If you’ve found a measure of interest in our earlier posts reviewing Neil Shubin’s
Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body, Paul Chambers’ Bones of Contention: The Archaeopteryx Scandals, or Deborah Cadbury’s Terrible Lizard: The First Dinosaur Hunters and the Birth of a New Science, or in any of the related excerpts and updates to the reviews, you may also find yourself intrigued by Step-By-Step Evolution, an elucidating article on transitional fossils appearing earlier this year in Science News.
Transitional Fossils: Tiktaalik, Archaeopteryx, Gerobatrachus & Sticklebacks
TOXMAP
The National Library of Medicine’s Division of Specialized Information Services has updated its interactive TOXMAP to include the most recently reported data from the Environmental Protection Agency’s Toxic Release Inventory and Superfund Program.
TOXMAP is a Geographic Information System that uses maps of the United States to let you visually explore information on toxic chemical releases and Superfund cleanup sites.
As the NLM explains, “Federal law requires facilities in certain industries, which manufacture, process, or use significant amounts of toxic chemicals, to report annually on their releases of these chemicals to the EPA TRI Program. Superfund sites are those throughout the United States and its territories which contain substances that are either designated as hazardous under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), or identified as such under other laws.
TOXMAP helps users create nationwide, regional, or local area maps showing where TRI chemicals are released on-site into the air, water, and ground. It also identifies the releasing facilities, color-codes release amounts for a single year or year range, and provides multi-year aggregate chemical release data and trends over time, starting with 1987. Maps can also show locations of Superfund sites on the National Priority List , listing all chemical contaminants present at these sites. Users can search the system by location (such as city, state, or ZIP code), chemical name, chemical name fragment, release medium, release amount, facility name and ID, and can filter results to those residing within a pre-defined or custom geographic region. TOXMAP also overlays map data such as US Census population information, income figures from the Bureau of Economic Analysis, and health data from the National Cancer Institute and the National Center for Health Statistics.”
For instance, a quick look at zip code 67060 will display a map of Haysville and the greater Wichita metropolitan area, informing you that as of the end of 2007 (the latest year for which complete data are available) there were 28 TRI facilities in the metroplex reporting chemical releases, out of 21,677 nationwide. It would also inform you that there are no Superfund NPL sites in the area. (There are 1,619 nationwide). Among the 28 local sites you’ll find complete reporting details for Air Products Manufacturing Corporation at 6601 South Ridge Road, Haysville. You can quickly discern that, during 2007, nearly half of the chemicals released by Air Products consisted of ammonia (70,550 pounds), and nearly another third of methanol (45,660 pounds). You can then track Air Products’ annual releases of ammonia and methanol over the past two decades, back to 1988.
Much additional detailed information is available via TOXMAP and the allied linked resources, which can be of substantial utility to those interested in tracking toxic chemical releases, assessing environmental impact, or comparing disparate local environments.
John Tyler’s Birthday
Today is the 219th birthday of John Tyler, tenth president of the United States and the first to assume office upon the death a sitting president. John Tyler had assumed the office of Vice President a mere month prior to the death of President William Henry Harrison on April 4, 1841. Through determined action, Tyler established the precedent of the Vice President becoming President – not merely “Acting President” – upon the death of an incumbent president, a precedent eventually formalized by the adoption of the 25th Amendment to the Constitution.
Arguably a much more important president than his relative obscurity might imply, we’ll look at Tyler and his presidency tomorrow in greater detail as we review Edward P. Crapol’s John Tyler: The Accidental President.
Your Inner Fish — A Postscript
One last look back at Neil Shubin’s Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body:
On the Rocks
“Every rock sitting on the ground has a story to tell: the story of what the world looked like as that particular rock formed. Inside the rock is evidence of past climates and surroundings often vastly different from those of today. Sometimes, the disconnect between present and past could not be sharper. Take the extreme examples of Mount Everest, near whose top, at an altitude of over five miles, lie rocks from an ancient sea floor. Go to the North Face almost within sight of the famous Hillary Step, and you can find fossilized seashells. Similarly, where we work in the Arctic, temperatures reach minus 40 degrees Fahrenheit in the winter. Yet inside some of the region’s rocks are remnants of an ancient tropical delta, almost like the Amazon: fossilized plants and fish that could have thrived only in warm, humid locales. The presence of warm-adapted species at what today are extreme altitudes and latitudes attests to how much our planet can change: mountains rise and fall, climates warm and cool, and continents move about. Once we come to grips with the vastness of time and the extraordinary ways our planet has changed, we will be in a position to put this information to use in designing new fossil-hunting expeditions.
“If we are interested in understanding the origin of limbed animals, we can now restrict our search to rocks that are roughly 375 million to 380 million years old and that were formed in oceans, lakes, or streams. Rule out volcanic rocks and metamorphic rocks, and our search image for promising sites comes into better focus.
“We are only partly on the way to designing a new expedition, however. It does us no good if our promising sedimentary rocks of the right age are buried deep inside the earth, or if they are covered with grass, or shopping malls, or cities. We’d be digging blindly. As you can imagine, drilling a well hole to find a fossil offers a low probability of success, rather like throwing darts at a dart board hidden behind a closet door.
“The best places to look are those where we can walk for miles over the rock to discover areas where bones are ‘weathering out.’ Fossil bones are often harder than the surrounding rock and so erode at a slightly slower rate and present a raised profile on the rock surface. Consequently, we like to walk over bare bedrock, find a smattering of bones on the surface, then dig in.
“So here is the trick to designing a new fossil expedition: find rocks that are of the right age, of the right type (sedimentary), and well exposed, and we are in business. Ideal fossil-hunting sites have little soil cover and little vegetation, and have been subject to few human disturbances. Is it any surprise that a significant fraction of discoveries happen in desert areas? In the Gobi Desert. In the Sahara. In Utah. In Arctic deserts, such as Greenland.
“This all sounds very logical, but let’s not forget serendipity. In fact, it was serendipity that put our team onto the trail of our inner fish. Our first important discoveries didn’t happen in a desert, but along a roadside in central Pennsylvania where the exposures could hardly have been worse. To top it off, we were looking there only because we did not have much money . . . .”
The Sword of Lincoln, Preview 3
President Lincoln meets with General McClellan at the time of Antietam
Jeffrey D. Wert, in his history of the Army of the Potomac, The Sword of Lincoln, examines the intricate relationship between Lincoln and his most difficult wartime commander, George Brinton McClellan:
“The enemy’s proximity to Washington and its defiance formed the background of a dispute, which mounted in intensity and in consequences, between McClellan and the administration. At its most basic level, it was an argument over preparations and timing. At its most significant level, it defined the relationship between a popularly elected government in a struggle for its existence and the role of its premier army in that struggle. Its two central figures were the army commander and the president of the United States.
“When McClellan assumed command in the aftermath of Bull Run, he had to strengthen the capital’s defenses and forge a weapon that could undertake field operations. He argued correctly that it would require time to accomplish both. On August 2, in a memorandum prepared at the request of Lincoln, he stated his strategic ideas and the requirements for victory. At the heart of the document was his assertion that the enemy had made Virginia ‘their battle-field – and it seems proper to make the first great struggle there.’ The Federal war aim should be a limited one – the restoration of the Union, while adopting ‘a rigidly protective policy as to private property and unarmed persons, and a lenient course as to common soldiers.’
“He had no doubt that victory would result only from the application of ‘overwhelming physical force.’ Such a force, ‘the main Army of Operations’ or his army, would need 273,000 men in 283 regiments of infantry, cavalry, and engineers and 100 field batteries. ‘It is perhaps unnecessary to state,’ he concluded, ‘that in addition to the forces named in this memorandum strong reserves should be formed, ready to supply any losses that may occur.’
“How deeply McClellan believed that he needed an army of such size is difficult to assess. He surely knew that the administration would need months, if not longer, to recruit, arm, and equip this ‘main Army of Operations,’ while also meeting the requests of commanders in other theaters. In turn, he would refuse to undertake a major offensive until he had an army of sufficient strength, armament, and training.
“McClellan supported his argument for a sizeable army with inflated estimates of enemy numbers. On August 8, he reported that Johnston had at least 100,000 troops in front of the Federals. Five weeks later, he placed the figure at 170,000, while his department had barely 80,000 officers and men. At the same time, he called Allan Pinkerton, the head of a detective agency, to Washington to conduct intelligence operations. By the end of September, Pinkerton, who used the name E.J. Allan, had twenty-four agents in the field.
“Together Pinkerton and McClellan submitted overestimates of Confederate strength, a pattern that would characterize McClellan’s tenure as army commander. Pinkerton deliberately overstated the number of Rebels, and McClellan knew it. On October 4, when the agent reported Johnston’s strength as 98,400, far less than the 170,000 that McClellan had stated earlier, the general did not forward this estimate to the War Department. ‘No other general,’ historian Stephen W. Sears has asserted, ‘exaggerated in such monumental proportions or for so long a period.’
“His assessments of enemy numbers defy logic. His reports painted a portrait of a ‘vast machine’ constructed by the Confederacy, although its white male population was only one-third that of the North. If the Lincoln administration could not marshal such manpower, how could the newly organized Davis government? McClellan, however, evidently believed his own reports, which provided him with a logical base for his strategic and command decisions. He could justify his unwillingness to advance against the Rebels until preparations had been completed. Likewise he justified his cautious tactics when he met the foe. But these overestimates could, however, cripple, if not paralyze, the army when an opportunity to strike arose.
“If the difficulties between McClellan and the administration had been only questions about numbers, readiness, and timing, they might have been resolved. But it went deeper than that, for McClellan had a record of quarreling with superiors and an abiding contempt for politicians. From his days at West Point through his years in the army, he had clashed ‘with anyone in authority,’ according to Sears.
“It is not surprising then that McClellan ignited a feud with Winfield Scott within days of his appointment. ‘The old man . . . cannot long retain command I think,’ he informed his wife on august 2. ‘When he retires I am sure to succeed him, unless in the mean time I lose a battle – which I do not expect to do.’ Six days later, after he had ‘a row’ with Scott – most likely over the adequacy of the capital’s defenses – he described the general-in-chief to Ellen: ‘I do not know whether he is a dotard or a traitor! . . . he is a perfect imbecile. He understands nothing, appreciates nothing & is ever in my way.’ Six weeks later, he wrote that Scott ‘threw down the glove & I took it up, I presume war is declared.’
“His letters to his wife during these months contain a litany of his troubles and also harsh descriptions of Lincoln and Cabinet members. At different times, McClellan called the president ‘an idiot,’ ‘a rare bird,’ and ‘the original gorilla, about as intelligent as ever. What a specimen to be at the head of our affairs now!’ Following a Cabinet meeting, he railed to Ellen: ‘I can’t tell you how disgusted I am becoming with these wretched politicians – they are a most despicable set of men & I think [Secretary of State William] Seward is . . . a meddling, officious, incompetent little puppy.’ As for Lincoln, ‘The Presdt is nothing more than a well meaning baboon.’
“McClellan’s antipathy toward political leaders reflected a common opinion within the professional military. He and fellow officers had seen the pernicious effects, as they thought, of political interference with the army in Mexico. Mcclellan was contemptuous of and condescending toward them. In his thinking, he was a general beset with a numerically superior force in front and an ignorant and obstructive government in the rear. ‘It is perfectly sickening,’ he wrote in another letter to Ellen, ‘to have to work with such people & to see the fate of the nation in such hands.’
“The army commander’s disdainful attitude festered and worsened over time. He failed to understand that the conflict was fundamentally a political contest. Campaigns and battles would derive much of their significance from their impact on public opinion. The war had begun in a boiling cauldron of politics; its resolution rested on the steadfastness of the political will of Northerners and Southerners.
“As Henry Hunt said, ‘Revolution devours her children,’ and revolution was afoot in the land. Its shape remained undefined, but it could not be limited. Like a swelling current, it would scour and establish new courses. The war tested, as never before, the military would be intertwined with politics. Blinded by his prejudices, McClellan refused to see that ‘the fate of the nation’ rested ‘in such hands.’ He was a soldier breasting a powerful stream.
“Despite his private, belittling descriptions of Lincoln, McClellan enjoyed the support of the president during the summer and fall. Lincoln conferred frequently with McClellan, joined the general at reviews of the troops, worked tirelessly to recruit and equip the army, and even defended the commander when others complained about the army’s inertia. He witnessed the disagreements between Scott and McClellan over the capital’s security and strategy. A patient man, Lincoln accepted McClellan’s argument for more men and more time.
“Lincoln, however, never lost sight of his greatest burden as president – to sustain his fellow citizens’ will to wage war against the Confederacy for as long as it might require and at whatever its cost. He had tapped into the outpouring of nationalism after Fort Sumter and had exploited the new resolve after the defeat at Bull Run, but he knew that it would not endure without success on battlefields. The foundation of the Union cause resided at isolated farmhouses, on dusty village roads, and amid the bustle of city streets. Military inactivity or stalemate could erode away some of that foundation.
“While the union war effort encompassed both the Eastern and Western theaters, most of the Northern press and populace focused on the Army of the Potomac. It had the primary burden of defending Washington. If the national capital fell, the Union cause would be no longer politically sustainable. In turn, the Confederate capital beckoned a mere hundred miles to the south as it had before Bull Run.. Although Federal successes in the West ultimately led to the collapse of the Confederacy, the war’s main battleground rested in Virginia. Here, the southerners had their best opportunity to secure a favorable political settlement with battlefield victories. Here, too, the Army of the Potomac, with the shadow of Washington upon it, carried more than any other union command, the political will of the North.
“Military necessity and political reality bound Lincoln to the Army of the Potomac. His almost unremitting attention to its operations reflected this tie. Its fortunes would be his. The relationship between him and its commander would be a central theme of the war in the East. In George McClellan he would find his most difficult subordinate. One of them believed the army belonged to him. The other knew it belonged to the country.”
Recaptured Moonbeams
Moon's Copernicus Crater -- Lunar Orbiter Photo 1966
To date, they have recovered only two of more than 2,000 priceless images from the Lunar Orbiter program of the mid-60s. But the story reported by the Los Angeles Times in NASA’s Early Lunar Images, In a New Light is a triumph for all humankind. It is also a critical warning of the plague that will increasingly vex our data-rich but evanescent culture – the loss of a heritage which is beyond valuation.
Earthrise -- Lunar Orbiter Photo 1966
Your Inner Fish/Tiktaalik Update
Tiktaalik illustration by National Science Foundation's Zina Deretsky
Earlier today we posted a brief review of Neil Shubin’s
Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body, following three earlier excerpts from the text on The Hard Parts – Conodonts & Ostracoderms, on Why History Makes Us Sick and on the fascinating primitive tetrapod Tiktaalik.
For those who have read the book, or whose attention has been captivated by one or more of the excerpts mentioned, a number of recent and relatively recent reports have appeared in Science Daily which may well prove to be of further interest.
Just today, a report on recently published research by Shubin and colleagues appeared in the article Evolution of Fins and Limbs Linked With Gills. Additional and related information is available in the earlier New Genetic Data Overturn Long-held Theory Of Limb Development and in Scientists Discover Evolutionary Origin of Fins, Limbs. Other germane items may be found in Primordial Fish Had Rudimentary Fingers and Coelacanth Fossil Sheds Light On Fin-to-Limb Evolution.
Also of interest might be the National Science Foundation’s release New Fossils Fill the Evolutionary Gap Between Fish and Land Animals, from which the illustration above was derived.
Moving the Memorial Bricks, Phase 1
As construction of the new Haysville Community Library nears completion, one of the many remaining tasks is the moving of the memorial bricks which have paved the walks at the front and along the west side of the old library. At the new library, the bricks will pave the walkway at the main entrance.
As you can see from the montage which follows, this work, too, is well under way.
Your Inner Fish
A Brief Review of Neil Shubin’s Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body
Less lyrically than Loren Eiseley, and with less intensity than Stephen Jay Gould, Neil Shubin of the University of Chicago and the Field Museum has written an excellent, substantive, and lucid work for the popular reader which successfully puts you in touch with Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body.
We’ve already previewed a few selections from Shubin’s book with an earlier excerpt on The Hard Parts – Conodonts & Ostracoderms, another on Why History Makes Us Sick and finally in a brief overview of the extraordinary Tiktaalik.
As may already be evident from these selections, Shubin pursues a thoroughly integrative approach to the study of biology, seeking to understand evolutionary development by utilizing the full spectrum of evidence at hand, from the paleontological to the anatomical, through the embryological to the genetic realm. This multidimensional perspective is not only illuminating, it is captivating, and quite readily accessible for any intelligent and interested reader.
As Shubin writes, “Carl Sagan once famously said that looking at the stars is like looking back in time. The stars’ light began the journey to our eyes eons ago, long before our world was formed. I like to think that looking at humans is much like peering at the stars. If you know how to look, our body becomes a time capsule that, when opened, tells of critical moments in the history of our planet and of a distant past in ancient oceans, streams and forests. Changes in the ancient atmosphere are reflected in the molecules that allow our cells to cooperate to make bodies. The environment of ancient streams shaped the basic anatomy of our limbs. Our color vision and sense of smell has been molded by life in ancient forests and plains. And the list goes on. This history is our inheritance, one that affects our lives today and will do so in the future.”
I heartily recommend Your Inner Fish.
A few more very brief samples from the work:
Discovering ‘the Organizer’
“In the 1920s Hilde Mangold, a graduate student in Spemann’s laboratory, started to work with small embryos. The fine control she had of her fingers made her able to do some incredibly demanding experiments. At the stage of development with which Mangold worked, the salamander embryo is a sphere about a sixteenth of an inch in diameter. She lopped off a tiny piece of tissue, smaller than a pinhead, from one part of the embryo and grafted it onto the embryo of another species. What Mangold transplanted wasn’t just any patch, but an area where cells that were to form much of the three germ layers were moving and folding. Mangold was so skilled that the grafted embryos actually continued to develop, giving her a pleasant surprise. The grafted patch led to the formation of a whole new body, including a spinal cord, back, belly, even a head.
“Why is all this important? Mangold had discovered a small patch of tissue that was able to direct other cells to form an entire body plan. The tiny, incredibly important patch of tissue containing all this information was to be known as the Organizer.
“Mangold’s dissertation was ultimately to win the Nobel Prize, but not for her. Hilde Mangold died tragically (the gasoline stove in her kitchen caught fire) before her thesis could even be published. Spemann won the Nobel Prize in Medicine in 1935, and the award cites ‘his discovery of the Organizer and its effect in embryonic development.’
“Today, many scientists consider Mangold’s work to be the single most important experiment in the history of embryology.
“At roughly the same time that Mangold was doing experiments in Spemann’s lab, W. Vogt (also in Germany) was designing clever techniques to label cells, or batches of them, and thus allow the experimenter to watch what happens as the egg develops. Vogt was able to produce a map of the embryo that shows where every organ originates in the egg. We see the antecedents of the body plan in the cell fates of the early embryo.
“From the early embryologists, people like von Baer, Pander, Mangold, and Spemann, we have learned that all the parts of our adult bodies can be mapped to individual batches of cells in the simple three-layered Frisbee, and the general structure of the body is initiated by the Organizer region discovered by Mangold and Spemann.
“Cut, slice, and dice, and you’ll find that all mammals, birds, amphibians, and fish have Organizers. You can even sometimes swap one species’ Organizer for another. Take the Organizer region from a chicken and graft it to a salamander embryo: you get a twinned salamander.
“But just what is an Organizer? What inside it tells cells how to build bodies? DNA, of course. And it is in this DNA that we will find the inner recipe that we share with the rest of animal life.”
Extracting DNA in Your Kitchen
“As we’ve seen, DNA is an extraordinarily powerful window into life’s history and the formation of bodies and organs. Its role is particularly important where the fossil record is silent. Large parts of bodies – soft tissues, for example – simply do not fossilize readily. In these cases, the DNA record is virtually all we have.
“Extracting DNA from bodies is incredibly easy, so easy you can do it in your kitchen. Take a handful of tissue from some plant or animal – peas, or steak, or chicken liver. Add some salt and water and pop everything in a blender to mush up the tissue. Then add some dish soap. Soap breaks up the membranes that surround all the cells in the tissue that were too small for the blender to handle. After that, add some meat tenderizer. The meat tenderizer breaks up some of the proteins that attach to DNA. Now you have a soapy, meat-tenderized soup, with DNA inside. Finally, add some rubbing alcohol to the mix. You’ll have two layers of liquid: soapy mush on the bottom, clear alcohol on top. DNA has a real attraction to alcohol and will move into it. If a goopy white ball appears in the alcohol, you’ve done everything right. That goop is the DNA.
“You are now in a position to use that white glop to understand many of the basic connections we have with the rest of life . . . .”
Ears to Hear
“In 1837, the German anatomist Karl Reichert was looking at embryos of mammals and reptiles to understand how the skull forms. He followed the gill arches of different species to understand where they ended up in the various skulls. As he did this again and again, he found something that appeared not to make any sense: two of the ear bones in the mammals corresponded to pieces of the jaw in the reptiles. Reichert could not believe his eyes, and his monograph reveals his excitement. As he describes the ear-jaw comparison, his prose departs from the normally staid description of nineteenth-century anatomy to express shock, even wonderment, at this discovery. The conclusion was inescapable: the same gill arch that formed part of the jaw of a reptile formed ear bones in mammals. Reichert proposed a notion that even he could barely believe – that parts of the ears of mammals are the same thing as parts of the jaws of reptiles. Things get more difficult when we realize that Reichert proposed this several decades before Darwin propounded his notion of a family tree for life. What does it mean to call structures in two different species ‘the same’ without a notion of evolution?
“Much later, in 1910 and 1912, the German anatomist Ernst Gaupp picked up on Reichert’s work and published an exhaustive study on the embryology of mammalian ears. Gaupp provided more detail and, given the times, interpreted Reichert’s work in an evolutionary framework. Gaupp’s story went like this: the three middle ear bones reveal the tie between reptiles and mammals. The single bone in the reptilian middle ear is the same as the stapes of mammals; both are second-arch derivatives. The explosive bit of information, though, was that the two other middle ear bones of mammals – the malleus and incus – evolved from bones set in the back of the reptilian jaw. If this was indeed the case, then the fossil record should show bones shifting from the jaw to the ear during the origin of mammals. The problem was that Gaupp worked only on living creatures and didn’t fully appreciate the role that fossils could play in his theory.
“Beginning in the 1840s a number of new kinds of fossil creatures were becoming known from discoveries in South Africa and Russia. Often abundantly preserved, whole skeletons of dog-size animals were crated and shipped to Richard Owen in London for identification and analysis. Owen was struck that these creatures had a mélange of features. Parts of their skeletons looked reptile-like. Other parts, notably their teeth, looked like mammals. And these were not isolated finds. It turns out that these ‘mammal-like reptiles’ were the most common skeletons being uncovered at many fossil sites. Not only were they very common, there were many kinds. In the years after Owen, these mammal-like reptiles became known from other parts of the world and from different time periods in earth history. They formed a beautiful transitional series in the fossil record between reptile and mammal.
“Until 1913, embryologists and paleontologists were working in isolation from one another. At this time, the American paleontologist W.K. Gregory, of the American Museum of Natural History, saw an important link between Gaupp’s embryos and the African fossils. The most reptilian of the mammal-like reptiles had only a single bone in its middle ear; like other reptiles, it had a jaw composed of many bones. Something remarkable was revealed as Gregory looked at the successively more mammal-like reptiles, something that would have floored Reichert had he been alive: a continuum of forms showing beyond doubt that over time the bones at the back of the reptilian jaw got smaller and smaller, until they ultimately lay in the middle ear of mammals. The malleus and incus did indeed evolve from jawbones. What Reichert and Gaupp observed in the embryos was buried in the fossil record all along, just waiting to be discovered.”
Wonderful Life
Recent short articles in both Science Daily (Fossil Fragments Reveal 500-Year-Old Monster Predator) and New Scientist (Jigsaw Complete for Ancient Predator) have focused on the “apex predator” of the Cambrian food chain, the ancestral arthropod Hurdia victoria. This ancient invertebrate carnivore was unearthed long ago from the Burgess Shale formation of British Columbia, but has only recently received proper recognition of its structure and nature.
If you’ve never before read the fascinating story of the Burgess shale, Stephen Jay Gould’s Wonderful Life: The Burgess Shale and the Nature of History is an absolute must read. It’s one of Gould’s many astounding excursions into the amazing realm of natural history.
20th Century Generations
The Population Reference Bureau, in its Population Bulletin for March 2009, offers a fascinating 20-page examination of 20th Century US Generations, a portrait of the seven American generations born spanning the years from 1871 to 2001. The publication looks at a broad spectrum of similarities and differences between the generations, including generation size, comparative childhood experience, education, jobs, marriage and family, political identity and much more. Written by Elwood Carlson, a professor of sociology at Florida State University, it is an engaging and enlightening little document.
For a quick introduction to the report see this brief highlight.
Haysville Community Library 