From the sun-drenched slopes of the Sierra Madre in Mexico to a once-in-a-decade heatwave on the Thames in London, this tour guide's summer became a learning expedition into the heart of Victorian science—stepping directly into the world of Alexander von Humboldt and Charles Darwin. For years, my heart has been rooted in the coastal mountains of Jalisco, Mexico, where I share the wild, tropical wonders of the Vallarta Botanical Gardens with travelers from around the world. "B