Some things never change. Dying terribly from bone cancer, for instance: that’s something humans have been doing from about the beginning of our time. Has it always been like this, or was there some blissful period, in our species’ salad days, in which no one perished from bone cancer? Which sickness has burdened us — or our ancestors, or any lifeform — the longest?
To find out, for this week’s Michelle D. Hamilton Associate Professor, Anthropology, Texas State University
My arena is skeletal remains, so I’m going to approach this question from the perspective of some of the oldest diseases present on bones. We have to start with a few caveats, however. Diagnosing disease on ancient skeletal remains can be difficult, because some diseases can mimic each other (for example, bone destruction due to infections may look like bone destruction caused by neoplastic tumours).
Additional difficulties in diagnosing disease in ancient bones are that 1) the great majority of human diseases don’t affect the skeletal system (think plague, influenza, smallpox, cholera, etc.) and 2) even among those diseases capable of modifying bone, it is still possible that the individual dies before skeletal modification takes place, leaving no trace of the disease even though it could have been their cause of death (this conundrum is known as the Osteological Paradox among paleopathologists and others who study disease in ancient human skeletons).
Having noted that, however, some of the oldest diseases we have direct skeletal evidence for are found on dinosaur species dating to around 250 million years ago, when Pangaea was still a continent and no human ancestors yet roamed the land. They include many dinosaurs found with neoplastic tumours, and a dinosaur with tuberculosis-like infectious lesions on the ribs.
In humans and their ancestors, some of the earliest skeletal evidence for disease includes the same classes of disease that affected dinosaurs, and continue to affect us today. The earliest neoplastic-like tumours of bone have been found on an Australopithecine ancestor from almost 2 million years ago, and on Homo ergaster from 1.5 million years ago (cancer has been a curse on planet earth for a long time). Tuberculosis-like infectious lesions have been found on a Homo erectus fossil from 500,000 years ago.
Tuberculosis is still active across the globe today, with the worrying development of highly infectious antibiotic-resistant strains of TB that no longer respond to any known treatments.
As a species, we modern humans are still susceptible to many of the same conditions and pathogens that affected our most distant ancestors. And novel epidemic diseases are always emerging; we usually only become aware of them when people begin dying for unknown reasons (for example, HIV/AIDS, Hanta virus, SARS, avian flu, MERS-CoV, Ebola, etc.). It’s a dangerous world out there!
Associate Professor, Anthropology, University of South Carolina, who studies health and disease in past human populations using their skeletal remains
The answer to this question depends on what you mean by “disease” and what organism (at risk of disease) you are interested in. I’m an anthropologist, so I’m going to focus on humans. If we define disease as a disruption of homeostasis that causes harm to a person, the term encompasses a huge variety of conditions, such as neoplasms (abnormal growth of cells, including cancers), infectious diseases, endocrine disorders (such as type 1 diabetes), cardiovascular disease, neurological degeneration, and many, many more.
Most of my own research focuses on bubonic plague in medieval populations, so I’m particularly interested in infectious diseases in the past. Infectious diseases are caused by pathogens and parasites, such as prions, viruses, bacteria, fungi, protozoa, and helminths (worms). Human activities and population patterns (e.g. overall population size and density) affect which infectious agents we come into contact with and which diseases can be maintained in our populations.
For the vast majority of human history, we lived in small forager (hunter-gatherer) bands (and some people still do today); in that context, people were primarily affected by infectious diseases caused by pathogens or parasites that can survive for a long time outside of a host in the environment, or in zoonoses that are picked up from wild animals. It likely wasn’t until the adoption and intensification of agriculture and animal domestication, and subsequent major increases in population size and density, that we were affected by the kind of viral diseases that only persist in relatively large populations, with continual introduction of many susceptible individuals (e.g. like measles or, smallpox.).
So, what specific disease has been affecting humans the longest? I suspect some kind of helminthic, protozoal, or bacterial infection, but I don’t know! There is a lot of work currently being done using analyses of DNA from pathogens that are circulating today, and DNA extracted from ancient environmental samples and human remains. What we know about the antiquity of diseases that exist today is changing very rapidly, so the answer might be clearer in the near future.
Professor, Anthropology and Archaeology, Wesleyan University
The simple answer to the question is that we don’t know. Many diseases — using the term loosely, without strictly defining what a disease is — predate historical sources, so the answer comes from the study of paleopathology, which in turn relies on the studies of archaeology, paleontology and ancient DNA (aDNA). Evidence of diseases that old are lesions in bone or DNA from the pathogen. Neither bones nor DNA preserve well in the fossil record, and those samples that are recovered represent only a very small fraction of what originally existed. Furthermore, most diseases don’t affect the skeleton and thus leave no trace.
Tuberculosis DNA has been recovered from 9000-year-old human skeletons found buried beneath the Mediterranean of the coast of Israel. Skeletal lesions are difficult to diagnose, but a possible TB infection has been suggested for a 500,000-year-old skeleton of Homo erectus from Turkey. Leprosy has affected humans for at least 100,000 years and possibly much longer, according to DNA studies. Scientists have identified a malignant tumour in a foot bone of a 1.6-1.8 million-year-old hominin fossil from South Africa, and a benign tumour in a 2 million-year-old hominin at a nearby site.
Of course, diseases are found in other species. The frontispiece of Roy L. Moodie’s classic 1923 book, The Antiquity of Disease, shows a bone hemangioma from the spine of a dinosaur. Moodie also documented diseased plants from the Paleozoic period. A widely-held theory is that the mitochondria providing energy to cells are the descendants of a bacteria related to the pathogen that causes Rocky Mountain spotted fever. In other words, the infection of one cell type by another was crucial to the development of eukaryote cells—the cells that make up plants and animals, before there were plants and animals.
Subject Leader, Anthropology and Archaeology, Liverpool John Moores University
I’d say cancer is the oldest confirmed disease. A 2016 study found evidence of bone cancer in a foot bone dated to around 1.7 million years ago in South Africa. It belonged either to our direct ancestor, Homo erectus, or perhaps an ancient relative, Paranthropus robustus—a species that became extinct around this time. Given the date, I suspect it was from Homo erectus, as Paranthropus generally died out by this time.
Researchers have found bone cancer (a benign form) in a 90 million year old titanosaur (like a big brontosaurus) in South America. Other types of dinosaurs have also been found with bone cancer, some of which would have been malignant— duck-billed dinosaurs, for instance who lived during the Cretaceous period (which ran from about 149 to 66 million years ago). And before that, the oldest evidence is in a North American fish that lived between about 360-300 MYA.
Associate Professor and Chair, Anthropology, Macalester College
The oldest disease is probably a bacterial infection. I can imagine that, right along with the evolution of the first eukaryotic life, there was a prokaryote waiting to exploit it. This would have been the first evolutionary arms race, a fight that we’re still waging today. In addition, bacteria have ruled this planet since nearly the beginning. Every major adaptive radiation was likely accompanied by a parallel bacterial radiation.
The Cambrian Explosion, cool, but think of all of the new species for bacteria to use. The Age of the Dinosaurs, ditto, but on land. The Planet of the Apes (the Miocene), probably saw the rise of many of the bacterial diseases that humans encounter today. And in the Anthropocene, humans are actually shaping the evolution of these bacteria through the use of antibiotics. Once again, bacteria dominate the planet.
Teaching Assistant Professor, Anthropology, University of North Carolina at Chapel Hill
Some paleontologists have suggested findings of osteoarthritis in dinosaurs as well as tooth infections, and both of those diseases are found in humans and our hominin ancestors as well. Also among early diseases is cancer. Once we as humans started living in closer quarters and spreading out around the world, though, diseases came with us: leprosy in humans is thought to go back at least 100,000 years, tuberculosis in humans dates to perhaps 70,000 years ago, and infection with Helicobacter pylori (which causes stomach ulcers) probably started around 60,000 years ago.
Since we have only a minuscule fraction of the bones of everyone who ever lived, though, and only a fraction of those have evidence of disease, I imagine that most of our future knowledge of the antiquity of disease will come from genetic advances in studying the evolution of disease-causing organisms.
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