Chickens: How We Got Here

A red junglefowl outside.
The modern Red Junglefowl- provided by Francesco Veronesi through a CC BY SA 2.0 License

Updated September 23, 2020

A Long Road To The Present

The domestic chicken that we know and love (Gallus Domesticus) has an early history shrouded in mystery. We know that their ancestor, the Red Junglefowl, still lives in the wilds of Southeast Asia, and the prevailing theory suggests that early domestic chickens were kept in China nearly 8000 years ago. How they spread across the world is up for exploration, following trade routes and the silk road. Some scholars trace their journey to America over a thousand years ago through Polynesian sailors traveling to South America. Regardless of how the chicken got around, it’s no debate that due to human intervention, domestic chickens are remarkably different than their jungle-dwelling relatives.

Chicken Challenges

Modern domestic chickens have been selectively bred for specific human-desired traits, much to the detriment of their own wellbeing. In the case of Cornish crosses and other large breed chickens (often referred to as “Broilers” or “Meat Breeds”), the chickens most commonly consumed by people, they have been bred to be significantly larger and more docile than their wild counterparts. Since the 1950’s, when chicken feed was fortified with antibiotics and vitamins that could keep them indoors, Cornish crosses have been selectively bred in staggering numbers to almost double the size of their mid-century counterpart, with 80% larger breasts. These chickens now reach industry “slaughter weight” as early as 42 days. This rapid growth contributes to a variety of health challenges, especially leg and joint problems and heart failure. A 2008 study of over 50,000 chickens discovered that, by 40 days of age, over 27% of the chickens had impaired walking capability and 3.3% were nearly unable to walk.

In addition to Cornish crosses, we use the term “large breed” to refer to other chickens who have been bred to grow quickly- not as quickly as Cornish crosses, but faster than other breeds- and are typically marketed as “free-range broilers.”  As a group they are often called “colored hybrid broilers” but include many different Trade names such as Freedom Ranger, Red Ranger, and Kosher King. These chickens face similar health challenges as Cornish crosses. For more information regarding how to properly care for large breed chickens, check out our resource here. 

Chickens bred for their egg-laying ability produce a significantly larger amount of eggs annually than their wild counterparts and face their own unique health challenges as a result. The Red Junglefowl lays approximately 10 to 15 eggs in an entire year, in one or two clutches. A modern “egg-laying” hen has been bred to lay between 250 and over 300 large eggs in a year. Considering that it takes around a day for an egg to be formed, this means that these hens could be in the midst of producing an egg year round- a highly taxing and potentially dangerous process; egg overproduction can lead to fatal reproductive tract diseases such as cancer, egg yolk impactions, peritonitis, egg binding, and malnutrition and osteoporosis. Although a domestic chicken can live on average between ten and fifteen years, hens bred for heavy egg production (such as white Leghorns and sexlink hybrids) typically live closer to five years due to health complications related to egg production. In the commercial egg industry, hens are killed when their egg production or health declines, typically between one to two years old. Male offspring of “egg-laying” hens are killed shortly after birth as they hold little value to commercial egg production (and they face a similarly cruel fate in most backyard chicken settings).

In addition to using selective breeding practices for egg and meat production, other chickens have been bred for use in cock fighting or as ornamental breeds, and some breeds are considered “dual purpose” because they are often exploited for both their eggs and their flesh.

Today, domestic chickens still share many characteristics with their wild counterparts; although smaller, the Red Junglefowl still looks remarkably similar to many birds we’ve gotten to know. And though many may believe that a chicken craves wandering on an open plain, they actually feel much safer and more content spending their outdoor time in a forested area with shady trees. Maybe they’re looking for their own jungle to call home!


The Domestication History Of Chickens | Thought Co

Non-Cornish Chicken Care | Farm Sanctuary

Large Breed Chicken Care | Farm Sanctuary

Eggs: What Are You Really Eating? | Free From Harm

The Genetically Modified Chicken | One Green Planet

Broiler Chickens Bred For Fast Growth Have A Hard Time Walking | Science Daily

How The Chicken Conquered The World | Smithsonian Magazine

Updated on December 23, 2020

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