Q.The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation ?

A scientific explanation must propose a mechanism that is, in principle, testable, based on known natural processes, and consistent with independently established principles — not an appeal to an unverifiable supernatural act.

• Explanation (a) claims that nature 'immortalised' the Samurai's face on crab shells as a tribute — this invokes a purposeful, supernatural act with no proposed physical mechanism and no way to test or falsify it. It is a legend, not a hypothesis.
• Explanation (b) proposes a concrete mechanism: fishermen, out of respect, released any crab whose shell resembled the Samurai's face rather than eating/selling it. Over many generations, crabs with that shell pattern survived and reproduced at higher rates than others, so the pattern became more common in the population — this is a straightforward application of selection acting on heritable variation (here, human/artificial selection rather than natural predator-driven selection, but the same underlying logic Darwin used). It makes testable predictions (e.g., the pattern should be more pronounced in regions/times with stronger fishing pressure and cultural reverence for it) and requires no supernatural cause. …

Identify the defining feature of a scientific explanation — a testable, mechanism-based account grounded in established principles (h …

• Picking (a) because it 'sounds more dramatic/respectful,' ignoring that scientific validity is about testability, not sentiment.
• Missing that (b) is an example of selection (often called 'artificial selection' here, since humans are the selecting agent) acting on a heritable trait a …