{"id":119761,"date":"2026-11-06T06:01:58","date_gmt":"2026-11-06T11:01:58","guid":{"rendered":"https:\/\/bgodinspired.com\/?p=119761"},"modified":"2026-11-06T06:01:58","modified_gmt":"2026-11-06T11:01:58","slug":"why-does-the-left-brain-control-the-right-side-of-the-body","status":"publish","type":"post","link":"https:\/\/bgodinspired.com\/index.php\/bible-resources\/bible-and-science\/why-does-the-left-brain-control-the-right-side-of-the-body\/","title":{"rendered":"Why Does the Left Brain Control the Right Side of the Body?"},"content":{"rendered":"<div class='booster-block booster-read-block'>\n                <div class=\"twp-read-time\">\n                \t<i class=\"booster-icon twp-clock\"><\/i> <span>Read Time:<\/span>5 Minute, 51 Second                <\/div>\n\n            <\/div><p>Touch your left shoulder with your right hand. Now notice what just happened. The part of your brain that sent that order sits on the left side of your head. The left brain control of the right side of the body is so normal that most of us never ask about it. But it is strange. Why would a brain cross its wires?<\/p>\n\n<p>A new paper has a bold answer. It says the crossing is more than 500 million years old, and that it began with an eye.<\/p>\n\n<h2>Why does the left brain control the right side of the body?<\/h2>\n\n<p>Each half of your brain mostly runs the opposite half of you. The left side handles the right hand, right foot and right-side touch. The right side handles the left. Stroke doctors rely on this every day. Damage on one side of the brain shows up as weakness on the other side of the body.<\/p>\n\n<p>The usual guess is that the crossing must give some advantage, like faster reflexes or better balance. Nobody has shown that it does. And that is where the new idea begins.<\/p>\n\n<div class=\"convertkit-form wp-block-convertkit-form\" style=\"\"><script async data-uid=\"6491fb8269\" src=\"https:\/\/bgodinspired.kit.com\/6491fb8269\/index.js\" data-jetpack-boost=\"ignore\" data-no-defer=\"1\" data-no-optimize=\"1\" nowprocket><\/script><\/div>\n\n\n<h2>The eye that flips the world<\/h2>\n\n<p>In late 2026, two researchers at the University of Minnesota, Daniel Delie Wang and Martin Wessendorf, published a theoretical paper in the journal <em>Frontiers in Neuroanatomy<\/em>. Their proposal starts with a simple fact of optics. A round lens turns the image upside down and left to right. Light from your left lands on the right side of your retina, and the other way round.<\/p>\n\n<p>An early animal with eyes like that had a problem. Its brain needed a map of the world, and the world arrived flipped. The authors propose that the fix was to cross the visual wiring, so that the left half of the world is mapped on the right half of the brain. That visual map, they say, is probably about 500 million years old, from the time of the first jawless fishes.<\/p>\n\n<p>Then comes the interesting part. Touch, pain and movement already had to report to that visual map and take orders from it. So they were built to match. The crossing spread from the eyes to the rest of the body. If this is right, the arrangement was inherited rather than chosen, because the first fix became the template for everything built after it. Biologists call a trait like that a &#8220;spandrel&#8221;: a byproduct, like the curved gap that is left between two arches.<\/p>\n\n<h2>What the paper does not say<\/h2>\n\n<p>This is a proposal, not a finding. Nobody ran an experiment. The case rests on comparing living animals and reasoning about their ancestors. The authors themselves point to a possible test: the inner skull casts of early fossil vertebrates might one day show the wiring layout. Until then, it is a well-argued idea and nothing more.<\/p>\n\n<p>It also does not say the crossing is bad. It only says that the crossing may not have been picked for performance. Evolution reuses what already works, and what was built first gets built on.<\/p>\n\n<p>For readers who like the story of how eyes work, we covered a related one: <a href=\"https:\/\/bgodinspired.com\/index.php\/bgodinspired-news\/gene-therapy-for-blindness-goggles\/\">gene therapy for blindness and the cells that learned to see<\/a>. And if you like the idea that a brain may be rearranging itself rather than breaking, see <a href=\"https:\/\/bgodinspired.com\/index.php\/bgodinspired-news\/bgodinspired-science-news\/aging-brain-changing-jobs\/\">the aging brain that may be changing jobs<\/a>.<\/p>\n\n<h2>The left-handed fact that gets overlooked<\/h2>\n\n<p>Here is a small thing that sits oddly beside all this. Because of the crossing, a left-handed person is steering their favorite hand from the right side of the brain. Roughly one person in ten is wired that way. For much of history, that was treated as a defect to be corrected. Children were made to switch hands in many places.<\/p>\n\n<p>One of the oldest history books we have goes the other way. It records a deliverer named Ehud, a left-handed man whose weapon was hidden where nobody thought to look. It also records seven hundred left-handed slingers in one tribe who could aim at a single hair and not miss. The writers did not apologize for the wiring or explain it away. They treated the odd side as the strong side, as if something bigger had been watching the whole time and saw a gift where a crowd saw a flaw. We have a closer look at that story in <a href=\"https:\/\/bgodinspired.com\/index.php\/articles\/heroic-deliverance-ehuds-bold-strike-against-oppression-in-judges-315\/\">Ehud, the left-handed deliverer<\/a>.<\/p>\n\n<p>That does not settle where the wiring came from. A byproduct can still be a gift. A body built on a 500-million-year-old accident can still throw a stone with astonishing accuracy.<\/p>\n\n<h2>What to take from it<\/h2>\n\n<ul>\n<li>Your brain crosses because a very old design fixed one problem and then everything else was built on top of it.<\/li>\n<li>The crossing was probably not chosen for speed or skill. That is what the authors propose, and it is still untested.<\/li>\n<li>How your body is wired tells you little about what you can do with it.<\/li>\n<\/ul>\n\n<p>Next time you reach across for a cup of tea, think about it. A long chain of animals, each one working with what it inherited, ended up in the hand that picked it up.<\/p>\n\n<h2>Discussion question<\/h2>\n\n<p>Do you think a trait has to be &#8220;chosen&#8221; to be useful, or can something that began as an accident still be a gift? Tell us what you think in the comments.<\/p>\n\n<div class=\"convertkit-form wp-block-convertkit-form\" style=\"\"><script async data-uid=\"6491fb8269\" src=\"https:\/\/bgodinspired.kit.com\/6491fb8269\/index.js\" data-jetpack-boost=\"ignore\" data-no-defer=\"1\" data-no-optimize=\"1\" nowprocket><\/script><\/div>\n\n\n<h2>Share this<\/h2>\n\n<p>Your right hand is run by your left brain, and a new paper says the crossed wiring may be 500 million years old, left over from how eyes flip the world. https:\/\/bgodinspired.com\/index.php\/bgodinspired-news\/bgodinspired-science-news\/<\/p>\n\n<p>Plot twist: the crossed brain wiring might be an accident of ancient eyes, not a design for performance. Still works great though.<\/p>\n\n<h2>Q&amp;A<\/h2>\n\n<h3>Why does the left side of the brain control the right side of the body?<\/h3>\n<p>A new proposal says it started with vision. A round lens flips the image, so early vertebrates crossed their visual wiring to keep a correct map of the world. Touch and movement circuits then followed the same crossed pattern. It is a hypothesis, not a proven fact.<\/p>\n\n<h3>How old is the crossed wiring in the brain?<\/h3>\n<p>The authors of the 2026 paper in Frontiers in Neuroanatomy propose it dates to about 500 million years ago, in the first vertebrates. They infer this from comparing living animals, because no fossil evidence has been found yet.<\/p>\n\n<h3>Does crossed brain wiring make us faster or more skilled?<\/h3>\n<p>No one has shown that. The proposal argues the crossing may be a byproduct of ancient eyes rather than an advantage. Whether crossed wiring beats uncrossed wiring has not been tested.<\/p>\n\n<h3>Why are some people left-handed if the right brain runs the left hand?<\/h3>\n<p>Left-handed people use the same crossed wiring as everyone else. Their right hemisphere simply takes the lead for fine hand control. 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A new proposal traces the crossed wiring back 500 million years, to the way an eye flips the world.<\/p>\n","protected":false},"author":1,"featured_media":119760,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_wp_convertkit_post_meta":{"form":"-1","landing_page":"0","tag":"0","restrict_content":"0"},"footnotes":""},"categories":[3550,3708],"tags":[],"class_list":["post-119761","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bible-and-science","category-nature-and-creation"],"_links":{"self":[{"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/posts\/119761","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/comments?post=119761"}],"version-history":[{"count":1,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/posts\/119761\/revisions"}],"predecessor-version":[{"id":119762,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/posts\/119761\/revisions\/119762"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/media\/119760"}],"wp:attachment":[{"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/media?parent=119761"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/categories?post=119761"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bgodinspired.com\/index.php\/wp-json\/wp\/v2\/tags?post=119761"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}