A head for Numbers
A typically separate group of people has trouble not with reading and writing, but with learning basic mathematics. Dyscalculia affects some 6 percent to 8 percent of the world population, studies suggest. As with dyslexia, something of a genetic component exists, with identical twins sharing dyscalculia almost 60 percent of the time.
Several brain areas activate when subjects perform calculations, in particular the intraparietal sulcus, located at the top-back area of our heads.
"This appears to be the 'math center' of the brain," said Melissa Libertus, a postdoctoral fellow in the department of psychological and brain sciences at Johns Hopkins University. "If this part of the brain has a problem, then those people have math problems."
ABCs or 123s
Libertus has just published a paper showing that preschoolers have varying degrees of "number sense," or an innate ability to estimate quantities. It's likely, Libertus said, that people with higher inborn skills perform better at math throughout their lives. Similarly, Eden has studied children with precocious reading abilities, showing that some of us just have a knack.
On the other hand, being born with dyslexia or dyscalculia, does not necessarily produce a math or language person. In this way, upbringing and education frequently lead to language or math preferences based on innate strengths and weaknesses.
"Of course, environment and experience play a major role," Butterworth said. Parents who have a lot of books around the house might encourage a child to get more into reading and writing, whereas math games promote doing sums instead.
Human calculators and polyglots
Although our brains are evolutionarily hard-wired for speech and a basic sense of numbers, we must be taught to read, write and do arithmetic. And regardless of one's natural abilities, practice — to an extent — can make perfect.
Many prodigious "human calculators," for example, admit to being obsessed with numbers, thinking about and working with them all day. Similarly, polyglots such as Emil Krebs, a German man who claimed mastery of 68 languages, must study hard to become fluent in non-native tongues.
Supporting this "practice makes perfect" view is that fact that language or math abilities are not tied to IQ scores. Shakuntala Devi, an Indian woman, astoundingly multiplied two 13 digit numbers in her head in 28 seconds, yet possessed an average IQ.
Math "savants" go even further, such as Dustin Hoffman's character in "Rain Man." These rare individuals perform feats of mathematical wizardry but have terrible verbal skills and low IQ scores.
Ultimately, markedly skewed abilities in language and math come about from a confluence of factors, researchers agree. Genes, development and personal zeal all determine our letter grades and where we fall on the number line.