Gaby
Civilization as we know it would not exist without domesticated animals. But domestication also brought humanity a host of serious diseases that repeatedly escalated into epidemics and pandemics.
A new study led by geogeneticist Martin Sikora of the University of Copenhagen highlights that the onset of animal domestication and livestock breeding coincided with spikes in animal-to-human diseases such as plague (Yersinia pestis) and relapsing fever (LBRF).
Archaeologists have long suspected that when nomadic hunter-gatherers in Eurasia began forming large pastoral communities around 12,000 years ago, the risk of pathogen transmission from animals to humans increased. Now, ancient DNA methods have helped scientists confirm that hypothesis.
What the Researchers Discovered
The scientists analyzed 405 billion DNA sequences collected from 1,313 ancient human remains across Eurasia. That dataset allowed them to identify numerous microbial genes.
The team compiled enough data to create a 12,500-year chronicle of the emergence and spread of major human diseases. They found that a significant portion of those microbes originated from external sources such as animals.
Many of the microbial strains infecting humans remained stable across the sampling period. Zoonotic pathogens—those transmitted from animals to humans—appear in human remains dating back roughly 6,000 years, a turning point from hunter-gatherer to agricultural societies.
The team also discovered a large accumulation of zoonotic microbes in human remains about 5,000 years old from across Eurasia. That spike suggests steppe herders migrating to new regions brought not only agricultural knowledge but also diseases carried by domesticated animals.
They say the rise in zoonotic disease isn’t solely the result of direct interactions between humans and animals. It may also be linked to growing population density, worsening local hygiene, and increases in rodents, fleas, lice, and ticks. For example, outbreaks of relapsing fever have historically correlated with poor living conditions and hygiene.
Animal Domestication and Human History
Today, zoonotic diseases account for more than 60 percent of re-emerging infectious diseases. However, several millennia ago these microbes were new to humans, Science Alert reports.
The researchers believe prehistoric societies on the Eurasian steppes, which encountered zoonotic pathogens earlier than other groups, gained advantages: steady sources of meat and milk and more time to adapt to new animal pathogens.
The team says more research is needed to better understand these outbreaks. Still, the study provides compelling evidence that animal domestication represented a major lifestyle shift that helped spread zoonotic infections. Overall, domestication has had a profound impact on global health and human history.
The results of the study were published in the journal bioRxiv.
