Looks like it’s probably man-made! Big surprise, huh?
Professors Michael Zimmerman and Rosalie David in England have an intriguing suggestion in their recent study of mummies: cancer may be a largely man-made disease. The study found no evidence of the disease in ancient corpses — leading to the theory that cancer may be the result of diet, pollution, and other man-made causes such as early use of snuff.
The researchers examined tissue from hundreds of Egyptian mummies and found only one case with cancer traces. Likewise, an earlier study of thousands of Neanderthal bones produced only one sample with possible cancer traces.
Some of the first published accounts of cancerous growths have been linked directly to such man-made causes as the use of snuff.
Such accounts largely occurred in the last 200 years with early accounts of nasal cancer (from snuff) and scrotal cancer in chimney sweeps — both in the eighteenth century.
I had actually read that there are some viruses(I believe it was only viruses and not bacteria) that actually fight cancer. They are harmless to ordinary human cells, but not to cancerous human cells. The problem is, we now clean everything so well that there is no opportunity to actually get any of them anymore. They used to be in most water sources. The one I had heard of was the reovirus. But, from the sound of it, there were others.
I do believe humans have increased their chances of getting cancer through various methods. I also believe that nature had a way of limiting cancer, and we have handily defeated those as well.