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Are Galápagos Finches “Evolution in Action”?

Image: Darwin's finches, via Wikimedia Commons.

Author’s note: Are Darwin’s finches1 “a particularly compelling example of speciation” as well as “evolution in action”? In a series of posts starting today, I offer some notes on the question of whether macroevolution is happening on the Galápagos Islands. Please find the full series here.

Twenty-one years ago the National Academy of Sciences2 published the second edition of a book called Science and Creationism. This and the following revised editions of 2008 and 20173 are now called Science, Evolution and Creationism.4 The book is widely accepted as an up-to-date guide providing excellent information on the modern theory of evolution, defending it as the absolutely true and only scientific and realistic answer on the origin of species. That is not only for the “76 million students enrolled in U.S. schools”5 in 2020. It is also thought to provide valuable information on the topic for the English-speaking public in general.6

“A Particularly Compelling Example”

In the second edition, the Galápagos finches (aka, Darwin’s finches) are addressed as follows (1999, pp. 10/11): 

A particularly compelling example of speciation involves the 13 species of finches studied by Darwin on the Galápagos Islands, now known as Darwin’s finches. The ancestors of these finches appear to have immigrated from the South American mainland to the Galápagos. Today the different species of finches on the island have distinct habitats, diets, and behaviors, but the mechanisms involved in speciation continue to operate. A research group led by Peter and Rosemary Grant of Princeton University has shown that a single year of drought on the islands can drive evolutionary changes in the finches. Drought diminishes supplies of easily cracked nuts but permits the survival of plants that produce larger, tougher nuts. Droughts thus favor birds with strong, wide beaks that can break these tougher seeds, producing populations of birds with these traits. The Grants have estimated that if droughts occur about once every 10 years on the islands, a new species of finch might arise in only about 200 years. [Emphasis added.]

An accompanying figure seeks to convince the students ad oculus with the note: “The different species of finches on the Galápagos Islands, now known as Darwin’s finches, have different-sized beaks that have evolved to take advantage of distinct food sources.”7 

Let us emphasize especially, as quoted above: “The Grants have estimated that if droughts occur about once every 10 years on the islands, a new species of finch might arise in only about 200 years.” Hall and Hallgrimsson comment in their textbook (2014, p. 411): “By documenting evolution in action in natural populations, the work of the Grants has made profound contributions to our understanding of the evolutionary process8 (emphasis added).

In the words of Cressey in a Nature article of 2009: “Darwin’s finches” were “tracked to reveal evolution in action.”9 Or again: “Evolution in action detected in Darwin’s finches.”10 Or Sangeet Lamichhaney of Harvard University (2020): “The results indicated that diversity in HMGA2 gene allowed for a rapid evolution of smaller beak size in medium ground finch, thereby providing an evidence of a gene behind ‘evolution in action’ recorded in real time.”11 For more such examples, simply google the phrases “Galápagos finches” and “Evolution in action.” You will receive many relevant hits.

Next, “Galápagos Finches and a Surprising Deletion.


  1. The generally used term “Darwin’s finches” is a paradigm of a misnomer. See: Frank J. Sulloway (1982): Darwin and His Finches: The Evolution of a Legend. Journal of the History of Biology 15: 1-53. In contrast, the more rarely used but definitely apt term “Galapagos finches” is correct as, for example, the Hawaiian honeycreepers. 
  2. “The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters.” “Attractive in presentation and authoritative in content, Science and Creationism will be useful to anyone concerned about America’s scientific literacy: education policymakers, school boards and administrators, curriculum designers, librarians, teachers, parents, and students.” https://www.ncbi.nlm.nih.gov/books/NBK230204/
  3. https://www.ncbi.nlm.nih.gov/books/NBK230201/ Already in its title the book confuses creationism with intelligent-design theory. For a longer review of the 1999 edition see http://www.ideacenter.org/contentmgr/showdetails.php/id/1131. See also Behe, https://evolutionnews.org/2016/10/philosophical_o/.
  4. National Academies Press (17 November 2017).
  5. http://www.tulane.edu/~bfleury/tssp/Science,%20Evolution,%20amd%20Creationism.pdf
  6. https://www.census.gov/newsroom/press-releases/2018/school-enrollment.html
  7. https://www.nationalacademies.org/evolution/resources, https://ncse.ngo/review-science-evolution-and-creationism
  8. https://www.nap.edu/read/6024/chapter/1#vii (all chapters available), https://www.ncbi.nlm.nih.gov/books/NBK230201/figure/mmm00010/?report=objectonly, https://www.ncbi.nlm.nih.gov/books/NBK230201/figure/mmm00010/?report=objectonly
  9. B. K. Halland B. Hallgrimsson (2014): Strickberger’s Evolution. Fifth Edition. Jones & Bartlett Learning. Burlington.
  10. https://www.nature.com/articles/news.2009.1089: “Whereas Darwin thought that a new species would take a considerable amount of time to appear, Keller says that this paper “shows how rapidly reproductive isolation can develop.” The Grants aren’t yet ready to call 5110’s lineage a new species, a term fraught with difficulty for evolutionary biologists. “There is no non-arbitrary answer to the question of how many generations should elapse before we declare the reproductively isolated lineage to be a new species,” they say. “For the present it is functioning as a [separate] species because its members are breeding only with each other.”
  11. https://www.sciencedaily.com/releases/2016/04/160421145759.htm. Sangeet Lamichhaney, Fan Han, Jonas Berglund, Chao Wang, Markus Sällman Almén, Matthew T. Webster, B. Rosemary Grant, Peter R. Grant, Leif Andersson. A beak size locus in Darwin’s finches facilitated character displacement during a drought. Science, 2016 DOI: 10.1126/science.aad8786.