E-Mail IMAGE: Justin Bernstein, Ph.D., senior author and an assistant professor in the Department of Philosophy. view more Credit: Adam Bernstein As early as the Neolithic period (circa 3900 BC), the domestication of animals likely led to the development of diseases including measles and smallpox. Since then, zoonotic disease has led to other major transnational outbreaks including HIV, Ebola, SARS, MERS, and H1N1 swine flu, among others. Currently, more than half of all existing human pathogens, and almost three-quarters of emerging infectious diseases, are zoonotic in nature. COVID-19 is the latest and most impactful zoonotic event of the modern era, but it will certainly not be the last.