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 the exact cause of hot flashes is not fully understood, hot flashes that occur in the perimenopause are thought to be due to a combination of hormonal and biochemical fluctuations brought on by declining estrogen levels.