The colour of Indian aurochs cows

We know nothing about the colour of the Indian aurochs with certainty, except for the fact that it must have had the E⁺ allele on the Extension locus, because the majority of zebus have it and it is also found in taurine cattle, suggesting that it was already present in the common ancestor of the primigenius and namadicus lineages. That means namadicus must have had the colour that has both phaeomelanin and eumelanin (red and black pigment), dispersed in some pattern across the pelage, a white muzzle ring and testosterone-dependent eumelanisation. Very likely sexual dichromatism was present, i.e. that bulls and cows had different colours. Some zebu breeds have retained a certain degree of sexual dichromatism, with the bulls being slightly darker than the cows. The colour of the cows is in the focus of this post. 

Many zebu cows that have the production of phaeomelanin enabled (the mutation disabling the production of red pigment is quite common among zebus and perhaps originated in that lineage) are almost homogeneously reddish-orangish-brown, with a dark brown dorsal stripe (that is not always present), lightly coloured rings around the eye and a lightly coloured area on the ventral side of the trunk and the inner side of the limbs. Black or very dark areas are (almost) absent. A colour consisting of a reddish-brown base colour with a dark dorsal stripe is sometimes also found in taurine cows, albeit rarely. It is much more common in zebu cows. The only black or very dark areas in zebus having that colour are, if present, along the anterior side of the forequarters, either down to the carpals or to the toes. I consider it quite likely that this is the original colour of female Indian aurochs cows and it can be seen in breeds like Red Kangayam. 

The reason for my assumption is that female Java banteng have a very, very similar colour. They are orangish-reddish-brown, with a dark dorsal stripe, lightly coloured areas on the inner side of the limbs and the ventral side of the trunk, they even have the dark areas on the forelimb, except for the part that is completely devoid of pigments. In fact, if those white “socks” and buttocks were not there, the colour would be almost identical. I see two possible explanations for that similarity: a) the common ancestor of both species had this colour and it is the ancestral trait, thus was also present in the Indian aurochs b) introgression from banteng into the zebu after domestication. As for the latter possibility, the introgression of banteng or their domesticated form Bali cattle is documented for some lineages of zebus. But I consider it less likely that this is the reason for the similarity in coat colour as in this case this colour would not be found in taurine cattle too, which it is, albeit rarely. Also, Red Kangayam are found in Southern India, where banteng introgression is less likely for geographic reasons. This makes the assumption that it is inherited from a common ancestor more likely, since such a close similarity in more or less closely related species is probably not a coincidence. If this colour was already present in the common ancestor of the Java banteng and the zebu, it is the most parsimonious assumption that it was present already in the Indian aurochs. That colour is in fact not all too special. Wildtype coloured calves in taurine and indicine cattle are usually reddish brown with a dark dorsal stripe, the cows retaining this dark dorsal stripe and having almost no black or dark brown areas just means that the process of growing what is the adult coat colour in bulls is stopped earlier than in European aurochs cows, which often had black heads, necks and legs or were even black with a red colour saddle, as cave paintings show. 

However, this colour being the result of banteng introgression into zebus after domestication cannot be ruled out completely, and in the lack of artistic depictions showing the Indian aurochs and the fact that female zebu appear in a wide variety of colours we can only guess what its colour was like. I think the colour shown by the Red Kangayam is a very plausible one for namadicus cows, but this has to remain a speculation, as long as we do not have any direct evidence of the coat colour of the Indian aurochs.