The Positive Manifold
At the turn of the twentieth century, psychologist Charles Spearman made a counter-intuitive discovery. The natural assumption was that the more you specialize in one thing, the worse you’ll be at other things. Instead, Spearman discovered that the expertise gained through specialization is transferrable. Spearman’s discovery—that areas of expertise positively correlate—became known as “the positive manifold.” And it led to the realization that there exists what Spearman called “general intelligence” or the “g factor.”

So this Six at 6 is all about the g factor…
Nothing Is Siloed
Lin-Manuel Miranda went to Wesleyan University to dual major in film and theater. Soon after he got to Wesleyan, he dropped film. Two majors were too much. When asked about ultimately specializing in theater, he said he learned a valuable lesson. “The mindset,” he said, “that everything can feed each other—that’s the biggest lesson I took away. Nothing is siloed.” He talks briefly about working on the live action adaptation of The Little Mermaid, which informed decisions he made in his feature directorial debut, Tick, Tick…Boom! His time at Wesleyan, he continues, “helped me develop that mindset, being able to step back and make connections across different disciplines.”
Seeking Input Outside The Usual Channels
Eighteen years after the Exxon Valdez spill in Alaska’s Prince William Sound, the Oil Spill Recovery Institute (OSRI) was still looking for a solution. Thirty-two thousand gallons of oil was still stuck. So in 2007, the OSRI posted their problem to InnoCentive—an “Open Innovation Marketplace” where outside “Solvers” offer solutions to a “Seeker’s Challenge”. A chemist from Illinois named John Davis saw the Challenge posted on the InnoCentive site and began thinking. Before he was a chemist, Davis worked in construction pouring concrete. “Concrete vibrators,” Davis explains, “[are] used to restore liquid flow to concrete that has begun to set-up prematurely.” Making connections across different disciplines, Davis wrote up his solution: “Slushy frozen oil-sea water mixtures in sub-arctic waters behave very similar to fresh poured (uncured) cement, for which a concrete vibrator is used to allow it to flow more freely. My solution…use modified pneumatic concrete vibrators to keep the oil-water slush moving with more fluidity.” Davis’ solution won and is used to remove crude oil from arctic waters around the world. “It is a perfect illustration,” Davis writes, “of how seeking input outside of the usual channels to solve a problem can lead to new insights and discoveries that may otherwise have been missed.” It is the perfect illustration of the positive manifold, of how expertise is transferrable.
The Anatomy Of The Sistine Chapel
More than painting or sculpting, from an early age, Michelangelo was obsessed with anatomy. His contemporary Ascanio Condivi said of Michelangelo’s anatomical knowledge, “those who have spent their lives at it and made it their profession hardly know as much as he does…He was so learned and rich in knowledge of that science that he has often had in mind to write a treatise, as a service to those who want to work in sculpture and painting.” His plans for this anatomical treatise got sidelined in the early 1500s when Michelangelo was commissioned by Pope Julius II to paint the ceiling of the Vatican’s Sistine Chapel. It would be his first attempt at painting frescoes. In this new domain, his contemporary Georgio Vasari wrote, Michelangelo planned “to paint the human body in its best proportioned and most perfect forms and in the greatest variety…He was satisfied with justifying himself in that field in which he was superior to all his fellow-craftsmen, and to lay open the way of the grand manner in the painting of nudes, and to express his great knowledge, [his] facility in this art in its principal province, which is the human body.”
The Neuroscience of Practice
Using positron emission tomography (PET) scans to study how the brain burns calories when working on a cognitive task, neuroscientist Richard Haier made an unexpected discovery. Haier calculated the rate of glucose (the energy supply of the brain) metabolism while subjects performed a cognitive task. “To our surprise,” he writes in The Neuroscience of Intelligence, “all of the correlations were negative…The individuals with the highest test showed the lowest activity in the brain.” The counter-intuitive results led to The Brain Efficiency Hypothesis of Intelligence: the harder the brain works, the less productive it is. In a follow-up study, Haier did a PET study of practice. Through practice, Haier wanted to know, can you make the brain more efficient? “Perform[ing] a complex task,” he writes, “brain activity decreases with practice, consistent with the brain becoming more efficient.”
And, he found, the increased brain efficiency from practice/learning is transferrable. This, he writes, is “consistent with Spearman’s positive manifold.”
Joel’s Pretty Good on The G-Factor
After becoming the president of basketball operations of the Philadelphia 76ers, Daryl Morey was asked about the 76ers’ star center Joel Embiid. “Joel is shockingly smart,” Morey said. “I shouldn’t say shockingly—if you make it to the top in anything, usually you’re pretty good on g.”