Cancer Unveiled: Evolution, Multicellularity, and the Making of a Disease

3.5 Living with an Ancient Adversary: From War to Evolutionary Management

Peto’s paradox and life-history strategies together trace a simple yet unsettling boundary: evolution can push cancer risk down, redistribute it over the life course, and trade it off against other demands, but it cannot make the risk vanish. Large, long-lived species like elephants and bowhead whales show that powerful cancer suppression is possible, yet even they are not cancer-proof. Small, fast-living species show the opposite compromise: weaker late-life protection is tolerated because few individuals reach the ages at which cancer would dominate. Across this spectrum, the same pattern recurs. Once a lineage commits to being multicellular, and especially to being large and long-lived, it acquires an ancient adversary it can negotiate with but never fully escape.

That adversary is not a foreign invader but a possibility inherent in cellular life: the evolution of lineages that prioritise their own proliferation and survival over the multicellular whole. Deep time makes clear that this possibility has been realised repeatedly. Tumours in dinosaur bones, cancers in early mammals, lesions in ancient humans, and cancer-like growths in plants, corals, and fungi all testify that wherever bodies composed of many cells arise, somatic cheating eventually follows. What differs across species and eras is not whether the adversary exists, but how often it appears, when in life it strikes, and how effectively the organism can hold it in check.

For humans, this means that cancer is not an aberration bolted onto an otherwise harmonious design. It is a consequence of the same architecture that allows us to grow, heal, and live long lives. Our bodies invest heavily in somatic maintenance, including DNA repair, cell-cycle checkpoints, apoptosis, senescence, immune surveillance, and tissue architecture, but those systems were tuned by selection in environments where infectious disease, injury, and resource stress were major threats, and where few individuals routinely lived into their eighth or ninth decade. Under those conditions, strong protection in childhood and reproductive years is heavily favoured, while the payoff from perfect late-life suppression is comparatively small. The result is what we see today: many tissues remain cooperative for decades, but the risk of somatic cheating rises sharply with age, especially in environments and lifestyles that differ from those in which our defences evolved.

This evolutionary backdrop has an important implication for how we imagine our relationship with cancer. If no lineage has found a cost-free way to abolish somatic cheating over hundreds of millions of years, then the idea of a single decisive “war” that ends cancer forever is biologically implausible. The war metaphor suggests an external enemy, a finite campaign, and the possibility of total victory if only we wield enough force. The picture that emerges from deep time is different. Cancer is not outside us. It is a recurring failure mode of our own cellular society. It is not a static foe but an evolving population of cells that responds to the pressures we impose. And it is not something evolution has failed to notice; it is something evolution has constrained, at a cost, as far as trade-offs allow.

This does not make cancer any less threatening. It does change what counts as a realistic goal. The lesson of Peto’s paradox is that bodies can be made safer but not perfectly safe. The lesson of life history theory is that every increment of safety must be purchased at the expense of resources taken from elsewhere, growth, reproduction, or other aspects of maintenance. Together they point away from fantasies of absolute eradication and toward a more modest but more achievable aim: to live with this ancient adversary in ways that minimise its impact on lives and lifetimes, rather than to imagine that it can be banished altogether.

Reframing our aims in this way requires rethinking not just biology but metaphors. War language has been powerful in rallying funding, public attention, and emotional resolve. It resonates with the fear and urgency that a cancer diagnosis brings. But as a strategic guide, it has serious flaws. War invites maximalism. If the enemy is absolute evil, then any escalation in “firepower”, higher doses, more aggressive combinations, more extreme interventions, feels justified. In an evolutionary system, however, escalation is not neutral. It is a selective force. Each round of high-intensity treatment eliminates sensitive cells but also clears ecological space for resistant clones to expand, sometimes turning a partially controllable tumour into a more dangerous, treatment-refractory disease.

An evolutionary management perspective starts from a different set of questions. Instead of asking only “How can we kill the tumour?” it asks “What selective pressures are we creating?” “Which clones will thrive under this regimen?” and “How will the tumour’s ecology change in response?” In this view, therapies are not just weapons but tools that shape the evolutionary landscape inside the body. Their success depends not only on how much damage they inflict now, but on what kinds of tumours they leave behind.

The comparative evidence in this chapter offers a useful analogy. When evolution “designed” an elephant or a bowhead whale, it did not simply ramp up every possible defence simultaneously. It selected particular combinations, more TP53 copies here, better DNA repair there, slower cell turnover somewhere else, because those combinations fit each lineage’s broader life history. Similarly, effective cancer care cannot consist solely of turning all the therapeutic knobs to maximum. It must find combinations and sequences of interventions that fit the “life history” of the tumour and the patient’s body: how fast the tumour grows, how heterogeneous it is, how resilient the host tissues are, what other risks the patient faces, and what goals they value.

In practice, this is what evolutionary management of cancer means. In some situations, especially when cancers are localised and detected early, an all-out attempt at eradication remains the best option. In others, particularly where disease is widespread, genetically diverse, and tightly intertwined with vital tissues, long-term control may be more realistic and more humane than a short, intense “battle” that selects for highly resistant remnants. Strategies such as adaptive therapy explicitly embrace this logic. By modulating treatment to keep sensitive cells in play, they aim to use competition within the tumour to suppress the most dangerous clones, trading short-term tumour shrinkage for longer-term stability.

Deep time helps justify this shift in mindset. Evolution’s “solutions” to cancer have never involved removing somatic evolution from bodies altogether. Instead, they involve constraining, delaying, and redirecting it so that multicellular life can still flourish. The goal has always been conditional peace rather than permanent victory: enough order for bodies to grow, reproduce, and often age, despite the ever-present possibility of cheating. Evolutionary management in the clinic is an attempt to do something similar on the timescale of individual lives, to make cancer, where it cannot be prevented or cured, more like a chronic, manageable part of living in a complex body rather than an all-or-nothing war that must be either won or lost.

Framed this way, living with an ancient adversary is not a call to complacency. It is a call to precision about what can and cannot be changed. We cannot rewrite the basic fact that we are made of evolving cells, nor the trade-offs that follow from being long-lived, reproducing organisms. We can, however, change the environments in which somatic evolution unfolds: by reducing avoidable damage, by strengthening early detection, by choosing therapies that anticipate adaptation rather than ignoring it, and by aligning treatment goals with the realistic possibilities of control, containment, and, where achievable, cure. The rest of this book turns inward to show how those principles play out inside tumours and in the clinic. But the foundation lies here: in recognising cancer as an old, recurring adversary built into multicellular life, and in choosing, on that basis, to move from a language of war to a practice of evolutionary management.