How did the pestle and the white invade our plates? Where do the 80 billion chickens present in all parts of the planet come from? To what is due the extraordinary success of a species whose individuals alone weigh as much as all the birds in the world put together? It is to this delicate question that the in-depth article that has just been published by the PNAS. “We have revisited more than 600 archaeological sites in 89 countries based not only on the analysis of geological layers giving an approximate date of the bones found but by a direct analysis by carbon 14″, explains Ophélie Lebrasseur, researcher at the Center for Anthropobiology and Genomics at Paul Sabatier University in Toulouse and co-author of the article.
First of all, this work settles its account with a few poorly substantiated scientific assertions. It must be said that the subject is difficult. Interest in the remains of bird bones present on archaeological sites is relatively recent and there are therefore few exploitable elements. The dating by age of the geological layers where the relics are discovered (taphonomy) is uncertain and can lead to false interpretations on sites that have not been excavated finely. Furthermore, gallus gallus can easily be confused with cousins of their Phasianidae family such as pheasants. Finally, the ancestor of our chickens, the golden rooster, comes from the forests of Thailand where archaeological sites are rare. Despite these obstacles, the authors are adamant. Thailand is indeed the country of origin of our Gallus gallus domesticus and among the species of the genus Gallus, Gallus spadiceus is, according to genetic analyses, the great ancestor. Exit, therefore, the works dating from 1988 claiming that the chicken comes from northern China and that its domestication dates back 8000 years. “It is much too cold there for this species and our analyzes show that there was confusion with pheasants”, denounces Ophelie Lebrasseur. Similarly, studies fixing origins in the Indian subcontinent are discarded because of hasty conclusions from single taphonomic examinations.
Skeletons found in Bronze Age tombs
The research team has identified the only three archaeological sites where carbon-14 dating leaves no doubt. The Neolithic site of Ban Non Wat thus covers a period from -1650 to -1250 BC, in a region of eastern Thailand where golden roosters of the species still live. gallus gallus and Gallus spadiceus. Several factors support this hypothesis. Many chicken bones were found near the houses. Then whole skeletal remains are present in graves alongside other domesticated animals like pigs and cattle from this Bronze Age. Two elements which plead for a strong proximity of the bird and the Man. Studies claiming that the golden rooster is found in India within the Harappan culture of the Indus basin between -2600 and -1900 BC are not confirmed by carbon dating and again an error of interpretation geological layers is highlighted.
The golden rooster is a forest species that also likes to frequent areas of regrowth of less dense trees whose soil was previously exploited by burning.
How did the pestle and the white invade our plates? Where do the 80 billion chickens present in all parts of the planet come from? To what is due the extraordinary success of a species whose individuals alone weigh as much as all the birds in the world put together? It is to this delicate question that the in-depth article that has just been published by the PNAS. “We have revisited more than 600 archaeological sites in 89 countries based not only on the analysis of geological layers giving an approximate date of the bones found but by a direct analysis by carbon 14″, explains Ophélie Lebrasseur, researcher at the Center for Anthropobiology and Genomics at Paul Sabatier University in Toulouse and co-author of the article.
First of all, this work settles its account with a few poorly substantiated scientific assertions. It must be said that the subject is difficult. Interest in the remains of bird bones present on archaeological sites is relatively recent and there are therefore few exploitable elements. The dating by age of the geological layers where the relics are discovered (taphonomy) is uncertain and can lead to false interpretations on sites that have not been excavated finely. Furthermore, gallus gallus can easily be confused with cousins of their Phasianidae family such as pheasants. Finally, the ancestor of our chickens, the golden rooster, comes from the forests of Thailand where archaeological sites are rare. Despite these obstacles, the authors are adamant. Thailand is indeed the country of origin of our Gallus gallus domesticus and among the species of the genus Gallus, Gallus spadiceus is, according to genetic analyses, the great ancestor. Exit, therefore, the works dating from 1988 claiming that the chicken comes from northern China and that its domestication dates back 8000 years. “It is much too cold there for this species and our analyzes show that there was confusion with pheasants”, denounces Ophelie Lebrasseur. Similarly, studies fixing origins in the Indian subcontinent are discarded because of hasty conclusions from single taphonomic examinations.
Skeletons found in Bronze Age tombs
The research team has identified the only three archaeological sites where carbon-14 dating leaves no doubt. The Neolithic site of Ban Non Wat thus covers a period from -1650 to -1250 BC, in a region of eastern Thailand where golden roosters of the species still live. gallus gallus and Gallus spadiceus. Several factors support this hypothesis. Many chicken bones were found near the houses. Then whole skeletal remains are present in graves alongside other domesticated animals like pigs and cattle from this Bronze Age. Two elements which plead for a strong proximity of the bird and the Man. Studies claiming that the golden rooster is found in India within the Harappan culture of the Indus basin between -2600 and -1900 BC are not confirmed by carbon dating and again an error of interpretation geological layers is highlighted.
The golden rooster is a forest species that also likes to frequent areas of regrowth of less dense trees whose soil was previously exploited by burning. The idea developed by the article is that the bird would have been attracted by the plant upheavals caused by the beginnings of agriculture. “HAS Ban Non Wat, Non Nok Tha and Ban Na Di, the three major archaeological sites in eastern Thailand, the cultivation of rice without irrigation arrived after -1500 BCE, which corresponds with our observations on the presence of the bird close to man”, continues Ophélie Lebrasseur. gallus gallus would therefore have been attracted by the transformation of the forest environment but also by the presence of the grains of rice and millet on which it feeds.
A rapid conquest of India, Asia Minor and then the Mediterranean basin
The re-reading of the archaeological sites subsequently shows an east-west and not a north-south colonization linked to the cultivation of cereals. Because the bird remains subservient to warm regions. Thus, its arrival in India is reviewed at the end of the second millennium BC when the cultivation of cereals was already widespread in the Indus basin. Diffusion is then relatively rapid: Iraq around -1200, Mesopotamia and the Middle East between -1150 and -950, Egypt of the Achaemids around -500 with evidence of breeding under the Ptolemy era ( around -350). In the Mediterranean basin, it is the Greeks who prove to be the greatest “dispersers” because of the speed of the maritime trade routes. The presence was confirmed around -800 in Italy where the remains of bones were found in two sites of Greek colonies occupied from -776 to -540. There is no evidence of presence in France before the first century after our era. And it takes nearly 500 more years for the British Isles and Scandinavia to be reached. This whole chronology is now well established thanks to the work of European researchers from all the disciplines involved, brought together in the project “cultural and scientific perceptions of the interactions between humans and chickens” started in 2014. This is how papyri Egyptians, bas-reliefs from Mesopotamia, remains of Assyrian temples and religious texts were used. An example: the chicken is completely absent from the Bible, but present in the New Testament.
A thousand years is what it takes for a tropical species to acclimatize to temperate climates. But maybe not for temperature issues. “To bear the cold, it is enough to eat moretable Michèle Tixier-Boichard, researcher at INRAe in Jouy-en-Josas and specialist in the hen genome. On the other hand, we were able to determine by comparison of the genome of the golden rooster and a current chicken, the mutation of the gene for adaptation to the rhythm of alternation of day and night, which shows that it is the variations in duration greater light and darkness in temperate countries than in tropical countries, which constitutes the main obstacle to adaptation, particularly for physiological functions such as egg formation”.
A precious gift before being food
It remains to be determined why Man made the bird travel. Eating cannot be the main motivation. The current golden rooster never weighs more than a kilo and has little flesh. Hence the idea that, in the first phase of cohabitation, the bird should be kept for cultural reasons: the beauty of its plumage, a valuable exotic gift, or even a fight between males. This is what is developed in a collective article by archeology units from English universities retracing the spread of chicken in Europe between -800 and the High Middle Ages published in May 2021 in the scientific journal Antiquity. The authors cite in particular Julius Caesar who, in “of the Gallic Wars” affirms that the bird was rare and precious, too much to eat. Of the 23 remains dating from the oldest in the 8th century BC to the most recent, in the High Middle Ages, none shows any sign of predation. Better, most of the skeleton members found were found in graves. The long traces of an individual found in England show that the animal was two years old at the time of its death and that it had therefore probably died of old age. And a leg also unearthed in England shows attempts to heal a broken bone.
In the laboratory, comparison of modern chicken bones (top) and ancient chickens. Copyright Jonathan Rees/ Cardiff University
It is therefore only a few centuries after its cohabitation with Man, that the chicken loses its status as a rare and revered animal to become an ordinary food. That’s all recent chicken history. Since the Middle Ages, thanks to selection on farms at first, then by agro-industry since the 1950s, Gallus gallus domesticus doubled in size and tripled in weight while laying hens increased from a few eggs per year to more than 300 for the most productive individuals. Poultry has thus become a staple of the dining table.Homo sapiens and a heavyweight in the global economy. The relentless selection continues without there being a change of species. A golden rooster from the forests of Thailand where it still lives (IUCN considers it not endangered) can still fertilize a laying hen from a caged farm. “Genome mutations weren’t all that big“, says Michèle Tixier-Boichard astonished. Next August, the world hen congress will be held in Paris. And between two sessions on biotechnologies applied to the urban cousins of the rural golden rooster, genomics specialists will wonder about the ethical questions raised by such intense exploitation of a species.