“Why Evolution Is True”

Jerry A. Coyne, “Why Evolution Is True” , Viking, 2009, 245 Pages
Jerry A. Coyne of the University of Chicago's ecology and evolution department has explained evolution and natural selection in terms that anyone can understand; all of it backed up in a scientific way. The primary point of this book is that evolutionary theory is an empirical, provable method of debunking the creation (Intelligent Design) myth.
• 375 million years ago the Tiktaalik roseae emerged from the water to bridge the span between fish and amphibians. Through natural selection its’ descendants would eventually produce humans, about 60,000 to 100,000 years ago.

My Notes:
Pg. xvi: Darwin’s theory that all of life was the product of evolution and that the evolutionary process was driven largely by natural selection, has been called the greatest idea that anyone ever had. But it is more than just a good theory, it also happens to be true. Although the idea of evolution itself was not original to Darwin, the copious evidence he mastered in its favor convinced most scientists and many educated readers that life had indeed changed over time. This took only about ten years after The Origin was published in 1859. But for many years thereafter, scientists remained skeptical about Darwin’s key innovation: the theory of natural selection. Indeed, if ever there was a time when Darwinism was “just a theory,” it was the latter half of the nineteenth century, when evidence for the mechanism of evolution was not clear, and the means by which it worked—genetics—was still obscure. This was all sorted out in the first few decades of the twentieth century, and since then the evidence for both evolution and natural selection has continued to mount, crushing the scientific opposition to Darwinism. While biologists have revealed many phenomena that Darwin never imagined—how to discern evolutionary relationships from DNA sequences, for one thing—the theory presented in The Origin of Species has, in the main, held up steadfastly. Today scientists have as much confidence in Darwinism as they do in the existence of atoms, or in micro-organisms as the cause of infectious disease.

Pg. 3: In essence, the modern theory of evolution is easy to grasp. It can be summarized in a single sentence: Life on earth evolved gradually beginning with one primitive species-perhaps a self-replicating molecule—that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species, and the mechanism for most (but not all) of evolutionary change is natural selection. When you break that statement down, you find that it really consists of six components: evolution, gradualism, speciation, common ancestry, natural selection, and nonselective mechanisms of evolutionary change.

Pg. 10: Until about 30 years ago, biologists used visible features like anatomy and mode of reproduction to reconstruct the ancestry of living species. This was based on the reasonable assumption that organisms with similar features also have similar genes, and thus are more closely related. But now we have a powerful, new, and independent way to establish ancestry; we can look directly at the genes themselves. By sequencing the DNA of various species and measuring how similar these sequences are, we can reconstruct their evolutionary relationships.

Pg. 15: In science, a theory is a well-thought-out group of propositions meant to explain facts about the real world. Atomic theory is not just the statement that “atoms exist”, it is a statement about how atoms interact with one another, form compounds, and behave chemically. Similarly, the theory of evolution is more than just the statement that “evolution happened”; it is an extensively documented set of principles that explain how and why evolution happens. For a theory to be considered scientific, it must be testable and make verifiable predictions…. Because a theory is accepted as “true” only when its assertions and predictions are tested over and over again, and confirmed repeatedly, there is no one moment when a scientific theory suddenly becomes a scientific fact. A theory becomes a fact (or a “truth” when so much evidence has accumulated in its favor)—and there is no decisive evidence against it—that virtually all reasonable people will accept it. This does not mean that a “true” theory will never be falsified. (Maybe Einstein’s modification of Newton’s gravity fits in here).

Pg. 28: The first organisms, simple photosynthetic bacteria, appear in sediments about 3.5 billion years old, only about a billion years after the planet was formed. These single cells were all that occupied the earth for the next 2 billion year, after which we see the first simple organisms having true cells with nuclei and chromosomes. Then, around 600 million years ago, a whole gamut of relatively simple but multicelled organisms arise, including worms, jellyfish, and sponges….Terrestrial plants and four legged animals, the earliest of which were lobe finned fish, appeared about 400 million years ago…. Fifty million years later we find the first true amphibian, and after another 50 million years reptiles come along. The first mammals show up around 250 million years ago (arising, as predicated, from reptilian ancestors), and the first birds, also descended from reptiles, show up 50 million years later. After the earliest mammals appear, they, along with insects and land plants, become ever more diverse, and as we approach the shallowest rocks, the fossils increasingly come to resemble living species. Humans are newcomers on the scene—our lineage branches off from that of other primates only about 7 million years ago, the merest sliver of evolutionary time. If the entire course of evolution were compressed into a single year, the earliest bacteria would appear at the end of March, but we should not see the first human ancestors until 6 a.m. on December 31.

Pg. 51: The evolution of whales from land animals was remarkably fast: most of the action took place within only 10 million years. That is not much longer than the time it took us to diverge from our common ancestor the chimpanzees, a transition that involved far less modification of the body. Still, adapting to life at sea did not require the evolution of any brand-new features—only modification of old ones.

Pg. 54: There is no reason why a celestial designer, fashioning organisms from scratch like an architect designs buildings, should make new species by remodeling the features of existing ones. Each species could be constructed from the ground up. But natural selection can act only by changing what already exists. It cannot produce new traits out of thin air (I have a problem with this statement). Darwinism predicts then, that new species will be modified versions of older ones. The fossil record amply confirms this prediction.

Pg. 64: Vestigial traits make sense only in the light of evolution. Sometimes useful, but often not, they are exactly what we would expect to find if natural selection gradually eliminated useless features or refashioned them into new, more adaptive ones. Tiny, nonfunctional wings, a dangerous appendix, eyes that cannot see, and sill ear muscles simply do not make sense if you think that species were specially created.

Pg. 90: We know now that the similarities between African and South American plants are not surprising, for their ancestors once inhabited a super continent—Gondwana—that split into several pieces (now Africa, South America, India, Madagascar, and Antarctica) beginning about 170 million years ago. Every bit of biogeographic detective work turns out to support the fact of evolution.

Pg. 132: Unlike the influenza virus, polio and measles viruses have not evolved resistance to the vaccines that have now been used for over fifty years. (I would sure like to know more on why this is so).

Pg. 172: Ernst Mayr defined a species as a group of inter-breeding natural populations that are reproductively isolated from other such groups. This definition known as the biological species concept, or BSC. This definition has become the standard for defining what a species is.

Pg. 195: Molecular data derived from DNA and protein sequences confirm that we diverged from our relatives, the chimpanzees about 7 million years ago. The gorilla is a slightly more distant relative, and orangutans more distant yet (12 million years since the common ancestor).

Pg. 200: LUCY found 1974. When Lucy’s fragments were assembled, she turned out to be a female of a new species, dating back 3.2 million years. She was between twenty and thirty years old, three and a half feet tall, weighing a scant sixty pounds, and walked on two legs.

Pg. 206: Around 28,000 years ago, the Neanderthal fossils vanish; it appears that the idea that they evolved into humans is incorrect. It is proposed that Homo sapiens apparently elbowed out every other hominin on earth.

Pg. 214: At the genetic level human beings are a remarkably similar lot. That is just what we would expect if modern humans left Africa a mere 60,000 or 100,000 years ago. There has been little time for genetic divergence, although we have spread to all corners of the world, breaking up into various far-flung populations that were genetically isolated until recent decades.