In 1904, Psychologist Charles Spearman noticed something interesting about school children's academic performance. Students who excelled in one subject tended to do well in others even when those subjects appeared quite different. He proposed that a common underlying ability, which he called the general intelligence factor, or
g, could explain these correlations. [1]
Today, g is one of the most robust findings in differential psychology. The tendency for different cognitive abilities to correlate positively has been replicated across numerous studies. g typically accounts for around 40 to 60% of the variance in cognitive test performance and is predictive of numerous life outcomes, including educational achievement and occupational performance. [2]
Evidence of g isn't confined to humans either. Studies of mice have identified a general cognitive factor explaining roughly 30 to 40% of the variation in performance across different learning tasks [3]. We have similar results for primates and birds.
To put it simply, intelligence tends to generalize. Humans who tend to have higher verbal skills also tend to have higher spatial skills, better memories, and faster processing speed. Someone with the cognitive ability to become an exceptional chemist might just as easily have become an exceptional mathematician or software engineer. The knowledge and skills required are obviously different, but the underlying cognitive abilities that make someone successful in one intellectually demanding field often transfer to others.
And yes, there is also evidence of g in LLMs [4].
[1] https://www.jstor.org/stable/1412107
[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8293439/
[3] https://pmc.ncbi.nlm.nih.gov/articles/PMC2614349/
[4] https://www.sciencedirect.com/science/article/pii/S016028962...