Medieval skeleton with cancerous lesions
When I began reading about paleo-oncology last summer, I came across an estimate by the Czech anthropologist Eugen Strouhal of how many cases of suspected cancer had been found in ancient European skeletons: 176. The number, from a paper published in 1996 in the International Journal of Paleopathology, didn’t include Egyptian mummies or cases from other continents. And by the time I was writing the Times story referred to in my previous post, I had found about 20 more recent discoveries. Adding all of these reports together, I felt safe in concluding that about 200 cases of ancient and prehistoric cancer have been found by archaeologists.
That doesn’t sound like a lot, and some scholars like Luigi Capasso, an Italian anthropologist, have argued that cancer was extremely rare before the environmental assaults that came with industrialization. Others, like Dr. Strouhal, have suggested that the few cases researchers have stumbled across might be the tip of an iceberg — that there is a core rate of cancer that has remained fairly steady since prehistoric times.
The issue can quickly become political, and I was looking for some perspective. Of all the people who lived and died in millennia past, how many can paleo-oncologists possibly have examined? I was surprised to learn that by 1 A.D. the cumulative population of the earth was already approaching 47 billion and had nearly doubled by 1750. (The estimate, obviously very rough, is from a study by Carl Haub of the Population Reference Bureau.) So much for the notion that more people are alive today than have ever walked the earth. Not even close.
The next number I needed was one that, as far as I can see, had not been published before: the total number of human skeletons that have been dug up by archaeologists and made available for scientific study. Two experts I asked arrived independently at the same approximation: About 100,000. That would make the sample size only about 1/10,000th of 1 percent. For palaeo-oncologists it is even smaller than that: only a portion of those skeletons has been systematically examined for bone cancer. That is not much to hang an argument on, and I am left in the same quandary. Is cancer a natural (though unwanted) biological phenomenon, or a Frankensteinian creation of modern times?
George Johnson
talaya.net
4 Comments
I’m biased against the industrialization argument, so this leads me to want to turn the question on its head: without accurate data on historical cancer rates, how could anyone even know that they’ve increased, let alone the reason why?
Hi George,
I am slow to get around to reading, but both this post and your Times article made me ponder a medical question…does all cancer (if left untreated) eventually metastasize to and show up in bones?
Also, what about animal skeletons? Must be many more of them unearthed, right? If Weinburg’s idea about multicellular life holds true, then shouldn’t we also be able to track it in animal remains? Or do most animals die from predation before cancer would have had time to kick in?
Clearly, you’ve got me interested…
Kendall,
I’m glad to have you as a reader. From what I have learned so far, some cancers are more likely to metastasize than others and each tends to seek out different targets. Breast and prostate cancer have a propensity for bone. Ovarian and colon cancer rarely go there. For carcinomas in general, the lung and liver are the most likely target for metastasis. Bone is third. Whether any cancer that didn’t kill its host would eventually end up in the skeleton is something I do not know.
Dwayne,
You have put your finger on one of the mysteries I’ll be grappling with in the book. In developed countries with reasonably competent record-keeping, changes in the incidence of different kinds of cancers can be plotted. And even then the causation is controversial — how much is from early detection and how much from diet, exposure to carcinogens, etc.? When you look back even a century, death records become much less reliable — and cancer was considered a stigma so another cause of death was often listed. Go back even further and you are relying on scant historical records and the archaeological ambiguities I wrote about in the article.