Pop open a carton of grocery store eggs and all 12 of them look identical. Gleaming white and nutritious. Open a carton of eggs laid by a mixed backyard flock of hens and the eye is greeted with a delightful array of shell colors, sizes, and shapes. They are as fascinating as they are delicious.
Chickens enjoy a genetic blend of 20,000 to 23,000 genes in over a billion base pairs. That’s not far short of humans with 20,000 to 25,000 genes and 2.8 billion base pairs. People come in all sorts of sizes, shapes, hues, and personalities, so it’s not surprising that chickens can be nearly as varied.
Grocery store eggs are the product of massive laying operations with thousands of hens in a single building. Producers strive for uniformity. Grading and sizing ensure that every egg looks exactly like the others. They’re the same color, usually white, and the same size, and usually nearly the same shape. Nutritious but boring.
Most flock-tending families delight in eggs that are both gorgeous and different. Pop the top off their egg carton and different varied shell colors, sizes, and shapes offer distinction. Diversity produces these gorgeous and delicious nest gems.
Hoover’s catalog lists breeds that lay eggs with white, light brown, brown, dark brown, blue, green, and olive shells. Some breeds lay mostly extra-large eggs, while others tend toward medium or small. Buying a variety guarantees that a carton of eggs will be intriguing. But just why do eggs vary so?
Chickens were domesticated from wild jungle fowl roaming the forests of southeast Asia. They laid white eggs. A great place to see wild chickens today is on Hawaii’s island of Kauai. They’re everywhere, often leading a procession of chicks. These birds, which are similar to the true wild chickens, lay white eggs.
Hundreds of years ago people living around the Mediterranean Sea created white egg laying breeds from wild ancestors. These include Leghorns, Minorcas, and Anconas. Leghorns and crosses developed from them produce nearly all of today’s commercial white eggs.
Back before recorded history a mutation likely caused a hen or hens to lay brown eggs. For some reason these were preferred by people living in northern and western Europe. They developed classic brown egg layers like Orpingtons and Sussex. Brown egg layers crossed the ocean in slow sailing ships. Intrepid Yankee breeders eventually created American brown egg breeds like Rhode Island and New Hampshire Reds, Plymouth Rocks, Wyandottes, and Jersey Giants.
Because Leghorns lay more eggs, while eating less feed than husky brown egg layers, they became the prime producer of commercial eggs. Eventually strains of productive brown egg layers were developed, like the ISA Brown, that today produce most commercial brown eggs.
Homeowners can order chicks from Hoover’s that will lay white, brown, dark brown, blueish and greenish eggs. Here are a few interesting egg tidbits:

Egg Shell Color
• A pigment called protoporphyrin creates brownish or reddish tint to eggshells.
• The pigment biliverdin produces greenish or bluish shades.
• The degree of pigmentation determines how dense the shade or color will be on the eggshell.
• White eggshells lack these pigments.
• Usually the intensity of brown egg color diminishes as a hen ages.
• Brown, green, blue, and white eggs are all equally nutritious.
Egg Shape
Eggs are “egg shaped” for a reason. Put an egg on the kitchen table and gently push it. The asymmetric shape causes it to roll in a circle. Seabirds that nest on exposed rock ledges over the ocean have the most asymmetric shaped eggs. That keeps a rolling egg inside the nest instead of rolling off the ledge into the water. Many owls and other birds that nest in hollow trees where it’s impossible for an egg to roll out generally lay roundish eggs. Chickens fall somewhere in between seabirds and owls in egg shape. Every once in a while, a hen will lay an odd-shaped egg or even one without a shell. But, that is unusual.
Egg Size
The first eggs that pullets lay are usually small, but after a month or two they are much larger. There isn’t a direct correlation between a hen’s body size and the eggs she lays. Brahmas, for example, are huge birds that lay small to medium size eggs. Leghorns weigh about half as much but lay larger eggs and, usually, more of them.
Hens are Individuals
Individual hens generally lay eggs of the same shape throughout their lives. For example, a bird that lays exceptionally pointy eggs will continue to lay that shape eggs while another hen of the same breed might lay more rounded ones. An occasional hen will lay eggs with shells that feel like sandpaper while her coop mates lay exceptionally smooth and glossy ones.
Part of the fun of caring for a backyard flock is enjoying the great diversity of chicken breeds and the rich colors, sizes, and shapes of the eggs they lay. A dozen varied eggs are as fun to see as they are tasty and nutritious.