A new study of 3654 Vietnam War veterans finds that men with lower IQs are more likely to suffer from dozens of health problems – from hernias, to ear inflammation, to cataracts – compared with those showing greater intelligence.I also found Geoffrey Miller's conceptualization of general intelligence useful:
This offers tantalising – yet preliminary – evidence that health and intelligence are the result of common genetic factors, and that low intelligence may be an indication of harmful genetic mutations. [. . .]
Journal reference: Intelligence (DOI: 10.1016/j.intell.2009.03.008)
Even within my own field, evolutionary psychologists tend to misunderstand general intelligence as a psychological adaptation in its own right, often misconstruing it as a specific mental organ, module, brain area, or faculty. However, it is not viewed that way by most intelligence researchers who, instead, regard general intelligence as an individual-differences construct—like the constructs “health,” “beauty,” or “status.” Health is not a bodily organ; it is an abstract construct or “latent variable” that emerges when one statistically analyzes the functional efficiencies of many different organs. Because good genes, diet, and exercise tend to produce good hearts, lungs, and antibodies, the vital efficiencies of circulatory, pulmonary, and immune systems tend to positively correlate, yielding a general “health” factor. Likewise, beauty is not a single sexual ornament like a peacock’s tail; it is a latent variable that emerges when one analyzes the attractiveness of many different sexual ornaments throughout the face and body (such as eyes, lips, skin, hair, chest, buttocks, and legs, plus general skin quality, hair condition, muscle tone, and optimal amount and distribution of fat). Similarly, general intelligence is not a mental organ, but a latent variable that emerges when one analyzes the functional efficiencies of many different mental organs (such as memory, language ability, social perceptiveness, speed at learning practical skills, and musical aptitude). ...