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.
A hot flash, sometimes called a hot flush, is a quick feeling of heat and sometimes a red, flushed face and sweating. The exact cause of hot flashes is not known, but may be related to changes in circulation. Hot flashes happen when the blood vessels near the skin's surface dilate to cool. A woman may also sweat to cool down her body. And some women have a rapid heart rate or chills. Hot flashes with sweating can also happen at night.