Developing The Theory
When Darwin returned from his voyage on the HMS Beagle he became an instant scientific celebrity, with his various collections of rocks, fossils and zoological specimens earning him acceptance into the scientific establishment. He began writing papers, mainly on geological topics, and conversing with leading scientists of the day.
As Darwin published accounts of his voyages and analyses of his various finds, he began to conceive of an idea that species are not “immutable”, that they could change over time. When Darwin’s fossils were reconstructed they revealed strange extinct creatures that no longer existed – such as a rodent the size of a rhinoceros and a sloth the size of an elephant. When his bird specimens from the Galapagos islands were examined, it was revealed that on each island there was a different species of finch, each one modified in different ways.
In this critical time during the inception and development of Darwin’s theory of evolution, Darwin began to re-evaluate his views on New Zealand and its significance to natural history. Tied up with the evolutionary ideas that Darwin was considering was the idea that species do not stay in one place – geographical separation meant that they would experience different environmental pressures and be required to adapt in different ways. New Zealand, with its isolation, its lack of native land mammals and its unique collection of flora and fauna provided a powerful case study in examining these ideas. In a letter to the geologist Julius Von Haast, Darwin writes:
“I really think there is hardly a point in the world so interesting with respect to geographical distribution as New Zealand”
One scientist whom Darwin frequently corresponded with on the topic of New Zealand was the great British botanist Joseph D. Hooker, who and how very similar species are found in Chile and across the southern hemisphere islands. A friendly rivalry struck up in which Hooker believed that this could be explained by ancient land bridges, whereas Darwin believed it was the result of dispersal by sea, wind and animals. To prove his hypothesis, Darwin performed a range of experiments with seeds, floating them in salt water and germinating them.
seeds to test, Darwin goaded him:
“I believe you are afraid to send me a ripe (Kowhai) pod for fear I should float it from N. Zealand to Chile!”
New Zealand is also mentioned in many of Darwin’s letters to a host of scientific colleagues and public figures in both Europe and New Zealand. In a letter to the Governor of New Zealand George Grey, Darwin recommends that limestone deposits around the Bay of Islands be investigated for Moa bones, as New Zealand is “eminently instructive…in its lack of terrestrial (mammals).” He also requests that New Zealand scientists examine whether there is any evidence of the country being covered in glaciers, as he felt past climates might have had a large impact on its natural history.
