Remember the iconic Darwin’s finches rattling through the textbooks, proving Darwinism? Well,
Few beside historians know about the crisis of evolution in the late 19th century continuing into the early 20th century. At the time, most intellectuals had been convinced of evolution in some form, but critics of Darwin’s natural selection were many. Neil Thomas writes about that period in his new book, Taking Leave of Darwin. Even before Darwin died in 1882, he was feeling the pressure of critics against his theory and was relying more on the Lamarckian notions he had tried to supplant. Doubts about natural selection increased well after the rediscovery of Mendel’s laws of heredity. Finally in the 1930s the “Neo-Darwinists” breathed a sigh of relief when they found a way to incorporate Mendelism. Their relief led to strong confidence in Darwinian evolution that roared into overconfidence at the Darwin Centennial and still reigns today. New findings are unraveling that confidence.
More scientists are realizing that organisms have other ways to inherit traits. In 2017, some of those methods were introduced here. Last month, Emily Reeves categorized some of the sources of genetic change. In her table, “random copy errors” and “chemically induced mutagenesis” were only two of them. At the CELS conference in June, engineers and biologists mooted some cutting-edge ideas of internal reprogramming by organisms enabling them to adapt to changing environments. That almost sounds Lamarckian: if an organism can “learn” adaptations and pass them on, is that “inheritance of acquired characteristics” due to “use and disuse”? Whatever it is, it is not unguided variation in the sense Darwin taught. Any process that shares existing information is also anti-Darwinian. That includes horizontal gene transfer (HGT), hybridization and introgression.Evolution News, “Non-Mendelian Inheritance Undermines Neo-Darwinism” at Evolution News and Science Today (August 13, 2021)
More remarkable yet:
Of all things, Darwin’s finches are coming up for debate again. Lifetime finchologists Peter and Rosemary Grant just published a paper in PNAS that conjures up “Morphological ghosts of introgression in Darwin’s finch populations.” The ghosts spooked them.
The ghost of hybridization is scaring them into changing their view of finch evolution by natural selection. The information on beak size from an extinct species apparently is showing up in some living species. This can only be due to information-sharing between the islands. If this happens in one of the most famous icons of evolution, where else is it occurring?Evolution News, “Non-Mendelian Inheritance Undermines Neo-Darwinism” at Evolution News and Science Today (August 13, 2021)
If even Peter and Rosemary Grant must adapt, something is changing for sure… Specifically Darwinian speciation of Darwin’s finches was their claim to fame.
This is a great time to be a recovering Darwinist. The world is much more interesting than that.
See also: Darwin’s finches, not a typical example of evolution at all
What we learned when we talked to the fossils