Taxon Surrogate Profiles Europe # 4: Bos (taurus)

            Of all the proxies necessary to fully restore the European megafaunal assemblage, the aurochs (Bos taurus primigenius) is perhaps the most difficult to replicate in a satisfactory way. Attempts have been made for almost a century to breed them back in to existence through the crossing and selection of primitive cattle (Bos taurus taurus), but this has had limited success. Unlike horses, cattle do not go feral easily. Generations of selection for neoteny and docility have made even some of the least derived and demanding breeds feeble in comparison to their wild relatives. When they do live semi-feral they remain very habitat-specific and often require additional feeding. On top of that the traits known to have been possessed by the aurochs are spread very unevenly amongst its descendants, and animals showing more than half of them are very rare. You can certainly combine all of these traits in one population, but there is so much heterogeneity in cattle that getting them in one individual is almost impossible and getting them in enough animals to form a large founding herd has become a pipe dream. I’m going to posit some possible solutions, but I won’t pretend to know the best way.

            Probably the most straightforward way is to pursue cloning. We have DNA from several aurochs at this point and we can compare their genomes to that of living cattle. Unfortunately true cloning, wherein a living cell nucleus is implanted into a new egg and fertilized in a surrogate, is probably not possible as we would need an intact aurochs cell to start. Cloning only a few aurochs would be a poor start for genetic diversity as well, and you’d probably have to backcross them with cattle. However, direct splicing of wildtype alleles into a cattle genome might be possible if it were determined which genes were important. That might also be difficult considering how many genetic differences there might be, and the number of genes that might control things like body shape and horn size. There would be a lot of trial and error necessary to get it right, which is already the case with the breeding projects. Genetic engineering is also a very expensive process potentially, and though that may lessen over time, the effort necessary to identify important modifiers may remain high.

            Breeding primitive cattle over time is certainly cheaper, and perhaps more practical, but it definitely is not easy, and there are a million different opinions on the best way to do it. Forming a herd for conservation grazing using local cattle is easy enough, but these are still livestock under the law and will require additional feeding and veterinary care. Creating something that looks and behaves like a wild animal, and which can be left to its own devices with minimal human intervention, is considerably harder. There are certain breeds with a more aurochs-like phenotype than others, and this is especially true for some of the Lusitanian breeds like Sayaguesa (and their close relatives Serrana Negra and Alistana-Sanabresa), Tudanca, and Limia, but it also true for various breeds from across Europe. I certainly have my favourite breeds to use to meet this goal, but so does everyone else, and there will be issues regardless. Even the most primitive cattle have problems with hormonal expression, with this being less evident in fighting bull breeds, which still have some neotenous features. These lead to short faces, flat or concave backs with no shoulder hump, reduced sexual dichromatism, and long bodies with short legs. Basically, trying to breed an aurochs from a bull is liking trying to breed a wolf from a dog. You might get something that looks kind of like a wolf but it won’t act like one, and you’ll still get domestic features like floppy ears and white spots showing up.

            One potential method that might yield interesting results is hybridization. Now, I know that’s my solution for everything, but that’s only because I think it’s a legitimately useful tool for this kind of thing. Wild bovines have many of the traits we’re looking for in an aurochs effigy, there would just remain the question of which species to use. Bison (Bos bison ssp.) are out, since the aurochs and European bison were sympatric and we want to discourage hybridization in areas where both types of bovine are used. Yaks (Bos grunniensssp.) are in the bison lineage, so they should probably also be excluded. They do have some impressive horns, but they also possess many non-aurochs like traits associated with hair growth/colour and general body-form. Gaurs (Bos gaurus ssp.) share some ecological and morphological affinities with bison as well, and the kouprey (Bos sauveli) is likely extinct. That leaves the banteng (Bos javanicus). Now, while studies based on mitochondrial DNA place the banteng as being only distantly related to the aurochs, studies based on nuclear DNA, which I find more reliable, actually place it as being quite close phylogenetically. I think the Javan banteng (Bos javanicus javanicus), is the best variety to use, due to its perfect sexual dichromatism. The males are all dark brown to black, and the females all have an orangey-buff colour, a trait shared by the Eurasian aurochs. They are also the only banteng subspecies with the same number of chromosomes as cattle. An experiment breeding banteng to some of the more primitive Iberian breeds of cattle, like Sayaguesa or Maronesa, could potentially produce some very interesting results. There are two phenotypic traits that will have to be bred out, and potentially one or two behavioural ones, but the potential for hormonal improvement, non-domestic behaviour, and general robustness would make it worth it in my opinion. The white socks and rump of the banteng are dominant traits in existing cattle-banteng hybrids, making it an easy thing to breed out, which really just leaves the non-aurochs-like horns, which is already a trait that will need to be bred out in some of the primitive cattle breeds that might be used. Banteng also have a less confrontational style of fighting between bulls, but this may be selected out naturally. Something that is worth noting is that only the females of banteng-cattle crosses are fertile, and this will have to be accounted for in the breeding process. All backcrosses are fertile though, so that only affects the first generation hybrids. Apparently crosses with Indian cattle (Bos taurus indicus) which are also aurochs descendants, albeit of different subspecies (Bos taurus namadicus), produce fertile male offspring with banteng, but sources are a bit inconsistent on the matter. A hypothetical breeding plan would go as follows:

Male javanicusx Female taurus

-       F1 hybrid female, 1/2 javanicus, 1/2 taurus

-       javanicus X-Chromosome, taurus X-Chromosome and mDNA

Male taurusx Female F1

-       F2 hybrid male, 1/4javanicus, 3/4 taurus

-       taurus Y-Chromosome, either javanicusor taurus X-Chromosome, taurus mDNA

-       Select males that don’t show the banteng-type markings for breeding

Male F2 x Female taurus

-       F3 hybrid male, 1/8 javanicus, 7/8 taurus

-       taurus Y-Chromosome, taurus X-Chromosome and taurus mDNA

-       Integrate these animals into breeding-back herds to improve development and behaviour

Banteng are a tropical species, and this is worth noting for areas in central/northern Europe where cattle might be rewilded. Banteng are a hardy species, and cattle with slight banteng influence should do very well in most areas, as any climatic disadvantage should be counteracted by the adaptations of the base breed. For example, in the colder regions of the eastern steppe, a herd of 75% Podolian ancestry (ex. Maremmana, Podolica), 20% Lusitanian ancestry (ex. Sayaguesa, Limia), and 5% Javan ancestry might do very well. A herd in southern Spain might have similar proportions of Lusitanian and Javan ancestry, but be predominantly made of more arid-adapted Iberian breeds like Maronesa, Pajuna, or Lidia (fighting bull). What is important is that the herds can survive in the areas available to them without too much assistance, and that the desired traits are present in the herd to select upon over time. Natural selection will help this process along as well, as will occasional culling of bulls with an excess of undesired traits. I had originally planned to describe a similar plan to what I had proposed for horses, wherein different breeds become different varieties for the various European ecotypes, but due to the greater disparity in the appearance of wild vs domestic cattle when compared to horses, and the consequently smaller number of suitable breeds, there would probably end up being more like three or four types rather than nine, with herds in the colder regions of the north and east being descended from some of the same stock as those from founding herds in the south and west, only with greater proportions of ancestry from cold-adapted breeds. In general the strategy when forming new populations should, in my opinion, be to assemble herds of the most aurochs-like local cattle, or failing that the most aurochs-like cattle from a similar climate, and then slowly phase in breeds which possess desirable traits not found in the existing population. Certain breeds may be used to improve specific traits across several populations. As an example, the Chianina, from Italy, is one of the largest commercially-available breeds in the world and is itself a very old breed. Introgression from this breed, or from less common breeds of similar size (ex. Maltese cattle), could help to increase the size of aurochs-like cattle, which is important since the aurochs could be as tall as two metres at the shoulder, and weigh as much as a metric tonne, a size attained only by the largest of living cattle. Another breed, the Watusi of Africa, has also been used in breeding projects to contribute a greater horn size, as well as general robustness and improved ease of birth. The aurochs had very large horns and although many primitive European breeds possess horns of the right shape, they are of a smaller size which is a difficult thing to breed against if the genes aren’t there. The strategy with these breeds would not be to integrate them directly into existing herds, but to use them in the creation of individuals which will be integrated after a few generations of controlled breeding. 

            This is going to be a long process. It’s been going on, on and off, for almost a hundred years and we’re still not really there. Granted, we didn’t have the knowledge then that we have now, and progress has accelerated in the last twenty years, but cattle breed slowly and it can be very difficult to see progress in a short amount of time. It may be another fifty years of slow acclimatization and selection before we get an individual that’s sufficiently aurochs-like, and another fifty after that to get all of those traits in a population. We have to play the long game with this one, as is the case with many restoration efforts, but in the meantime we can build up primitive herds for use in our various European grazing projects and set the stage for the process to continue. This is going to be more difficult than it will be to re-establish herds of bison or water buffalo (which I will talk about in my next article), but it will be equally necessary for rewilding in areas where those species are not ideal. After all, all three varieties were once native to Europe, and each had their own unique ecological roles and habitat preferences. If you ask me, the more native megafauna we can restore, the better. Their environmental and economic benefits will become invaluable as land abandonment and vegetative succession continues.