Why do all modern giraffes have long necks, while fossils of giraffe ancestors have both long necks and short necks? According to the discarded concept of use and disuse, it’s because the short necked giraffes stretch their necks to reach the food, then pass on the longer, stretched neck to their offspring. Instead, according to Darwinian evolution, a wide variety of neck lengths originally were present, and then a food scarcity at low elevations selected against the short necked giraffes, leaving only the giraffes with the genes for long necks as the survivors. (Credit: Unsplash/public domain)

Ask Ethan: What should you do when a respected theory is false?

Every leading scientific idea today will eventually be proven wrong: superseded by a more correct one in the future. Getting there is hard.

Quick take:

• Every theory, no matter how well-backed it is or how well-respected it is, is limited in its power: in how successfully it can describe reality, over what range it’s valid, and for what its blind spots or failings are.
• There are many prevailing, popular ideas in a variety of fields that also lack the necessary supporting evidence, yet they continue to be well-respected and lead to not just widespread misconceptions, but harmful policies.
• While it’s vital to consider what is, or might be, true and valid about any idea that’s put forth, it’s also important to be humble before the Universe, and consider that there are already plenty of discovered phenomena out there that we don’t yet fully understand.

At every point in our quest to understand the world and universe — the one around us and the one within us — we can only start based on what we know and can imagine at present. We are biased by what we know and what we’re ignorant of, and we’re also influenced by the range of experiences that we’re…