Disease, throughout human history, refers to any condition that impaired normal bodily function or health. Humanity has grappled with various forms of illness for millennia, shaping societies, migrations, and even evolutionary paths. Identifying the oldest diseases presents a complex challenge, as direct evidence from deep time is often scarce and open to interpretation. Scientists piece together clues to understand the health of our earliest ancestors and the ancient origins of ailments that still affect us today.
Unearthing Ancient Illnesses
Scientists employ diverse methodologies to reconstruct the health of ancient populations. Paleopathology, the study of ancient diseases, primarily involves examining human remains such as skeletons, mummified tissues, and fossilized feces (coprolites). Skeletal remains are valuable, as bones and teeth can preserve evidence of conditions like joint diseases, infections, trauma, and tumors for thousands of years. Distinctive marks on bones, like those from tuberculosis or leprosy, can indicate past infections.
Ancient DNA (aDNA) analysis is a key molecular technique that retrieves genetic material from ancient biological samples. This allows researchers to directly identify pathogen DNA, offering insights into their evolutionary pathways and historical spread. For example, aDNA can confirm disease diagnoses when skeletal changes are ambiguous, and can detect pathogens that leave no visible traces on bones. This technology has advanced understanding of past epidemics and pathogen evolution.
Archaeological findings offer further context by revealing ancient living conditions, dietary patterns, and societal behaviors that impacted health. Analyzing grave soil can uncover fossilized remains of intestinal parasites, enhancing understanding of ancient health burdens. Beyond physical remains, historical texts and artistic depictions provide valuable accounts of illnesses and early medical interventions. These diverse lines of evidence, often combined, allow scientists to piece together disease in the past.
The Primeval Pathogens
Several conditions are candidates for the oldest diseases to affect humankind, with evidence stretching back into prehistory. Tuberculosis (TB) shows skeletal changes in human remains dating back 8,000 to 10,000 years ago from the Near East, coinciding with the Neolithic revolution. A controversial suggestion of TB exists in a Homo erectus fossil from Turkey around 490,000 to 510,000 years ago. More definitively, ancient DNA confirms TB in 9,000-year-old human bones found off the coast of Israel.
Leprosy has its oldest documented skeletal evidence in a 4,000-year-old skeleton from India. This individual exhibited pathological changes in the face and limb bones consistent with the disease. While textual references to leprosy are found in Asian texts from 600 BCE, direct skeletal evidence confirms its earlier presence.
Malaria has been identified through ancient DNA in human remains dating back 5,600 years ago in Germany. Evidence of human resistance to malaria, detected through DNA analysis in ancient Arabian populations, suggests the disease was present at least 5,000 to 6,000 years ago, coinciding with the advent of farming. Written accounts from ancient Greece and Rome also describe fevers consistent with malaria.
Cancer, often perceived as a modern affliction, has deep historical roots. The earliest evidence of a malignant tumor in a hominin is a 1.7-million-year-old toe bone from South Africa, diagnosed as osteosarcoma. An even older benign tumor, dating back 1.98 million years, was found in a vertebra of Australopithecus sediba. These findings indicate cancer is not solely a product of modern lifestyles.
Dental caries, or cavities, have a long history. Evidence of common tooth decay appears in 13,700-year-old human teeth from Morocco, predating widespread agriculture. A 14,000-year-old tooth from Italy shows signs of ancient dental intervention, where a cavity was manipulated with stone tools. This challenges the notion that cavities became prevalent only with carbohydrate-rich agricultural diets.
Arthritis, particularly osteoarthritis, has afflicted hominids since Paleolithic times. The earliest clear signs in humans are observed in skeletal remains from Native Americans and Egyptian mummies dating back as far as 4500 BC. This degenerative joint condition, characterized by stiffness and pain, has been identified in human remains spanning thousands of years, suggesting a long association with human existence.
Why No Single “Oldest” Disease?
Pinpointing a single “oldest disease” is inherently complex due to several interconnected factors. The definition of “disease” can vary, and conditions considered ailments today might have been common or unremarked upon in ancient societies. The nature of archaeological and genetic evidence presents limitations. Many diseases, particularly viral infections or those that kill rapidly, leave no discernible traces on skeletal remains, which are often the primary source of ancient health information.
Even when bone changes are present, they can be non-specific, making definitive diagnoses challenging without additional molecular evidence. Ancient DNA analysis, while powerful, faces hurdles like degradation and potential contamination of samples. The distinction between infectious diseases, caused by external pathogens, and non-infectious conditions like degenerative diseases or cancers, further complicates the search. Non-infectious conditions often arise from biological processes inherent to life, potentially predating specific human populations.
Many pathogens have co-evolved with their hosts, including early human ancestors, over immense periods. This long-standing co-evolutionary relationship means some disease-causing agents existed alongside or even before the emergence of modern humans, making a singular origin point elusive. The dynamic interplay between hosts and pathogens suggests an ongoing evolutionary arms race rather than a static beginning, making the quest for one “oldest” disease a continuous scientific inquiry.