How Old Is Cancer? A 255-Million-Year-Old Human Ancestor Had A Tumor
Cancer is older than mammals themselves, based on a tumor found in a 255-million-year-old human ancestor.
A report in JAMA Oncology says scientists studying the jaw of a gorgonopsian, an extinct animal that predates mammals and looks like a reptile, found what looked like miniature teeth of varying diameter at the roots of the jaw’s actual functioning teeth. Their exact shape and position varied but they were circular and found on the side of the jaw closer to the lip than the tongue, and clustered closer to the opening of the mouth than to the throat. Where the miniature teeth invaded the area belonging to a functioning tooth’s root, it appeared to negatively affect the surface of the tooth and the tissue within it.
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According to the researchers, “this ancient condition closely resembles compound odontoma,” a type of tumor in humans that is marked by “miniature teeth that can cause resorption of the functional tooth root.”
The American Medical Association said in a statement that an odontoma is a common type of tumor but its exact causes are “not well understood.”
“Odontomas have been reported in a handful of fossil mammals up to a few million years old but were previously unknown in deep pre-mammalian evolutionary history,” the study noted. The new information from “such a distant relative of humans” gives experts clues on how diseases that affect mammals formed over time, and suggests that this particular condition is not likely related to mammals’ features specifically but rather began a lot earlier in the evolution of vertebrates.
Source: Whitney MR, Mose L and Sidor CA. Odontoma in a 255-Million-Year-Old Mammalian Forebear. JAMA Oncology. 2016.
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