It’s been just 150 years since the publication of “On the Origin of Species,” in which Charles Darwin outlined his argument that all life forms descended from a common ancestor.

That is scarcely an eyeblink in the epic context of evolutionary time, so perhaps we ought not to get too bent out of shape over a Gallup Poll suggesting that less than half of American adults are willing to acknowledge that Darwin was on to something.

In fact, data gathered on the bicentennial celebration of Darwin’s birthday and re-posted this week show that just 39 percent of those surveyed in a 2009 random sample of 1,018 respondents said they “believe in the theory of evolution,” while 25 percent reject Darwin’s argument outright.

Another 36 percent, or nearly all the rest of those surveyed, said they had no opinion either way, which strikes us as a little like having no opinion whether the law of gravity has merit.

Americans’ continuing reluctance to embrace Darwin’s argument is slightly more alarming when you consider that virtually everything biologists have since discovered either confirms or refines his theory of natural selection.

What is most worrisome, to those of us who struggle in the even more amorphous realm of public policy, is the absence of consensus about the validity of basic scientific method — the process of testing hypotheses about how the world works against repeated and disciplined observations of the world. How can Americans find common ground on the subject of, say, global warming, if most of us remain suspicious about a scientific consensus that has endured more than a century longer?

The good news, according to Darwin, is that nature favors adaptations that enhance a species’ survival. So, assuming observation continues to bear out his theory of evolution, not only is our species’ eyesight improving, but also its capacity to acknowledge what our eyes see.