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Despite the menacing track record of emerging pathogens, “Mother Nature is the world’s worst bioterrorist,” a long-overused catchphrase of scientists and public health professionals, is in urgent need of retirement.

Born in the maelstrom of Sept. 11, 2001, and the anthrax attacks that followed, the saying was meant to warn against fixating on bioterrorism while neglecting the risks posed by naturally emerging pathogens. This warning proved prescient. In the next several years, the all-consuming “war on terror” waged by the U.S. would fuel a tenfold boost in biodefense spending, and the focus on bioterrorism would be so strong that, when SARS hit the world stage in 2003, the editorial board of the journal Nature felt the need to remind its audience that the pandemic was not just a “fire drill” for a terrorist attack, but also a trial run for a future pandemic.


Sobriety and disillusionment around the war on terror started to set in toward the middle of the decade. In concert with this transition in public opinion, the meaning of the popular refrain “world’s worst bioterrorist” subtly shifted: Instead of admonishing people to pay due attention to naturally emerging pathogens, the phrase was increasingly used to downplay or dismiss the real — and growing — risks posed by bioterrorism and other human-engineered biological threats.

This new usage was on prominent display during the last decade’s debates over controversial “gain-of-function” avian influenza experiments, in which scientists sought to study the emergence potential of this deadly virus by artificially enhancing its transmissibility between mammals. Proponents of the unusually risky research suggested that, since “nature is the real bioterrorist,” the experiments’ disputed benefits outweighed their potential harms. As Samuel Stanley, chair of the National Science Advisory Board for Biosecurity, affirmed in 2017, “I believe nature is the ultimate bioterrorist and we need to do all we can to stay one step ahead.”

More recently, some leading biotechnologists have expressed similar sentiments. For example, while Twist Bioscience CEO Emily Leproust has written at length about how gene synthesis companies like Twist can better guard against the misuse of their technology by malevolent or reckless actors, she has also invoked the “ultimate bioterrorist” meme to downplay such risks. In a recently published interview, she noted, “I am concerned with the risks. There is potential for massive loss of life. But the risk isn’t from some postdoc or high schooler. The largest risk is from nature. … Nature is the greatest bioterrorist. The biggest losses of life have been from nature.”


Taken together, these examples show that this meme no longer serves us well. It is undoubtedly a mistake to underestimate the threats from natural pathogens. At the same time, it is equally unwise to wield this 19-year-old expression like a magic wand, intending to briskly banish concerns about people causing harm with biology. We can’t afford to blind ourselves or others to the uncomfortable truth that, with each passing day, humans grow more capable of outdoing nature and harnessing biotechnology to cause harm on a staggering scale, by either cruelty or carelessness.

Nature has no interests, motives, or political goals. To the extent it can be said to “want” anything, it is to perpetually enhance populations’ differential reproductive success, which only rarely aligns with causing greater harm to humans. Notably, the trillions of bacteria living in the average human’s colon appear to have adapted toward a peaceful and often mutually beneficial coexistence with their host. And even deadly pathogens may theoretically evolve toward making humans less sick if doing so opens up more opportunities for transmission between hosts.

The process of natural selection, for all its power, is highly constrained in its ability to generate “superbugs” possessing a diabolical suite of traits. Like human bioengineers, natural selection must work around stubborn physiological trade-offs between traits, such as genome replication rate and mutation rate. But natural selection is also handicapped by near-sightedness, driving improvements in traits that enhance a population’s fitness in its current environment with no attention to maintaining or improving traits that enhance fitness in other environments.

If creating an especially deadly pathogen were like winning a soccer match against a formidable opponent, natural selection would be competing with all the cunning of an especially persistent horde of 5-year-olds, glued to the ball and only ever capable of playing offense, defense, or goalie at any one time.

By contrast, modern biologists are gaining the ability to see the whole field, develop an intuition about where the ball will be next, and play multiple positions simultaneously. Through a combination of rational design, directed evolution, breeding, and brute force trial and error, they can increasingly engineer organisms that excel in multiple desired functions at once, such as the ability to grow quickly in a massive industrial fermenter while churning out commercially valuable biomolecules. This growing capability promises tremendous benefits for agriculture, industry, and human health, but its potential application to the creation of pathogens poses serious concerns.

It is worth emphasizing that trained biologists — let alone terrorists — still have difficulty one-upping natural selection’s creative output. Our understanding of biology is very much in its infancy. Yet our knowledge and capabilities are maturing rapidly, as evidenced by Twist’s prolific gene synthesis capabilities, along with recent feats in predicting protein structure, gene editing, and genome assembly. We are much closer to this exciting but frightening horizon today than we were in 2001, and this trend will likely persist.

It’s also worth noting that, when it comes to weapons-grade biotechnology, states likely pose a greater risk than non-state terrorists. States have vastly more resources to support the development of biological weapons, and about 23 are known or suspected to have maintained biological weapons programs in the 20th century. Some programs, like North Korea’s, likely persist to this day. As countries jockey for advantage, state biological weapons programs remain an ever-present danger, despite the treaties and export controls designed to rein them in. Covid-19, which has exposed countries’ vulnerability to biological threats, has done little to mitigate this danger.

Accidental releases pose an additional source of anthropogenic biorisk. Thanks to the U.S. government’s monitoring program, we know that dozens of agents and toxins with the potential to pose a severe threat to public health and agriculture are reported accidentally lost or released from U.S. labs every year. We also know that accidental releases around the world have already caused significant harm. Such risks increase as biotechnology expands across the world and gains in strength.

Biotechnology, with all its promise and peril, is moving fast. It’s irresponsible of us to shrug off current and emerging biotechnological threats by reciting “Nature is the ultimate bioterrorist” like some article of faith. As with global warming, the cost of willful ignorance and inaction is high — and increasing.

Our health security requires that we engage cautiously but honestly with the full spectrum of evolving biological risks, striving toward solutions with open eyes and moral courage.

Chris Bakerlee is a Ph.D. candidate studying evolutionary genetics at Harvard University and a fellow in the Council on Strategic Risks’s Fellowship for Ending Bioweapons Programs.

  • This article makes perfect sense to me as a layman just trying to catch up with all that is happening- but it skirted around one topic which I think deserves some serious attention – it has never been clear to me how we can be sure the current pandemic is not the result of a gain of function experiment gotten loose from the lab.
    I understand there are good reasons to think it was not “engineered” , or so the virologists say, I take their word for that.
    But how do we know gain of function research in a bat virus, at the Wuhan Institute of VIrology, did not get loose – quite possibly in one of the people working there – then spread from there?
    As best I can understand, there were many people against Gain of Function research -but it went forward anyway – no offense to them, their intentions may have been good, and they may have done their best to do it right, but in all honesty, what percentage of all people – scientists included – would have the courage to say “I screwed up, I pushed for Gain of Function research, and it was very successful, far TOO successful, then it got loose, I am to blame for pushing for the research, doing it not carefully enough, and therefore, the worldwide pandemic,” ???

    Practically NO ONE.

    In considering this possibility, one must also consider – if you have a large enough group, someone might well admit fault – some people just do that, no matter what .

    In China, those people will be taken away and never heard from again. And because surveillance is complete, they will not get the message out first, either. It seems pretty likely more than one person in the Institute has been disappeared-they had one who disappeared, then later reappeared – but only on TV, making a video – and only with a mask on – so you could not be at all sure it was the same woman.

    I can not judge the wisdom of Gain of Function research overall – I am not sure virologists really can – I think both sides went on gut feelings – but I CAN judge the wisdom of doing Gain of Function in CHINA – IT WAS STUPID.

    I realize many scientists are there, and the chance of a new virus emerging there is very high – and it could be done much cheaper – none of that was reason enough.

    Now, we have a very powerful country, capable of doing all the research it wants, which has seen very clearly that an epidemic can do great damage to the United States, while they will only lose a few hundred thousand people – Xi Jin Ping will not hesitate to sacrfice a few hundred thousand, by all the evidence we have, where he has had huge numbers of people secretly murdered already.

    We probably have no choice but to do more Gain of Function research – MUCH more of it – but it needs to be brought back to the US, and of course, have very good safeguards – and, I would say, to the extent possible, ongoing vaccination programs to both keep the researchers safer and have something to stop an escape immediately.

    But we can not forego it now, IMO – too many people have seen how easily we can be brought down by a new virus, and so we have to keep doing the research to head them off.

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