America is a nation of egg eaters: The average U.S. adult eats about five eggs each week.

Eggs are cheap, versatile and nutritious, which is why they've emerged as a quintessential supermarket staple, along with milk and bread. But egg prices, which animal rights advocates say have been tamped down by brutal farming practices, are on the rise this month. That's because a California law prohibiting the sale of eggs from hens housed in cramped cages took effect on Jan. 1. According to the law, chickens must be granted at least 116 square inches of floor space, a span that scientists determined provides enough room for wing-flapping and turning around.

To continue selling eggs in California, major egg producers across the country have had to adjust their operations. Rather than immediately build new henhouses, most chicken farms are now opting to halve the number of chickens in their existing cages, NPR recently reported. Fewer chickens mean fewer eggs sold at higher prices. The Egg Industry Center at Iowa State University last month released a forecast estimating a 15 percent price increase.

For farms such as the Midwest's Centrum Valley, which maintains henhouses populated by more than 1 million chickens apiece, long-term compliance will be costly: "You're talking about millions upon millions of dollars," the company's chief executive recently told The New York Times. But the new rule isn't as daunting to South Carolina's small-scale egg farmers, many of whom already use roomier cages and sell their product exclusively to local markets.

Here, seven more things to know about eggs:

1. Reptiles beat birds to the egg-laying punch, but it's the avian version of the protein that caught on with humans. According to the American Egg Board, fowl were domesticated in East India by 3200 B.C. Within 1,500 years, laying hens were being raised in China and Egypt; the practice reached Europe by 600 B.C. While chickens aren't the only birds producing desirable eggs - duck eggs, goose eggs, quail eggs and ostrich eggs can all claim various culinary glories - chicken eggs are considered the global standard. There are hundreds of different chicken breeds, but the white leghorn, which may trace its roots to Tuscany, is the most common layer in the U.S.

2. Eggs taste the same whether their shells are white, brown or speckled, but consumers have strong preferences about which eggs will grace their plates. Brown-shell eggs are popular in Ireland and France, for example, while white-shell eggs are prized in Egypt. All eggs are white to start, but certain egg shells pick up pigments during their 26-hour trip through the hen's oviduct. According to Michigan State University, color is a matter of genetics: "Orpingtons lay brown eggs and Ameraucana produce blue eggs." If you're not familiar with various chicken breeds, you can predict the color of a hen's eggs by checking the color of her earlobes.

3. Prior to 1911, the baskets that are now associated primarily with Easter egg hunts were the main way to transport eggs. But the baskets offered no assurance against breakage, as a British Columbia newspaper publisher learned from overhearing an argument between a deliveryman and a hotel owner tired of paying for broken eggs. Joseph Coyle, who would also contribute a pocket cigar cutter to society, came up with a carton with "individual cushioned slots," The Globe and Mail recounted. In 1919, Coyle gave up newspapering and opened a series of factories to manufacture his invention.

4. Egg cartons today are emblazoned with lots of phrases intended to conjure images of happy chickens and healthful eggs. The Salt, NPR's food blog, recently published an overview of what the verbiage really means. According to the glossary, a few of the terms, such as "farm fresh" and "all-natural," have no meaning whatsoever. Other terms are accurate, but potentially misleading: "No hormones" indicates only that the farm is complying with federal law, since it's illegal to give hormones to poultry. And while "vegetarian diet" is an odd claim, since chickens are naturally omnivorous, it probably refers to an all-corn diet. Finally, "cage free" means hens are raised in an aviary, although the average cage-free hen has no more than 1 square foot of living space: Cage-free hens are twice as likely as their caged counterparts to die in captivity, usually from a fatal pecking. If you're seeking eggs from hens brought up in a setting that approximates a natural environment, your best bet is an egg labeled "pasture-raised."

5. Eggs are notoriously high in cholesterol. But they're also an excellent source of B vitamins and minerals. For eaters who don't suffer from diabetes or cholesterol management issues, there is no increased risk of heart disease associated with consuming one egg a day. Still, the Harvard School of Public Health warns, "This research doesn't give the green light to daily three-egg omelets. You also need to pay attention to the 'trimmings' that come with your eggs. To your cardiovascular system, scrambled eggs, salsa, and a whole wheat English muffin are a far different meal than scrambled eggs with cheese, sausages, home fries, and white toast."

6. In the U.S., eggs go in the refrigerator. But in Europe, they're left out at room temperature. That's a result of two different strategies for ensuring food safety (Whole Foods has crunched the salmonella data, and concluded that a person who eats one egg per day can expect to eat one contaminated egg every 54 years.) American producers wash their eggs, and then refrigerate them to make up for having scrubbed off a protective layer, while European producers sell their eggs unwashed.

7. Omelets long have been the ultimate skill test for classically trained chefs in the West, but eggs are increasingly making other appearances on upscale menus. (Los Angeles Times critic Jonathan Gold told Eater that "eggs on everything," was the most grating trend of 2014.) When the American Egg Board surveyed the restaurants on Bon Appetit's list of best new restaurants, it found a sandwich of marinated mushrooms, sauteed kale and soft eggs; a wagyu burger topped with an over-easy egg; and eggs plated with porchetta and kimchi.