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No evidence of chicken bones in Neolithic and Bronze Age Northern China (Eda et al. 2016)

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No evidence of chicken bones in Neolithic and Bronze Age Northern China (Eda et al. 2016)

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One of the most significant criticisms came from a paper by Eda et al. (2016) in which 1831 birds, including 429 purported chicken bones, were analysed from 18 Neolithic and Bronze Age sites in Northern China.

Impressively, none of the bones analysed could be identified as a chicken or junglefowl with the pheasant being predominant.

This was achieved using various morphological criteria that distinguish between Gallus and Phasianus species.

For example, pheasant femur's possess a pneumatic foramen on the greater trochanter that is absent in Gallus species.

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Galliformes are heavy-bodied ground-feeding birds and account for the majority of domestic bird species.

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There are 185 species, across 54 genera, and include chickens, pheasants, junglefowl, partridges, and turkeys.

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Geographic distribution of individual junglefowl species in Southeast Asia and proposed dispersal routes of the domestic chicken (Lawal and Hanotte 2021, 2).

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This genus refers to the four extant junglefowl species:

Red junglefowl (Gallus gallus)

Sri Lankan junglefowl (Gallus lafayetti)

Grey junglefowl (Gallus sonneratii)

Green junglefowl (Gallus varius)

These species all naturally inhabit Southeast Asia.

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The chicken (Gallus gallus domesticus) is generally agreed to have been domesticated from the red junglefowl (Gallus gallus).

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Chickens are remarkably simple animals to manage by humans:

They can be kept within a settlement because of their small size compared to most domestic animals.

They are omnivorous animals - consuming seeds, other plant matter, and small invertebrates, household waste - capable of sourcing their own food.

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NB - the radial and ulnar carpals are not labelled in this diagram; the tibiotarsus (tibia) and tarsometarsus (metatarsus) are mislabelled.

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The chicken is found across all levels of society throughout history (Serjeantson 2009, 267).

Humans exploit them in a variety of ways that are visible today and in the archaeological record:

Meat and eggs

Clothing (feathers and skins) and ornamentation (feathers and bones)

Ritual and iconography - i.e., cockfighting and exoticism.

Pets

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Global distribution of the chicken in birds per square kilometre (Robinson et al. 2014, 7).

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The chicken is the most widespread domestic animal in the world.

Click here for link to article.

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Tarsometarsus of female chicken (left, no spur or scar), male chicken (middle, spur present), and immature chicken (right, spur scar) (Serjeantson 2009, 275).

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Cockerels - and most other male Galliformes - are defined by a spur (bony projection) on the medial tarsometatarsus.

However, spurs are present in a small number of female chickens.

Immature cockerels are identified by a spur scar, the site where the spur fuses.

Spurs also have a potential in the ageing of male chickens as they form and fuse after they have reached sexual maturity (around 4 months old).

For example, Doherty et al. (2021) - analysing male chickens of known age - show that the spur only appears significantly fused in individuals >2 years old.

Additionally, the spur was only fused in all individuals >6 years old.

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Tarsometatarsus of male, female, and immature chickens

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Development and formation of medullary bone in a female bird (Serjeantson 2009, 50).

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A characteristic of most female birds is the development of medullary bone around and during the time of egg laying.

In effect, it is an additional supply of calcium - stored in the bone - that is used in egg calcification.

It is common in the femur and tibiotarsus, an element often fragmented in the archaeological record.

A high incidence of chicken medullary bone in archaeological sites may indicate their management for egg production.

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Chicken bones are difficult to recover in the archaeological record as a consequence of their small size and high fragmentation.

Fragmentation may be caused through non-anthropogenic action - exaggerated by their pneumatic nature - or through anthropogenic processes such as butchery.

They are also very difficult to identify in the archaeological record as they are morphologically similar to other members of the Phasianidae family (i.e., pheasants and partridges).

This is developed upon in the discussion of chicken domestication.

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The chicken is a sexually dimorphic species with various differences between male (cockerels) and female (hens) chickens.

At its simplest, cockerel bones are generally longer and broader than hen bones.

However, the long histories of domestication have produced many breeds whose size differences vary between and within sexes.

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The 'eggsploitation' of chickens is generally considered from a dietary perspective (their meat and eggs). Therefore, there is an extensive literature related to this exploitation and a variety of methods considered.

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Evidence of intensive egg production from medullary bone (Lentacker and van Neer 1996)

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Evidence of intensive egg production from medullary bone (Lentacker and van Neer 1996)

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The authors analyse avifaunal remains from a Roman military fort ('Abu Sha'ar) and harbour (Berenike).

I'm focusing on Berenike as 92.5% of avifaunal remains were chicken (161/186); only 16.4% (9/55) of avifaunal remains at 'Abu Sha'ar were identified as chicken.

Analysis of chicken bones (n = 161) from Berenike showed that 66% of all bones contained medullary bone.

These were from pre-existing fragmented material and bones fragmented during the analysis.

This suggests that hens were slaughtered towards the end of the laying season as medullary bone is resorbed 1-3 weeks after laying.

The presence of immature chicken remains also supports this interpretation having been killed for their meat.

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Diachronic changes in chicken husbandry across the United Kingdom (Doherty et al. 2021)

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Diachronic changes in chicken husbandry across the United Kingdom (Doherty et al. 2021)

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The authors developed a formula - following their analysis of spurs on cockerels of known age - to apply in archaeological contexts.

Using this formula, the authors analysed 160 tarsometatarsi from the UK dating from the Iron Age to modern period.

Their analysis identified changing patterns in chicken husbandry across this period:
Cockerels, with spurs, were predominant in the Iron Age and Roman periods attesting to their non-dietary function - i.e., cockfighting - that is common across Europe in these periods.

From the Saxon to Norman periods, cockerels are less predominant and generally younger suggesting an increased focus on meat and egg production. This is associated with bans on the consumption of four-legged animals with the rise of Christianity.

Juvenile chicken bones are predominant from the High Medieval to Early Modern periods suggesting an emphasis on meat production. However, cockerels are present in significant numbers and at older ages associated with a renewed interest in cockfighting.

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Using ZooMS to identify chicken egg production from archaeological eggshell (Spengler et al. 2022)

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Using ZooMS to identify chicken egg production from archaeological eggshell (Spengler et al. 2022)

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This paper focused on the identification of chicken husbandry in 12 sites (residential (n  = 11); burial (n=1)) in Central Asia along the Silk Road.

They were interested in the dispersal of domestic chicken beyond its natural range and their exploitation.

The sites ranged in age from the last centuries BCE to medieval period (c.1200 CE).

Eggshell was sampled from sediments across all sites; at each site they were recovered in significant quantities.

Eighteen fragments were selected for ZooMS - all fragments from residential sites were identified as chicken.

They were also distinguished from close relatives using Liquid Chromatography tandem mass spectrometry (LC-MS/MS).

The ubiquity of chicken eggshell was suggested to represent intensive egg production with the chickens having lost the natural habit of the red junglefowl (1 brood per year of ~6 eggs).

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A reconstruction of chicken husbandry practices in Roman Britain (Maltby et al. 2018)

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A reconstruction of chicken husbandry practices in Roman Britain (Maltby et al. 2018)

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A reconstruction of chicken husbandry practices in Roman and Anglo-Saxon Britain

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A reconstruction of chicken husbandry practices in Roman and Anglo-Saxon Britain

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Examples of papers integrating multiple methods to reconstruct chicken husbandry practices

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Examples of papers integrating multiple methods to reconstruct chicken husbandry practices

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Though not strictly part of the chicken's skeletal anatomy, the eggshell is a common encounter on archaeological sites where they were managed.

This are generally very fragmented though are visible to the naked eye when in significant quantities.

Their fragmentation and small size requires the wet sieving of sediments in which they are found.

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Chickens are generally considered from a dietary perspective in the archaeological record.

However, there is considerable evidence attesting to their ritual/religious roles in society prior to any significant evidence for meat/egg production.

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A relatively intact Roman cooking pot with an associated chicken from Roman Hungate, York (Connelly n.d., 4).

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There is a surprisingly high number of Roman burials in which a chicken - buried in a pot - is associated.

The chicken was regarded as food for the afterlife being found predominantly in cooking pots.

They were also associated with Mercury - the god of merchants, travellers, and travellers alongside the guide to the underworld - being considered to 'herald in the new day'.

For example, 9/111 Roman burials at Hungate, York, (pictured above) possessed a chicken and parallels evidence across the Roman empire.

Significant quantities of chicken bones were also found at the Temple of Mithras in London.

Click here for the article on chicken burials at Roman Hungate, York.

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Human-headed roosters from a wall painting from Akchakhan-kala, Central Asia (Betts et al. 2012)

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Human-headed roosters from a wall painting from Akchakhan-kala, Central Asia (Betts et al. 2012)

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The chicken is also regarded with significant power in Zoroastrian beliefs, and particularly in the Avestan cult as depicted in the wall painting above.

Click here for the article on these wall paintings.

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Chicken burials in the High-Medieval Basque Country, Spain (Grau-Sologestoa 2018)

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Chicken burials in the High-Medieval Basque Country, Spain (Grau-Sologestoa 2018)

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Evidence of votive offerings/deposits are also recorded in a High-Medieval (12th-13th centuries CE) Christian context in Basque Country, Spain.

Here, at least six chicken burials have been recorded in the foundations of buildings in this region.

This is considered evidence of a continuity of folk religion alongside the more formalised Christian practices in this period.

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Examples of tarsometarsi with the removed spur from Medieval Norway (Walker and Meijer 2020, 133).

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Evidence of cockfighting in Medieval Norway (Walker and Meijer 2020)

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Evidence of cockfighting in Medieval Norway (Walker and Meijer 2020)

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Cockfighting is a bloodsport that has been practiced wherever the chicken has been introduced.

In this article, the authors analysed the tarsometarsi and argued that cockfighting was common practice in Medieval Norway alongside the keeping of chickens for meat and eggs.

This was suggested by a high percentage of adult male cockerels possessing a fused spur (49% or 128/258 bones analysed).

Additionally, 16/128 tibiometatarsi had the spur deliberately removed (pictured above) which is common in cockerels kept for cockfighting.

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The geographic location and timing of chicken domestication is intensely debated.

It was generally accepted since the 19th century that chickens were domesticated form the red junglefowl (Gallus gallus) because of their similar morphology and behaviour.

However, mtDNA and nuDNA analysis in the 21st century attests to their being multiple origins of the domestic chicken (see Wang et al. (2020) (left)).

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Northern China as a domestication centre?

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Northern China as a domestication centre?

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Multiple origins of chicken domestication (Wang et al. 2020)

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Multiple origins of chicken domestication (Wang et al. 2020)

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In this study, the authors sequenced the whole genomes of 863 birds (including 627 domestic chickens and the rest junglefowl).

They identified that the chicken's wild progenitor is Gallus gallus spadiceus, a subspecies of red junglefowl in southwest China, Thailand, and Myanmar.

However, 22.4% of their DNA is derived from other red junglefowl subspecies and junglefowl species associated with their distribution across South and Southeast Asia.

In addition to the hybridity, they produced an upper bound for domestication with the wild ancestor of the chicken having diverged from Gallus g. spadiceus ~15,000 years ago.

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863 genomes reveal domestication and origin of the chicken

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Evidence for a North Chinese domestication

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Evidence for a North Chinese domestication

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Northern China is one of a few regions in which agriculture was independently developed in the Neolithic period.

Associated with this, however, is the controversial view that the chicken was also domesticated in this period and in this region.

Proponents of this view argue that the oldest chicken bones are recorded in this region, dating to approximately 8,000 years ago.

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Mitochondrial evidence for chicken domestication in Northern China (Xiang et al. 2014)

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Mitochondrial evidence for chicken domestication in Northern China (Xiang et al. 2014)

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The view that chickens were domesticated in Northern China was most recently supported by a mitochondrial study by Xiang et al. (2014).

Thirteen mitochondrial genomes from archaeological chicken specimens - from Neolithic sites in Northern China - were sequenced.

All specimens were identified as a chicken, presenting evidence for their domestication in Northern China.

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Controversy surrounding Xiang et al.'s (2014) study

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Controversy surrounding Xiang et al.'s (2014) study

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The results from Xiang et al. (2014), that the oldest domestic chickens are found in Northern China, have been heavily criticised by a series of papers.

Some of these are highlighted here.

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No evidence of chickens in an Early Neolithic site in northwest China (Barton et al. 2020)

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No evidence of chickens in an Early Neolithic site in northwest China (Barton et al. 2020)

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In this paper, the authors sequenced the mitochondrial genome of purported chickens (n=8) from the Neolithic site of Dadiwan in northwest China.

These samples ranged from 7900-5900 cal BP.

Notably, no sample was identified as a chicken but rather as a common ring-necked pheasant.

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Purported chicken bones in the Xiang et al. (2014, 17565) are instead suggested to be from the genus Canis (see the bottom bone).

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A response to Xiang et al. (2014) by Peters et al. (2015)

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A response to Xiang et al. (2014) by Peters et al. (2015)

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Very shortly after the Xiang et al. (2014) a response was levied by Peters et al. (2015) that noticed several flaws in the paper such as:

1. The wild junglefowl are tropical animals, a climate that is not supported in North China today nor in palaeoclimatic records.

2. 'Chicken bones' included in the study also included Canid bones (see the figure above).

3. Xiang et al. (2014) argued that there were no post-Neolithic cultural layers at the sites studied in which chicken bones may persist. This is not true at all.

4. There are flaws in the design and presentation of the DNA sequencing and primers.

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Application of ZooMS to distinguishing between chicken and pheasant (Eda et al. 2020)

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Application of ZooMS to distinguishing between chicken and pheasant (Eda et al. 2020)

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The application of ZooMS has also been applied to the question of chicken vs. pheasant. This is particularly important where the chicken was introduced into regions with indigenous pheasant populations.

The article here is a 'proof-of-concept' showing the distinct collagen peptide mass fingerprints for the chicken and the pheasant in Japan.

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The oldest unambiguous evidence for domestic chicken and their subsequent dispersal (Peters et al. 2022)

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The oldest unambiguous evidence for domestic chicken and their subsequent dispersal (Peters et al. 2022)

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This significant and recent paper synthesised archaeological data from >600 sites across 89 countries to explore the domestication and dispersal of the chicken.
In agreement with Wang et al. (2020), the oldest unambiguous domestic chicken were found in Thailand at the Neolithic site Ban Non Wat and dating to ~1650-1250 BCE.

It was also possible to record the appearance of the domestic chicken beyond the wild junglefowl's natural range; for example:

Chickens are not reliably attested in the Indian subcontinent until post-1200 BCE (Jorwe period).

They are not recorded in Southwest Asia until ~1000 BCE.

In Northeast Africa, chickens are found from ~800 BCE onwards.

Chickens are also found in Mediterranean Europe post-800 BCE.

In Japan, chickens were not present until c.100 BCE (middle Yayoi period).

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Changes in chicken morphology and behaviour

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Changes in chicken morphology and behaviour

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In addition to the origins and timings of chicken domestication there is also focus on the morphological and behavioural changes of the chicken compared to wild junglefowl species.

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Reduction of wing size in captive junglefowl and domestic chickens (Eda 2022)

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Reduction of wing size in captive junglefowl and domestic chickens (Eda 2022)

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In this study, the major long bones of the forelimb and hindlimb was measured in modern wild junglefowl, captive junglefowl, and chicken species.
Overall, captive junglefowl and chickens were smaller than the wild junglefowl species.
Notably, the forelimb in captive junglefowl and chickens was thinner than the wild junglefowl; vice-versa for the hindlimb.

Eda (2022) argues that if these processes in modern animals are paralleled with ancient animals then in it is possible to understand the effect of early domestication in the archaeological record.

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In wild junglefowl, a single brood is laid (~ 6 eggs) by a hen every year.

However, where these eggs are removed the hen will continue to lay eggs.

This behaviour has been significantly enhanced by humans to which it is now possible for chickens to lay all year round.

Egg laying, however, may slow down during winter months.

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Yellow skin in chicken legs (Eriksson et al. 2008; Fink et al. 2014)

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Yellow skin in chicken legs (Eriksson et al. 2008; Fink et al. 2014)

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The red junglefowl - the principal wild ancestor of the chicken - has grey skin whereas the chicken has yellow skin.

The colour of their skin is regulated by the BCDO2 gene.

Genetic analysis by Eriksson et al. (2008) found that the yellow skin of chickens is a inherited trait from the grey junglefowl (Gallus sonneratii).

This was used to support a multiple origin of domestic chickens.

More recent analysis of western domestic chicken breeds by Fink et al. (2014) - of 80 chickens from 12 European archaeological sites (c.300 BCE to 18th century CE) has shown that this yellow-skin mutation was only heavily selected for in the past 500 years.