
Here's a great article on how cultural preferences through time have
affected the prevalence of horse color. Germany’s Leibniz Institute
for Zoo and Wildlife Research studied DNA horses through the ages.
During the Bronze Age and Iron Ages (2700 BC to 400 AD) the number of
horse colors detected increased from 6 to 9 with spotted and dilute
horses being common. During the Middle Ages, solid color horses,
especially chestnuts, were preferred, possible due to Biblical references to the Four Horseman of the Apocalypse.
Scientists admit their samples may have been biased since horses
analyzed were associated with the noble class. As reader, I noted that
the sample size was very small around 107 horses. Plus artwork from
the early and late middle ages show notable examples of spotted horses.
Examples: spotted horse shown on needlework from from Baldishol Church
in Norway circa early 1200s or the 16th century Hunts of Maximillian
tapestries. I wonder how carefully the genetic researchers checked with
historians and art historians on this topic.
For those Icelandic
horse aficionados out there, finds indicate that the prevalence of
spotted horses in Iceland today indicate that horses marked in this way
were introduced after 11th century AD, this contradicting that horses
were not imported into Iceland after the initial settlement.
“Strikingly, the Icelandic horses from the Viking Age show clear
differences from their modern counterparts. 'The samples we analysed
originated from graves around Iceland that date back to as early as the
middle of the 9th century, shortly after Iceland was settled. These
horses already carried the allele for Silver dapple (two of 19
individuals), a common trait in contemporary Icelandic horses, but they
did not carry any alleles associated with spotted phenotypes, although
such individuals are frequent in modern Icelandic horses. Therefore, we
assume that spotted phenotypes were introduced after the 10th/11th
century AD, which contradicts the popular claim that the import of
horses to Iceland was prohibited for almost 1000 years.”
https://www.horsetalk.co.nz/2016/12/09/horses-dreamcoat-colourful-history-unveiled/#ixzz4UYevTYks