Why are some people left handed?

Two theories predominate in the debates that rage on as to why a mere 4% o the population is left-handed. Most authorities agree, to the relief of many a mother of a left-handed child, that if the child prefers using the left hand, and functions well with it, there is no need to correct this "condition."

One theory centers on the two halves of the brain, i.e. the left half and the right half, each of which functions differently. Medical science believes that the left half of the brain predominates over the right half. The stem of this theory is the fact that nerves from the brain cross over at neck-level to the opposite side of the body, and nerves from the other side of the brain reciprocate. The end result is that the opposite sides of the body are supplied by the opposite sides of the brain.

The predominant left half of the brain, which graciously supplies the right half of the body, theoretically renders it more skillful in reading, writing, speaking, and working, and makes most people right-handed. "Lefties," however, are the product of an inversion, whereas the right half of the brain predominates, and they work best with the left side of their bodies.

Theory number two trickles down to the asymmetrical nature of the body. Examples of the asymmetry, which flows from head to toe, are that the right side of our faces differs slightly from the left, that our legs differ in strength, or that our feet vary in size. One aspect of this asymmetry is that for most people the right hand is stronger than the left.

There is no doubt that all exist in a "right-handed society," which manufactures most basics, including scissors, doorknobs, locks, screwdrivers, automobiles, buttons on clothing, and musical instruments for the 96%. Left-handed people compensate for this snobbery of sorts, by being members of an elite society, which includes many of the greatest geniuses, including Michelangelo, Leonardo da Vinci, and Jimi Hendrix.

For a list of other famous left-handers, click below:

Who are some of the most famous left-handed people?

Why are some people smarter than others?

Some people are smarter than others. Even in a multicultural world where no one is better and everyone is equally ordinary, we secretly still know that some people are smarter (politically correct disclaimer - others are just differently intelligent) than other people - but why that is has been a target of neuroscience for as long as it has existed as a discipline.

In a new article in Current Directions in Psychological Science, Eduardo Mercado III from the University at Buffalo, The State University of New York, describes how certain aspects of brain structure and function help determine how easily we learn new things, and how learning capacity contributes to individual differences in intelligence.

Cognitive plasticity is the capacity to learn and improve cognitive skills such as solving problems and remembering events. Mercado argues that the structural basis of cognitive plasticity is the cortical module. Cortical modules are vertical columns of interconnected neuronal cells. Across different areas of the cerebral cortex, these columns vary in the number and diversity of neurons they contain. Identifying how cortical modules help us learn cognitive skills may help explain why variations in this capacity occur — that is, why people learn skills at different rates and why our ability to learn new skills changes as we age.

Studies examining a number of different species have shown that, on average, a larger cortex predicts greater intellectual capacity. The source of this correlation is unclear, but Mercado believes that a "more expansive cortex provides more space within which a larger quantity and greater diversity of cortical modules can be distributed."

In other words, Mercado notes that when it comes to intellectual potential, it is not the absolute or even relative size that is important, but how many cortical modules (with various types of neurons) are available. These features of cortical organization and function determine how effectively our brain distinguishes events. This ability to differentiate events may be what enables us to learn cognitive skills.

One implication of this proposal is that experience can be as important as genetics in determining intellectual capacity. Specifically, structural changes of cortical modules generated by development and learning experiences may also contribute to individual differences in intelligence. As these networks of neurons develop over time, their diversity increases, leading to further increases in cognitive plasticity.

This research has important implications for improving educational techniques and can potentially lead to new methods for rehabilitating patients suffering from brain damage. In addition, understanding how cortical modules function may lead to new ways of increasing intelligence.

However, Mercado cautions that "new technologies for increasing cognitive plasticity have ethical implications far beyond those raised by doping in sports." He concludes, "The phrase 'changing your mind' may soon take on a whole new meaning."