The Invention of Nature

As they continued, Humboldt also investigated the cinchona forests in Loja (in today’s Ecuador) and once again recognized how humankind devastated the environment. The bark of the cinchona tree contains quinine which was used to treat malaria, but once the bark was removed, the trees died. The Spanish had stripped huge swathes of wild forest. Older and thicker trees, Humboldt noted, had now become scarce.

Humboldt’s enquiring mind seemed inexhaustible. He studied layers of rocks, climate patterns and the ruins of Inca temples, and was also fascinated with geomagnetism – the study of the magnetic fields of the earth. As they climbed across mountain chains and descended into valleys, he set up his instruments. Humboldt’s curiosity originated in his urge to understand nature globally, as a network of forces and interrelationships – just as he had been interested in vegetation zones across continents and the occurrences of earthquakes. Since the seventeenth century scientists had known that the earth is itself a gigantic magnet. They also knew that the needle of a compass doesn’t show the true north, because the magnetic North Pole is not the same as the geographic North Pole. To make matters even more confusing, the magnetic north and south move, which caused great navigational problems. What scientists didn’t know was whether the intensity of magnetic fields across the world varied randomly, or systematically, from location to location.

As Humboldt had moved south along the Andes from Bogotà to Quito, coming closer to the Equator, he had measured how the earth’s magnetic field decreased. To his surprise, even after they had crossed the Equator near Quito the intensity of the magnetic field had continued to drop, until they reached the barren Cajamarca Plateau in Peru which was more than 7 degrees and about 500 miles south of the geographic Equator. It was only here that the needle turned from north to south: Humboldt had discovered the magnetic equator.

They arrived in Lima at the end of October 1802, four and a half months after they had departed from Quito and more than three years after they had left Europe. Here they found passage to sail north to Guayaquil on the west coast of today’s Ecuador from where Humboldt intended to travel to Acapulco in Mexico. As they sailed from Lima towards Guayaquil, Humboldt examined the cold current that hugs the western coast of South America from southern Chile to northern Peru. The current’s cold, nutrient-loaded water supports such abundance of marine life that it is the world’s most productive marine ecosystem. Years later, it would be called the Humboldt Current. And though Humboldt was flattered to have it named after him, he also protested. The fishing boys along the coast had known of the current for centuries, Humboldt said, all he had done was to have been the first to measure it and to discover that it was cold.

Humboldt was assembling the data he needed to make sense of nature as a unified whole. If nature was a web of life, he couldn’t look at it just as a botanist, a geologist or a zoologist. He required information about everything and from everywhere, because ‘observations from the most disparate regions of the planet must be compared to one another’. Humboldt amassed so many results and asked so many questions that some people thought him to be stupid, because he asked ‘the seemingly obvious’. His coat pockets, one of his guides noted, were like those of a little boy – full of plants, rocks and scraps of paper. Nothing was too small or insignificant to investigate because everything had its place in the great tapestry of nature.

Cotopaxi with smoke plume (Illustration Credit 7.3)

They arrived at the port town of Guayaquil on 4 January 1803, on the same day that Cotopaxi suddenly erupted some 200 miles to the north-east. Having climbed every reachable volcano in the Andes, this was the moment Humboldt had been waiting for. Just as he was preparing to sail to Mexico, a new gauntlet was thrown down. Humboldt was torn. Keen to explore Mexico before returning to Europe, he needed to find passage soon if he was to sail before the annual hurricane season in summer. Otherwise they would be stuck until the end of the year in Guayaquil. But now there was also the lure of an erupting volcano. If they hurried, perhaps they could make it to Cotopaxi and back in time to catch a boat to Mexico. But the journey from Guayaquil to Cotopaxi was dangerous. Humboldt would have to cross the high Andes again, only this time towards an active volcano.