Humans evolved in a niche where the expected lifespan was about 30 years. Perinatal mortality was huge. Death from childbirth was huge. Few people survived to 40, much less 60 (despite the images of the wise, ancient tribal leader). Cancer was not “a thing” because most humans died before they reached the age of risk.

So, over the millions of years of human evolution before modernity, the adaptation was to avoid cancer past the age of reproduction and into the norm of energy expenditures to raise offspring (so, not only sexual maturity, but success rearing descendants). And even in modern humans, if you look at cancer rates in people under 30, they are quite low – about what you would expect for any other species that evolved in its niche (sharks, elephants, tigers, … ).

But with industrialization, hygiene, medical care, VACCINATIONS, nutrition, social protections, etc., people stopped dying from those other causes and started living to be 80. And there was no time for evolution to catch up and select individuals who accidentally acquired genes to support longevity without cancer.

The same is true for dogs, but the change is even more recent. Dogs evolved in a niche where the expected lifespan was 2-4 years. More than 50% deaths in the 1st year. Few dogs made it to 6, much less 10.

But then, with the transition from working animal to family member, better nutrition, protection from physical harms and predation, veterinary care, VACCINATIONS!!!, etc. dogs no longer died at 2 or at 4, but instead lived to 10. And again, evolution has not had time to catch up, because artificial selection replaced natural selection. And to top it off, with artificial selection we increased size (more risk for bone cancer) and added a few sprinkles that made certain dogs a bit (or maybe a lot?) more susceptible to certain cancers.

But the proof in the pudding is that the “genetic predisposition” or “breed predilection” does not result in young cancers, like heritable cancer syndromes do in people. Cancer still occurs very late in life – long after dogs pass the age that they evolved to reach with whatever peculiar cancer protective mechanism they have (that gives them 2 – 4 years). If you look at 4 year old dogs, the rate of cancer is extremely low.

In the end, we should celebrate the victory of being able to shatter the constraints of ageing that we carry from evolution, and be smart enough to modify our approach to recognize that we need to implement “artificial” methods for cancer prevention that allow for healthy ageing and long lifespans, hopefully with less cancer all around.

We call it, creating a world where we no longer fear cancer 🙂