What the Bible Says Genesis 1:11-12: And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so. And the earth brought forth grass, and herb yielding seed after his kind, and the tree yielding fruit, whose seed was in itself, after his kind: and God saw that it was good. Genesis 1:24-25: And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so. And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good. Of all clean birds ye shall eat. But these are they of which ye shall not eat: The eagle, and the ossifrage, and the ospray, And the glede, and the kite, and the vulture after his kind, And every raven after his kind, And the owl, and the night hawk, and the cuckow, and the hawk after his kind, The little owl, and the great owl, and the swan, And the pelican, and the gier eagle, and the cormorant, And the stork, and the heron after her kind, and the lapwing, and the bat. Deuteronomy 14:11-18, King James Version Plato (427 – 347 B.C.E.) Plato believed that the world is a mirage, that the only things that really exist are immutable Forms or Ideas, and that objects in the real world are just evanescent shadows of these Forms. In Book 7 of The Republic Plato explains this concept using the allegory of a cave with prisoners watching shadows on a wall producing by firelight shining over the real objects. Essentialism Essentialism, based on Plato’s concept of Forms, dominated Western thought for over 2000 years and impeded progress in biology. There was an ideal form of each animal and plant; individuals varied a little from the ideal form because they were imperfect copies, but the ideal form was “divine, deathless, intelligible, uniform, indissoluble, always the same as itself.” (Plato’s Phaedo) This concept was antithetical to the concept of evolution. Aristotle and the Scala Naturae Aristotle (384 – 322 B.C.E.) did believe in reality, and developed a “natural philosophy” that included many of today’s sciences, particularly physics and biology. He visualized nature as a ladder (the scala naturae) with earth at the bottom, then plants, then animals, then humans. Plato and Aristotle in Raphael’s The School of Athens Scala Naturae The Great Chain of Being Christianity added angels and God to the ladder, the “great chain of being,” with earth and minerals at the bottom, then plants, animals, humans, angels, and God in progressively higher levels. Some levels were subdivided into higher and lower animals, higher and lower humans (peasants, aristocrats, kings), and so forth. A sample of Aristotle’s biological writing: “Of birds, some take a dust-bath by rolling in dust, some take a water-bath, and some take neither the one bath nor the other. Birds that do not fly but keep on the ground take the dust-bath, as for instance the hen, the partridge, the francolin, the crested lark, the pheasant; some of the straight-taloned birds, and such as live on the banks of a river, in marshes, or by the sea, take a water-bath; some birds take both the dust-bath and the water-bath, as for instance the pigeon and the sparrow; of the crooked-taloned birds the greater part take neither the one bath nor the other.” – History of Animals, Book IX, 49B. A story by Aristotle “A story goes that the king of Scythia had a highlybred mare, and that all her foals were splendid; that wishing to mate the best of the young males with the mother, he had him brought to the stall for the purpose; that the young horse declined; that, after the mother’s head had been concealed in a wrapper he, in ignorance, had intercourse; and that, when immediately afterwards the wrapper was removed and the head of the mare was rendered visible, the young horse ran away and hurled himself down a precipice.” – History of Animals, Book IX, 47. The Immutability of Species For centuries it was believed that the different “kinds” of animals and plants had been created exactly as they were today, and had never changed: they were immutable. Also, because God’s creation was perfect, no animal or plant created by God had ever become extinct. Evidence began accumulating in the 18th and 19th century that there were extinct organisms; also, immutability became suspect. The Species Question What is a species? How can you tell if two organisms are the same species or different species? If two organisms can interbreed, are they of the same species? If they can’t, are they of different species? How can you tell if one organism is descended from the other, or both are descended from a (recent) common ancestor? Example of questions relating to species: • Modern humans (Homo sapiens) and Neanderthals (Homo neandertalis) are considered different species. Did H. neandertalis evolve into H. sapiens or were they both descended from some common ancestor? In either case, could or did they interbreed, and does H. sapiens have any H. neandertalis genes? • Wolves, jackals, coyotes, and dogs can all interbreed with one another. Are they one species, or different species, and if the latter, how many? The Species Question … Are sugar maples and red maples and Japanese maples all members of the same species, maybe just different varieties (whatever that means) of that species, or are they different species? Are Clemson Spineless okra and Red okra different species, or just varieties in a single species (okra)? What distinguishes species from varieties? For centuries most botanists and zoologists felt they knew the difference, but they didn’t always agree with one another. Those who carefully examined the species question usually became confused and uncertain the more they studied it. Different Species Concepts Traditionally, two groups of animals or plants were regarded as belonging to different species if they appeared to be sufficiently different: different “types” or “kinds” of organisms. But by this definition a monarch caterpillar and a monarch butterfly were different species. Today, the biological species concept is generally accepted: “Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.” – Ernst Mayr, What Evolution Is (2001) Wolves, jackals and coyotes are three natural populations that could but do not interbreed, so they are different species. Many examples are known of “sibling species” which resemble each other, live in the same area, but do not interbreed. Ring Species: Larus gulls In Europe there are two different species of gulls known as the herring gull and the lesser black-backed gull, the former living in Norway and the latter in Norway and the British Isles. They do not interbreed. Go around the north pole and the fact that they are different species becomes difficult to claim. Two different species of gulls in Norway: on the left, the herring gull, and on the right, the lesser black-backed gull. Around the arctic there is a “ring” in which the Larus gulls live. Going west from the British Isles, the lesser black-backed gull slowly changes into slightly different gulls such as the American herring gull, the Vega herring gull, etc., finally becoming the herring gull in Norway! Are these one species of gull, or two? The Ensatina Salamander Around the Central Valley of California, up the mountains a little, not down in the valley, are found a ring of Ensatina salamanders. Any two neighboring populations of these salamanders can and do interbreed. But on the western side, at the south end, is the plain Ensatina eschscholtzii, and on the eastern side, at the south end, is the large blotched Ensatina klauberi. These two species do not interbreed, so they appear to be different species by the biological species concept. However, they are morphologically identical and actually can interbreed, as if they were a single species. Important Biologists Before Darwin John Ray (1627 – 1705) Karl Linnaeus (1707 – 1778) Comte de Buffon (1707 – 1788) Erasmus Darwin (1731 – 1802) Jean-Baptiste Lamarck (1744 – 1829) Georges Cuvier (1769 – 1832) John Ray (1627 – 1705) English naturalist – really the father of English natural history. Published important works on plants, animals, and natural theology. Taught for a time at Trinity College, Cambridge, where Francis Willughby (1635 – 1672) was first his pupil, later his colleague and patron after Ray lost his position for not subscribing to the 1661 Act of Uniformity. John Ray’s Books Catalogus plantarum Angliae (1670) catalogued English plants, and was the basis for all later such works. Methodus planarum nova (1682) described Ray’s method of classifying plants, with particular emphasis on the difference between monocotyledons and dicotyldeons (plants germinating with one or two leaves). Historia generalis plantarum (3 vols., 1686, 1688, 1704) was his great taxonomic work. The Wisdom of God Manifested in the Works of the Creation (1691) was a very popular book espousing what came to be known as “natural theology.” Non-Botanical Writings by Ray and Willoughby John Ray was fond of amassing facts about many things, as shown by the subjects of some of his non-biological books: Collection of English Proverbs (1670), Collection of Out-of-the-way English Words (1674), and Collection of Curious Travels and Voyages (1693). Francis Willugby made a scientific study of games, which was published in 2003 as Francis Willughby’s Book of Games. It included a charming early description of football (the word he used), which used “a close that has a gate at either end; the gates are called Goals.” The ball? “They blow a strong bladder and tie the neck of it as fast as they can, and then put it into the skin of a bull's cod and sew it fast in. … The harder the ball is blown, the better it flies. They used to put quicksilver into it sometimes to keep it from lying still.” Carl Linnaeus Carl von Linné (Carolus Linnaeus) (1707 – 1778) Swedish biologist considered the father of modern taxonomy. Most of his life as a student and professor (from 1741) was spent at Uppsala University. Invented the bionomial nomenclature for organisms (e.g., Homo sapiens, Taraxacum officinale). Linnaeus … 1743 – created the modern Celsius temperature scale by fixing the melting point of ice at 0º and the boiling point of water at 100º, instead of the other way around as Anders Celsius had done! Created a taxonomy consisting of three kingdoms – animal, vegetable (plants) and mineral. His classification of plants and (to a lesser degree) animals became widely accepted. Kingdoms were divided into Classes, which were divided into Orders, which were divided into Genera (singular: genus), which were divided into Species, and then sometimes into taxa of a lower (unnamed) rank, essentially what we now call varieties in the case of plants. Linnaeus … The first edition of Linnaeus’ Systema Naturae, printed in the Netherlands in 1735, was only 11 pages long. Linnaeus kept adding to it and its 10th edition (1758) classified 4,400 species of animals and 7,700 species of plants. The bionomial nomenclature Linnaeus used had been developed in the late 16th and early 17th century by the Swiss botanists (brothers) Gaspard and Johann Bauhin, for some of the 6000 plants they described in their works, but it was Linnaeus who used it consistently and systematically. Linnaeus’ names are still in use, denoted by “L.” after the name, although modern genetic techniques have forced considerable revisions in his scheme. For example, okra is Hibiscus esculentus L. but today is called Abelmoschus esculentus; it was formerly regarded as a species of hibiscus but now is placed in the mallow family and only regarded as related to hibiscus. Two portraits of Linnaeus: his wedding portrait (1739) and one showing him in a Lapp costume (1737). Linnaea borealis (Twinflower) This flower, which he apparently first saw in Lapland, was Linnaeus’ favorite flower, named after him by his teacher, Jan Frederik Gronovius. He is seen holding it in many of his portraits, and he used it as his symbol when he was made a noble in 1757. Borage or Starflower Scientific classification of the Cicada-Killer Wasp Kingdom: Phylum: Subphylum: Class: Subclass: Infraclass: Superorder: Order: Suborder: Infraorder: Superfamily: Family: Subfamily: Tribe: Genus: Species: Animalia Arthropoda Hexapoda Insecta Pterygota Neoptera Endopterygota Hymenoptera Apocrita Aculeata Apoidea Crabronidae Bembicinae Gorytini Sphecius (Dahlbom, 1844) some 20 species described Georges-Louis Leclerc Comte de Buffon (1701 – 1788) French mathematician, biologist, cosmologist, naturalist. Keeper of the Jardin du Roi (now Jardin des Plantes) in Paris. Author of the incredible Histoire naturelle (44 volumes), translated into many languages. Buffon … Early in his career, he did important work in probability theory, using calculus. He solved the problem known as Buffon’s needle, the first geometric probability problem. If a needle of length l is dropped onto a plane with parallel lines a distance t apart, the probability that the needle will cross a line is 2l/tπ, which can be used to estimate π. Needle a crosses a line, needle b does not. Actually, the needle can be a (plane) noodle! (Buffon’s noodle) Buffon … His Histoire naturelle, générale et particulière was published from beginning in 1749 in 44 volumes (8 after his death). It contained everything known about the natural world at the time. It is online at www.buffon.cnrs.fr. Right: A “giant octopus” attacking a ship (Buffon, 1805). In fact, there exists a giant squid but no giant octopus, and the giant squid does not attack ships. Buffon … Buffon first explained the true “greenhouse effect” in a greenhouse, whose interior heats up when it is sunny (but not the atmospheric greenhouse effect). Buffon’s Law (biogeography): Buffon noted that different places, even though they had nearly the same environment, had different plants and animals. He attributed this to changing (evolving) after dispersal from the place of their creation. Darwin greatly admired Buffon. Today we realize that his views of evolution were more correct than those of Lamarck and Cuvier, who came after him. Erasmus Darwin (1731 – 1802) • Received his medical degree at Cambridge in 1755 after studying at Cambridge and Edinburgh • Became a physician at Litchfield and later Derby • Emphasized the power of the mind and paid close attention to mental as well as physical conditions – regarded many illnesses as having a mental origin. • Offered (but declined) post of Royal Physician by George III Erasmus Darwin (1731 – 1802) • He “believed in the hearty joys of women, food, a little gardening and agricultural improvement, some practical inventions to discuss with friends, and agreeable company in the evenings, with good books and plenty of children for his old age.” – Janet Browne, vol. 1, page 37 • Had a large physique and became so fat that a semicircle had to be cut into his dining table so he could dine at it and be able to reach his food. • Pockmarked from smallpox contracted in his early years. Erasmus Darwin’s Progeny • Father of at least 14 children with two wives and one mistress. • First wife Mary Howard (1739 – 1770) died of alcoholism, so Darwin insisted on his family and patients never using alcohol. She gave birth to five children, with three sons (Charles, Erasmus, Robert) surviving. • Fathered two illegitimate children with a young woman (“Mrs.” Parker) who cared for the young children and became his mistress. • Married a widow, Elizabeth Pole (illegitimate daughter of an aristocrat), and had seven more children by her. Children of Erasmus Darwin and Mary Howard Darwin Charles (1758 – 1778) – very gifted and intelligent and intended for a medical career like his father; died at age of 19 from an infection, possibly picked up during a postmortem examination. Erasmus (1759 – 1799) – encouraged by his father to go into law, but was not successful, became depressed, and committed suicide. Robert Waring Darwin (1766 – 1848) – pushed into a medical career by his father, who sent him to Edinburgh and constantly sought favors on Robert’s behalf, even though Robert hated medicine and would never have chosen it as a profession – so he resolved never to treat his own sons that way. Erasmus Darwin had little to do with Erasmus and Robert after remarrying and seeing to their education – he was more interested in his newest family. Erasmus Darwin’s Writings Many poems Poems about nature and evolution: The Economy of Vegetation The Loves of the Plants The Temple of Nature Prose works for scientists: Zoonomia (1794 – 1796) Phytologia (1800) The Loves of Plants “The most delicious poem upon earth.” “How strange it is that a man should have been inspired with such a enthusiasm of poetry by poring through a microscope, and peeping through the keyholes of all the seraglios of all the flowers in the universe!” – Horace Walpole Erasmus Darwin’s Take on Evolution Life appeared spontaneously early in earth’s history Self-generated variation and diversification led to all modern plants and animals, including humans No original creation or divine intervention was necessary; nature had its own “laws of nature.” (Erasmus Darwin was apparently an unbeliever, but never publicly denied the existence of God.) Mechanism of evolution: development of useful characteristics passed on to succeeding generations – basically, Lamarck’s theory of the inheritance of acquired characteristics. Organic Life beneath the shoreless waves Was born and nurs’d in Ocean’s pearly caves; First forms minute, unseen by spheric glass [microscope], Move on the mud, or pierce the watery mass; These as successive generations bloom, New powers acquire, and larger limbs assume; And breathing realms of fin, and feet, and wing, Thus the tall Oak, the giant of the wood, Which bears Britannia’s thunders on the flood; The Whale, unmeasured monster of the plain, The Eagle soaring in the realms of air, Whose eye undazzled drinks the solar glare, Imperious man, who rules the bestial crowd, Of language, reason, and reflection proud, With brow erect who scorns this earthy sod, And styles himself the image of his God; Arose from rudiments of form and sense, An embryon point, or microscopic ens! Jean-Baptiste Lamarck (1744 – 1829) 11th child in an impoverished aristocratic military family in Picardie. A soldier for several years until injured, after which he took up the study of medicine. Made important contributions to cell theory, botany, invertebrate zoology, and evolutionary theory. Became a member of the French Academy of Sciences in 1779. Lamarck … In 1781 Lamarck became a Royal Botanist associated with the great Jardin du Roi (“Garden of the King”) in Paris; in 1790, during the French Revolution, he renamed it the Jardin des Plantes (“Garden of Plants”), by which it is still known today. Between 1800 and 1822 he developed the first coherent evolutionary theory. [Note: This was after he turned 56.] While believing (like most biologists of his day) in the continual spontaneous generation of simple forms of life, he believed in transmutation, the changing of organisms into more complex forms in accordance with physical and chemical principles, in a strictly materialistic manner; he referred to this as Le pouvoir de la vie (“The force of life”). But also, organisms evolved through L’influence des circonstances (“The influence of the environment”), becoming adapted to their local environment. Lamarck’s Great Escalator of Being Originally an essentialist, Lamarck became convinced that molluscs changed (transmutation) over time. Instead of a great ladder of being, Lamarck visualized a great escalator of living things, all species constantly moving up the ladder, becoming more complex, while simple new beings were spontaneously generated at the bottom. The upward movement was evolution. The Inheritance of Acquired Characteristics Lamarck believed that the use and disuse of characters powered adaptation: “In every animal which has not passed the limit of its development, a more frequent and continuous use of any organ gradually strengthens, develops and enlarges that organ, and gives it a power proportional to the length of time it has been so used; while the permanent disuse of any organ imperceptibly weakens and deteriorates it, and progressively diminishes its functional capacity, until it finally disappears. “ Lamarck believed these characters were then inherited, a common belief in his time; this is referred to as “soft inheritance” and was accepted by most 19th century biologists. Lamarck was the first to use the word “biology” in its modern sense. Lamarck was constantly attacked by Cuvier, who did not believe in evolution, and so became something of a scientific pariah: Cuvier was “in” and Lamarck was “out”. When he died in Paris in 1829, he was very poor, his family had to seek government assistance, and he himself was originally buried in a lime-pit. Today, he is highly regarded for his work and his belief in and theorizing about evolution, although his theory of the soft inheritance of acquired characters – which was the best theory Darwin knew about – was disproved in the late 19th century by the work of August Weismann, who demonstrated the difference between somatic (body) and genetic (reproductive) cells. Georges Cuvier (1769 – 1832) French naturalist and zoologist who compared fossil animals with living animals and established the fields of comparative anatomy and paleontology. Cuvier and His Career Cuvier was actually German, his original name Johann Leopold Nicolaus Friedrich Kuefer, and he was educated in Germany. He came to France as a tutor to an aristocratic family in Normandy, and remained in France the rest of his life. A Protestant (Lutheran), he nevertheless was politically savvy and held many positions at French universities and in French scientific organizations, before, during, and after the French Revolution and the Napoleonic Era. A real “survivor.” His career was long and varied and dealt with both living and fossil animals. Cuvier’s Principle of Correlation of Parts “Today comparative anatomy has reached such a point of perfection that, after inspecting a single bone, one can often determine the class, and sometimes even the genus of the animal to which it belonged, above all if that bone belonged to the head or the limbs. ... “This is because the number, direction, and shape of the bones that compose each part of an animal's body are always in a necessary relation to all the other parts, in such a way that – up to a point – one can infer the whole from any one of them and vice versa.” Cuvier’s Ideas Cuvier’s work paved the way for the theory of evolution, but he himself did not believe in evolution. He believed that all present organisms had been created exactly as they were now and had never changed, pointing out that mummified cats and other animals in ancient Egyptian tombs were identical to those of today. He believed that fossils were the remains of previously existing organisms that had become extinct through some great catastrophe. Glimpses of Natural Selection before Darwin Several authors before Darwin wrote articles or books that mentioned something like natural selection, but none had any great impact, and none of the authors had fully developed their theories. William Charles Wells (1757 – 1817) Patrick Mathew (1790 – 1864) Edward Blyth (1810 – 1873) William Charles Wells (1757 – 1817) Wells was a Scottish-American physician, born in Charleston, South Carolina, educated in Scotland, who practiced in South Carolina. In 1818, shortly after his death, a book entitled Two essays … appeared which contained an appendix on An account of a female of the white race of mankind, part of whose skin resembles that of a negro, with some observations on the cause of the differences in colour and form between the white and negro races of man. This appendix described the idea of natural selection. Key quotation from Wells: “[What was done for animals artificially] seems to be done with equal efficiency, though more slowly, by nature, in the formation of varieties of mankind, fitted for the country which they inhabit. Of the accidental varieties of man, which would occur among the first scattered inhabitants, some one would be better fitted than the others to bear the diseases of the country. This race would multiply while the others would decrease, and as the darkest would be the best fitted for the [African] climate, at length [they would] become the most prevalent, if not the only race.” Note that Wells discussed natural selection only in reference to humans. Patrick Mathew (1790 – 1864) Patrick Matthew was a prosperous Scottish landowner and fruit farmer. In 1831 he published a book, On Naval Timber and Arboriculture, which described the principles of good timber forestry for the purpose of furnishing wood suitable for building the Royal Navy’s ships. He wrote that using only the best trees led to poorer trees in the timber forests, and advocated removing the poorer trees in the forests. This would lead to better trees and even new varieties of trees. “There is a law universal in nature, tending to render every reproductive being the best possible suited to its condition that its kind, or organized matter, is susceptible of, which appears intended to model the physical and mental or instinctive powers to their highest perfection and to continue them so. This law sustains the lion in his strength, the hare in her swiftness, and the fox in his wiles. As nature, in all her modifications of life, 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—either a prey to their natural devourers, or sinking under disease, generally induced by want of nourishment, their place being occupied by the more perfect of their own kind, who are pressing on the means of subsistence . . . “There is more beauty and unity of design in this continual balancing of life to circumstance, and greater conformity to those dispositions of nature which are manifest to us, than in total destruction and new creation . . . [The] progeny of the same parents, under great differences of circumstance, might, in several generations, even become distinct species, incapable of co-reproduction.” Matthew’s chief argument is given in the Appendix to his book, which attracted no attention, although it is also mentioned in the main text. Matthew claimed, and Darwin agreed, that he had anticipated the theory of evolution by natural selection, although he had not developed his ideas and, indeed, wrote many years later that there was evidence of design and benevolence in nature, and, in particular, that beauty could not result from natural selection. Consequently, he is not given much credit today for his ideas. Edward Blyth (1810 – 1873) Edward Blyth was originally a pharmacist, but decided to become a writer. In 1841 he was offered the curatorship of the museum of the Royal Asiatic Society of Bengal, so he went to India and remained there until poor health forced him to return to England in 1862. Blyth was poor most of his life, as he was not paid much for his work. Nevertheless, he worked hard and accomplished quite a bit as a naturalist. He obtained many bird specimens from fieldworkers and wrote about them; many birds of the area are named after him. Edward Blyth was a correspondent of Darwin’s and a fairly close friend all his life; he is often mentioned in Darwin’s books. In three articles published between1835 and 1837 in The Natural History Magazine (before he went to India) he described natural selection quite well, but thought of it only as a mechanism for preserving the original type of an organism, not for producing evolution or new species. Blyth was definitely a creationist. Darwin appears to have overlooked the significance of these articles, judging from his notebooks, probably from not being ready to think about mechanisms for evolution, or from not regarding species as immutable.