On The Origin of Evolution
John and Mary Gribbin
More books on Evolution
Evo is a fact. We can see it in nature, most famously among Darwin's galapagos finches, in the Earth's fossil record, and in the way bacteria evolve resistance to antibiotics.
Theories explain observed facts, in same way that Newton and Einsteins theories explained why things fall down and why planets orbit the sun. Darwin's T of E explained it in terms of natural selection.
Took a while to recognze that (a) fossils were formerly living creatures turned to stone, and (b) that rocks, and the Earth, were very old.
Robert Hooke was a polymath; he made major contributions to astronomy and microscopy, he was Christopher Wren's architectural partner in the rebuilding of London after the Great Fire of 1666 (and was the designer of many of the 'Wren' churches). He was born 1635 at Freshwater on Isle of Wight, where he grew up on high chalk hills full of seashells.
Probably the first science populariser with his book Micrographia, in which he made clear that fossils were either organic matter turned to stone, or are the impressions of living things. He noted that the rocks in which they were found must have been laid down in water, and since there are many such layers there must have been many great deluges, as well as Noah's flood. He explained that finding fossils on tops of hills, in deepest mines, and in stone quarries in mts far from seas, meant that the Earth had gone through multiple transformations over very long periods of time.
Hooke recognized that fossil ammonites were the remains of living creatures, and since there were no ammonites around today, that meant that species could go extinct. And this suggested that new species had arisen in their place. And all this was in 1705, 150 years before Darwin.
By second half of C18, increasing attention to idea that species changed. The term 'evolution' was first used by Frenchman Charles Bonnet, although he used it to explain preformation (that individuals were all created by God in the beginning, and were just nestled inside each other like Russian dolls) The word comes from Latin word for 'unrolling'.
Denis Diderot, French free thinker, produced encyclopedia 1751 - 72, where he explained that evo happened in imperceptible steps. Monboddo developed idea that languages had evolved, and this led to him suggesting that men and apes had started out from a common ancestral stage.
The Gift of Time: James Hutton and the age of the Earth. Hutton and John Davie invented a way to make sal ammoniac from soot, (This was impt for dyeing and printing, and had previously only available from Middle East at considerable cost.) making him financially independant. In 1785 he explained that the world is a continuous process of erosion of mts and sedimentation in the seas, in cycles taking millions of years.
Surveyor and canal builder William Smith worked as a mine inspector. He recognized that different strata he could see in the mines were arranged in regular pattern across the county, and that they also could be recognized by the specific fossils they held. Produced his first geological map of area around Bath in 1799 and eventually (1815) a geological map of England and part of Scotland.
1750 recog that central France covered with extinct volcanoes, and that the land around the Massif Central, in southern France, showed a pattern of basaltic rock that looked like lava flows. And all this was heavily eroded, implying that volcanism had happened many thousands of years before. Analysed by George Scrope who had witnessed a great Vesuvius eruption in 1822. He explained how volcanoes had been, and still were, building up new land.
Charles Lyell found remains of sea beds with oyster beds, 700 feet up Mt Etna, sandwiched between lava flows. He explained that mts such as Etna were built up over time by repeated lava flows, not by a single violent cataclysm (as Creationists tried to advocate, tying it to Noah's Flood)and that Etna itself was very old, but sat on rocks that were very young by geological standards, and so the Earth must be immensely old..
Interesting how world transport changed in C19. Lyell made repeated trips by steamer to N America, which let him both study geology of places like Niagara Falls, and travel by rail to give popular public lectures, boosting sales of his books, and giving him the income to carry on writing and revising his textbooks on geology.
Erasmus Darwin, Charles grandfather, published Zoonomia in 1794. mainly about medical topics, but he devoted one chapter to evolution. But it was buried so deeply that there was no controversy - even his grandson Charles Darwin, didn't read it until after his own book had been published. Erasmus highlighted the way selective breeding by humans had developed new kinds of plants and animals, and noted the way characteristics are inherited from parents. And he noted how birds had developed different beaks to deal with different nuts and seeds.
Erasmus also noted how male, but not female, birds of some species are armed with spurs. Since the hens don't have them, these are not for general defence, but for males fighting for the exclusive possession of the females. "The final cause of this contest amongst the males seems to be that the strongest and most active animal should propogate the species, which should thence become improved."
1813 three different writers published (unnoticed at the time) ideas about evo. James Pritchard assumed that all human races had a common ancestor, and that earliest men were almost certainly Negroes. William Wells presented what Charles Darwin later described as the first recognition of natural selection. Wells said that some accidental varieties of man in Africa would be better fitted than others to bear the diseases of the country. This race would multiply while others would decrease. Patrick Matthew, in an appendix of a book on naval timber, used terms such as 'natural process of selection', a 'principle of selection' and 'selection by the law of nature'.As Nature has a power of increase far beyond what is needed to supply the place of what falls by Time's decay, those individuals who possess not the requisite strength, swiftness, hardihood or cunning, fall prematurely without reproducing ..."
This was the same insight of Darwin and Wallace - that competition for resources winnowed out all but the fittest. The pressure for evo was the struggle for survival between members of the same species, not the competition with other species. A lion is not competing with the prey it feeds on, but with other lions for the ability to catch the prey. The prey is not competing with the lion, but with it's own species to escape the lion.
1819 an Eng surgeon, William Lawrence published Natural History of Man showed understood two key features of evo: first that offspring inherit only their connate (congenital, existing from birth) qualities and not acquired qualities, and second that the differences between varieties and species could only be explained by the occasional production of an offspring with different characters from the parents, and the propogation of such varieties by generation. He also pointed out explicitly that Genesis story impossible given the work of geologists such as Hutton et al that showed fossils in lowest strata were most different from today's animals, but gradually advance towards modernity as get closer to the surface.
Robert Fitzroy, captain of HMS Beagle, got appointment bc previous commander had committed suicide, worn down by the pressures of work and the loneliness of command. So when the ship was scheduled for an extended round the world survey trip that was to take several years, Fitzroy determined to take with him a gentleman companion who would be his intellectual and social equal, sharing his interest in the natural world, in whose company he would not be bound by the rigid requirements of naval discipline.
The search went through a chain of FOAFs before invitation fell to Charles Darwin. When the Beagle sailed in Dec 1831, Darwin took with him a library of 245 books. While Fitzroy ran his survey along the coast of S Am, Darwin was ashore finding fossils. One of the first he sent back was a giant sloth, a fossil mammal previously unknown to science. Caused a sensation when exhibited at British Assoc of Science , so Darwin first became well known in scientific circles.
The voyage showed Darwin multiiple examples of uplifting land, including being in the middle of an earthquake in Valdiva in Feb 1835, where parts of the land had risen by several feet. On his return to England, his papers describing uplift of the Andes did much to vindicate Lyell's suggestions. Darwin's presentation of detailed evidence of what he'd seen in S. Am was the start of widespread acceptance of gradualism and the great age of the Earth.
Charles Darwin and Alfred Wallace each independently came up with the explanation for how evo happened. Wallace started collecting to earn a living. Amazon trip ended in disaster when ship carrying years of specimen collecting sank on way back to England. He then went to Borneo and Sarawak. It was there he made observation that alone would have given him a place in history. He saw that the islands on either side of Wallace Line, even though having very similar environment and size had totally different populations of fauna and flora.
Wallace's epiphany (the equivalent of Darwin's Galapagos finches) came from observation of two groups of tiger crabs living on different soils - one on dark volcanic sand, the other on fawn river sands - and each had coloring so close to the sand they lived on, that it was often possible to detect them only by their shadows. He wrote to Darwin, explaining that having read Malthus, he understood that Nature provides far more baby animals than ever survive to adulthood, because the less fit ones are culled by disease or predators.
In 1858 a 'joint paper' of both Wallace's and Darwin's ideas presented to the Linnean Society, but without much reaction. But Darwin later said that it was Wallace's letter that gave him the kick in the pants to finish his book. The publication of Origin of the Species Nov 1859 marked the moment when the idea of evo by natural selection became part of mainstream science and public debate.
Wallace died in 1913, aged 90. He lived to see the beginnings of the answers which had bothered Darwin so much - timescale and heredity.
Heredity - the key understanding of both Darwin and Wallace was that like begats like, but imperfectly. There are no sudden transitions, but no offspring is a perfect copy of either parent.
Books by Title
Books by Author
Books by Topic