Premature Rejection Of The Younger Dryas Impact Hypothesis - Sound Familiar?

sagepub | Scientists have initially rejected many theories that later achieved widespread consensus. In some instances, the rejection lasted for half a century or more, until enough new evidence arrived to convert all but the most obstinate opponents, who often carried their opposition to the grave.¹ The canonical example in the earth sciences is continental drift. First proposed by Alfred Wegener in 1912, continental drift did not achieve consensus until the mid-1960s.² The theory of meteorite impact cratering on the Moon and the Earth provides another example. We can date its origin to a classic 1893 paper by the great American geologist G. K. Gilbert³ and the beginning of its broad acceptance to 1964 and the first returned photographs of lunar craters from the Ranger missions to the Moon. Both rejections stemmed mainly from the allegiance of geologists to the principle of uniformitarianism, which eschewed catastrophic events such as moving continents and colliding meteorites. Anthropogenic global warming offers a third example. First proposed by Svante Arrhenius in 1896, within a few years it had become almost universally rejected, based on a single, misinterpreted experiment.⁴ Its acceptance began with the first results of computerized climate modeling in the mid-1960s. The pioneer of climate modeling, Syukuro Manabe, won the 2021 Nobel prize in physics for his early work. Today we can only wonder what the effect would have been had scientists in the first half of the twentieth century retained AGW as a working hypothesis.

One would hope and expect that in the internet age, with its online journals, instant communication, and vastly improved scientific methods and instrumentation, premature rejection would be a thing of the past. The reaction to the Younger Dryas Impact Hypothesis (YDIH), introduced in 2007, shows that this assumption is incorrect.⁵ Within months of its appearance, two authors⁶ called the hypothesis a “Frankenstein Monster” and in 2011, the same two plus others⁷ compared it to UFOs and other examples of “pathological science” and wrote its “requiem.” Yet after a comprehensive review of the literature in 2021, Sweatman⁸ concluded: “Probably, with the YD impact event essentially confirmed, the YD impact hypothesis should now be called a ‘theory’.” The question this article seeks to answer is how scientists can so thoroughly reject a hypothesis, even write its requiem, only to have it emerge in little more than a decade strengthened and deserving of possible promotion to the status of theory.

 

It should have been clear to readers, including peer reviewers, that Pinter and Ishman had offered hyperbolic language but no actual evidence against the YDIH; that Surovell et al.³⁷ had failed to sample the YDB and/or made fatal errors in procedure; and that the samples reported by Scott et al.⁴⁰ and used by Pinter et al.⁷ and Daulton et al.⁴⁹ had not come from the YDB and therefore did not bear directly on the impact hypothesis. Instead of critically examining and rejecting these false claims, many geologists and impact specialists embraced them, thereby allowing an alleged absence of evidence to trump abundant, peer-reviewed evidence, even photographic evidence. Then a kind of “groupthink” seems to have set in, rendering the YDIH beneath further consideration.

 

The broader lesson from impact cratering, continental drift, anthropogenic global warming, and now the YDIH is that it is better to encourage further research than to prematurely condemn a novel, data-based hypothesis to the dust bin of science. Unfortunately, once a hypothesis has been prematurely rejected, even truly “extraordinary evidence” may not be enough to restore it to scientific respectability.