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half-life concept

Rob Sheldon: Biologists’ use of the term “half-life” shows just how tenuous many of their propositions really are

Recently, our physics color commentator Rob Sheldon took issue with the use of the term “half-life” to describe the survival of DNA in fossils. He says the term has a specific meaning with respect to radioactive decay that just does not apply to other events in nature. In the biology paper at issue, with “half-life” in the name, the authors explain and use the concept in connection with radiocarbon dating: Abstract: Claims of extreme survival of DNA have emphasized the need for reliable models of DNA degradation through time. By analysing mitochondrial DNA (mtDNA) from 158 radiocarbon-dated bones of the extinct New Zealand moa, we confirm empirically a long-hypothesized exponential decay relationship. The average DNA half-life within this geographically constrained Read More ›

Does DNA really have a “half life”? Physicist Rob Sheldon is skeptical

Sheldon: "As a physicist, I would like to point out that biologists are misusing the word "half-life". DNA does NOT have a half-life of 521 years. Radioisotopes have a half-life, because the nucleus is unstable to natural decay through the weak force (for isotopes of interest)." He goes on to say that the weak force of the universe "is unaffected by temperature, pressure, time, or chemicals." Not so for DNA. Read More ›