The Great Discoverer
On January 15, 2020 by ElyseRoundworms. Dinosaurs. Giant Sloths. No, these creatures are not residents of Old MacDonald’s farm or entries in J. K. Rowling’s Fantastic Beasts and Where to Find Them. Rather, they represent the tip of the iceberg of Dr. Joseph Leidy’s wide-ranging scientific discoveries. No matter how impressive your resume, you’ve got nothing on this 19th-century Renaissance man.
Leidy was born in Philadelphia in 1823. He parleyed his medical degree into a career as a paleontologist, parasitologist, geologist, anatomist, zoologist and just about every other -ist available in his era. He was prodigious across all these fields and published hundreds of scientific articles in his lifetime. And here I thought a biweekly blog was pretty good. . .
Unlike many geniuses, Leidy didn’t have to wait until he was dead for proper recognition; satirists paid him the honor of ridiculing him even during his lifetime:
This age is great in discoveries, and Dr. Leidy is a great discoverer. We won’t be surprised to hear of him finding some valuable gargle exuding from a door mat, a healing poultice percolating out of an old hair mattress, or a liver pad leaking out of an eight-day clock.
– The True Northerner, April 6, 1883
After all I’ve read about the “great discoverer,” it took me a moment to realize none of those inventions actually exist.
A full accounting of Leidy’s myriad accomplishments could fill—and has filled—a book, but who has time for that? Instead, please enjoy a selection of his most significant achievements and the sinking feeling that by comparison, you’re wasting your life—or is that just me?

1. He ruined the American pork export market.
If you haven’t had lunch yet, I suggest you do that now. Go ahead, I’ll wait.
Welcome back. Now that you’ve taken your last tasty bite, be on the lookout for diarrhea, abdominal pain and vomiting. And if those symptoms are followed by facial swelling, inflammation of the whites of the eyes, fever and muscle pains, you might have yourself a case of trichinosis brought about by roundworms living rent free in your intestines.
It may not have been the great mystery of the age, but in the mid-19th century, scientists and suffering patients alike were more than mildly curious about how the disease, known at the time to be caused by parasites, infected humans.
That’s when the newly minted Dr. Joseph Leidy staggered onto the scene. He had his eureka moment in 1846:
It was one day when he was at luncheon that he fairly stumbled on the discovery, which would have yet escaped him had it not been for his powers of observation. He leaned over a large, luscious-looking ham to cut off a slice as the meat portion of a ham sandwich. Something on the surface of the meat attracted his attention. He looked closer, and saw a number of tiny white specks no larger than pin points.
What they were he did not know, but he concluded he did not want any ham, or in fact anything to eat just at that moment. He put the ham away where no one else could get at it and carried the slice he had cut off up to his rooms. He placed these white dots under a microscope, and when they were properly focused they stood out plainly as the trichinae [roundworms] that had been found in the human body just eleven years before.
– The Indianapolis Journal, June 22, 1890
Leidy realized the culprit behind trichinosis wasn’t Colonel Mustard in the library with the candlestick but roundworms in undercooked meat with their larvae. Hope you didn’t have a ham sandwich for lunch.




Although it took two decades for the scientific community to accept the discovery, a 1901 Pathological Society of Philadelphia lecture estimated the resulting ban on American pork in Germany and France in the latter years of the 19th century lost American farmers and exporters millions of dollars. Just imagine what economic catastrophe Leidy could have wrought if he hadn’t been working on an empty stomach.
2. He made it harder to get away with murder.
In the same year as he laid the foundation for the ruin of American pork exporters, Leidy made life more difficult for another profession: murderers.
In January 1846, a farmer was killed in north Philadelphia. The police apprehended a suspect whose clothes and hatchet were covered in blood. Open and shut case, right? Not quite. The man claimed he had been slaughtering chickens, not farmers.
Investigators were stuck—until Leidy pulled out his secret weapon: his trusty microscope. He examined the red blood cells up close and definitively concluded they could not have been chicken blood. The suspect, who hadn’t watched enough “CSI” reruns, broke down and confessed, making Leidy the first person to use a microscope to solve a murder.
If any “CSI” producers are looking for a fresh spinoff, let’s talk. “CSI: 19th Century” has great potential.




3. He pioneered the field of paleontology.
If, like almost every child, you aspired to dig up dinosaur bones, you can thank Leidy. He examined prehistoric fossils from across the United States in the field’s early days and was a founder of vertebrate paleontology.
In 1858, he was instrumental in recovering the first nearly complete fossilized skeleton of a dinosaur, the Hadrosaurus foulkii, found in Haddonfield, New Jersey. It was eventually put on display in the Academy of Natural Sciences of Philadelphia.
Of dinosaur exhibitions, Leidy reportedly wrote: “They break up old and rather fixed views about the world being created just as we now see it. Nothing tends so much to lead people to believe in the existence of former races of animals, as such restorations.” At a time when Charles Darwin’s theory of evolution was beginning to make waves, that was no small feat.
After making his mark in yet another science, Leidy went back to ruining careers. He was accused of picking sides in the infamous Bone Wars, a conflict between rival paleontologists that eventually drove him out of the field all together. Fortunately, there were plenty of other creatures requiring his attention, ranging from extinct giant ground sloths to microscopic amoebae.




4. He popularized cremation.
Even in death, Leidy was a trailblazer. Shortly before he died in April 1891, he was among a group of physicians who formed a society for the “exhaustive post-mortem examinations of the brains of distinguished men and women who may be induced to bequeath them for the purpose in the interests of science.” Sounds like the beginning of the zombie apocalypse.
After the examination was concluded, presumably to protect humanity from zombies, Leidy started a trend:




While all the obituaries I can find paid tribute to Leidy’s accomplishments, some were more glowing than others:
It is to be observed that he, too, was one of the poor boys who must rise by their own efforts. He was even obliged to pay for his own education. He had his living to earn all the time he was pursuing scientific researches. Thus he probably failed to reach the highest that his powers were capable of grasping.
This is why we have so few purely scientific men in America. Bread and butter work and study for the love of study will not pull well together. Of the younger American men of science who are left, Professor Elliott Cones, of the Smithsonian institution at Washington, will perhaps come the nearest to taking Dr. Leidy’s place as a biologist.
– The Princeton Union, May 21, 1891
Ouch. I’m offended on behalf of both Leidy and Professor Elliott “Come-the-Nearest-but-Not-Quite” Cones.
A more fitting tribute to Leidy is to remember his enthusiasm for scientific discovery. When asked if he ever got tired of life, Leidy reportedly replied, “Tired! Not so long as there is an undescribed intestinal worm, or the riddle of a fossil bone or a rhizopod new to me.”
May we all find such passion in our own rhizopod, dinosaur fossil or intestinal worm.




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Welcome to Second Glance History! This blog seeks to uncover the people and the stories forgotten by history and give them another read through a modern lens. Join me every week as we examine the differences that divide and the common threads that connect the then to the now.
Hi Elyse:
I really like this Dr. Leidy fellow! Sounds like he definitely got the last laugh. Thanks for bringing him back to life so that we can enjoy his very interesting “discoveries” all over again!
Joe
I’m so glad you liked him, too! He’s certainly on my list of people I’d want to sit next to at a dinner party…but not while eating ham. Thanks so much for reading!
Enjoyed reading about one with such an inquiring mind! Feeling blessed that my zest for life is not dependent on the intestinal parasite population!
Thank you! Somebody had to research parasites, but I’m glad it was him and not us!