Is "breeding-back" necessary?

Originally, “breeding-back” as it was invented by the Heck brothers, aimed to recreate extinct species. We now know that this is not possible working with domestic descendants only, as the subject is much more complicated than just uniting visible traits found in primitive breeds. Therefore, the goal of “breeding-back” changed. Nowadays the main purpose of this method is to authentically replace the extinct wildtypes in the wild, filling the empty ecologic niche. In order to accomplish that, the set of criteria now also includes ecologic traits. The cattle (or horses, if there were “breeding-back” projects for horses) not only have to look like their extinct wildtype, but they also have to be capable of surviving in nature. Achieving that is not a big problem, was most primitive breeds already are very hardy landraces. 

But is “breeding-back” really necessary to fill the ecologic gap? 

 

For this question, the answer is pretty clear: no, it is not necessary. Releasing a couple of hardy landraces back into the wild would do the job as well, no elaborate selection on wildtype traits is actually necessary for these animals to survive in nature. While it is true that large, long-legged, athletic cattle with large horns will have a much easier time to defend themselves against predators than small, short-legged cattle without horns, natural selection will probably enforce wildtype traits anyway. Also, many landraces are already quite aurochs-like, such as Sayaguesa for example. They are large, have a comparably aurochs-like morphology and horns, and the colour is right as well (except for the very reduced sexual dichromatism). Add Maronesa genes by releasing both breeds in the same area and most aurochs fans will be satisfied. The same goes for Spanish fighting cattle (Lidia). The probability that they survive in nature and function like their extinct ancestor is very high, as there are feral cattle populations that descended from derived breeds that were not landraces (such as on the Ile Amsterdam or New Zealand). So just releasing a number of cattle from several primitive landraces and letting them breed for themselves and do their thing in natural areas will do the job sufficiently in any case. I have the suspicion that this is the plan the Tauros Programme. So far, they have done exactly that and nothing more (at least nothing that they have published). 

 

If that is the case, why doing “breeding-back” in that intensity at all? I see three main reasons: 

- to see how much similarity to the extinct wildtype can be achieved by selective breeding 

- educational purpose: by showing what an aurochs (or European wild horse) looked like and was like you educate people zoologically 

- a homogeneously wildtype-like phenotype is important for the public acceptance as a wild animal. If the cattle are heterogeneous in appearance they would look more like a bunch of escaped farm cattle, while the phenotype of the aurochs was undoubtedly that of a wild animal. There are indeed people who are against using cattle (or horses) in rewilding because they consider it animal cruelty to let domestic animals live in the wild. It is thus important for the public acceptance of the projects to communicate these are “special” animals bred to live in the wild. 

 

So from a purely ecological point of view “breeding-back” is not necessary. But having a breed of cattle that is as aurochs-like as possible certainly has some advantages. In the end, it is about authenticity. An authentic proxy for the aurochs is more satisfying for nature lovers, has a higher chance of being accepted as a wild animal in the public eye, is more educative, and probably has a higher ecologic fitness compared to randomly chosen landraces due to the selective advantages a wildtype-like phenotype likely has. It is also a matter of opinion. Surely there are more pragmatic people that do not care that much about authenticity, but there are also (perhaps more idealistic) people that do want to replace the aurochs as authentically as possible. And there is enough of the latter category that there are “breeding-back” projects, and even several of them.