Everyone knows.... that you should make your bed
Everyone knows... that you should wash chicken before you cook it
Everyone knows... that mayonnaise goes bad quickly
Everyone knows... that what we used to know is wrong, but what we know now is correct.
People are often wrong. Experts are only as good as their knowledge, observations, and ability to interpret what they see. In the three cases above, studies and new thinking have replaced "what everyone knows" with new knowledge – and they're all false.
While making your bed may seem tidy, it's been known by scientists for years that making your bed increases the growth of mites. During the night, you sweat and that moisture is absorbed by the bed. In turn this moisture provides a hospitable environment for the mites who breed and multiply as they feed on your dead skin cells. If their concentrations get too high, you may experience itchiness or other symptoms from their excrement. For the best results, don't make your bed, which helps it dry out during the day.
As for chicken, it's also been known for years that washing raw chicken increases the likelihood of food poisoning. Why? Because chicken meat and skin are often covered with harmful pathogens. While cooking the chicken kills these pathogens, washing the chicken just spreads them around to the sink, counter, cutting board... and your hands. It's far better to handle the chicken as little as possible and then wash your hands and anything else that has come into contact with the chicken.
And if you're choosing to make chicken salad out of that chicken, know that mayonnaise is a preservative, not something that makes the chicken go bad faster. Mayonnaise has a pH of 3.7, which is acidic enough to retard the growth of most bacteria. That doesn't mean food should be left out – bacteria will grow eventually. Just know that if you get sick, it was likely the chicken's fault rather than the mayo.
Don't believe me? See what Google says. And see what we've known for years.
Except that we haven't, have we? I'll wager that many of you believed some if not all of these pieces of wisdom. The fact that they're "time-honored" and dare I say "ancient wisdom" has no bearing on the fact that according to the best information we have available today, they're all false.
Yet many would claim that we not update what we "know" based on new information. Purveyors of "ancient arts" like homeopathy, Ayurveda, bloodletting, the four humors, acupuncture, and phrenology fail to embrace this idea.
Science is not about what we know, but about how we know. And we know that as we gather more information, we'll have a more accurate view of the way the world works.
And that means... I don't have to make my bed anymore. Yay science!