Category Archives: Evolution

May 14, 1864 (a Saturday)

A fragment of the Orgueil meteorite.

On this date, a carbonaceous chondrite disintegrated and fell in fragments near the French town of Orgueil. One specimen was immediately examined by the French scientist S. Cloëz, who commented that its content “would seem to indicate the existence of organized substances in celestial bodies.” Subsequently, several eminent chemists of the time, including Gabriel-Auguste Dubrée and Marcellin Berthelot, analyzed samples and confirmed the existence of organic materials in the rock. However, hopes of discovering actual living matter in the meteorite were dashed by the experiments of Louis Pasteur, as recounted by Carl Sagan:

[He] caused a special drill to be constructed, which, he hoped, would remove samples from the interior of the meteorite without contaminating them with microorganisms from outside. Using sterile techniques, Pasteur inoculated an organic medium to search for growth of any indigenous microorganisms which the meteorite interior might contain. The results were negative, and have relevance today: Pasteur extracted his sample shortly after the fall of the meteorite, and was, of course, a very careful experimentalist.

A fragment of the Ivuna meteorite (Tanzania, Africa, 1938).

Virtually all meteorites scientists have studied are former parts of asteroids. However, recent determination of the amino acid signatures within the Orgueil meteorite and Ivuna meteorite suggest that these compounds were likely synthesized from components such as hydrogen cyanide, which have been recently observed in the comets Hale-Bopp and Hyakutake. This suggests that the organic material in Orgueil and Ivuna is the product of reactions that once took place in the nucleus of a comet, which, if true, would make these meteorites the first to be identified as having come from a cometary nucleus. This would add to the evidence that the amino acids that helped generate life on Earth may have been delivered by meteorites that were derived from the remnants of comets.

May 12, 1835 (a Tuesday)

Charles Darwin by G Richmond.

On this date, Charles Darwin visited copper mines in North Chile.

May 9, 1836 (a Monday)

Charles Darwin by G Richmond.

On this date, HMS Beagle with Charles Darwin departed Port Louis, Mauritius.

May 8, 1834 (a Thursday)

Charles Darwin by G Richmond.

On this date, Charles Darwin’s expedition returned to the HMS Beagle.

May 7, 1925 (a Thursday)

Church/State sign.

On this date, the highly orchestrated arrest (but not detention) of John T. Scopes took place. The Tennessee legislature had earlier passed the Butler Act, which declared:

… that it shall be unlawful for any teacher in any of the Universities, Normals and all other public schools of the State which are supported in whole or in part by the public school funds of the State, to teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.

As a reaction to this, the American Civil Liberties Union had offered to defend anyone who so dared to teach evolution in Tennessee. Some local business owners in Dayton thought that their town might be able to get some easy publicity if they were able to come up with someone who they could say violated the Butler Act. Scopes had volunteered, and ultimately he was charged with teaching evolution to a high school class.

May 6, 1966 (a Friday)

ResearchBlogging.orgOn this date, American paleobotanist Elso S. Barghoorn of Harvard reported the discovery of Precambian spherical one-celled alga-like microfossils (named Eobacterium isolatum, which means “solitary dawn bacteria”) 3.4 billion years old, Earth’s earliest life forms. Barghoorn, with J. William Schopf, studied the 3.2 billion year old chert (a flintlike or quartz-like rock) of the Fig Tree formation in Transvaal, South Africa. Rubidium and strontium ratios in the chert suggested an age of over 3 billion years. The fossils are examples of prokaryotes, unicellular organisms that lack a nucleus and have a distinctive cell wall containing organic chemicals.

References:

  • Barghoorn, E.S., Schopf, J.W. (1966). Microorganisms three billion years old from the Precambrian of South Africa. Science, 152(3723), 758-763. DOI: 10.1126/science.152.3723.758

May 4, 1925 (a Monday)

George Rappleyea in June 1925

On this date, George Rappalyea, a 31-year-old transplanted New Yorker and local coal company manager, arrived at Fred Robinson’s drugstore in Dayton, Tennessee with a copy of a paper containing an American Civil Liberties Union announcement that it was willing to offer its services to anyone challenging the new Tennessee anti-evolution statute. Rappalyea, a modernist Methodist with contempt for the new law, argued to other town leaders that a trial would be a way of putting Dayton on the map. Listening to Rappalyea, the others – including School Superintendent Walter White – became convinced that publicity generated by a controversial trial might help their town, whose population had fallen from 3,000 in the 1890′s to 1,800 in 1925. Thus, the “Robinson’s drugstore conspiracy” to put Dayton, Tennessee on the map was put into motion.

The conspirators summoned John Scopes, a twenty-four-year old general science teacher and part-time football coach, to the drugstore. As Scopes later described the meeting, Rappalyea said, “John, we’ve been arguing and I said nobody could teach biology without teaching evolution.” Scopes agreed. “That’s right,” he said, pulling a copy of Hunter’s Civic Biology – the state-approved textbook – from one of the shelves of the drugstore (the store also sold school textbooks). “You’ve been teaching ‘em this book?” Rappalyea asked. Scopes replied that while filling in for the regular biology teacher during an illness, he had assigned readings on evolution from the book for review purposes. “Then you’ve been violating the law,” Rappalyea concluded. “Would you be willing to stand for a test case?” he asked. Scopes agreed. He later explained his decision: “The best time to scotch the snake is when it starts to wiggle.”

May 4, 1825 (a Wednesday)

T. H. Huxley

On this date, the English physician and biologist Thomas Henry Huxley was born in Ealing (then a village in Middlesex).  He received his medical degree from Charing Cross School of Medicine, becoming a physiologist, and was awarded many other honorary degrees. Huxley spent his youth exploring science, especially zoology and anatomy, lecturing on natural history, and writing for scientific publications.

Huxley earned the nickname “Darwin’s Bulldog” when he debated Darwin’s On the Origin of Species with Bishop Samuel Wilberforce in Oxford in 1860. When Wilberforce asked him which side of his family contained the ape, Huxley famously replied that he would prefer to descend from an ape than a human being who used his intellect “for the mere purpose of introducing ridicule into grave scientific discussion.” Thereafter, Huxley devoted his time to the defense of science over religion.

Darwin danced around human evolution in On the Origin of Species in 1859, not addressing the topic until 1871 in The Descent of Man. Yet Huxley wrote about human and primate paleontology in Man’s Place in Nature in 1863. He examined the similarities between humans and apes and noted that greater anatomical differences separate gorillas and chimpanzees from the lower apes than separate gorillas from people. He also mused:

Is [the philosopher or poet] bound to howl and grovel on all fours because . . . he was once an egg, which no ordinary power of discrimination could distinguish from that of a Dog? . . . Is mother-love vile because a hen shows it, or fidelity base because dogs possess it?

Huxley coined the term “agnostic” (although George Jacob Holyoake also claimed that honor). Huxley defined agnosticism as a method, “the essence of which lies in the rigorous application of a single principle . . . the axiom that every man should be able to give a reason for the faith that is in him.” Huxley elaborated: “In matters of the intellect, follow your reason as far as it will take you, without any other consideration. And negatively, in matters of the intellect do not pretend that conclusions are certain which are not demonstrated or demonstrable” (from his essay Agnosticism).  In his Essays on Controversial Questions (1889), he wrote:

Skepticism is the highest duty and blind faith the one unpardonable sin.

Huxley was president of the Royal Society of London, and was elected to the London School Board in 1870, where he championed a number of common-sense reforms.  His other essays included Agnosticism and Christianity (1889).  Huxley, appropriately, received the Darwin Medal in 1894.

May 3, 1877 (a Thursday)

Baron Nopcsa

Baron Nopcsa

On this date, the paleontologist Baron Franz Nopcsa von Felső-Szilvás (or Baron Franz Nopcsa) was born in Transylvania, which at that time was a part of Austria-Hungary. Making no effort to hide his homosexuality, he was often dismissed as “whacky” by other scientists, yet he made significant contributions to the fields of paleontology, geology, and evolutionary biology. He was also fascinated by the language and culture of Albania and aspired to become king of that country.

A gifted student, Nopcsa graduated from the prestigious Maria-Theresianum in 1897. His younger sister Ilona having discovered fossilized dinosaur bones in 1895 at the family estate at Szentpéterfalva in Săcele (Szacsal), Transylvania, Nopcsa enrolled at the University of Vienna to study them. He advanced quickly in his studies; on 21 July 1899, at the age of twenty-two, he held his first lecture at the Academy of Sciences in Vienna on “Dinossaurierreste in Siebenbürgen” (“Dinosaur remnants in Transylvania”) and attracted much attention with it.

With the defeat of Austria-Hungary at the end of World War I, Nopcsa’s native Transylvania was ceded to Romania. As a consequence, the Baron of Felső-Szilvás lost his estates and other possessions. Compelled to find paid employment, he landed a job as the head of the Hungarian Geological Institute.

But Nopcsa’s position in the Geological Institute was short-lived. He moved to Vienna with his long-standing male Albanian lover and secretary Bayazid Doda (also known as Bajazid Elmas Doda) to study fossils. Yet there he ran into financial difficulties and was distracted in his work. To cover his debts, he sold his fossil collection to the Natural History Museum in London. Soon Nopcsa became depressed. Finally, in 1933, he fatally shot first his lover and then himself. In a letter left for the police, he explained that his decision to commit suicide was the result of a nervous breakdown. He also stated:

The reason that I shot my longtime friend and secretary, Mr. Bayazid Elmas Doda, in his sleep without his suspecting at all is that I did not wish to leave him behind sick, in misery and without a penny, because he would have suffered too much.

Nopcsa was one of the first researchers who tried to “put flesh onto bones”, which became his main contribution to paleontology – and hence “paleobiology”. That is, he was fascinated not with the bones but rather with the living animals to whom they had belonged. He wanted to understand the world of the dinosaurs and how they lived in it – how they moved, how they fed, how they mated, and so on. For example, Nopcsa was the first scientist to suggest that these reptiles cared for their young and exhibited complex social behavior. Another of Nopcsa’s hypotheses that was ahead of its time was that birds evolved from ground-dwelling, feathered dinosaurs, an idea that found favor in the 1960s and later gained wide acceptance.  Additionally, Nopcsa’s conclusion that at least some Mesozoic era reptiles were warm-blooded is now shared by much of the scientific community.

The last meal of Compsognathus, illustration by Nopsca (1903)

Nopcsa studied Transylvanian dinosaurs intensively, even though they were smaller than their relatives elsewhere in the world. For example, he unearthed six-meter-long sauropods, a group of dinosaurs that elsewhere commonly grew to 30 meters or more. Nopcsa deduced that the area where the remains were found was an island (now called Haţeg or Hatzeg basin in Romania) during the Mesozoic era. He suggested that “limited resources” found on islands commonly have an effect of “reducing the size of animals” over the generations, producing a localized form of dwarfism. Nopcsa’s theory of insular dwarfism – also known as the island effect – is today widely accepted. Additional pygmy sauropods were recently discovered in northern Germany (analyzed by P. Martin Sander in Nature, 8 June 2006).

As a result of his investigations and publications, Nopcsa is sometimes considered to be the father of modern paleobiology, even though his original term for the field was “paleophysiology.”

References:

April 29, 1834 (a Tuesday)

Charles Darwin by G Richmond.

On this date, Charles Darwin’s expedition up the Santa Cruz River sighted the Cordilleras Range from a hill.

April 26, 1831 (a Tuesday)

Charles Darwin by G Richmond.

On this date, Charles Darwin graduated from Christ’s College, Cambridge with a B.A. degree.

April 15, 1772

Geoffroy aged about 70

On this date, the French naturalist Étienne Geoffroy Saint-Hilaire was born. Receiving a law degree in 1790, he went on to study medicine and science in Paris, at the Collège du Cardinal Lemoine. He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck’s evolutionary theories. Geoffroy’s scientific views had a transcendental flavor (unlike Lamarck’s materialistic views) and were similar to those of German morphologists like Lorenz Oken. He believed in the underlying unity of organismal design, and the possibility of the transmutation of species in time, amassing evidence for his claims through research in comparative anatomy, paleontology, and embryology.

Geoffroy spent much time drawing up rules for deciding when structures in two different organisms were variants of the same type – in modern terminology, when they were homologous. His criterion was connections between parts: structures in different organisms were the same if their parts were connected to each other in the same pattern. As Charles Darwin described his work in 1859, in The Origin of Species:

What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include the same bones, in the same relative positions? Geoffroy St. Hilaire has insisted strongly on the high importance of relative connexion in homologous organs: the parts may change to almost any extent in form and size, and yet they always remain connected together in the same order.

However, Geoffroy’s theory was not a theory of common descent, but a working-out of existing potential in a given type. For him, the environment causes a direct induction of organic change. Ernst Mayr labeled this view as “Geoffroyism”. It is definitely not what Lamarck thought (for Lamarck, a change in habits is what changes the animal). The direct effect of environment is not accepted today by any mainstream evolutionist; even Lawrence knew by 1816 that the climate does not directly cause the differences between human races.

Generalized protostome and chordate body plans illustrating inversion in the two lineages.

Generalized protostome and chordate body plans illustrating inversion in the two lineages.

In 1822 Geoffroy argued that the body-plans of arthropods and vertebrates were fundamentally alike except that one was the dorsoventral inverse of the other. Remarkably, his idea today is supported by a growing body of molecular developmental evidence. Holley et al (1995) have demonstrated that not only do the fruit fly and frog have homologous genes that promote dorsoventral patterning, but the homologous genes have opposite effects within each animal. In fact, the genes are functionally interchangeable – even though the product of sog ventralizes fly embryos, it dorsalizes frog embryos just like its homologue in the frog, chordin.

Interestingly, Geoffroy was a deist – he believed in a God, but also in a law-like universe, with no supernatural interference in the details of existence. This kind of opinion was common in the Enlightenment – many of the American “founding fathers” were deists – and goes with a rejection of revelation and miracles. Deists do not interpret the Bible as the literal word of God.

References:

  • Holley, S. A., Jackson, P. D., Sasal, Y., Lu, B., De Robertis, E. M., Hoffmann, F. M. and Ferguson, E. L., “A conserved system for dorsal-ventral patterning in insects and vertebrates involving sog and chordin,” Nature 376: 249-253 (1995).
  • Mayr, Ernst. The Growth of Biological Thought: Diversity, Evolution and Inheritance. (Cambridge, MA: Harvard Univ. Press, 1982) p 262.

April 15, 1857 (a Wednesday)

On this date, a 3-kg carbonaceous chondrite fell at Kaba, near Debrecen, Hungary. The arrival of this meteorite was described as follows in the book The Geologist (1859) by Samuel Joseph Mackie (pp. 285-6):

About 10 pm an inhabitant of Kaba, sleeping in the open air, was awakened by a noise, different from that of thunder, as he described it, and perceived in the serene sky a luminous globe, of dazzling brightness, following a parabolic course during four seconds. This phenomenon was observed by several inhabitants of the same place. As one of them was riding out the next morning, his horse was frightened by the sight of a black stone, deeply bedded in the soil of the road, the ground around it being depressed and creviced. When dug out the meteorite weighed about 7 pounds. The finder broke off some fragments, and the remainder, weighing 5-1/4 lbs., was deposited in the Museum of the Reformed College at Debreczin.

Samples of the Kaba meteorite and the Cold Bokkeveld meteorite were examined and found to contain organic substances by Friedrich Wöhler, who inferred a biological origin. Ironically, it was Wöhler who had shown that it was possible to make organic chemicals by inorganic means. However, it was only later appreciated that complex carbon molecules can be manufactured in space by purely chemical processes.

April 13, 1834 (a Sunday)

Charles Darwin by G Richmond.

On this date, HMS Beagle anchored at river mouth of Rio Santa Cruz, Patagonia.

April 10, 1835 (a Friday)

Charles Darwin by G Richmond.

On this date, Charles Darwin returned to Santiago, Chile.

April 6, 2006 (a Thursday)

*Tiktaalik roseae* fills in the evolutionary gap between fish and land animals.

On this date, two articles were published in the science journal Nature reporting the discovery of a fossil that might in time become as much of an evolutionary icon as the proto-bird Archaeopteryx. Several specimens of this transitional form, named Tiktaalik roseae, were found in late Devonian river sediments on Ellesmere Island in Nunavut, Arctic Canada.

References:

April 5, 1859 (a Tuesday)

Charles Darwin, aged 51

On this date, Charles Darwin sent his publishers the first three chapters of The Origin of Species, which became one of the most influential books ever published.

April 5, 1802 (a Monday)

Illustration by Felix Dujardin

On this date, the French physiologist, morphologist, and taxonomist Félix Dujardin was born. Dujardin is primarily known for his work with microscopic animal life, and in 1834 proposed that a new group of one-celled organisms be called Rhizopoda (meaning “root-foot”). This name was later changed to protozoa. In 1835, he disproved Ehrenberg’s hypothesis that microorganisms have the same organs as the more complex animals.

Also in 1835, he was the first to describe protoplasm, the jellylike material in animal cells which he called sarcode (from the Greek word σάρξ, meaning “flesh”). [Hugo von Mohl is credited with introducing the name protoplasm for it in 1846.] This substance, now called cytoplasm, was later found in living plant cells. Although the term protoplasm is rarely used any more in a strictly scientific sense, many of the notions associated with the term have survived. Thus it is still accepted that all living organisms are made largely of the same classes of substances such as salts and organic molecules, that some of these are organized into structures large enough to be seen in the microscope, and that water almost always is by far the most abundant material.

Dujardin’s written works include Histoire naturelle des infusoires (1840), Manuel de l’observateur au microscope (1842), and Histoire naturelle des helminthes (1844).

April 4, 1832 (a Wednesday)

Charles Darwin by G Richmond.

On this date, Charles Darwin aboard HMS Beagle arrived at Rio de Janeiro.

March 30, 1759 (a Friday)

A series of rock formations that Arduino categorized as "primary" and "secondary".

A series of rock formations that Arduino categorized as “primary” and “secondary”.

On this date, the Italian geologist Giovanni Arduino (1714-1795) wrote a letter to Professor A.Vallisneri the younger, in which Arduino proposed a classification of Earth’s surface rocks according to four brackets of successively younger orders: Primary, Secondary, Tertiary and Quaternary. Today, his Primary corresponds to the Precambrian and Paleozoic Era combined, his Secondary is the Mesozoic Era, and his Tertiary and Quaternary combine to form the Cenozoic Era.

March 25, 1833 (a Monday)

Jenkin

On this date, the English physical scientist and engineer Henry (Charles) Fleeming [pronounced "flemming"] Jenkin was born. No other attack on Charles Darwin’s theory of evolution has drawn more attention than Jenkin’s. Nearly every book in the history of evolution recounts the tale. It began in June, 1867 with Mr. Jenkin’s review of The Origin of Species in The North British Review (46: 277-318).

References:

  • Stephen Jay Gould, Bully for Brontosaurus: Reflections in Natural History (New York, NY: W.W. Norton & Co., 1991) 340 -353.
  • Ernst Mayr, The Growth of Biological Thought: Diversity, Evolution, and Inheritance ( Cambridge, MA: The Belknap Press of Harvard University, 1982) 512.

March 24, 1912 (a Sunday)

On this date, the American biochemist Sidney Walter Foxwas born. In the 1960s at the University of Miami, Fox found that when he heated Stanley Miller’s amino acids (created through simulation experiments) to temperatures that would have been present on the volcanic primordial Earth, in conjunction with aspartic and glutamic acids (also created through simulation experiments), they formed protein-like polymers that he called”proteinoids”.

Microsphere surface.

Fox observed that when proteinoids or “thermal proteins,” are placed in water, they self-organize into microspheres or protocells, possible precursors of the contemporary living cell. Under a microscope, the microspheres look like primitive cells. In fact, artificially fossilized microspheres are indistinguishable from the earliest known microfossils that date back to about 3.5 BYA. Fox argued that RNA or DNA need not date back to the origin of life, and he showed that proteinoid microspheres exhibit growth, metabolism, reproduction (by budding), and responsiveness to stimuli – all properties of life – though without a genetic system. Although hesitant to claim that these were alive, Fox stated that they were undeniably “protoalive”. This is not an evasive answer. As Tim M. Berra says in Evolution and the Myth of Creationism (1990):

For centuries, science knew nothing intermediate between non-living and living things, but today the distinction is not at all clear. Since life evolved from non-living matter, at some point we must arbitrarily draw a line and say that everything beyond that point is alive. Viruses, for example, appear to be alive when they infect a host, but seem to be non-living when outside a host.

As a result of his monumental discovery of thermal proteins and their self-organization into protocells and that these protocells exhibit virtually all of the properties associated with life, Sidney Fox was invited to lecture widely throughout the world. Even Pope John Paul II and his advisers, on at least three separate occasions, invited Fox to the Vatican to explain his work on the synthesis of cellular life in a test tube.

March 23, 1835 (a Monday)

Charles Darwin by G Richmond.

On this date, Charles Darwin reached Los Arenales, in the Andes.

March 23, 1769 (a Thursday)

William Smith's "A Geological Map of England and Wales and Part of Scotland" (1815)

William Smith’s “A Geological Map of England and Wales and Part of Scotland” (1815)

On this date, the English engineer and geologist William Smith was born. Smith was instrumental in extending the science of stratigraphy. His early work was as a miner and an engineer, for a canal-digging company. From this experience he observed the difference in rock layers. He also recognized that the same succession of fossil groups from older to younger rocks could be found in many parts of England, which he called the principle of faunal succession. He traveled the entire country to verify that relationships between the strata and their characteristics were consistent everywhere. Thus Smith created a profile of the entire country of England. His great geologic map of England and Wales (1815) set the standard for modern geologic maps. Many of the colorful names he gave to the strata are still in use today.

March 22, 1785 (a Tuesday)

Adam Sedgwick

On this date, the English geologist and paleontologist Adam Sedgwick was born. He was one of the founders of modern geology. Sedgwick was the first scientist to apply the name Cambrian to the geologic period of time, now dated at 570 to 505 million years ago. Twentieth-century research has uncovered so many excellent fossils in Cambrian sediments, especially the Burgess Shale in Canada, that this geologic period is sometimes referred to as the “Cambrian Explosion.”

Sedgwick attended Trinity College at Cambridge University, where he took holy orders in 1817. In 1818, he became Woodwardian Professor of Geology at Cambridge, despite the fact that he had no formal training in geology. His lectures at Cambridge were immensely popular; he was a spellbinding lecturer, and – breaking with the traditions of his time – his lectures were open to women, whom Sedgwick thought could make great contributions to natural history. He kept giving his famous lectures until 1871.

After passing his examinations for the Bachelor of Arts degree in January 1831, Charles Darwin began attending Sedgwick’s geology lectures, which he found fascinating. During the summer of 1831, Darwin was Sedwick’s field assistant in north Wales, and Darwin got a “crash course” in field geology from Sedgwick. This was an experience that proved valuable to Darwin over the next five years, on his round-the-world voyage on H.M.S. Beagle. During this voyage, Darwin sent geological specimens and reports to Sedgwick, who wrote approvingly to Darwin’s family:

He is doing admirably in S. America & has already sent home a Collection above all praise. – It was the best thing in the world for him that he went out on the Voyage of Discovery. . .

However, after reading The Origin of Species, Sedgwick candidly wrote to Darwin on November 24, 1859:

If I did not think you a good tempered & truth loving man I should not tell you that. . . I have read your book with more pain than pleasure. Parts of it I admired greatly; parts I laughed at till my sides were almost sore; other parts I read with absolute sorrow; because I think them utterly false & grievously mischievous– You have deserted– after a start in that tram-road of all solid physical truth– the true method of induction. . .

Sedgwick was opposed to Charles Lyell’s models of slow, gradual geological change and a more or less steady-state Earth. Instead, he followed Cuvier’s idea of multiple “catastrophes” that had destroyed much of Earth’s life. But Sedgwick did not object to evolution, or “development” as such theories were called then, in the broad sense – to the fact that the life on Earth had changed over time. Nor was he a “young-Earth” creationist – he thought that the Earth must be extremely old. Nevertheless, Sedgwick believed in the Divine creation of life over long periods of time, by “a power I cannot imitate or comprehend — but in which I believe, by a legitimate conclusion of sound reason drawn from the laws of harmonies of nature.” His problem was with the amoral and materialistic nature of Darwin’s proposed mechanism of natural selection, which Sedgwick thought was degrading to humanity’s spiritual aspirations. His letter of November 24 went on to state:

This view of nature you have stated admirably; tho’ admitted by all naturalists & denied by no one of common sense. We all admit development as a fact of history; but how came it about? Here, in language, & still more in logic, we are point blank at issue– There is a moral or metaphysical part of nature as well as a physical. A man who denies this is deep in the mire of folly. Tis the crown & glory of organic science that it does thro’ final cause, link material to moral. . . You have ignored this link; &, if I do not mistake your meaning, you have done your best in one or two pregnant cases to break it. Were it possible (which thank God it is not) to break it, humanity in my mind, would suffer a damage that might brutalize it–& sink the human race into a lower grade of degradation than any into which it has fallen since its written records tell us of its history.

Despite their differences, the two stayed friends until Sedgwick’s death in 1873.