By James Gamble via SWNS
Chickens first crossed the Silk Road to domestication 2,400 years ago, scientists have revealed.
A new study analyzing ancient eggshell fragments found chickens were widely domesticated in central Asia from around 2,400 years ago.
Researchers believe their domestication for egg production coincided with the discovery of hens’ ability to lay eggs year-round instead of just once a year like similar birds.
The international team of scientists behind the study says it offers important clues to understanding the preliminary stages of our domestication of animals.
Today, chickens are one of the most economically important animals in the world.
However, the story of their origins and dispersal across the ancient world remains shrouded in mystery.
New archaeological techniques recently led to the recognition that many bones previously thought to be from early chickens actually belonged to wild birds.
But in their new study, an international team of archaeologists, historians, and scientists discovered the earliest clear evidence of the raising of chickens for egg production.
Using eggshell fragments from archaeological sites spanning roughly 1,500 years, the researchers found that chickens were widely raised in Central Asia from approximately 400 BC to 1000 AD and were likely dispersed along the ancient network of Eurasian trade routes known as the Silk Road.
The researchers added that the abundance of eggshells further suggests that the birds were laying out of season and that it was this trait of prolific egg-laying that made the domestic chicken so attractive to ancient populations.
The research team collected tens of thousands of eggshell fragments from 12 sites located along the main Central Asian corridor of the Silk Road, using a method of biomolecular analysis called ZooMS to identify the source of the eggs.
Much like genetic analysis, ZooMS can make species identifications from animal remains such as bone, skin and shell but relies on protein signals rather than DNA – making it a faster and more cost-effective option.
Dr. Carli Peters, the study’s first author from the Max Planck Institute of Geoanthropology in Germany, explained: “This study showcases the potential of ZooMS to shed light on human-animal interactions in the past.”
The identification of these shell fragments as chickens and their abundance throughout the sediment layers at each site led the researchers to an important conclusion: the birds must have been laying more frequently than their wild ancestor, the red jungle fowl, which nests once per year and typically lays six eggs per clutch.
In central Asia, evidence suggests that the ability to lay a multitude of eggs made the chicken the economically important, domesticated bird we know today.
“This is the earliest evidence for the loss of seasonal egg laying yet identified in the archaeological record,” Dr. Robert Spengler, leader of the Domestication and Anthropogenic Evolution research group and principal investigator on the study, added.
“This is an important clue for better understanding the mutualistic relationships between humans and animals that resulted in domestication.”
The authors hope their study will demonstrate the potential of new, cost-effective methods and interdisciplinary collaboration to address long-standing questions about our past.
