It has long been established that the aurochs can be divided into several mainland subspecies: B. p. namadicus, the Indian (South-Asian) one, B. p. mauretanicus (African), B. p. primigenius (European) and B. p. suxianensis (East-Asian). I was not entirely happy with this taxonomy, as it is clear that they are not distinct, isolated clades but have a continuous range and the morphological differences between them are more like tendencies (such as that East-Asian ones tend to have a convex snout but these are not exclusive to them etc.) rather than clear autapomorphies. Recent genetic analyses suggest that the idea of mainland aurochs subspecies tied to certain regions is not tenable and that the evolutionary history of the aurochs was much more complex than what a taxonomy with four mainland subspecies would suggest. The island subspecies, however, are – at least in my opinion – a different story as they were clearly reproductively isolated for at least a certain amount of time. Two studies are of particular relevance for the phylogeny of wild Bos primigenius (or Bos taurus, depends on what you prefer).
Rossi et al., 2024: The genomic natural history of the aurochs.
38 aurochs genomes from the Late Pleistocene to Holocene were analyzed. The lines of taurine and indicine cattle diverged around 166-300kya. Taurine-line aurochs and indicine-line aurochs descend from a common population that lived around 390kya. Within the taurine-line aurochs, North Asian aurochs separated from Southwest-Asian aurochs after 100kya, splitting from a common ancestral population. More archaic aurochs, however, left a minor trace in those later taurine-line aurochs. The North-Asian aurochs haplogroups C and K split from the other taurine-line haplogroups P, Q, T, E and R around 96 to 72 kya.
Zhu et al., 2025: Revisiting aurochs haplogroup C: Paleogenomic perspectives from Northeastern China.
It covers all the mitochondrial haplogroups P, T, E, Q, R, G, K, C, I and shows a phylogenetic cladogram. The Central Asian haplogroup G is the basalmost one, basal to the group taurine + indicine line and separated around 400kya. R, so far found in North African aurochs, is closer to a clade of K and C from Asia than to T or P.
What is surprising to me is that the split between the taurine-line aurochs and indicine-line aurochs is that recent. This means that most namadicus fossils, which are from the Middle Pleistocene to the early late Pleistocene, cannot be considered ancestors of the zebu any more than other archaic aurochs from that time. It also means that the 700.000 year old Wadi Sarrat skull from Tunisia does not belong to the same line as late North African aurochs but is much more basal.
Looking at the phylogeny of the various aurochs haplogroups and comparing it to their location it becomes clear that the aurochs genomic history is much more complicated than a subdivision into four mainland subspecies would suggest. As Rossi et al. and Zhu et al. note, the range of the aurochs likely expanded and contracted with the countless climate oscillations during its existence, and looking at the relationship between R (North African) and K/C (Asia), clearly a lot of migration must have been involved.
I think that, based on the phylogeny of the various aurochs lineages, it is not useful to subdivide the mainland populations into subspecies. Especially as the type specimens for the respective subspecies taxa are not publicized (with the exception of B. p. primigenius, the Haßleben aurochs), which would be necessary to see which taxon equates to which genetic lineage. Apart from that, it would be of limited use to erect a subspecies taxon for each haplotype or genetic lineage given the diversity found within the aurochs. And we only know about half of the diversity found within the species, given that we do not have genomes from earlier aurochs. So now we know that there were non-crown-group aurochs in the late Pleistocene, that the split between indicine-line aurochs and taurine-line aurochs occurred fairly recently.
