His chronicle of his trip, The naturalist on the River Amazons, became a bestseller when it was published in 1863.
Hot flashes and nausea are most commonly caused by hormonal imbalances in the body, most notably, by sex hormones. For women, a decrease in estrogen is often to blame, whereas in men, testosterone deficiency can create the problem. Sometimes, the symptoms occur for reasons not related to those hormones at all.
The specific cause of hot flashes is often low estrogen and how that affects the hypothalamus. The hypothalamus is the part of the brain that controls sleep, appetite, sex hormones, and body temperature. Diminished natural estrogen levels trick the hypothalamus into believing that the body is too hot.