UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
What came first the chicken or the egg?
Question Date: 2006-01-20
Answer 1:

Scientists agree on where the first domestic chickens came from, saying that all chickens can be traced to the same ancestors - the Red Jungle Fowl from Asia. They were probably bred from this particular subspecies more than 8,000 years ago.

The male Red Jungle Fowl looks a lot like a storybook rooster but it is not identical to the domestic chicken we know. Man has managed to cultivate animals for over 10,000 years. Farm animals (cows, pigs, horses) as well as domestic cats and dogs have been bred by humans in a way that has changed them from their wild ancestors to suite mans needs. This process of change is actually what we know as evolution. In nature, living things evolve through changes in their DNA. In the chicken, like in other animals, DNA from a male sperm cell and a female ovum meet and combine to form a zygote -- the first cell of a new baby chicken. The zygote divides innumerable times to form all of the cells of the complete animal. When small mutations happen in the DNA that produces the zygote or even by the mixing of male and female DNA, a new zygote containing the mutations can produce a different kind of chicken. So the first official "domestic chicken" as we know it came out of an egg, laid by a different ancestral chicken.

The zygote cell is the only cell where DNA mutations could produce a new animal, and the zygote is housed in the chicken's egg. This means that the egg of the first domestic chicken came first.

Here is another way to look at your question: Scientists think that a group of egg-laying feathered dinosaurs were probably the ancestors of today's birds. It is thought that eggs evolved more than 1 billion years ago, in oceanic species. When land animals evolved, coming onto land, their eggs had a tough covering to retain moisture on dry land. Egg-laying animals like amphibians, reptiles, and insects prospered. The first "land eggs" pre-dated chickens by about 250 million years.

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use