Bone detective work paints picture of Late Iron Age horses in Switzerland

Location of investigated sites in Switzerland. 1 – Mormont, canton Vaud; 2 – Avenches/Aventicum, canton Vaud; 3 – Basel-Gasfabrik, canton Basel-City.
The locations of investigated sites in Switzerland: 1 is Mormont; 2 is Avenches/Aventicum; and 3 is Basel-Gasfabrik.

Researchers have painted a picture of what horses were like in Switzerland during the Late Iron Age, based on analysis of recovered bones.

The study team sought mitochondrial DNA, which is passed down through maternal lines, from 34 horse bones recovered from three Swiss archaeological sites.

They also measured the bones and found that all bar one of the horses would be classified today as ponies. They found there was little diversity in coat color, suggesting local inhabitants had made breeding decisions that avoided spotted patterns.

The genes of these horses still exerted an influence on today’s horses, more so the modern European breeds, particularly in northern European ponies.

Julia Elsner and her colleagues, writing in the Journal of Archaeological Science: Reports, said horses had enjoyed a prominent position in the Celtic world as status symbols and objects of veneration, yet little was known about them except that they were rather small.

The Late Iron Age, they noted, was a time defined by increasing inter-cultural contact between Celtic peoples and the Romans.

“This is, amongst other features, observable in the phenotypes of domestic livestock such as horses,” they said.

They based their work on the scientific examination of 32 horse bones from three Swiss sites – Mormont, Basel-Gasfabrik and pre-Roman Aventicum. Most of the remains dated from 150 BC to AD 30. Two Roman-era Aventicum samples dating to the late 1st to early 2nd century AD were also added to the analysis. Aventicum became a Roman colony in AD 71.

The study team set out to characterise the diversity of maternal lineages and coat colourations of the horses and to identify the sex.

They detected 11 mitochondrial haplotypes clustering into six haplogroups (B, D, F, I, X2, X3) in the ancient dataset of 19 individuals.

Large individuals were all male, they reported, but smaller stallions were also identified. The horses were bay, chestnut and black in colour. Spottings or dilutions were absent in all animals.

“With a simplified primer system to detect premature greying, white coats can be excluded as well,” they reported. “The limited colour range proposes selection for monochrome animals.”

Five horses were larger than 130cm, with the tallest measuring 149cm at the withers.

The average withers height of the Mormont horses was 124cm, or 119cm without the two largest animals. The average in Basel-Gasfabrik was 120cm and in Aventicum it was 137cm (141cm for the Roman-time individuals).

The researchers noted that Celtic horses were generally described as small – 110cm to 130cm at the withers – whereas the Romans also bred larger animals, over 140cm.

“Therefore, when encountering small and large horses in Celtic contexts, archaeozoologists often consider the small ones to be local, while larger ones are regarded as imported, endowed or looted.

“Some authors argue that the reason for the small size of the Celtic horse was poor pasture and low breeding interest but this interpretation contradicts the Celts’ reputation as stock breeders and mounted warriors.

“As small horses are more versatile and quick on the battlefield, it can be assumed that the Celts intentionally bred small horses. However, by the Late Iron Age, small and large horses were found to be coexisting in Celtic sites, for example in southern Germany or Luxembourg.

“The withers height of the investigated horses fell mostly within the variation of standard Iron Age horses, yet five individuals were larger than 130cm, reaching up to 149cm. Two of these were identified as male.”

Only one horse exceeded the defined pony maximum of 148cm.

They said the diversity they found in the maternal lines was striking, particularly given that the majority of horses, namely those from Mormont, belonged to what was probably a local population which should have included directly related individuals.

“The mitochondrial DNA variation of the Iron Age horses investigated here has survived in modern European breeds, particularly in northern European ponies,” they wrote.

Compared to modern indigenous breeds, Late Iron Age horses seem to have bequeathed more to northern European ponies, including British Isles pony breeds, than to Spanish breeds, they said.

“However, considering that domestic horses were first introduced to Switzerland in the Late Neolithic or Early Bronze Age, i.e. around 2500–2000 BCE, it is remarkable that most major haplogroups are present in the Iron Age archaeological record, notably in view of the rareness of archaeologic horse remains.”

In all, five mares and seven stallions were identified through testing, all from the hill site of Mormont.

“Coat colouration seems to be rather uniform,” they reported. “We would expect more variety.

“Breeders probably had noticed hearing, visual, and neurological impairment and even stillbirths coming along predominantly with spottings, especially in homozygous individuals and thus may have selected against those phenotypes.

“Notably premature greying resulting in a white coat regardless of original colour was also not detected. Again, we expected a different result, as white horses played an important role in Roman and also in Germanic ceremonies.

“However, of the horses investigated, only the specimens from Aventicum stem from an unambiguous ritual context and those were not preserved well enough for genetic coat colour identification.

“Assuming that ceremonial activities were also performed on the hill of Mormont, we find no evidence that specially coloured horses were preferred in rituals, which apparently also applies for sex as both females and males were present.”

Elsner was joined in the study by Sabine Deschler-Erb, Barbara Stopp, Jörg Schibler, and Angela Schlumbaum, all from the Integrative Prehistory and Archaeological Science within the Department of Environmental Sciences at Basel University, Switzerland; and Michael Hofreiter, from the Institute for Biochemistry and Biology at the University of Potsdam in Germany.

Mitochondrial d-loop variation, coat colour and sex identification of Late Iron Age horses in Switzerland
Julia Elsner , Sabine Deschler-Erb, Barbara Stopp, Michael Hofreiter, Jörg Schibler, Angela Schlumbaum.
The study, published under a Creative Commons License, can be read here

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