“The struggle for existence never gets easier. However well a species may adapt to its environment, it can never relax, because its competitors and its enemies are also adapting to their niches. Survival is a zero-sum game.”
As we settle into quarantine, many of us are wondering about how the response to COVID-19 could have been better. What could we have done differently and could these strategies have been implemented earlier? Experience can be a painful teacher but perhaps next time we can learn from the mistakes of this recent crisis and apply these lessons to the future. I am optimistic that this will be the case. The problem is that I’m not sure the root causes are being addressed.
Living With The Enemy
“The discovery was that the probability a family of animals would become extinct does not depend on how long that family has already existed. In other words, species do not get better at surviving (nor do they grow feeble with age, as individuals do). Their chances of extinction are random.”
Most of us go through our daily lives without thinking about the constant battle taking place within and outside our bodies at the microscopic level, that is, until something goes wrong. Bacteria, viruses, and parasites all fight for their own ends, some of which can benefit us, but more often than not it is to our detriment.
If we take the last century, many of the pandemics that humans have faced all share a common denominator: they originated in other species and then spread to humans. The Spanish Flu, HIV, Swine Flu, SARS, and COVID-19 all share this trait as a zoonotic disease. Zoonoses individually have a low probability of turning into a pandemic, but Mother Nature has always played roulette against humans. With a nearly unlimited supply of chips, eventually she gets lucky and double zero comes up. What’s changed is that Mother Nature also seems to be playing with more chips at a faster pace in recent times. Humans are in part responsible for this change.
“Parasites have a deadlier effect than predators for two reasons. One is that there are more of them. Human beings have no predators except great white sharks and one another, but they have lots of parasites. Even rabbits, which are eaten by stoats, weasels, foxes, buzzards, dogs, and people, are host to far more fleas, lice, ticks, mosquitoes, tapeworms, and uncounted varieties of protozoa, bacteria, fungi, and viruses. The myxomatosis virus has killed far more rabbits than have foxes. The second reason, which is the cause of the first, is that parasites are usually smaller than their hosts, while predators are usually larger. This means that the parasites live shorter lives and pass through more generations in a given time than their hosts. The bacteria in your gut pass through six times as many generations during your lifetime as people have passed through since they were apes. As a consequence, they can multiply faster than their hosts and control or reduce the host population. The predator merely follows the abundance of its prey.”
Despite the chaos and complexity that Mother Nature can represent at times, she does have some methods to her madness. The Earth is a pretty big place and for most of its existence, species haven’t traveled that far intragenerationally until very recently. Human ingenuity and the revolution in transportation that has taken place over the last hundred years or so has been a boon to human society. But as the human population grows, so does it’s demand for resources, especially food. Modern agricultural output has doubled in the last 60 years, all while using less land and labor. These agricultural innovations come at a cost. The interspecies contact from globalization and factory farming present risks at levels much higher than at any other time in human history. Avian flu claimed the lives of several hundred million chickens. Last year, swine fever killed over 40% of China’s pigs — an alarming number considering that China accounts for more than half the pigs in the entire world.
Being in a globalized society presents new pandemic risks to both us and the animals we eat that have never been present to such degrees in times past. About 50% of the roughly 1000 species of pathogens that are documented in livestock and pets are zoonoses. This implies that any barriers between these hosts and human beings are routinely breached by many different pathogens. More than 50% of the recognized pathogens of human beings can infect other vertebrate hosts, and many non-human pathogens can infect several hosts. There have been clear examples of viruses transferring between different animal hosts that caused outbreaks in other species. An even bigger concern is that some of these pathogens can transfer from human beings to animals and between different animal species before being transferred back to people, potentially enhancing pathogenicity through remixing and evolution.
When looking at emerging infectious disease events, zoonoses accounted for approximately 60% of cases since 1940. About 70% of these zoonotic diseases came from wildlife. Focusing on zoonotic viruses, despite accounting for less than 15% of all known species of human pathogens, they were 65% of the pathogens discovered since 1980. So what’s the big deal then if a majority of these cases come from wildlife rather than domesticated animals? If there is a higher host plasticity from viruses transmitted from direct contact with wildlife, surely the solution can’t be that hard. Just avoid the wildlife! Except that when you really start to think about the globalization piece of the puzzle, that means that everyone has to be mindful of this. Any taxonomically diverse species that are in close proximity to each other becomes a roll of the dice for cross-species transmission of viruses. This includes zoos, exotic pets, wet markets, and many other scenarios that put both humans and domesticated animals in close contact with wildlife. Compounding this problem is the opportunity for vector-borne transmission (e.g. mosquitoes or fleas) to humans. Each one of these represents a risk event for zoonotic diseases. Think of how many times these dice rolls happen on a yearly basis? Mother Nature, the degenerate gambler.
The Complexities Of The Enemy: Known Unknowns Versus Unknown Unknowns
“Arms race analogies are flawed, though. In a real arms race, an old weapon rarely regains its advantage. The day of the longbow will not come again. In the contest between a parasite and its host, it is the old weapons, against which the antagonist has forgotten how to defend, that may well be the most effective.”
If I asked you how the next terrorist attack would happen and who would be responsible for it, you might be able to deduce a pretty good list for both the weapon and the attacker. While you couldn’t say with certainty which specific method the attacker would use, I’m sure you could do a pretty good job of ranking some methods as more probable than others (using a gun versus a nuclear weapon), and safely eliminate some altogether (coordinating an asteroid from space to hit a specific target with a specific radius of destruction). Your strategy would be far from perfect, but taking steps to mitigate known risks could in turn insulate you from unknown risks. Similarly, the problem with COVID-19 and other zoonotic diseases is that we are dealing with extreme levels of uncertainty involving more global risk (though it is interesting to think about terrorists weaponizing pandemics). It can be difficult to predict what types of contact between specific species is most risky in terms of the severity for each zoonotic disease and at which point of taxonomic diversity should we be most concerned. Nevertheless, there are other insights that we do understand better. We know that bats and rodents are hosts to a disproportionately high amount of zoonoses relative to other species. Bats especially seem to be problematic as the transmission for these viruses have a high number of host switches on average between species. Low latitude countries also have higher risks based on where previous pandemics started and as farmers increase their presence in traditional wildlife areas through deforestation and other practices, the chance of both humans and livestock encountering these higher risk species increase.
Existence Is Not Futile
“The faster you run, the more the world moves with you and the less you make progress. Life is a chess tournament in which if you win a game, you start the next game with the handicap of a missing pawn.”
The goal of writing all this wasn’t to present a grim hopeless scenario that inevitably kills us. I’m not a doomer that relishes the opportunity to promote human depopulation and regressing back to our pre-agrarian roots. While it is true that the risk of zoonoses will always exist, there are many things we can do as a species to insulate ourselves from the more catastrophic risk factors. If there’s one thing I hope COVID-19 has taught us, it’s that when we are dealing with globalized risks, the choices of the individual are NOT independent. What you choose to do or not do has an impact on others, both close to you and far away. Imagine how many people contracted the virus because they refused to give up their vacation or some other reason that became trivial in hindsight, and then became attack vectors for new cities and towns that were completely uninfected.
For policymakers it’s important that they have serious conversations about the food supply chain (arguably all supply chains at this point). They need to create incentives for the individual and corporation dealing with livestock to maintain better long term practices to reduce contact with high risk wildlife, or have strategies to silo the risk when an outbreak occurs. Asking these people to implement these practices on their own will not work because the added costs and inefficiencies at the individual level create an incentive to optimize for the short term. This in turn increases the unfavorable conditions that can lead to pandemics for both humans and livestock. If the government has one role, it is to manage the tail risk that this represents. There is a good amount of money that goes towards human medical research in this domain, but only a fraction devoted to the veterinary medical side. The irony is that you could argue the research and prevention of zoonoses is far more important in both domains because of how globalized our society is. I’m not a huge fan of government regulation but these are areas which could potentially affect everyone if not understood and mitigated properly.
Communication between countries and reliable data become increasingly necessary in tracking local hot spots and focusing resources on areas in which taxonomically diverse species and livestock occur in higher frequencies. Technology has been a great advantage in this detection and prediction, and will accelerate as the issue becomes more of a priority globally. In terms of food production, more synthetic animal protein companies are also coming to fruition, and hopefully will allow us to reduce the consumption of livestock that we consume, thereby reducing the amount of attack vectors from agriculture. Exotic pet stores, wet markets, and anything else related to the procurement of wild animals in proximity to domesticated animals and humans need to be carefully re-examined.
“Not my problem” is no longer an acceptable argument for why any country should refuse to participate in these measures, as the externalities that a pandemic produces affects us all. This wasn’t a black swan before and it most certainly will not be if it happens again. If we’re going to continue gambling with Mother Nature, let’s make sure we tilt the odds in our favor.
Note: All quotes are from Matt Ridley’s “The Red Queen”. I highly recommend this book as he brilliantly explains the competitive processes that are constantly at play between species and sexes.
Sources:
https://www.contagionlive.com/news/zoonotic-threats-as-unpredictable-as-they-are-dangerous
https://www.nature.com/articles/srep14830
https://www.nature.com/articles/nature06536
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3712877/
https://www.ers.usda.gov/amber-waves/2015/september/us-agricultural-productivity-growth-the-past-challenges-and-the-future/
https://www.nytimes.com/2020/01/01/opinion/china-swine-fever.html
http://www.cidrap.umn.edu/news-perspective/2004/04/canada-kill-19-million-poultry-stop-avian-flu
https://www.nature.com/articles/ncomms1796
