History of science – Greg Laden's Blog

Difference and Disease: Excellent new book on medicine and race in the 18th century British empire

Greg Laden — Fri, 02 Nov 2018 00:17:48 +0000

Suman Seth is associate professor in the Department of Science and Technology Studies, at Cornell. He is an historian of science, and studies medicine, race, and colonialism (and dabbles as well in quantum theory). In his new book, Difference and Disease: Medicine, Race, and the Eighteenth-Century British Empire, Seth takes on a fascinating subject that all of us who have worked in tropical regions but with a western (or northern) perspective have thought about, one way or another.

As Europeans, and Seth is concerned mainly with the British, explored and conquered, colonizing and creating the empire on which the sun could never set no matter how hard it tried, they got sick. They also observed other people getting sick. And, they encountered a wide range of physiological or biosocial phenomena that were unfamiliar and often linked (in real or in the head) to disease. A key cultural imperative of British Colonials as to racialize their explanations for things, including disease. The science available through the 18th and 19th century was inadequate to address questions that kept rising. Like, why did a Brit get sick on his first visit to a plantation in Jamaica, but on return a few years later, did not get as sick? If you have a model where people of different races have specific diseases and immunities in their very nature, how do you explain that sort of phenomenon? How might the widely held, or at least somewhat widely held, concept of polygenism, have explained things? This is an early version of the multi-regional hypothesis, but more extreme, in which god created each type of human independently where we find them, and we are all different species. (Agassiz, with his advanced but highly imperfect geological understanding, thought the earth was totally frozen over with each ice age, and repopulated with these polygenetic populations of not just humans, but all the organisms, after each thaw).

Seth weaves together considerations of slavery and abolition, colonialism, race, geography, gender, and illness. This is an academic book, but at the same time, something of a page turner. Anyone interested in disease, colonial history, and race, will want to re-excavate the British colonial world, looking at disease, illness, and racial thinking, with Suman Seth as your guide. I highly recommend this book.

Darwin Quotes, Assembled

Greg Laden — Mon, 19 Mar 2018 18:54:11 +0000

From Janet Browne, the author of Charles Darwin: A Biography, Vol. 1 – Voyaging and other works about Charles Dawin, The Quotable Darwin.

Quotes by Charles Darwin are not just the stuff of memes. Even the fake quotes. They can be the center of long arguments, or at least, they can significantly augment the arguments. For example, did you know that while Darwin never used the term “missing link” he did talk about missing links quite a bit, missing links are central to his thinking about evolution, and all those writers of today who claim that we must never speak of missing links are misguided?

My point being, Darwin quotes aren’t just quotes. They are piece of data related to the development of thought about evolution. There are about 300 pages of just quotes, organized by topic, a timeline of Darwin’s life (just a few pages), and an index. Not all the quotes are by Darwin, some are by others responding to him. Many of the quotes are from letter, labeled, of course, as to whom the letter was writtng.

I happen to have the hardcover version. It is a nicely bound, smallish format binding, a bit like a bible in size and shape. Of course. But since the book is about quotes, and this is sometimes something you might want to look up, one might seriously consider the Kindle version which would allow text searches, to the not very evolved extent Kindle devices let you do that.

In case you did not know, Janet Browne is a top Darwin biographer, an historian of science, currently at Harvard but hailing from Great Britain. She has written extensively on Darwin’s correspondence and other writings.

The Brain: An Illustrated History of Neuroscience

Greg Laden — Thu, 19 Nov 2015 18:01:24 +0000

In 1817, Karl August Weinhold had a go at a real-life Frankenstein’s monster — only in his version he uses a cat. The German scooped out the brain and spinal cord of a recently dead cat. He then pured a molten mixture of zinc and silver into the skull and spinal cavity. He was attempting to make the two metals work like an electric pile, or battery, inside the unfortunate cate, replacing the electrical of the nerves. Weinhold reported that the cat was revived momentarily by the currents and stood up and stretched in a rather robotic fashion!

It’s Alive!!!!

Weinhold’s reanimated cat was just the tip of the iceberg. In those days, the same days during which Mary Shelley wrote Frankenstein, the forerunners of modern neuroscience were reanimating all sorts of animals (it started, of course, with frogs) including humans, with suitably horrifying results, using primitive electricity generating machines and ingeniously placed probes.

The Brain: An Illustrated History of Neuroscience (Ponderables 100 Ideas That Changed Histoy Who Did What When) (Ponderables 100 Discoveries That Changed Histoy Who Did What When) by the prolific Tom Jackson (see list below) mentions the cat story in a small sidebar, but several of the 100 moments in neuroscience relate to this sort of early scientific activity. The idea of the book is to put a large topic, in this case the history of neuroscience, into 100 bite sized pieces (with a 101st item at the end, a sort of technical summary) in chronological order. The result is a very browsable and fascinating book, an educational and entertaining coffee table item, even a good gift idea.

I know something about neuroscience and brain evolution, and even a bit about the history of this research, and I found most of the entries to be reasonable, well researched, and accurate. There is sufficient debunking of some of the bad ideas (about race, IQ, etc.), though I would like to have seen Jackson’s treatment of lateralization to have been a bit more probing and nuanced, since that is one of the areas where pop culture has overstayed its welcome. Still, the book is scientifically accurate, not to deep yet not a gloss.

One of the neat features of the book is a giant pull out unfoldable wall poster that is a timeline of the history of neuroscience. I’ll probably give that to my wife for her to hang in her biology classroom, especially since she teaches a fair amount about brains and intends to expand on that teaching over the next couple of years.

The other side of the foldout timeline is a set of optical illusions, including the blind spot test, the arrows affecting the apparent length of the line test, and a lot of the other usual illusions, all very well done with quality presentation and printing.

There are bits at the beginning and end of the book (including item 101, mentioned above) that serve as reference material. There is an index, though it is not dense (for example, having noted the cat story I use above, I tried to look it up in the Index but couldn’t find it). Also as an appendix is a explication of several key open questions in neurobiology (the “Imponderables”). Also, references are supplied.

The illustrations are excellent throughout.

This book is for anyone interested in science, especially neuro. If you cover this topic in your High School or Middle School classes, it is a good book to have in your library. It would make an excellent gift for the science-oriented person you know, especially since it is just out and they won’t have it yet.

This is part of the Ponderables series of illustrated books published by Shelter Harbor Press.

Other books by Tom Jackson:

Mathematics An Illustrated History of Numbers (100 Ponderables)


The Elements: An Illustrated History of the Periodic Table (100 Ponderables)



The Universe An Illustrated History of Astronomy (Ponderables)



Physics: An Illustrated History of the Foundations of Science (Ponderables 100 Breakthroughs That Changed History Who Did What When)



Philosophy: An Illustrated History of Thought  (Ponderables 100 Ideas That Changed History Who Did What When)



Chilled: How Refrigeration Changed the World and Might Do So Again



Magic School Bus Presents: Insects: A Nonfiction Companion to the Original Magic School Bus Series



Exploring Nature: Monkeys: Baboons, Macaques, Mandrills, Lemurs And Other Primates, All Shown In More Than 180 Enticing Photographs (Exploring Nature (Armadillo))

How scientists unraveled the El Niño mystery

Greg Laden — Thu, 04 Dec 2014 16:26:28 +0000

The Road to Paris is a web site created by the ICSU, “…a non-governmental organization representing a global membership that includes both national scientific bodies (121 National Members representing 141 countries) and International Scientific Unions (30 Members),” founded in 1931. If the ICSU had not existed when the UN was formed, the UN would have formed it. Think of the ICSU as the UN of Science. More or less.

(Follow Road to Paris on Twitter.)

Anyway, “Road to Paris” refers to the 2015 international meetings on climate change, and the purpose of the web site is to provide excellent information about climate change, up to date, so those engaged in that process, either as direct participants or as onlookers, will be well informed.

“Fishing in pink waters: How scientists unraveled the El Niño mystery” is an amazing piece of work written by Daniel Gross (I made minuscule contributions), looking at the history of the science of the El Nino Southern Oscillation, which is one of the most important climate or weather related things on this planet. This is timely, because we are expecting an El Niño to form over the winter. Maybe. Well, eventually we will have an El Niño. (It has been an unusually long time since the last strong one.)

Why didn’t Darwin discover Mendel’s laws?

Greg Laden — Fri, 27 Feb 2009 20:26:15 +0000

Perhaps we are all subject to falling into the trap of what I call the Hydraulic Theory of Everything. If you eat more you will be bigger, if you eat less you will be smaller. Emotional states are the continuously varying outcome of different levels of a set of hormones, forming “happy” or “stressy” or “angry” cocktails. Your brain is a vessel into which life pours various elixirs. Too much of one thing, and there will not be enough room for something else. Even political arguments are hydraulic. The ‘balanced’ middle view between two arguments is like the mixture of contrasting primary colors on a pallet.

But some, even many, things in life do not work this way. The body stores or uses fat, and obtains energy from various sources, and controls energy through metabolic level and activity levels, such that there is not a clean, simple one to one correspondence between pieces of pie and inches of waistline. The mid point between two opposed political argument very rarely actually exists, and even more rarely would ever be accepted by anybody. And so on.

A very non-hydraulic system that is often seen as one is genetic inheritance. The traits that the average person knows about seem to blend more often than not. A person seems to be a mixture of that person’s parents. Even when there are digitally distinct traits, there are numerous such traits, some following mother, some father, some the mail carrier, such that the gestalt of the offspring still seems like a blend of parents. Hydraulically, like a martini or a Minnesota hot dish.

And that is how Darwin thought inheritance worked, and this misconception kept that great thinker and great experimentalist from figure out the relatively simple conclusions adduced by Gregor Mendel.

Heredity and variation were two concepts that played a central role in Darwin’s development of the theory of evolution by natural selection. The enormous effort he devoted to their analysis is reflected not only in the entire two-volume The Variation of Animals and Plants under Domestication, but also in countless experiments and observations narrated elsewhere. Yet despite a lifetime’s efforts, he never came close to understanding the logic of inheritance, while his views on the nature and causation of variation oscillated back and forth between a concept of random, quasi-physical events outside environmental control, which indeed looks decidedly modern, and a concept, evidently owing much to his predecessors, of environmentally driven adaptive change transmitted to the germ cells.

This is the opening paragraph of a paper, just out, by Jonathan C. Howard, asking “Why didn’t Darwin discover Mendel’s laws? The paper, in the Journal Biology, is an excellent and detailed discussion of this question. And it really is not simple. It has been proposed in the past that Mendel was more prepared than Darwin to figure out inheritance, given the particulars of his training and background. But Howard, while agreeing that this may be true, points out that Darwin had seen and to some degree recognized what were thought of a “units of inheritance” of certain traits, traits of interest to breeders and the like, but rejected their importance in the larger evolutionary picture.

(In other words, Darwin did not think that Micro evolution was too important!)

Howard explored Darwin’s “Pangenesis” hypothesis, and explores the idea that Pangenesis predisposed Darwin to understand variation as continuous, and not discontinuous, as one would have to do to really get genes.

The important and interesting thing about Howard’s thesis is to unravel the standing argument about why Darwin did not advance a viable genetic theory.

Darwin is occasionally criticized as an imprecise, nonnumeric naturalist, a man of ideas, perhaps brilliant and original in that mode, but not a scientist like those of today. … Mendel’s rational, experimental analysis of the inheritance of unit characters is without question a work of great genius. …. However, if Darwin failed to discover Mendel’s laws, it was not so much because of what he lacked in genius or numeracy or the experimental cast of mind, but rather because of the forceful tendency of what he already possessed. His focus on continuous variation as the source of evolutionary change was not wrong, and coupled with the power he could see in the integration of infinitesimals over time he built his case on the solid foundation of Lyell’s uniformitarian thinking. Much of variation and inheritance was simply opaque in those terms, but continuous variation, not unit characters, was, for Darwin, the way forward. Thus Darwin boxed himself in, unable to see the laws of inheritance in continuous variation, unable to see the real importance of discontinuous variation where the laws of inheritance could be discerned.

… Which is really, or at least also, a problem with Lyell as well as Darwin, this confusion and conflation uniformitarianism and uniformness. Even Steve Gould got that wrong. But we’ll talk about that some other time.

Jonathan C Howard (2009). Why didn’t Darwin discover Mendel’s laws? Journal of Biology, 8 (2) DOI: 10.1186/jbiol123

The Giants’ Shoulders # 8

Greg Laden — Sun, 15 Feb 2009 11:45:23 +0000

“The Giants’ Shoulders” is a monthly science blogging event, in which authors are invited to submit posts on “classic” scientific papers. Information about the carnival can be found here.

The last Giants’ was hosted at The Questionable Authority, here. The next issue will be hosted at The Evilutionary Biologist: All Science, All The Time, which resided here.

Since this is Darwin Month in Darwin Year and almost, indeed, Darwin Day, we start with … Paleontology. We’ll get to Darwin at the end.

Early palaentologists and the Giant killer lungfish from Hell as well as the Revenge of the Giant Killer Lungfish from Hell, at Laelaps, serve as instructive historical arguments worth a read by any paleontologist, fishy or otherwise.

Today, “spooky” in physics means stuff that happens at the smallest scales with photons and other subatomic bits and pieces. But back in the 18th and 19th centuries, simple electricity and magnetism was sufficiently spooky to keep everyone busy. Skullsinthestars writes about the complex history of discovery of the connection between the two, revealing a complex plot involving Faraday, Morichini, Somerville and the rest of them: A physics history-mystery: magnetism from light? Also from Skulls we have “Do optics like Darwin’s Dad!” The same author also has an historical look at the role of Evolution in pulp fiction, here.

We’re coming up on the golden anniversary of some very important experiments that were milestones in confirming relativity and were enabled by a breakthrough in nuclear physics, the Mossbauer effect. Mossbauer’s discovery (published in 1958) of the Mossbauer effect … Read about this in Testing Einstein at Swans on Tea.

The Aetosaur Paper That Changed Everything is very interesting foray into nineteenth century (and later) palaeontology, implicating everyone from Agassiz to Cope to B.J. Small, posted at Chinleana.

Ninja Cats are a recent phenomenon, but the question of the moon’s influence on human behavior has a long history. PodBlack Cat explores this literature: Ninja Kittens Don’t Steal The Moon – Crime Rates And Lunar Phase Research

An excellent post on how the heck alloys work, which in turn is based on models developed during the pre-WWII days, is posted at Materialia Indica: Classics in Materials Science: The Bragg-Williams model of order-disorder transformations.

John J. McKay has produced a tour de force series of blog posts on the history of everything, tied together with the theme of a mysterious specter haunting Europe and Asia from the late seventeenth century onward. “Some said it was a monster that lived underground; others said it lived in the water. No one had seen it alive. It was said to die on exposure to sunlight or air. All, however, agreed that it was an enormous beast–bigger than anything known–and that it had teeth (or horns) longer than a man. The natives called it ….” Click here to find out. And here, here, here, and here. Oh, and here. This is really great stuff. It should be a book!

It seems that almost every important thread of biological research eventually runs through the world of birds at some point or another. Grrrrrrrrrrrl Scientist speaks to this in particular with regards to species radiations in her post: Meet the Great Speciators: The White-Eyes

A book review for you: Tides of History by Michael S. Reidy at The Dispersal of Darwin Blog. … “I received this book from the publisher last year, so I am now finally able to put up my review. But I also had to read it for my current graduate class on historical writing, taught by Michael Reidy (my advisor and the author of the book!).” What luck!

Everybody hates Francis Bacon. Srsly. Chris Mooney covers this, so far, in Part I and Part II of a post of the same name.

Ah, now on to Darwin. We start with Larry Moran, who claims to not really be a Darwinist, Re-reading the Origin of Species. Then we move on to yours truly, re-reading the Voyage of the Beagle.

Then we have Mike Dunford, on Darwin, Experimentalist.

A Primate of Modern Aspect blog discusses Darwin, The Descent of Man, and Human Evolution

This just in from SciCurious: Friday Weird Science: Of Testicles and Cocks

Pagel on Darwin

Greg Laden — Thu, 12 Feb 2009 14:48:10 +0000

Mark Pagel, evolutionary theorist extraordinaire, has published an Insight piece in Nature on Natural selection 150 years on. Pagel, well known for myriad projects in natural selecition theory and adaptation, and for developing with Harvey the widely used statistical phylogenetic method (and for being a reader of my thesis) wishes Charles Darwin a happy 200th birthday, and assesses this question:

How has Darwin’s theory of Natural Selection fared over the last 150 years, and what needs to be done to bring this theoretical approach to bear as we increasingly examine complex systems, including human society?

Pagel discusses both the controversial nature of and the sheer simplicity of Darwin’s Natural Selection, very briefly summarizes the range of applications that has been made of it, then focuses on the core questions “which cut across the hundreds of specific topics of evolutionary investigation.” Pagel will not conclude, as was recently suggested by the New York Times, that Darwin needs to die (or Darwinism at least) for us to get on with our work in applying evolutionary theory. Quite the contrary, in fact.

The core areas Pagel addresses are: Descent with Modification, Variation, Speciation and Adaptation. These concepts are interwoven with questions about the nature of tinkering and perfection and Gouldian contingency. Since Pagel’s Insight is itself a well adapted summary of a huge set of questions, it would be absurd for me to summarize it for you here. Just get it and read it. But I will make a few comments on selected items.

Pagel, because he just can’t stop himself from doing this sort of thing, compiled and analyzed a huge data set. This consisted of papers “that include the term ‘natural selection’ in their title, abstract or keywords, recorded separately for subject areas as identified by the ISI Web of Knowledge. Data are derived from a search on ‘natural selection’ in November 2008, yielding 14,232 hits over all years.”

From this he produces a graph that shows several interesting things. For instance, there is a huge range of subject areas in which Natural Selection appears non-trivially. Genetics and Heritability and Evolutionary biology unsurprisingly top the list. Psychology, Nutrition, and Pathology are modestly represented. Meteorology sports several hundred papers with the term. The lowest number is found in Chemistry.

Alarming and disturbing, not to mention annoying, is the fact that the lower-ranked subject areas include most of the medical subjects. This underscores my long time assertion that medical research pays an insufficient level of attention to Evolutionary Theory.

Pagel is a wanton adaptationist. In a paper some years ago, he articulated a position on adaptation that I have slightly modified and named after him, which I call Pagel’s Wager. Pagel’s Wager is this: If you observe a heritable system in nature, bet it is an adaptation. You’ll usually win the bet. More importantly, the cost of betting against a heritable system being an adaptation is very high. You miss getting to work on (or at least think about) something interesting.

In the paper under consideration, Pagel summarizes his current thinking on this:

Which view is correct? Not everything is an adaptation: human blood just happens to be red, and human chins might be relics of the way the human jaw develops. But the weight of evidence suggests that it is probably wise not to bet against natural selection. The struggle for existence means that traits have to pay their way. The traits observed now probably improve an animal’s chances of surviving and propagating, and those traits that do not will tend to be lost. For example, fish that have adapted to life in dark underwater caves lose the ability to see.

I have also defined another biological guideline called Pagel’s Rule. He does not address this concept in the Nature Insight piece, but I’m inclined to give it to you anyway:

“In considering two or more adaptationist explanations for a given trait, where all else is equal, determine which is the most insidious or evil. That is likely to be the correct explanation.”

Regarding contingency, Pagel makes an interesting comment (referring to a paper in the same issue of Nature). As you will already be aware, the “contingency” concept, championed by Stephen Jay Gould, is that if you play the ‘tape of evolution’ again and again, you will get quite different results each time. Pagel mentions what might be Gould’s favorite example of this phenomenon: If the whopping big object that hit the earth about 65 million years ago missed, the evolution of mammals would have been a very different story, and it is likely that not even Stephen Jay Gould himself would have evolved. (Well, SJG did not put it exactly that way ….). Pagel reviews some of the evidence testing this idea and concludes that “Contingency does not seem to be the pervasive force that Gould suspected.” And he’s got a point.

Pagel crams a LOT more into this small paper, including commentary on human evolution and human language, co-evolution, and speciation. I’ll leave you with this bit on Darwin and diversification:

The size and details of monophyletic groups illustrate an important feature of life. Rather than designing each species from scratch, as an engineer might, evolution is conservative, using the same designs over and over. Darwin recognized, as the comparative anatomist Geoffroy Saint-Hilaire had before, that the hands of moles, horses, porpoises and bats all used the same bones.

Please find the paper, read it, and enjoy it. Link and references below.

Since I’m sitting at a computer that automatically puts me through to Nature, I am not absolutely certain, but I think you can access the article here.

Mark Pagel (2009). Natural selection 150 years on Nature, 457 (7231), 808-811 DOI: 10.1038/nature07889

Elephants and Horses

Greg Laden — Thu, 12 Feb 2009 13:07:03 +0000

In 1833, Darwin spent a fair amount of time on the East Coast of South America, including in the Pampas, where he had access to abundant fossil material. Here I’d like to examine his writings about some of the megafauna, including Toxodon, Mastodon, and horses, and his further considerations of biogeography and evolution.

reposted

In the vicinity of Rio Tercero…

Hearing … of the remains of one of the old giants, which a man told me he had seen on the banks of the Parana, I procured a canoe, and proceeded to the place. Two groups of immense bones projected in bold relief from the perpendicular cliff [but] I could only bring away small fragments of one of the great molar-teeth … sufficient to show that the remains belonged to a species of Mastodon. The men who took me in the canoe, said they had long known of them, and had often wondered how they had got there: the necessity of a theory being felt, they came to the conclusion, that … the mastodon formerly was a burrowing animal!

In remote St. Fe …

A tooth which I discovered … interested me much, for I at once perceived that it had belonged to a horse. Feeling much surprise at this, I carefully examined its geological position, and was compelled to come to the conclusion, that a horse, which cannot … be distinguished from the existing species, lived as a contemporary with the various great monsters that formerly inhabited South America. Mr. Owen and myself, at the College of Surgeons, compared this tooth with a fragment of another, probably belonging to the Toxodon, which was embedded at the distance only of a few yards in the same earthy mass. No sensible difference in their state of decay could be perceived; they were both tender, and partially stained red. … Certainly it is a marvellous event in the history of animals, that a native kind should have disappeared to be succeeded in after ages by the countless herds introduced with the Spanish colonist! But our surprise should be modified when it is already known, that the remains of the Mastodon angustidens (the tooth formerly alluded to as embedded near that of the horse, probably belonged to this species) have been found both in South America, and in the southern parts of Europe.

Weighty considerations of the distribution of extinct and extant fauna lead Darwin to the neighborhood of modern geological concepts.

Very few species of living quadrupeds, which are altogether terrestrial in their habits, are common to the two continents, and these few are chiefly confined to the extreme frozen regions of the north. The separation, therefore, of the Asiatic and American zoological provinces appears formerly to have been less perfect than at present. The remains of the elephant and of the ox have been found on the banks of the Anadir (long. 175Â° E.), on the extreme part of Siberia, nearest the American coast: and the former remains, according to Chamisso, are common in the peninsula of Kamtschatka. On the opposite shores, likewise, of the narrow strait which divides these two great continents, we know, from the discoveries of Kotzebue and Beechey, that the remains of both animals occur abundantly: and as Dr. Buckland has shown they are associated with the bones of the horse, the teeth of which animal in Europe, according to Cuvier, accompany by thousands the remains of the pachydermata of the later periods. With these facts, we may safely look at this quarter, as the line of communication (now interrupted by the steady progress of geological change) by which the elephant, the ox, and the horse, entered America, and peopled its wide extent.

Now, here we have Darwin on the verge of understanding the rise of the Panama Land bridge (or something like that) based on the biogeography. The above passage, the following passage, and other material is very frustrating. If Darwin was not such a geological gradualist he could have advanced geology to the 1950s with a single fell swoop of reasoning!!!!

The occurrence of the fossil horse and of Mastodon angustidens in South America, is a much more remarkable circumstance than that of the animals mentioned above in the northern half of the continent; for if we divide America, not by the Isthmus of Panama, but by the southern part of Mexico, .. where the great table-land presents an obstacle to the migration of species, … we shall then have two zoological provinces strongly contrasted with each other. Some few species alone have passed the barrier, and may be considered as wanderers, such as the puma, opossum, kinkajou, and peccari. The mammalogy of South America is characterized by possessing several species of the genera of llama, …, tapir, peccari, opossum, anteater, sloth, and armadillo. If North America had possessed species of these genera proper to it, the distinction of the two provinces could not have been drawn; but the presence of a few wanderers scarcely affects the case. North America, on the other hand, is characterized by its numerous rodents, and by four genera of solid horned ruminants, of which section the southern half does not possess a single species.

Just so you know, South and North America were separated, and had largely independent mammalian evolution (and migration), until very recently, about five million years ago, when the isthmus of Panama was raised.

Darwin is seeing the very time-deep echo of this event, masked by subsequent migration of North American mammals in to South America, and clouded by the more pressing (to him) question of Old World and New World relationships.

It is interesting that the monkey’s (appearing in both the old world and new world tropics) don’t freak him out. They freak me out.

Visit The Beagle Project Blog

Rheas and the Birth of Evolutionary Theory

Greg Laden — Wed, 11 Feb 2009 12:06:53 +0000

Everyone knows about Darwin’s Finches, of the Galapagos Islands. But of course, Darwin made observations of birds throughout his travels on The Beagle. Here, I present a number of passages from The Voyage that include some of these observations.

Struthio Rhea

I will now give an account of … the Struthio Rhea, or South American ostrich. This bird is well known to abound over the plains of Northern Patagonia, and the united provinces of La Plata. It has not crossed the Cordillera; but I have seen it within the first range of mountains on the Uspallata plain…. The ordinary habits of the ostrich are familiar to every one. They feed on vegetable matter; such as roots and grass; but at Bahia Blanca, I have repeatedly seen three or four come down at low water to the extensive mud-banks which are then dry, for the sake, as the Gauchos say, of catching small fish. Although the ostrich in its habits is so shy, wary, and solitary, and although so fleet in its pace, it falls a prey, without much difficulty, to the Indian or Gaucho armed with the bolas. When several horsemen appear in a semicircle, it becomes confounded, and does not know which way to escape. They generally prefer running against the wind; yet at the first start they expand their wings, and like a vessel make all sail. On one fine hot day I saw several ostriches enter a bed of tall rushes, where they squatted concealed, till quite closely approached. It is not generally known that ostriches readily take to the water. Mr. King informs me that at the Bay of San Blas, and at Port Valdes in Patagonia, he saw these birds swimming several times from island to island. …When swimming, very little of their bodies appear above water, and their necks are extended a little forward: their progress is slow. On two occasions, I saw some ostriches swimming across the Santa

The following passage is thought by some Darwin scholars to reflect one of Darwin’s most significant “aha” moments, leading to his understanding of evolutionary processes. The bird described here is known as the Avestruz Petise, and was named by the ornithologist Gould as Rhea darwinii. However,since the bird was earlier named (based on reports, not specimens) Pterocnemia pennata (the Lesser rhea), Darwin’s name does not survive today in the annals of taxonomy.

Read the passage then I’ll note its presumed significance.

…I repeatedly heard the Gauchos talking of a very rare bird which they called Avestruz Petise. They described it as being less than the common ostrich (which is there abundant), but with a very close general resemblance. … The few inhabitants who had seen both kinds, affirmed they could distinguish them apart from a long distance. … This species occurs most rarely on the plains bordering the Rio Negro; but about a degree and a half further south they are tolerably abundant. …They are said to prefer the plains near the sea. When at Port Desire, in Patagonia (lat. 48Â°), Mr. Martens shot an ostrich; and I looked at it, forgetting at the moment, in the most unaccountable manner, the whole subject of the Petises, and thought it was a two-third grown one of the common sort. The bird was cooked and eaten before my memory returned. Fortunately the head, neck, legs, wings, many of the larger feathers, and a large part of the skin, had been preserved. From these a very nearly perfect specimen has been put together, and is now exhibited in the museum of the Zoological Society. Mr. Gould, who in describing this new species did me the honour of calling it after my name, states, that besides the smaller size and different colour of the plumage, the beak is of considerably less proportional dimensions than in the common Rhea …

Eventually, Darwin made note of the fact that over time, distinct but similar species seemed to differ by grades (such as in size) in the fossil record, as and the same pattern could be seen across geographical space. In his notebooks, he was to eventually note that the variation across space and time seemed to be two ways of looking at the same pattern of change. He made the link between biographical variation in the Rhea and the finches on the Galapagos and similar variation seen in the fossil fauna such as discussed here, along the South American Atlantic coast.

In a note book dated to “1836 and after” (late in the voyage), Darwin wrote a passage that has been the focus of a great deal of attention. In it, he demonstrates his waffling about the nature of species. He frames his introspection in terms of “creation” and at the same time struggles with the evidence from biogeography, which suggests that closely related species would have a common ancestor. He also addresses extinction. Darwin is essentially asking “… where are the transitional forms?”

Remember, this is his notebook writing … it is very much stream of consciousness, conflicting, and hard to understand. I’ll provide you with the entire relevant passage unedited except for the removal of some geologizing. It is painful and wonderful at the same time:

Speculate on neutral ground for 2 Ostriches: bigger one encroaches on smaller;–change not progressive; produced at one blow, if one species altered. …

Should urge that extinct Llama owed its death not to change of circumstances; reversed argument, knowing it to be a desert. Tempted to believe animals created for definite time:–not extinguished by change of circumstances.

The same kind of relation that common ostrich bears to Petisse–[S. Darwinii] and difft. kinds of extinct Guanaco to recent. In former case position, in latter time (or changes consequent on lapse), being the relation, as in first cases distinct species inosculate [To pass into; to join or unite so as to become continuous; to blend] so must we believe ancient ones [did] not gradual change or degeneration from circumstances, if one species does change into another it must be per saltum–or species may perish. This representation of species important, each its own limit and represented. Chiloe creeper; Fournarius, Callandria. Inosculation alone shows not gradation.

an animal in two (gemmiparous by nature or by accident) we see an individual divided either at one moment or through lapse of ages. Therefore we are not so much surprised at seeing Zoophite producing distinct animals, still partly united, & egg which becomes quite separate. Considering all individuals of all species as each one individual divided by different methods, associated life only adds one other method where the division is not perfect.

Dogs, Cats, Horses, Cattle, Goat, Asses, have all run wild and bred, no doubt with perfect success. Showing how creation does not bear upon solely adaptation of animals. Extinction in same manner may not depend. There is no more wonder in extinction of species than of individual.

When we see Avestruz [the Petisse or smaller Ostrich, Struthio Darwinii] two species certainly different, not insensible change; yet one is urged to look to common parent? Why should two of the most closely allied species occur in same country? In botany instances diametrically opposite have been instanced–

Of this passage, Nora Barlow (in her publication on these notebooks) wrote, in 1945:

We can see the mill at work, grinding out hypotheses. … In biological fields the throes of question and doubt, of comparison of masses of facts, of discardings and reviewing, were still to continue for 23 years before the Theory of Evolution as we know it, found expression.

Well said, Nora.

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Fossil Quadrupeds

Greg Laden — Tue, 10 Feb 2009 14:07:14 +0000

Charles Darwin wrote a book called Geological Observations on South America. Since Fitzroy needed to carry out intensive and extensive coastal mapping in South America, and Darwin was, at heart, a geologist more than anything else (at least during the Beagle’s voyage), this meant that Darwin would become the world’s expert on South American geology. Much of The Voyage is about his expeditions and observations. Part of this, of course, was figuring out the paleontology of the region.

reposted with minor revisions

Bahia Blanca is a port at the northern end of Patagonia. Chapter V of The Voyage begins:

THE Beagle arrived on the 24th of August, and a week afterwards sailed for the Plata. With Captain Fitzroy’s consent I was left behind, to travel by land to Buenos Ayres.

I tried Googling that … using “get directions.” Google maps was unable to compute a route. In fact, Google Maps has no roads whatsoever in Argentina. But, I was able to make a map showing the two locations, to give you an idea of what this must have been like. Darwin walked (well, there were horses) between these two points:

And along the way, he found some fossils. Here are brief excerpts describing some of his finds. As you read through this (it’s long, but I’ve tried to edit it down as much as possible) keep in mind the following things: Evidence for evolution, climate change, large scale global synthesis, connections between observations and theory. It is all here. This is Darwin coming to an understanding of the Big Picture of Evolution.

At Punta Alta, a low cliff, about twenty feet high, exposes a mass of [sediment] containing numerous recent shells. We may believe a similar accumulation would now take place … where tides and waves were opposed. In the gravel a considerable number of bones were embedded. … the following list may give some idea of their nature: 1st, a tolerably perfect head of a megatherium, and a fragment and teeth of two others; 2d, an animal of the order Edentata, as large as a pony, and with great scratching claws; 3d and 4th, two great Edentata related to the megatherium, and both fully as large as an ox or horse; 5th, another equally large animal, closely allied or perhaps identical with the Toxodon …, which had very flat grinding teeth, somewhat resembling those of a rodent; 6th, a large piece of the tesselated covering like that of the armadillo, but of gigantic size; 7th, a tusk which in its prismatic form, and in the disposition of the enamel, closely resembles that of the African boar; it is probable that it belonged to the same animal with the singular flat grinders. Lastly, a tooth in the same state of decay with the others: … but the part that is perfect, resembles in every respect the tooth of the common horse.* … the space in which they were collected could not have exceeded one hundred and fifty yards square. It is a remarkable circumstance that so many different species should be found together; and it proves how numerous in kind the ancient inhabitants of this country must have been.

… in another cliff of red earth, I found several fragments of bones. Among them were the teeth of a rodent, much narrower, but even larger than those of the HydrochÃ¦rus capybara; the animal which has been mentioned as exceeding in dimensions every existing member of its order. There was also part of the head of a Ctenomys; the species being different from the Tucutuco, but with a close general resemblance.

The remains … were associated … with shells of existing species. … similar to the species now living in the same bay: it is also very remarkable, that not only the species, but the proportional numbers of each kind, are nearly the same [as the modern fauna] … If I had not collected living specimens from the same bay, some of the fossils would have been thought extinct … We may feel certain that the bones have not been washed out of an older formation, and embedded in a more recent one, because the remains of one of the Edentata were lying in their proper relative position (and partly so in a second case) …

…

From the shells being littoral species … we may feel absolutely certain that the remains were embedded in a shallow sea, not far from the coast. From the position of the skeleton being undisturbed, and likewise from the fact that full-grown serpulÃ¦ were attached to some of the bones, we know that the mass could not have been accumulated on the beach itself. …

From the general structure of the coast of this part of South America, we are compelled to believe, that the changes of [elevation] have … of late … been in one direction, and … very gradual. If, then, we look back to the period when these quadrupeds lived, the land probably stood at a level, less elevated only by a few fathoms than at present. Therefore, its general configuration since that epoch cannot have been greatly modified; …

The surrounding country, as may have been gathered from this journal, is of a very desert character. … Here, then, is an apparent difficulty: we have the strongest evidence that there has occurred no great physical change to modify the features of the country, yet in former days, numerous large animals were supported on the plains now covered by a thin and scanty vegetation.

That large animals require a luxuriant vegetation, has been a general assumption, which has passed from one work to another. I do not hesitate, however, to say that it is completely false; and that it has vitiated the reasoning of geologists, on some points of great interest in the ancient history of the world. The prejudice has probably been derived from India, and the Indian islands, where troops of elephants, noble forests, and impenetrable jungles, are associated together in every account. If, on the other hand, we refer to any work of travels through the southern parts of Africa, we shall find allusions in almost every page either to the desert character of the country, or to the numbers of large animals inhabiting it. The same thing is rendered evident by the many sketches which have been published of various parts of the interior. When the Beagle was at Cape Town, I rode a few leagues into the country, which at least was sufficient to render that which I had read more fully intelligible.