The growing importance of livestock on the planet threatens biodiversity and puts human and animal health at risk.

The domestication of cattle, swine, poultry and other animals as livestock for their meat, milk, eggs and labor proved revolutionary for human societies around the planet. For one thing, it boosted food security as it freed people from the need to hunt by providing them with a readily available means to feed themselves.

Yet not all has been well with animal farming, least of all to the animals involved. The practice, especially when conducted on an industrial scale, has led to horrendous animal abuse.

But it isn’t just animals that have suffered. We have inherited several lethal pathogens from livestock, including the influenza virus that likely jumped to humans from poultry, possibly in China, during ancient times and continues to sicken and kill millions of people worldwide each year.

Domesticated animals continue to be reservoirs of potentially deadly pathogens that could infect people. That is especially worrying in this era of the Covid-19 pandemic. Worse: the expansion of livestock husbandry has been leading to massive losses of biodiversity around much of the planet. A case in point is the continued decimation of the Amazon’s beleaguered forests in Brazil to make way for yet more grazing ground for cattle.

According to a team of researchers, between 1960 and last year the number of epidemics affecting people increased in tandem with the loss of local biodiversity. By analyzing records, they discovered that as many 16,994 epidemics were caused by 254 infectious diseases inherited from livestock animals around the planet during those six decades.

“The emergence of epidemics is a worrying sign for the future of species conservation as it could well signal biodiversity’s march towards extinction,” write the authors of a new study on how emerging new diseases, livestock expansion and biodiversity loss are all intertwined globally.

“The relation between the number of endangered species and the number of epidemics first increases, then peaks, before finally declining,” they explain. “However, the risk of an epidemic does not decrease with the disappearance of a species, but on the contrary, is further relayed by the growing number of head of cattle.”

Perhaps none of this should come as news. Farmed animals far outnumber their wild counterparts and we live in close proximity to them. Of domesticated cattle alone, there are around a billion at any one moment. Meanwhile, the number of chickens in the world ballooned to nearly 24 billion in 2018 from around 14 billion in 2000 and the trend is bound to increase in coming years.

“[T]he growing importance of livestock on the planet, while threatening biodiversity, increasingly puts human and animal health at risk,” the scientists explain, adding that livestock expansion depends on several local variables such as the growth of human populations, changes in dietary habits, agricultural industrialization and the cultural importance of livestock.

The solution worldwide lies in transitioning to vegetable proteins in favor of animal ones, at least in part. Beef production, for instance, requires 28 times more land than the production of pork and chicken. It also requires 11 times more water and produces five times more climate-warming emissions.

“When compared to staples like potatoes, wheat, and rice, the impact of beef per calorie is even more extreme, requiring 160 times more land and producing 11 times more greenhouse gases,” The Guardian explained apropos of a study published in the Proceedings of the Natural Academy of Science last year.