“Charles Darwin” Essay on Facebook

Hecktoen International, a Journal of Medical Humanities, posted an article by Daniel W. Nebert.  pdf link is here. Title and first few paragraphs are here: Link to the Hectoen website for the full article is HERE.

Daniel W. Nebert, BA, MS, MD
Cincinnati, Ohio

This year we celebrate the 156th anniversary of Charles Darwin’s book, On the origin of species by means of natural selection, one of the greatest landmark scientific advances of all time. As the ship’s only “naturalist biologist”, Darwin sailed around the world from England (1831–36) on the HMS Beagle. His observations and many collected samples,Hektoen_Darwin_Evol_Nebert_2015_snake made while visiting the Galapagos Islands for only five weeks, set into motion the “theory of natural selection.” Although he had conceived the broad idea before 1840, the first edition of his book was not published until 1859, largely because of his religious background: in 1831 he had received a BA degree in theology from Cambridge University, and his wife was a devout Anglican. Darwin’s developing realization–that all life on the planet originated from a common ancestor and continues to evolve based on “survival of the fittest”–flew in the face of religious thought at that time.

After Darwin published the Origin of Species in 1859, the patterns of social thinking were re-formed around the concepts of evolutionary biology. Within a little more than a decade, the concept of evolution was adapted to almost every field of social and philosophical enquiry. By contrast, previous philosophical and scientific investigations had looked on any concept or subject that was fixed and permanent, as superior to anything that would change or pass away. Interestingly, Darwin’s grandfather Erasmus Darwin had written in 1794 a philosophical essay, Zoonomia, in which he had suggested that all warm-blooded animals may have arisen from “one living filament.”

Darwin later published The Descent of Man, devoted to the workings of natural selection among civilized nations. He saw man as a social animal who from earliest times had practiced division of labor and exchange of goods. He felt that the struggle among races depended entirely on intellectual and moral qualities, rather than physical qualities.

What was it about the Galapagos Islands that stimulated Darwin? Rising above the ocean surface three to four million years ago, each volcanic island developed its own “mini-climate,” and the archipelago was sufficiently distant from the Ecuadorian coast that relatively few animals and plants arrived from the mainland. Consequently, each species that had arrived diverged over time, adapting to its changing environment. For example, Darwin observed that finches on different islands had developed variations in beak size and shape–related to the type of seeds available for food.

These observations can now be explained on the basis of irrefutable scientific facts–as a result of new archeological data and radioisotope-dating of rocks and the fossils therein, combined with the discovery of the DNA helix (1953), techniques to sequence DNA in the 1970s, forty years of advances in molecular biology and genetics, and during the past two decades development of high-throughput genomic DNA-sequencing and powerful bio-informatics software programs. We now know that DNA is the principal genetic material, existing as long chains comprising almost always the same four bases (adenine, guanine, thymine, cytosine) that exist in chromosomes of a cell. Genes are made of DNA, located in linear fashion along each chromosome; they code for proteins, which represent long strings of amino acids. Variations of specific bacterial genes often also exist in yeast, fly, worm, fish, mouse, and also humans; however, mutations in DNA, and thus changes in amino-acid sequence of each protein, have slowly occurred–over millions of years.

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