Charles Darwin was born Feb. 12, 1809, five decades before he would forever change the field of biology with "On the Origin of Species." Another book, published 143 years later, dubbed his opus on evolution "the single best idea, ever."

The editors of that book helped found Darwin Day in the 1990s, honoring not just Darwin, but also "the achievements of humanity as represented in the acquisition of verifiable scientific knowledge." People had already been celebrating Darwin's birthday on Feb. 12 for decades, but Darwin Day became a global holiday for science, with Darwin as its patriarch — sort of like a less jolly, more scholarly Santa Claus.

But while Darwin's discovery of natural selection has revolutionized science, it has also inspired generations of critics. Some distrust it for religious reasons, seeing it as a threat to creationism or "intelligent design," and some just don't like to think of people as animals. Darwin wasn't anti-religion, though; he was on track to be a clergyman before his fateful Galapagos trip, and he's buried at Westminster Abbey.

Promoting peace between science and religion is the focus of another Darwin-themed event this month: the Clergy Letter Project's Evolution Weekend, held every year on the weekend nearest Darwin's birthday. The idea is for religious groups to discuss evolution, whether in a sermon or just as a side topic in Sunday school. Some advocates of intelligent design dismiss this as a push to "Darwinize," but it has still spread to hundreds of congregations in five countries and 43 U.S. states.

There have also been renewed efforts lately to make Darwin Day a U.S. holiday. Former U.S. Rep. Rush Holt of New Jersey, for example, introduced a resolution in 2013 "expressing support" for the federal designation of Darwin Day, an idea first floated in 2011 by former Rep. Pete Stark of California.

"Charles Darwin is even more than the author of the theory of evolution, as great as that is," Holt said in a statement. "He represents a way of thinking, a philosophy, a methodology. It was his thirst for knowledge and scientific approach to discovering new truths that enabled him to develop the theory of evolution. This lesson, about the value of scientific thinking, is almost as valuable as the theory he uncovered."

Holt's efforts failed, but Rep. Jim Himes of Connecticut took over fighting for the Darwin legislation, saying he has championed it because “science and truth remarkably always need advocacy against the forces of nostalgia and fear and irrationality.”

Darwin Day balloon Balloons commemorate Darwin Day at the University of Arizona. (Photo: Katja Schulz/flickr)

If you'd like to honor Darwin's legacy but aren't sure how, here are a few suggestions:

Host a Phylum Feast: Darwin enthusiasts have been holding yearly Phylum Feasts on Feb. 12 since at least the 1970s. A Phylum Feast is a potluck dinner in which all the dishes are as biodiverse as possible — ideally, each should come from a different phylum. Darwin reportedly enjoyed eating "birds and beasts ... unknown to human palate," and many people still see this as a way to embrace our evolutionary past.

"Most of our day-to-day food comes from a small number of domesticated vertebrates and grasses," writes Phylum Feast enthusiast Frederick Schueler, "but by seeking out and identifying the diverse biotic sources of our diet in this meal, we remember our origin as omnivores, and our relatedness to other lineages."

Make "primordial soup": Of course, the idea of a Phylum Feast can make conservationists cringe, especially when the menu includes rare or exotic items like minke whale. Phyla diversity is also limited at some grocery stores, often making such feasts impractical. But you could always just make another Darwin Day favorite instead: "primordial soup." Named after the cocktail of amino acids believed to spark the first life on Earth, this dish is wide open to interpretation — from simple stews to Phylum Feasts in a pot.

Attend a Darwin Day event: There are hundreds of Darwin Day events worldwide every year, and darwinday.org offers a partial list of upcoming options. Many are one-day affairs, including several held on Evolution Weekend rather than Darwin Day itself. But the site also lists an array of longer events, like annual "Darwin Week" celebrations in Charleston, South Carolina, as well as Naples, Italy. Darwin Day originally focused on scientific lectures, but today it includes debates, museum exhibits, film festivals, art shows, essay contests and more. Some use the holiday to jointly honor U.S. President Abraham Lincoln, who was also born on Feb. 12, 1809.

Go to church: Evolution Weekend is organized by the Clergy Letter Project in hopes of mending an old rift between Darwin and some religious groups. The goal is to foster open discussion about evolution in places of worship, an attempt to "show that religion and science are not adversaries." That doesn't mean capitulating on the scientific validity of evolution, though. It just means spending one weekend focusing on common ground rather than rehashing the same old debates from the Scopes monkey trial.

As the CLP explains on its website:

"Religious people from many diverse faith traditions and locations around the world understand that evolution is quite simply sound science; and for them, it does not in any way threaten, demean, or diminish their faith in God. In fact, for many, the wonders of science often enhance and deepen their awe and gratitude towards God."

Read "On the Origin of Species": Not only is the full text of Darwin's seminal work available online, but so are all of his publications. It's a lot to absorb in one day, or even three days, but a chilly February weekend might nonetheless be a good time to dig in — with a steaming bowl of primordial soup, of course.

For more information about evolution by natural selection, check out this classic (and animated) explanation by the late astronomer and science educator Carl Sagan:

Editor's Note: This story has been updated since it was first published Feb. 10, 2012.

Happy Darwin Day and Evolution Weekend
Charles Darwin's birthday has become not just an international holiday, but an entire evolution-themed weekend. Here are five ideas for how to celebrate.