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Humanity's divergence into left and right handedness

Approximately 200,000 BC- 50,000 BC
By now (if not earlier) humanity's predecessors have diverged into two distinct types in terms of dexterity-- right-handers and left-handers; the majority are right-handed; hominids in general are living in small, roaming groups

Signposts perspectives on the past

This page last updated on or about 10-24-06

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BACK to contents: Perspectives 59,999,999 BC- 51,000 BC...


-- "Humans Switched To Fast Food When Slow Prey Ran Out" By Maggie Fox, Reuters Limited; http://dailynews.yahoo.com/; 1-9-99

"...handedness, one of few firm behavioral boundaries separating humans from other animals."

-- The evolution of right- and left-handedness ["http://www.eurekalert.org/pub_releases/2006-02/uocp-teo022806.php"]; 28-Feb-2006; Contact: Suzanne Wu swu@press.uchicago.edu 773-834-0386 University of Chicago Press Journals

"...lefties have probably been around much longer than believed at least 5 million years, when scientists say humans and apes branched on the primate family tree. And evolution has purposely kept them."

-- Chimps hand over new clue to brain By DAVID WAHLBERG; Cox News Service; December 06, 2004

"Truly ambidextrous people, who have indifferent preference for either hand, are extremely rare."

-- What Makes a Lefty: Myths and Mysteries Persist - Yahoo! News ["http://news.yahoo.com/s/space/20060322/sc_space/whatmakesaleftymythsandmysteriespersist;_ylt=As0ge5J3tqjoRfb1InwEuwoDW7oF;_ylu=X3oDMTBiMW04NW9mBHNlYwMlJVRPUCUl"] by Corey Binns; LiveScience.com; Mar 22, 2006; news.yahoo.com

Note that by now (200,000 BC- 50,000 BC) the majority of humanity has likely become right-handed. Why? Perhaps because of the differences in vulnerability to ingesting mind-altering substances-- since left-handedness and right-handedness traits seem to be accompanied by such differences in psychoactive susceptibility.

AUTHOR'S NOTE: The differences between left-handed and right-handed people described here are meant only to apply on average, not as absolutes. That is, some right-handed people will possess certain left-handed attributes, and vice versa. And then there's the ambidextrous to consider as well...Please keep such exceptions in mind as this item is examined. END NOTE.

Right-handed people are less sensitive to neuro-toxins than left-handed people. As early humanity often encountered periods of starvation, as well as gradually roamed over more and widely varying terrain and climates, experimentation in foodstuffs was essential. Some plants and animals however contain nerve toxins, and would have done anything from kill or sicken eaters, to bring on hallucinations which would have made them much more vulnerable to accidents or attacks by other people or animals. Ergo, lefthanders, being more vulnerable to such effects, would have died at a higher rate, leaving the predominantly right-handed population humanity will consist of by 1999 AD.

Of course, it isn't a 'clean sweep' for righthanders; a small percentage of left-handers also survive the toxic foods filter, either by accident or some competitive advantage(s) over right-handers in another area, somewhat narrower in scope than resistance to psychoactive food and drink. What might such advantages be?

Between six and sixteen percent of 20th century humans are left-handed. Besides the differences noted above with right-handers, left-handedness is also associated with a higher incidence of epilepsy and learning disorders than right-handedness.

-- WHY MOST PEOPLE ARE RIGHT-HANDED From Science Frontiers Digest of Scientific Anomalies ["http://www.knowledge.co.uk/frontiers/"] #36, NOV-DEC 1984 by William R. Corliss, citing Liz Grist; "Why Most People Are Right-Handed," New Scientist, 22, August 16, 1984

"...10 to 12 percent of the human population has historically preferred the left hand."

-- What Makes a Lefty: Myths and Mysteries Persist - Yahoo! News ["http://news.yahoo.com/s/space/20060322/sc_space/whatmakesaleftymythsandmysteriespersist;_ylt=As0ge5J3tqjoRfb1InwEuwoDW7oF;_ylu=X3oDMTBiMW04NW9mBHNlYwMlJVRPUCUl"] by Corey Binns; LiveScience.com; Mar 22, 2006; news.yahoo.com

Left-handed advantages may lie in certain intellectual capacities (among other things). For instance, there's some hints of broader and deeper connections between the two brain hemispheres of left-handers compared to right-handers. The corpus callosum of left-handers is some 11 percent greater in size than that of right-handers, indicating greater integration of both brain hemispheres in processing information. Lefthanders' brain functions also tend to be less specialized into particular brain regions than right-handers, possibly rendering left-handers more hologramic in their brain functionality. Thus, this might imply that in cases of severe brain or nervous system injury or disease, the left-handers might enjoy faster healing and recovery than right-handers. Such capacities could prove useful in recovery from strokes, for instance. Keep in mind though that the interface bias in the modern world could itself be the cause of the larger corpus callosum in left-handers, developed to help them better cope with the prejudicial man-made environment around them. Or, the bigger corpus callosum may simply be a requirement to support the more generalized functionality of the left-handed's brain. Too, higher generalization of brain function may mean greater redundancy and therefore less efficiency overall. Which may leave lefties better able to bounce back after brain damage, but allow undamaged righties to outdo undamaged lefties in certain deep intellectual pursuits.

-- LEFT-HANDERS HAVE LARGER INTERBRAIN CONNECTIONS From Science Frontiers Digest of Scientific Anomalies ["http://www.knowledge.co.uk/frontiers/"] #42, NOV-DEC 1985 by William R. Corliss, citing Sandra F. Witelson; "The Brain Connection: The Corpus Callosum is Larger in Left-Handers, " Science, 229:665, 1985

Another intellectual advantage of left-handers could be greater resistance to suggestion or persuasion; of course, this may also point to greater aggressiveness on the part of left-handers in general, and could just as easily be a disadvantage in many situations as a boon. For instance, it might lead lefties to question everything they are shown or told, which could slow them down in traditional education and training environments. But in cases of brainwashing, harmful peer pressures, con games, and cult indoctrination it would seem an extra defensive edge for the lefties. They may not so easily be talked into things as their right-handed brethren. One clue to all this is the greater difficulty in hypnotizing the left-handed relative to the right-handed. Righties concentrate more easily and intently than lefties. On the down side, it would seem someone like an Einstein (deep thinker) would require a right-handed disposition. On the other hand, a leftie may be less likely to suffer a surprise attack due their typically "broader attention" to the environment around them than righties. A leftie might also more easily attain and maintain a position of leadership than a rightie, given these tendencies.

-- IT'S EASIER TO HYPNOTIZE RIGHT-HANDERS From Science Frontiers Digest of Scientific Anomalies ["http://www.knowledge.co.uk/frontiers/"] #39, MAY-JUN 1985 by William R. Corliss, citing Liz Grist; "Hypnosis Relies on Left-Brain Dominance," New Scientist, 36, August 2, 1984

Left-handers might possess better memory capacities than right-handers, at least in certain niche areas, like navigation (remembering how to get from point A to point B).

-- Chimps hand over new clue to brain By DAVID WAHLBERG; Cox News Service; December 06, 2004

It appears left-handers also have an advantage in more violent societies. Of course this may just be due to their contrary handed orientation to the majority of the population (where righties are usually less experienced fighting lefties but lefties are usually more experienced fighting righties), and so disappear where left-handedness-right-handedness more nearly approaches parity, or lefties actually become the majority.

"They discovered a correlation between levels of violence and the proportion of the left-handed population the more violent a culture, the higher the relative proportion of left-handers."

"...the ratio of left-handers to right-handers is higher in successful sportspeople than it is in the general population, suggesting there is definite advantage...in competitive games..."

-- Left-handers win in hand-to-hand combat by Will Knight; 08 December 04; NewScientist.com

-- Left-handedness common in Ice Age By Dr David Whitehouse; 13 February, 2004; bbc.co.uk

"Left-handedness could be beneficial in times of violence..."

-- What Makes a Lefty: Myths and Mysteries Persist - Yahoo! News ["http://news.yahoo.com/s/space/20060322/sc_space/whatmakesaleftymythsandmysteriespersist;_ylt=As0ge5J3tqjoRfb1InwEuwoDW7oF;_ylu=X3oDMTBiMW04NW9mBHNlYwMlJVRPUCUl"] by Corey Binns; LiveScience.com; Mar 22, 2006; news.yahoo.com

"...in the adversarial mode, lefties have a competitive advantage as long as they remain rare..."

"This parallels some social interactions in human cultures, such as sporting competitions in which left-handed players enjoy an advantage over their right-handed opponents."

-- Lefties have the advantage in adversarial situations ["http://www.eurekalert.org/pub_releases/2006-03/yu-lht032306.php"]; Contact: Janet Rettig Emanuel janet.emanuel@yale.edu 203-432-2157 Yale University; 23-Mar-2006

Other differences between the left and right-handed include:

In the future world of the 20th and 21st centuries, left-handers will be much more subject to serious accidents throughout their lives than right-handers. This may help bring about the fact that only around one percent of surviving 80 year olds will be left-handed in the late 20th century (lefties hold their own mortality-wise with righties until around age 33, after which the tide turns decidedly against them).

AUTHOR'S NOTE: I believe I've seen a study somewhere that would challenge somewhat the information above. How? With indications that at least some left-handers switch hand preferences as they get older, perhaps to better cope with the right-handed bias in the environment. If this is so, then the long term survival rate of people who begin life as left-handers may be higher than the above item states. END NOTE.

A major contributor to this high rate of future accidents may be that much of modern society will be built to better serve right-handers (since they are in the majority). This form of 'biased interface' to everyday objects will include many power tools, vehicle controls, and other items.

20th/21st century left-handers will also seem more prone to immune system and neurological problems, as well as smoking, alcoholism, and certain types of cancer, thus lowering their overall life expectancy compared to right-handers (wherever such afflictions are influenced by stress, the built-in bias of future equipment and surroundings may be a contributing factor to the shorter lives).

-- GAME OF LIFE FAVORS RIGHT-HANDERS From Science Frontiers Digest of Scientific Anomalies ["http://www.knowledge.co.uk/frontiers/"] #68, MAR-APR 1990 by William R. Corliss, citing Leigh Dayton; "The Perils of Living in a Right-Handed World," New Scientist, p. 32, October 28, 1989, and Wayne P. London; "Left-Handedness and Life Expectancy," Perceptual and Motor Skills, 68:1040, 1989

-- DO RIGHT-HANDERS LIVE LONGER? From Science Frontiers Digest of Scientific Anomalies ["http://www.knowledge.co.uk/frontiers/"] #58, JUL-AUG 1988 by William R. Corliss, citing Diane F. Halpern, and Stanley Coren; "Do Right-Handers Live Longer?" Nature, 333:213, 1988


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All text above explicitly authored by J.R. Mooneyham copyright © 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 by J.R. Mooneyham. All rights reserved.
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