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.
Although other hormonal conditions can cause them, hot flashes most commonly are due to menopause â the time when a woman's menstrual periods stop. In fact, hot flashes are the most common symptom of the menopausal transition.