Historical perspectives[ edit ] Prior to the 20th century, it was a commonly held view that men were intellectually superior to women. He stated that this was because women did not possess the same level of rational thinking that men did and had naturally superior abilities in skills related to family support. During the early twentieth century, the scientific consensus shifted to the view that gender plays no role in intelligence. He did, however, find "rather marked" differences on a minority of tests.
I discovered this recently at a brain-cutting lesson given by Jean-Paul Vonsattel, a neuropathologist at Columbia University. On the day I visited, there were half a dozen brains sitting on a table.
Vonsattel began by passing them around so the medical students could take a closer look. When a brain came my way, I cradled it and found myself puzzling over its mirror symmetry. It was as if someone had glued two smaller brains together to make a bigger one.
Vonsattel then showed us just how weak that glue is. He took back one of the brains and used a knife to divide the hemispheres. He sliced quickly through the corpus callosum, the flat bundle of nerve fibers that connects the halves.
The hemispheres flopped away from each other, two identical slabs of fleshy neurons. Sometimes surgeons must make an even more extreme kind of slice in the brain of a patient.
A child may suffer from epilepsy so severe that the only relief doctors can offer is to open up the skull and cut out the entire hemisphere in which the seizures start. After the surgery, the space soon fills with cerebrospinal fluid. It may take a child a year of physical therapy to recover from losing a hemisphere—but the fact that patients recover at all is stunning when you consider that they have only half a brain.
It makes you wonder what good two hemispheres are in the first place. In fact, scientists have spent a lot of time pondering this very question. Their best answer has a lot to do with the form and evolutionary history of our bodies.
From early in our development as embryos, humans take on a left-right symmetry that eventually gives rise to our two eyes, our two big toes, and every paired structure in between. All vertebrates are symmetrical in the same way, as are butterflies, scorpions, and a vast number of other invertebrates.
There were some obvious survival benefits from left-right symmetry. With muscles and limbs on both sides of their bodies, animals could move forward quickly and efficiently.
Once established, symmetry had a powerful effect on how new organs evolved. Eyes and antennae tended to develop in left-right pairs, for example. When early fish began to evolve complex brains, those too developed according to left-right rules.
The human brain is very different from the brain of a lamprey, but in both species the neocortex—the outer layers of the brain—is divided into two mirror-image hemispheres.
Of course, our bodies are not perfectly symmetrical heart on the left, appendix on the rightand neither are our brains. Some regions are slightly bigger on one side than on the other, and these differences translate into imbalances in how the human brain works.
Most people, for example, tend to favor their right hand over their left.
The same region on the right side is not so vital. The right half of this region, known as the facial fusiform area, does most of the work of recognizing. These sorts of findings helped to turn the hemispheres into pop phenoms.
Academics made some big claims about the hemispheres as well. In the s psychologist Michael Corballis of the University of Auckland in New Zealand argued that the asymmetry of the brain —known as lateralization—was a key step in the evolution of our species, giving us language and additional mental powers that other animals lack.
The article originally said that biliterality came from the common ancestor of all animals. Today Corballis readily admits he was wrong.
Lateralized brains are not unique to humans.
Parrots prefer picking up things with their left foot. Toads tend to attack other toads from the right but go after prey from the left.
Zebra fish are likely to look at new things with their right eye and familiar things with their left. Even invertebrates are biased. Pinar Letzkus, a vision researcher at Australian National University, rewarded bees with sugar whenever they extended their tongue at the sight of a yellow rectangle on a computer screen.
He then fashioned tiny eye patches and put them on a new set of subjects. Bees with their left eye covered learned almost as quickly as did bees without a patch.
But bees with their right eye covered did far worse. The broken symmetry of the nervous system may thus be as old as the symmetry itself.The Difference Between a Full-Time and Part-Time Student by Hazel Baker Deciding to make the transition from a full-time to a part-time student or vice versa is a choice that can significantly impact the amount of time it takes for students to earn a degree, the amount of financial aid that they are eligible to receive, their eligibility for certain tax benefits .
Weekly time commitment is also a factor in the decision between full-time and part-time studies. Students who work full-time, or have family or social commitments that require a significant amount of their days usually opt for part-time studies. In this lesson, we discuss the similarities and differences between the eukaryotic cells of your body and prokaryotic cells such as bacteria.
Eukaryotes organize different functions within. Type or paste a DOI name into the text box. Click Go. Your browser will take you to a Web page (URL) associated with that DOI name.
Send questions or comments to doi. Question: Do you know the difference between Okinawan Karate & Japanese Karate? I didn’t. Until I visited Okinawa – the birthplace of Karate.
Wow! Since then, I’ve revisited the amazing island over a dozen times. I even lived there in , studying Japanese at Okinawa University. So I can assure you There are MANY differences between Okinawan and Japanese [ ].
Introduction. The incredible media coverage of the Sumatra Earthquake and Tsunami of December 26, , provided the world with images provoking both incredible sadness at the tragic loss of life, and awe at the destructive release of energy from one brief convulsion of Earth’s crust.