Welcome to brain Stuff, a production of iHeartRadio, Hey brain Stuff Lauren vogelbamb here. The age old question of what came first, the chicken or the egg has confounded many and inspired plenty of hopefully friendly debates. Here's the dilemma. A chickens come from eggs, but you need a chicken to lay an egg. But can we figure out the answer to this question once and for all. Let's look at the evidence for both sides of the argument. Eggs have existed in nature for more than a billion years,
long before of any chicken was on the scene. Technically, an egg is just a container bound by membranes that allows an embryo to grow and develop with nutrients and at least a little protection from the harsh outside world. Almost all sexually reproducing species make eggs. An egg is just another word for the specialized cells that are female sex cells. Now. Animals originally laid their relatively simple eggs in ponds and other water borne environments, because otherwise the
eggs would have dried out at some point. Though maybe around three hundred and twelve million years ago, give or take, amniotic eggs came on the scene. These were eggs with three extra membranes inside. These membranes created a complex system within the egg to support the developing animal. A nutrient system, a waste system, a wave of exchanging air with the outside world aka respirating, and a bonus, a shell that would protect the egg even it did get dry on
the outside. This allowed for land based reproduction and paved the way for today's birds and reptiles and mammals too, though we tend to develop those life support structures in an internal placenta instead of an external egg. But okay, let's talk chickens. In nature, living things evolved through changes in their DNA. In an animal like a chicken, a DNA from a male sperm cell and a female egg meet combined to form a zygoat, which is the first
single cell of a new baby chicken. This first cell divides innumerable times to form all of the specialized cells of the complete animal. Although those cells do all kinds of different work in the animal's body, they usually all contain exactly the same DNA, the DNA that was created when the zygoat was created. So, in the case of chickens, a fertilized egg laid by a hen should hatch into a baby chick and either a butting hen or rooster
will be revealed. Once the chickens hatch, the process starts all over again. They grow, produce sex cells, and might well reproduce to create more fertilized eggs. Fun side note, female chickens will produce in lay eggs whether they get fertilized or not, kind of similar to how female humans usually produce eggs and then ject them through mensturation, whether they get fertilized or not. So yes, the chicken eggs that we eat are just large unfertilized female sect cells
which happened to be delicious when poached or scrambled. But okay, we were talking about what came first. Eggs predated chickens by a long shot, but these were not chicken eggs. The very first chicken would have been a genetic mutation from two other birds that we might call proto chickens.
The domestication process that led to this event happened over a long period of evolutionary history, during which the genetic makeup of all of these non chickens was edited through small changes caused by the mixing of the parent's DNA or mutations to that DNA that produced each new zygoat.
So what eventually happened was that two non chickens mated and the DNA in their new zygoat contained the combinations and or mutations that produced the first chicken that was more or less like the ones we know and love today. Scientists believe that the parents of the first chickens were
red jungle fowl, which are native to Southeast Asia. At some point long in the past, people there got to work domesticating red jungle fowl, that is, breeding them specifically for desirable traits such as less aggression and in this case, more prolific egg production. The road toward chicken, and thus toward chickens crossing roads, seems to have been a complex one. Archaeological evidence has suggested that the first true chicken appeared
around ten thousand years ago. However, DNA analysis and a bit of advanced probability mathematics has suggested that the chicken diverged from the red jungle fowl much farther back, around fifty eight thousand years ago, and also that some of the modern chickens jeans, like the ones that sometimes create the yellow color on the skin of their legs come
from interbreeding with other types of jungle fowl. After that, at any rate, if a chicken developed from a red jungle fowl egg, then you could argue that the chicken came first, and afterward it grew up to produce the first chicken egg. But consider it this, Before that first true chicken zygoat, there were only non chicken jungle foul species. The zygoat's cell is where DNA combinations and mutations take place to produce the blueprint for a new animal. The
zygoat cell then grows its own egg. So therefore, the first true chicken egg must have come before the first fully realized chicken queed. Today's episode is based on the article what came first, the Chicken or the Egg? On
HowStuffWorks dot Com written by Leah hoy. The Brainstuff is production of iHeartRadio in partnership with how stuffworks dot Com, and it is produced by Tyler klang A. Four more podcasts from my heart Radio visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.