Iberian Genotype Samples
During the time period between the late Neolithic and Copper Age, black horses emerged in the Iberian population. Over time the population of horses with the Black phenotype increased to the point that there was approximately even numbers of Bay and Black horses in this location.
Four of the eight fossils sampled from this time period contained a genotype coding for the
Bay phenotype. These horses all had two dominant Extension Genes (E/E) and at least one copy of the functional Agouti Gene (A/a). Because these fossils had at least one dominant (functional) copy of each of these genes, their base coat color was Bay.
The other four horses sampled from the time period had a genotype that coded for the Black phenotype.
All of the fossils that had the coat color genotype for a black horse had two copies of the non-functional Agouti Gene (a/a) and two copies of the functional Extension Gene (E). Unlike the European horse population at the time, none of the fossils in this location exhibited a mutation at the Extension Locus.
Similarly, none of the horse fossils showed any evidence of having the Overo (EDNRB), Tobiano (KIT13), Sabino (KIT16), Cream (MATP), or either variation of the Silver Gene (SILV9 and SILV11). This shows that the fossils had no variation to their base color.