Livestock species, such as cattle, now account for more biomass than all wild mammals combined.
For the bacteria living within these animals, this massive expansion represents an opportunity to proliferate and spread globally through trade networks.
Campylobacter is one of several, harmful bacteria that can cause intense food poisoning symptoms like fever, vomiting, and diarrhoea.
Australian and British researchers analysed the genomes of more than 1000 individual Campylobacyer jejuni bacteria from a range of host organisms, uncovering genetic lineages that have become specialised to live and spread in cattle.
They suggest that this specialisation coincided with the intensification of cattle agriculture in the 20th century, showing how pathogens can adapt to changing environments.