Mad About Science:

By Brenden Bobby
Reader Columnist
Brought to you by the Sandpoint Library

Eggs are one of our most versatile foods, and also the key to the survival of most living species on the planet. Ever wonder how they work?

Me too, mostly because I slept through the drone of high school biology.

Seriously, they hadn’t made learning fun, yet!

So, what’s an egg?

You probably have one in the morning for breakfast most days. A chicken egg is a pretty good representation of most eggs.

It’s a vessel for the miracle of life to safely occur within. But the process isn’t magic.

In the case of a chicken, the egg, out in the open, is the end result. If the hen exists alone, the egg will be consistently infertile. Great for us, unless we want chicks.

If you introduce a rooster, suddenly, chances are any future eggs are going to be fertile, but the ones already laid won’t be. A rooster can’t fertilize an already laid egg because the shell (and hormones) prevents him from fertilizing it.

However, while the eggs are still forming inside of the hen, should the rooster and hen engage in the dance with no pants, the rooster’s sperm will merge with the forming egg, creating a fertilized egg. As the fertilized egg travels through the hen it will begin to form into the shape we recognize, gaining all of the nutrients it needs to hatch and the shell it requires to protect it during development.

Whoa, Brenden, keep this PG.

Sorry, sorry, biology is a messy process.

So the egg is fertile, why?

When the sperm and the nucleus of the egg first merged, they created something called a zygote. This is a merging of two sets of DNA into a eukaryotic cell, the most primitive form of embryonic life. Using DNA from both parents, the cell has the blueprints it needs to start building the baby it will become. The entire genetic past, present and future is condensed into something smaller than you can see with your naked eye.

This part of the process is identical for virtually all animals. Humans included.

Humans don’t lay eggs!

No, we don’t, but we make them. We also expel them once a month. The difference between our eggs and a chicken’s egg is that our anatomy holds the fertilized egg inside of us as it develops, while a chicken’s egg is expelled with the intention of hatching the baby. We are the egg’s shell.

A human baby is completely helpless after birth. If you were to leave a baby alone after birth, it would inevitably die. Baby chicks, on the other hand, have been preprogrammed by at least 120 million years of biological evolution to be completely autonomous after hatching. A clutch of baby chickens left alone after hatching in favorable conditions would be able to forage, hide from predators, locate water and grow into adulthood without the presence of an adult. It’s extremely unlikely, but the chances of a chick surviving to adulthood, no matter how small, still beat the absolute zero of an abandoned human baby.

Depressing as that might be, let’s swing the pendulum back. As long as a human baby has a parent fostering it, it will inevitably develop into an adult. Human development is vastly different from that of a chicken. We use more resources, require more nutrition, and look what we can do when we grow into adulthood. We figured out how to make tubes made of metal lift off the ground with explosions, leave the planet and come back.

A chicken can’t say that. It may be autonomous after birth, but it will never, ever aspire to be an apex predator or achieve written words or create civilization as long as humans dominate the earth.

Don’t feel bad for them. They had 120 million years to do this, and didn’t. It’s our chance. We’ll take them with us wherever we go, though. Maybe someday, somewhere on a forgotten human colony millions of years from now, a race of sentient birds will rise, and some quirky chicken library tech will be penning an article on how chicken eggs work.

Well, that took a strange turn.

We just sort of glazed over just about everything other than impregnation and birth. There is some serious stuff going on between these two points!

Essentially, the cells start dividing, following the blueprint offered by the parental DNA. The entire embryo doesn’t develop all at once, it favors stages of development, developing certain organs before others that vary based on nutrients available or the instructions of the genetic code. This process can vary greatly from creature to creature.

In the case of chickens, you can watch most of the process unfold before your eyes with a trick called candling. As any kid in 4-H knows, if you take a flashlight, set an egg on top and block out the excess light around the base with your fingers, the light will illuminate the interior of the egg. We use this to determine viability before and during incubation. You can watch the shadow of the embryo as it grows, which is much more exciting than it sounds.

I really wouldn’t suggest plunging a flashlight into a pregnant mom to replicate the results, unless you really, really like getting hit extremely hard in the face.

This is an intricate subject, and one that I can’t accurately cover in a word crunch, but it’s a subject that’s extremely well-documented. If you’ve ever been at all curious about how this process takes place, I encourage you to look it up. It’s not as confusing or intimidating as you might think. Just more than I can cover in this article!

Gosh, I say that a lot. Either way, I hope you enjoyed the thought of a chicken Brenden somewhere out there in the stars. I bet he’s a real handsome bird.