Adaptive Advantages Of The Kiwi Egg

Darwin’s idea was comparable to a bird’s egg, slowly getting bigger inside of him until the time was right for it to hatch: “Ovulation had occurred. Fertilization had occurred. Now came growth, from the microscopic scale of a single ovum to… well, to whatever size it would reach before laying” (p. 52). Quammen warns readers not to think of it as any regular sized egg, but to think of it as a kiwi’s egg. Kiwis are flightless birds native to New Zealand. They are closest on the phylogenetic tree to ostriches, rheas, emus, and cassowaries (p. 53). This family of birds, called the ratites, are found across many different diverse places. It is hypothesized that they walked across these many lands until continental drift took place (p. 53). In comparison

What are the adaptive advantages for kiwi females (and for males, who do much of the incubating) of such heavy investment in a single chick? How has the kiwi lineage changed over evolutionary time? Did the egg evolve toward largeness? Or did the bird itself evolve toward smallness… while the egg stayed as it was? If the bird shrank and the egg didn’t, why not?” (p. 54). Quammen’s purpose of bringing up the kiwi egg, however, was not to pose these questions, but simply for metaphorical purposes. Every time he looks at the X-Ray of a female kiwi with her huge egg, Quammen thinks, “There’s Darwin during the years of gestation” (p.

He had written a volume on coral reefs that would be published very soon, and his future plans involved a book on volcanic islands. These were both part of his Zoology of the Beagle series, which would eventually come to have three novels. The book on coral reefs alone had taken Darwin twenty months to compile, spread across the span of four years. One month, in May, he and Emma decided to go to Staffordshire for a vacation at her family home. They remained there a month, and then Darwin left to stay with his father and sisters in Shrewsbury alone. Along with his family, Darwin had also left his notebooks behind, though that didn’t stop his thinking. Because he was free from other work, Darwin was able to use that time as an opportunity to finally write a bit about transmutation. He sketched out the ideas, evidence, and arguments. It amounted to about thirty-five pages, just a brief outline of the book he planned to write in the