Coronaviruses and the Human Meat Market

Note: A shorter version of this essay by Dr. Russ Mittermeier, GWC Chief Conservation Officer, first appeared on The Revelator on April 3, 2020

Over the course of my career, I have come down with a seemingly endless variety of tropical diseases: leishmaniasis, amoebic dysentery, dengue, schistosomiasis, leptospirosis, countless bouts of diarrhea of unknown origin, dozens of cases of food poisoning, numerous secondary infections, pinworm, hookworm, wandering hookworm, and about three dozen botflies in various parts of my body. I even had a close call with the Marburg virus, standing just outside a big cave on Mt. Elgon in Uganda in 1984, a site where several people died of this virus years later after entering the same cave. I didn’t go in at that time, partly because I don’t like caves and partly because there were elephants rumored to be inside.

After a couple of decades in the tropics, I started to think more and more about this issue of new and reemerging diseases (like Monkey-B virus, Ebola, HIV/AIDs, Dengue, Chikungunya, and Zika, as well as SARS and MERS, which are also coronaviruses), what it meant to the wellbeing of our own species, and how it related to the conservation of biodiversity, the main focus of my career.

Over the course of his career, GWC's Dr. Russ Mittermeier has been thinking about his "human meat market" hypothesis, which today seems to be playing out with the COVID-19 coronavirus. (Photo courtesy of Russ Mittermeier)

For decades now I’ve had a hypothesis that seems to be playing out now with the latest coronavirus, COVID-19, and that was cited in Richard Preston’s groundbreaking book, The Hot Zone, in 1994 after I shared the idea with him in a phone call. I call it the “human meat market hypothesis.” If you look at the course of evolution, you see that certain species become abundant, or even super-abundant, for whatever reason. Along with this success, you also see the accompanying evolution of predators, parasites and pathogens to take advantage of this huge food resource, this mass of protoplasm, this “meat market” of living creatures. These include, aside from the large and obvious mammalian carnivores, a wide variety of viruses, bacteria, protozoans, or rickettsia to make use of these super-abundant species.

Examples abound in nature—the American Bison herds of the American west; Wildebeest on the savannas of East Africa; White-lipped Peccaries in the forests of Amazonia; Capybara in the flooded grasslands of Brazil, Venezuela and Colombia; Saiga Antelope in Russia; Mexican Free-tailed Bats in Texas; concentrated seabird colonies in many parts of the far north, and many others. Predators and parasites/pathogens evolve to depend on these species for their survival.

A Meat Market…of Humans

Here’s the twist: We humans have become an extremely successful and super-abundant species, as well as a huge source of food for potential predators, parasites and pathogens—a human monoculture, a “human meat market.” Saber-toothed Tigers and Cave Bears were a problem for us in the past, and Tigers, Lions, Leopards, Polar Bears, Grizzlies, Nile and Saltwater Crocodiles, and Great White Sharks still try to eat us from time to time. It is unlikely that new predators are going to emerge at this point, leaving parasites and pathogens as our major adversaries in the future (and at present!).

The more simplified and less diverse ecological systems become, especially in huge and ever-expanding urban areas, the more we will become the targets of these emerging pests, unbuffered by the vast array of other species in a healthy ecosystem. What is more, the increasing urbanization of our own species provides an avenue for rapid transmission of both old and new diseases, with ever more densely concentrated populations living in often less than sanitary conditions. It even opens up the possibility of an older widespread contagious disease combining with a new disease.

If these pathogens and parasites are emerging from the natural world, some might wonder why we don’t just eliminate the wild animals that are the carriers, much like the Chinese did after the SARS outbreak when they killed tens of thousands of civets. But doing so can also have catastrophic effects. Killing host species could lead to widespread killing of wildlife in general, greatly impacting critical ecosystem services like predation of pest species that may carry even more diseases. And do we really want biodiversity to be reduced to a handful of species like cockroaches, rats, mice, pigeons, English sparrows, and even certain highly adaptable monkey species with which we share our urban environments, and which themselves are known to be agents for disease transfer (think rat-borne bubonic plague in the Middle Ages)?

The continuing consumption of wild animals (aka ‘bushmeat’) in regions like China, Southeast Asia, West and Central Africa, Amazonia and elsewhere provides a direct human connection to parasites and pathogens that would otherwise be restricted to different species of wild animals living in their natural habitats. These wild animals have coevolved with their pathogens, and in the wild pose little to no risk to humans. However, anyone who has ever visited these dreadful markets knows how unsanitary they are and how easily they can cause direct infections to human consumers, which is how this most recent coronavirus made its way to humans. The only surprise is that these kinds of outbreaks have not happened more frequently.

Slow Loris in a market. (© E.Bennett, WCS)

Indeed, if our own abundance were not enough, another shocking statistic is that our domestic animals are an even bigger “meat market” for pathogens and parasites than we are. Domestic mammals alone account for 60% of all mammalian biomass on Earth, compared to our 36% and only 4% for all wild mammals. No wonder we have to pump domestic animals full of antibiotics to avoid the occasional outbreaks of diseases such as mad cow, swine flu (also originating in China), foot-and-mouth disease, avian influenza, fish lice and an evolving reovirus around salmon farms, and other epidemics of domestic animal production. The combination of the two, the human meat market that we all represent and our own domestic animal meat market, is proving deadly.

How to Protect Ourselves

So, what does this mean for conservation? First of all, we need to protect the full range of biodiversity on our planet, since diverse, healthy and functioning ecosystems protect us as well. We don’t want our Earth to become increasingly less diverse, with humans (and our domestic animals) becoming increasingly easy targets for the viruses, bacteria, protozoans and other parasites and pathogens that will certainly appear and find us to be the best and most readily available source of meat.

Deforestation--or the destroying on our forested wildlands and the homes of wildlife--is another factor pushing pathogen-carrying host animals closer to humans. (Photo by Robin Moore, Global Wildlife Conservation)

Next we simply have to stop removing wild animals from their natural habitats for human use and consumption, practices that put us into direct contact with their parasites and pathogens. We strongly encourage countries that are actively engaged in the commercial trade of terrestrial wildlife for food, medicines, and pets to ban these practices permanently. China has already done so in response to COVID-19, but how long will such a ban last? China also enacted a ban in one province (Guangzhou) after the SARS outbreak in 2003, but the markets opened up again shortly after the threat passed—and now we have COVID-19. Vietnam’s government is also preparing a directive to stop its $18 billion wildlife trade market. African countries should also ban commercial bushmeat consumption. Some have made feeble attempts to do so, but most haven’t stuck.

What is more, these bans need not only be maintained; they also need to be strictly enforced including by focusing on the vast illegal underground markets.

Third, as a society we need to move away from large-scale meat consumption in general, and transition to plant-based diets (or even cell- or microbe-based meats).

This latest coronavirus has given us yet another wake-up call, as have similar outbreaks in the past few decades. So far, I would say that we have been lucky, since there hasn’t been a massive disease outbreak since the 1918 Spanish Flu pandemic, although many others such as HIV have proven deadly (over 32 million dead and counting).

Unless the world takes action to protect our wildlife and conserve our wildlands, the pandemic caused by the COVID-19 coronavirus could become our new norm.

We can’t yet determine how severe this latest outbreak will be, but it should help to prepare us for the future, not just in band-aid approaches like more masks, hand-sanitizers and test kits, and an eventual vaccine, but also in attacking the underlying causes of these outbreaks to prevent them much more effectively in the future. We simply must put an end to the commercial trade in wild animals for food, for medicine and for pets— for the health of our planet and for us humans who live on it, but who continue to destroy it with such callousness and ignorance.

Dr. Russ Mittermeier is Global Wildlife Conservation’s Chief Conservation Officer. In this role, he leverages his extensive experience and network to protect wildlife and wildlands—enormous reservoirs of biodiversity and key components in preventing runaway climate change— particularly in biodiversity hotspots and critical wilderness areas. Mittermeier came to GWC from Conservation International, where he served as president from 1989 until 2014, and most recently as executive vice chair.  He also chairs the IUCN/SSC Primate Specialist Group.

(Top photo by James Cridland via Flickr Creative Commons)