapped in the habit of thinking the sun perpendicularly rises east-west to my position conundrum. "High Noon" in places closer to the arctic circle is quite low in the horizon. Specifically, the area above the Tropic of Cancer is of interest. Here, hominids throwing projectiles south would have the sun in their eyes for the entire year.
- Also concentrate on the evolutionary mindset over immediate effects. For this concept, it's better to have a mindset of a geologist than an geneticists. We may want the immediate and larger results similar to what one gets with a plane traveling with a tailwind or headwind. Rather, the effect is with crosswinds giving an evolutionary advantage over millions of years. By the theory of evolution, sea creatures didn't evolve legs overnight.
- Jdcrutch's Critque
- Coriolis was a mistake. Sorry. http://www.google.com/#q=suade+definition Our languages are constantly evolving. I'm open to edits on language if a more academic style is necessary. I was more focus on conceptual ideas and critiques.
- also: "graduations" may seem like an odd word for gradually in the noun tense so pre-empting: http://www.merriam-webster.com/dictionary/gradation?show=0. Attempting to use in a gradually sense but may be construed as a ceremony.
- WHPratt's comments — Preceding unsigned comment added by Ilupper (talk • contribs) 20:00, 19 January 2014 (UTC)
That sounds vaguely like the explanation (not in this article, but probably in another) as to how baseball fields are ideally oriented: so that the fielders have to deal with the setting sun and not the batter. Of course, this assumes that they'll occasionally playing through sunset, but never at dawn. (Of course, this explains the term "southpaw" for a left-handed pitcher. However, I'm not sure that applies to warfare, where an attack may take place at sunrise. WHPratt (talk) 12:38, 18 October 2013 (UTC)
- WH Pratt, thanks for reference. Yes, there's a consistent disadvantage for throwers looking southward in the northern hemisphere. Focusing on hunter/gatherer groups, their prey can see them first before they can see them thus increasing the distance that hunters have to engage their potential meal. Northern facing hunters would have an opposite effect.
- So why it works*
There are two main sticking points that most other theories have yet to answer:
- 1) Why haven't we evolved to be left-handed dominate?
- 2) Why is the ratio the way it is? If you believe 80-20 or 90-10 ratios by different estimates, why has it not evolved to 70-30 or 60-40 ratios?
This theory attempts to take a physiological approach to how in a natural environment our bodies have adapted, much akin to opposable thumbs or walking upright freeing our arms to do other tasks besides locomotion. Whereas lateralization and genetic theories will stop at letting us know where the parts of the brain or genes control handedness, this physical approach will take the answer the rest of the way.
The specific mechanism for this theory is that those hunter-gatherer groups generally above the Tropic of Cancer and under the influence of the Westerlies threw better right-handed towards the south. The tolerances on a southern directed throw was much greater; decreasing the allowances of shorter distance and undistracted aim. In the 90% of human history when most societies were hunter-gathers, we were more evenly distributed over the planet. As our civilizations progressed, those hunter/gatherer groups that experienced the most population growth was coincidentally above the Tropic of Cancer (European, Egyptian, Fertile Crescent, Indus Valley, and Yellow River). And thus the ratio of our current right-handers. Genetically, the larger population affected the gene pool of those in the southern hemisphere so statistically, we have a quorum on the same ratio throughout the world.
/* Genetic factors */ deletion due to failed verification
This statement does not correlate with the citations provided.
"Other mechanisms may play a role in handedness, for example hormone signalling. Medland et al. found a CAG repeat length variant in the androgen receptor gene (AR) that is positively correlated with left-handedness in females, and negatively correlated in males. This same variant is positively correlated with testosterone levels in males, and negatively correlated in females." This may help to explain why there are more left-handed men than women (around 12% in men versus 10% in women globally). However, another study has found that this variant is instead associated with mixed-handedness in males (and not left-handedness), conflicting with the original results.
One citation provided is a meta-study, that doesn't give explanation on why "left handedness" is more prevalent in males, just that it is more prevalent in males, the other citation provided states the exact opposite of the above text:
Behav Genet. 2005 Nov;35(6):735-44. Opposite effects of androgen receptor CAG repeat length on increased risk of left-handedness in males and females.
"Likelihood of left handedness increased in those individuals with variants of the androgen receptor associated with lower testosterone levels"
The article states: "When two left-handers compete against each other, they are both likely to be at the same level of practice as when right-handers play other right-handers." Isn't this a logical flaw? Left handers do not have additional amounts of practice against other left-handers. Only 10% of the population is left-handed so left-handers should also be inexperienced against other left-handed people. When two left-handers compete against each other, they are both likely to be at the same level of practice as when right-handers play left-handers. Alternately, perhaps it's just that the wording of the sentence is poor, and the intended meaning is "When two left-handers compete against each other, both are likely to have the same amount of practice, similar to a situation with two right-handers compete, both are likely to have the same amount of practice." Yet here, the problem is that the amount of practice is not equal, since right-handers would have had 90% of their practice in that type of situation, yet left-handers would have only had 10%. The amount of practice is not the same in comparing left- to right-handers, yet the sentence takes "two left-/right-handers" as its unit of measure. Not sure how to fix but the current statement is unclear. Can I just delete it because it's not useful and confusing? Twocs (talk) 02:35, 11 January 2014 (UTC)
Section "Prenatal vestibular asymmetry" added;
"Previc, after reviewing a large number of studies, found evidence
that the position of the fetus in the final trimester and a baby's
subsequent birth position can affect handedness. ..."