The cool thing about science is that it’s open to revision.  If new data shows a different solution and the solution stands up under repeated, intensive review, then science changes its stance.

Museums are great places to see this kind of scientific progress in three dimensions.

The Blue Goose diorama at the Carnegie Museum of Natural History is good example.  When the diorama was created in 1925, the blue goose was considered a separate species from the snow goose. The diorama was devoted to the unique “blue” species.

But the blue goose isn’t a separate species at all.  By 1961 genetic tests had shown that the blue goose is a dark color morph of the snow goose.  According to Birds of North America Online, the color is “controlled by a single locus, the blue allele being incompletely dominant to the white.”   Although the blue color is somewhat dominant, snow geese tend to pick mates the same color as their parents so their white color persists.

The plaque next to the diorama explains how we’ve learned new things over time.

So when you hear a scientist making statements that include words like “may indicate” or “likely,” consider this.  Scientists aren’t being vague.  They’re speaking carefully from data that’s currently available. When they get even stronger evidence they’ll let you know. Statements like this are truthful: “Scientific studies indicate that extreme weather events such as heat waves and large storms are likely to become more frequent or more intense with human-induced climate change.” It only sounds vague to our society hungry for absolutes.

Meanwhile, we do know this is true: Blue geese are a color morph, not a separate species.

Visit the dioramas at the Carnegie Museum of Natural History on the first floor near Discover Basecamp.

(photos taken at Carnegie Museum by Kate St. John. photo of snow geese from Wikimedia Commons; click on the image to see the original)