I often define intelligence as the cognitive ability to adapt, but in neurologists speak of neural adaptability, which has a more scientific definition. Neural adaptability is measured by hooking your head up to an EEG monitor and calculating the ratio of brain amplitudes evoked from having you hear a clicking sound at random intervals, to the brain amplitudes evoked from having you hear a clicking sound when ever you press a device.
The higher the ratio, the higher the IQ on average. This is because more adaptable brains conserve energy by not wasting brain activity on what they already expect.
On page 155 of The g Factor, Arthur Jensen suggests that in the general U.S. population, neural adaptability may correlate as high as 0.8 with IQ, which is about as high as two well respected IQ tests correlate with each other.
It seems IQ really is a biological construct and not a cultural one.