6 ways evolutionary medicine can transform our health

Evolution might be the last thing on your mind when going to see a physician, but evolutionary processes impact our health every day. It’s the reason cancer cells can become resistant to chemotherapy, and bacteria to antibiotics. It’s how animal viruses can enter the human population and spark global pandemics. Even the rise in modern health problems, such as obesity, can be traced back to evolutionary principles. The list goes on.

How can we overcome these challenges? The conventional strategy is counterattack. For instance, by developing new antibiotics and chemotherapies to replace those that are no longer effective. But this drug-discovery treadmill doesn’t address the central problem – the evolutionary process itself.

Together with colleagues from various fields, we recently published a new roadmap for evolutionary medicine in the journal Frontiers in Science. We explore how evolutionary medicine can spark biomedical innovation and improve public health policy – helping us understand, prevent, and treat many of the greatest health threats we face.

Elephants rarely get cancer. Giraffes have the highest blood pressure of any animal, but don’t suffer from the effects of hypertension, such as kidney damage and stroke. These are just two examples of animal species that are impervious to serious human medical conditions because of evolved characteristics. And we’re only just beginning to scratch the surface — there may be many disease resistance mechanisms hidden in plain sight, among the biodiversity of the natural world. Systematically searching these out and investigating the biology behind them could help us overcome a range of high-impact human diseases and conditions from diabetes to ageing and beyond.

Though conventional cancer therapies can be effective, they can also drive drug resistance and be toxic to patients. Cancer cells are adaptive organisms that can evolve to evade chemotherapy and other treatments. If a small population of chemotherapy-resistant cancer cells develops during treatment, then killing off all drug-sensitive cancer cells gives the resistant population a competitive edge. Before long, the tumour might become fully resistant to the drug – causing treatment failure or necessitating alternative therapeutics that may have adverse health effects.

Extinction and adaptive therapies are strategies that address this problem. With extinction therapy, the tumour is targeted with two complementary treatments separated by a brief duration that doesn’t allow resistance to arise. Adaptive therapy, on the other hand, aims to stabilize the size of the tumour by preserving a population of drug-sensitive cells with low drug doses over extended periods. This type of therapy might give hope to patients suffering from advanced cancers where complete tumour eradication is unlikely.

Antimicrobial drugs, such as antibiotics and insecticides, have greatly contributed to human health, curing infections and securing our food supply. But the effectiveness with which antimicrobial drugs kill their targets is also their undoing. Like chemotherapy, they create conditions that drive the evolution and dominance of resistant strains.

Evolutionary medicine offers several alternative options. For example, microbes can only undergo a limited number of genetic adaptations in a short timeframe. Therefore, administering several antimicrobials together can ensure susceptibility to at least one of the drugs.

Another potential strategy is to develop anti-evolution drugs that counter the evolutionary process itself. Bacteria can actively share their DNA with other bacteria in a process called horizontal gene transfer. This is how resistant genes can quickly spread across a population – and even to different species. We could slow or even stop this process by designing drugs that target this gene-sharing mechanism.

A deeper understanding of the evolutionary processes by which microbes acquire resistance could inspire further strategies. Some ideas are already in development, such as anti-antibiotics – a potential solution to help prevent some hospital-acquired infections, and the therapeutic use of viruses known as phages.

Human genes evolved to optimise our survival and reproduction in a world vastly different from the one we live in now. Paradoxically, some adaptations that originally helped us thrive are now harming our health – a phenomenon called “evolutionary mismatch”. For example, our ability to store energy as fat was an asset in the past when food was scarce. However, in societies where food is now plentiful, this has led to the rise of obesity, type 2 diabetes, and cardiovascular disease.

An evolutionary perspective clarifies that these Anthropocene-related conditions are not simply the consequences of misguided lifestyle choices, but are systematically driven by environmental and societal factors. Interventions focused on the individual (such as exercise and dietary changes) often don’t work. An evolutionary approach would aim to change the relevant ecological conditions instead, for example via food taxes, food marketing restrictions, and policies that promote healthy diets and exercise.

It’s no secret that many of us engage in unhealthy behaviours, such as smoking or unsafe sex, despite recommendations. Evolutionary medicine can help explain why and offer solutions.

One possible explanation is the constant competition between the three main evolutionary goals: growth, reproduction, and ability to survive. Since our bodies cannot support all to the same extent at the same time, we experience health trade-offs. For example, people who can't meet their basic needs might be less preoccupied with long-term health considerations and be more likely to take risks. This could explain why some young men choose not to use condoms: they may be unconsciously prioritising reproduction over the risk of HIV infection, especially in environments where mortality risks are high.

Viewing people’s behaviour through the lens of evolutionary principles would help shape more effective public health policies. Such policies would seek to promote healthy behaviours by improving people's prospects – providing everyone with access to education and job opportunities, while ending food insecurity, discrimination, and crime.

The COVID-19 pandemic was a devastating example of evolution in action. As it swept across the globe, the SARS-CoV-2 virus continually mutated into new variants. Evolutionary models were essential for tracking these variants, predicting their properties, and informing responses. Evolution-based approaches will be pivotal to predict, monitor and manage future infectious disease outbreaks, including new animal pathogens of risk to humans.

Evolutionary medicine has enormous potential, but also many challenges to its adoption – as explored in the article hub at Frontiers in Science. Greater interdisciplinary collaboration is vital to systematically leverage its insight-generating power to benefit human, animal, and planetary health.