Were the last Polish aurochs deliberately bred to domestic cows?

I keep on looking meticulously into old primary sources, desperately trying to find something “new” about the aurochs or at least something that was not discussed much in the literature. This time I might have found something interesting.

 

C. Gesner, 1583

 

Gesner in a 1583 edition of Historia animalum writes that aurochs were hunted by seizing a calf, binding it to a post so that adult animals come at its calls for help. He also describes the wisent and the aurochs, so he knew both are different animals, but the wisent section shows an aurochs skull Gesner was sent from England and a drawing of a bovine head that could be an aurochs. It shows downwards and inwards facing horns, the curly forehead hair and barely any beard and smooth hair on the neck. Some domestic bulls have a “mane”, which is why the presence of the frizzy hair in the throat of the depicted animal does not rule out an aurochs to me, and the skull is definitely an aurochs.

 

S. v. Herberstein, 1556

 

Even more interesting is Siegmund von Herberstein’s text Rerum Moscoviticarum Commentarii from 1556. Yes, it's the one with the woodcuts of his taxidermied aurochs and wisent. But there are also editions showing a depiction of an aurochs in the wild with a bulky but short trunk, curly hair between the horns and – as usual – incorrect horns.

 

The book is freely available on the web in Latin, German and English. In the English translation (Notes upon Russia), on p. 96 it is written:

 

“Masovia, which borders on Lithuania, is the only province which has in it the kind of buffalo which in the language of the country is called thur, but which we Germans may with propriety call urox. They are a sort of wild oxen, not unlike tame oxen, except that they are entirely black, with a line down the back having white blended with it. They are not very plentiful, and there are certain districts which are charged with the care of them; and it only in some few preserves that they are kept. They are allowed to herd with tame cows, but have a mark set upon them to distinguish them. This is done because they are afterwards looked upon as degraded by the other buffaloes, and are not admitted into their herd; and the calves which are produced by the cross breed are not long lived. The King Sigismund Augustus, at the time I was ambassador at his court, made me a present of one which was just dropped, and which the hunters had taken, driven half-lifeless from the herd. It had the skin which covers the forehead cut away, which I suppose was done for some purpose, but from thoughtlessness I neglected to enquire why it was done. This is certain, that girdles made of the hide of the urox are much esteemed, and it is a vulgar opinion that parturition is assisted by wearing them”

 

I find this paragraph highly interesting. First of all, we can be sure it refers to the aurochs, because it is explicitly referred to as “thur”, which is Polish for aurochs – in historic Poland, wisent and aurochs were never confused for each other because both animals were still extant and noticed as different species. Also, he mentions that the aurochs is very rare and is taken care of in certain districts of Masovia, which were probably Jaktorow and Wiskitki because of the given time Herberstein wrote the text. He also refers to the brutal ritual that the frizzy curly hair between the horns is cut of from the aurochs alive in order to make belts that are supposed to ease parturition, which is also described by Swiecicky (van Vuure, 2005). Herberstein also mentions the lightly coloured dorsal stripe. So he is definitely talking about aurochs on this paragraphs, and so far his notions are in agreement with other sources.

What is the most striking part of the paragraph, however, is that he writes that aurochs were allowed to herd with domestic cows. Schneeberger, who visited Jaktorow, described that aurochs bulls that were seen covering domestic cows were shot and given to the farmer in order to compensate him. However, different districts might have had different handling practices. But what is really curious is that aurochs were marked in order to distinguish them in the herd – one would actually assume that aurochs were easy to distinguish by their size (yes, historic aurochs were slightly smaller than Pleistocene ones, but Schneeberger still mentions aurochs from the same region being “much larger” than domestic cattle), behaviour and overall appearance. Of course rural domestic cattle were less-derived than today. Perhaps it would indeed be not that easy to distinguish an aurochs in a, say, Sayaguesa herd to the untrained eye. But it is still a notion that sounds dubious to me. What is also very interesting and slightly less curious is that aurochs would not have accepted the bull that was with the domestic cows afterwards. This is surprising, given that adult bulls would have been more or less solitary anyway, but not entirely implausible (perhaps recognizable by the changed scent of the animal) – there were certainly aspects of the aurochs’ behaviour that we do not know about.

Herberstein also mentions that the hybrid offspring would have been short-lived. This is roughly in agreement with Schneeberger, who states that domestic cows covered by aurochs bulls will miscarry or give birth to a “non-viable calf”. So we have two independent historic sources describing interbreeding problems between aurochs of that time and region with domestic cattle of that time and region. Therefore, there might indeed have been some reproductive barriers between these bovines. Another possibility would be that this reflects just a rumor among farmers of that region. I can imagine farmers not being very happy with aurochs hybrids and perhaps a myth that they cannot successfully interbreed developed over Chinese whispers. But that is just a speculation. What we do know from genetic evidence, however, is that European aurochs did interbreed with domestic cattle on this continent and produced viable and fertile offspring that left genetic traces in modern European cattle.

 

So, were aurochs bulls deliberately added to domestic herds in these very late historic times, perhaps in order to increase hardiness and robustness of the cattle? This is not entirely implausible, given that Poland is also known for having created zubrons, hybrids of domestic cattle and wisent, for this very reason. However, what does not make sense is if the hybrid calves were non-viable or short-lived, why would farmers let aurochs cover the cows? That would have been an economic loss, as Schneeberger describes (which is why the bulls were shot and given to the farmer). Another possibility is that only female hybrids were kept by the farmers and the male hybrids were not of any use because of their behaviour, in which case the farmer might still have received compensation for the 50/50 chance of an economic loss. However, I am engaging in speculation after speculation here, we simply do not know.

 

However, this did not hinder me from painting a branded late-surviving aurochs amongst a domestic cow herd:

 

“Buffalo” actually means aurochs

 

“Bubal” originally was the Arabic word for aurochs, after its extinction it got transferred to the bubal hartebeest. The Romans turned this into bubalus when they captured aurochs from Africa, until they adopted urus from Germanic ur. Bubalus then changed to buffalus and finally to buffalo – so Herberstein is historically correct in referring to the aurochs as buffalo here. Therefore, if there is a discussion if “buffalo” should only refer to members of the Bubalini clade or also to bison, historically both positions are wrong, the all-original buffalo is the aurochs.

 

Polish Landraces that could be interesting

 

This prompted me to look into Polish cattle landraces, two of which are particularly interesting. The Polska Czerwone, the Polish Red, has the same reddish brown colour as Angeln cattle but a much more aurochs-like and less derived build in having a shorter trunk, longer legs, a more athletic body and a larger head. You can see them in this or this video for example.

The second one, the Bydle bialogrzbiete, the Polish Whiteback, is another interesting one. Not only for its build, but because some bulls of the breed have been found to carry Y chromosome haplotypes not found in any international breed – but do not get too excited about that, this particular Y chromosome diversity has also been found in another landrace, the Polish whitehead breed, and is likely of taurine origin and not a reminiscence of interbreeding with the last Polish aurochs.  

 

Prusak et al. 2015: “Y chromosome genetic diversity and breed relationships in native Polish cattle assessed by microsatellite markers”, Turkish Journal of Biology.

 

Nevertheless, those Polish landraces would be a great addition to the “breeding-back” pool, especially as the Polish dislike Heck cattle for political reasons. A project working with these Polish landraces, adding breeds for body size, horn size and colour, could be worthwhile pursuing.

 

 

Domestic bull skeletons vs. the Prejlerup bull

It took me a few weeks to finish it, but I finally have finished the sketches of what the skeletons of several aurochs-like domestic bulls might look like by inferring from the living animal, and I added a skeletal drawing of the Prejlerup bull in what I consider an anatomically correct posture.

 

1. The Prejlerup bull in an anatomically correct posture

 

I used the photo of the Prejlerup bull in profile view to draw a skeletal drawing in a more natural position, by measuring piece by piece and putting it in exactly the same position as in the Tauros bull skeleton sketch I posted weeks ago. This is the result:

 

As you can see, the sketch looks quite different from the mount. The mount looks more spectacular by a) having the hindlegs bent too much and b) the spine in a too horizontal position, making the hump appear larger than it was. The latter aspect is something I overlooked in many of my previous reconstructions, most notably this one. The Prejlerup bull is still rather short-trunked, and also the largest complete skeleton of European aurochs that we have (at least as far as I am aware of). Life reconstruction of the “new” skeletal position is about to come.

 

2. The bull skeleton sketches compared to the Prejlerup bull

 

Additionally to the inferred skeleton of the Tauros bull I posted weeks ago, I did the same for the Heck bull Albatros, the Taurus bull Köpcös as much as for a Lidia and Chianina bull. Here are the sketches compared to the Prejlerup bull:

 

What becomes apparent when looking at the skeletal sketches is not only the well-known differences in proportions (longer trunk, shorter legs, smaller head) but also the depth of the ribcage. While the Chianina and Heck bulls have the least deep ribcage, possibly due to indicine influence in both breeds (Watussi in Heck), the Taurus, Tauros and Lidia bulls are better in this regard, but still not as deep as in the aurochs. What is also surprising is that the Heck skeleton and the Chianina skeleton look quite similar in proportions in having a small head, a very shallow ribcage and not that large of a hump; except for trunk length, where the Chianina is of course built shorter.

Now let’s look at trunk length. As you know, I measure trunk length as the upper margin of the shoulder blade down to the hooves for height and the length from the anteriormost point of the humerus to the posteriormost point of the pelvis. That way I circumvent that hump size, i.e. height of the shoulder spines, can vary considerably and thus would give wrong results. I divide the trunk length by shoulder height. These are the results:

1. Prejlerup (1: 1,05)

2. Taurus (1: 1,13)

3. Tauros (1: 1,15)

4. Chianina and Lidia (1: 1,17)

5. Heck (1: 1,27)

 

Therefore, the aurochs has the shortest and Heck the longest trunk of this selection; this is nothing new. What may be surprising is that Lidia and Chianina have the same ratio. Chianina are generally described as a long-legged breed and Lidia as a short-legged breed. The solution to this apparent paradox is that Lidia have a deep ribcage, while Chianina have a very shallow ribcage, giving the illusion of super-long legs.

 

So, who’s the winner of the domestic bulls in terms of aurochs-likeness? I would say both Köpcös and the dutch Tauros bull. Their skeletons resemble the Prejlerup bull pretty much in terms of proportions and are within aurochs variation (as already noted, the Prejlerup bull is particularly short-trunked). Actually, all of the bulls with the exception of the Heck bull are within aurochs variation, as the ratio of the skeletons mounted goes from 1:1,05 to 1:1,19, the “longest” being the Cambridge specimen. Lidia and Chianina are at the upper end of the spectrum, Köpcös and Tauros in the solid mean I would say.

 

However, there is a huge caveat to this method I employed for this post: first of all, using only one photo per bull can be misleading due to camera angle. The same individual can look quite different on different photos. Also, trying to infer the actual robustness of the individual bone elements, f.e. the cristae and fossae for muscle attachments, does not work by looking at the living animal. Only the proportions and the angle of the elements to each other can be inferred with some degree of certainty. And lastly, there is considerable variation within aurochs-like breeds, selecting single individuals really only tells us about those particular individuals. I am sure I can find a Heck bull that is within the aurochs trunk length range and also Tauros and Taurus individuals that are not.

But until we have assembled skeletons of aurochs-like cattle to compare with aurochs skeletons, these sketches are the best I have for this purpose.

 

A rigorous comparison of the skeletons of aurochs-like breeds and aurochs would be necessary anyway, I recently doubt the notion that aurochs skeletons are more robust with better muscle attachments than those of the domestics – but more on this in an upcoming post.

 

3. updated life reconstruction

 

You know me, I could not resist doing a new aurochs life reconstruction. I did a sketch of the Store-damme skeleton with the same method and reconstructed the soft tissue around it, looking at contemporaneous aurochs depictions for guidance. I think the result resembles the cave engraving from Dordogne pretty close. I am not 100% comfortable with the somewhat “domestic” looking trunk yet, but it is compatible with the evidence.

 

 

 

 

 

 

Skeletal sketch of a Tauros cattle bull

Grazelands Rewilding posted this Tauros cattle bull on their Instagram page a while ago. I strongly suspect that this individual is heavily influenced by Maremmana and most likely also Sayaguesa, perhaps it even is simply a Sayaguesa x Maremmana cross. I love clear shots in profile because they are excellent to judge the animals’ anatomy. I used the photo to try to infer the skeleton from the living animal, which is actually quite feasible with domestic cattle, because often you can see the joints of the limb elements, the shoulder blade and the pelvis under the skin of the living animal.

This is the result:

 

The ratio of the trunk length (from the first thoracic vertebra to the posterior end of the pelvis) to shoulder height (from the ground to the upper end of the upper margin of the bony part of the scapula) is 1:1,23 (shoulder height : trunk length). This is well outside the range of the aurochs skeletons I have examined to far, ranging from 1:1,06 (Prejlerup skeleton) and 1:1,19 (Cambridge). This means that the trunk is longer in this Tauros cattle bull than in what we find in the aurochs, which is not unusual at all for domestic cattle – quite the contrary, even in “breeding-back” cattle. 

 

I also have photos of Taurus and Heck cattle in a nice clear profile; I will do sketches of their skeletons and compare it to those of the Tauros cattle bull.  

 

 

Using AI for aurochs reconstructions

AI generated images are not my taste at all, but I have been experimenting with ChatGPT lately. Precisely, I used it on my aurochs reconstructions with the prompt “make it photorealistic”. The results were not always perfect, but some are quite good I think. The AI tends to make the trunk longer and the legs shorter, which is probably because of the cattle photos it was trained with, so I had to correct some of the results for the proportions, but not all. Today I want to share some of the results. Note that I neither claim AI generated images are "art" nor that I acclaim any copyright to these results. I merely attempt to create the perfect aurochs reconstruction. 

 

-) based on my Vig aurochs painting

Readers of my book "Breeding-back wild beasts" will know my painting of the Vig bull. I uploaded it to GPT and prompted it to make it photorealistic. As you see, it made the proportions a bit more domestic and I had to restore the dorsal stripe, but overall I think the result is ok.

-) turning Lamarck into an aurochs

I modified a photo of the Taurus bull Lamarck from 2013 and gave it more aurochs-like horns plus the curly hair on the forehead, then I prompted GPT to make it photorealistic. The result is quite good I think, although I am not 100% satisfied with the horns.

 

-) the “Augsburg aurochs” scenery

I did a painting with acrylics that is supposed to reconstruct the oil-based original of C.H. Smith’s “Augsburg aurochs”, with the landscape based on the 19^th century one. Smith reported the original showed a sooty black colour with a white chin and coarse hair. I uploaded the painting to GPT and prompted it to make it photorealistic, and I think the result is really, really good. It looks a lot like I imagine a European aurochs bull to look like, and captures the “Augsburg” essence well.

 

-) painting of the Stuttgart skull

The skull exhibited at the Stuttgart museum am Löwentor is a very interesting one, as it has quite wide-ranging, almost banana-like horns. I did a 3D reconstruction of those horn cores and sculpted a sheath over them, so that I have an idea what they might have looked in life. I used them as template for a painting, and uploaded the painting to GPT with the usual prompt. I really like the result, I think it gives a good impression of what that skull might have looked like in life.

 

-) Store-damme bull with Holstein bulls as a template

This is based on a sketch of the Store-damme skeleton that I reconstructed in flesh and blood looking at Holstein bulls – whether this breed is the best comparison is very debatable, I was just curious on what it would look like. Then I uploaded it to GPT with the prompt “paint it photorealistical like a Sayaguesa bull” because when I prompt it using the word aurochs it often results in bulls with a colour saddle.

 

-) Store-damme bull with young Lidia/Sayaguesa as a template

This is a sketch from a little animation I did a while ago with the same prompt as above. I am very satisfied with this one, I think the result looks very realistic and is also very aesthetically appealing to me.

 

 

Realtalk: will the aurochs ever come back?

Back in my teenage years, I was very much into Mesozoic dinosaurs. It changed in my late teens and shifted towards recently extinct animals, especially ungulates, because these animals are much closer to our time and thus more graspable. My enthusiasm for aurochs was partly always fueled by the thought that, because of its very recent extinction, it might one day come back with new technology. But will that ever happen?

 

In the past, I made posts on why the aurochs would be the prime candidate for “de-extinction”. You can go here, for example. Having had a deeper look into the genetic framework around CRISPR-Cas9 and what would be necessary for a successful “de-extinction” of the aurochs, I changed my mind fundamentally. The aurochs might actually be a very tricky case, if not technically impossible. Let’s have a look at why that might be the case step by step:

 

1. The reconstructed genome is not the original genome

 

Ancient DNA does not come as a nice, complete DNA strand, but as isolated fragments that are used to try to infer the original genome. Many pieces cover duplications of sequences. For the reconstruction, you need a template, a close relative that is used for puzzling the pieces together. In the case of the aurochs genomes, domestic cattle and related wild bovines are used as a template. The problem: structural variations, such as duplications of genes (that can have a huge impact on the organism), have a high risk of staying undetected in this method. For example, if the aurochs had an additional copy of a gene of the FGF family, or at least an additional enhancer, it would explain why aurochs were taller, larger, had more developed horns, and such a robust skull; yet, the duplication would stay undetected because the template (the genome of the related species) does not have it. Thus, even if scientists manage to create a bovine that has 100% of the reconstructed aurochs genome, there is the risk that this reconstruction is different from the original genome, with those differences having a large impact on the development of the animal – maybe even lethality.

 

2. Creating a bovine with 100% of the reconstructed genome is technically basically impossible

 

Domestication changed the hormonal and developmental system of cattle dramatically, with the morphological changes being a consequence of that. Not only were probably hundreds or even thousands of genes determining the hormonal and developmental regime of the animals affected by domestication, but also the accompanying regulatory sequences and epigenetic programs. So if we were to change a cattle genome into a (reconstructed) aurochs genome, we are probably talking about hundreds or thousands of edits, with a technique that only allows one change at a time and might also produce errors. It is highly impracticable.

 

3. Even exchanging a few important alleles would be problematic

 

Many of the changes during domestication did probably not change the proteins produced by the genes directly, but when, where and how long the genes are expressed. The typical domestic paedomorphy is basically a prolonged juvenile gene expression. “Removing” paedomorphy would make the bovines already a lot more aurochs-like. But developmental genes are part of a highly nuanced system with complex interactions between the individual genes, and changing a few “key genes” can lead to wrong expressions, distorted development or even lethality. And even in more discrete traits, such as horn shape, even if we identify a gene that regulates the classic aurochs horn shape and we were to insert the allele into a cattle genome, there is no guarantee the allele would work the way it would work in an aurochs, because the genetic, epigenetic and developmental environment is different. It would have to be executed by “trial and error”, which would require a large number of cattle individuals and many breeding generations. And if the inserted aurochs allele is to work in a proper, aurochs-like fashion, it would require the developmental program of an aurochs and not of domestic cattle, which brings us to the problem illustrated in point 2 again. Just inserting an aurochs allele into a domestic developmental framework might lead to distorted development and traits that are nothing like an aurochs’ at all.

 

4. In the same time span and at much lower cost, good “breeding-back” cattle could be released into a suitable reserve and natural selection does the rest

 

Implanting a few “key” alleles from ancient DNA into “breeding-back” cattle would require research on which alleles are to be inserted and a lot of trial and error to not disrupt the animal’s development, and it would probably work only with one allele per generation. Considering this, breeding for a more aurochs-like phenotype might actually have been the more efficient way all along. It selects for aurochs-like traits without disrupting the developmental pathways – surely, it takes long, but so would genome editing. And both strategies will not result in an original aurochs.

Therefore, my take on the subject currently is take the best “breeding-back” cattle, release them in a suitable area and let natural selection do the rest. According to my “dedomestication hypothesis”, that I am sure many of my readers are familiar with, wildtype traits (be it morphological, ethological, hormonal/developmental) will have a selective advantage over the domestic counterparts and the cattle will become continuously more wildtype-like with time. The cost of letting natural selection do the rest is virtually zero compared to highly effortful genome editing, which has no guarantee that it will work as planned. Therefore, I think that before we try to create an “aurochsified” cattle in the lab, we should concentrate our resources on finding or creating an area where a large-enough population of “breeding-back” cattle can live under natural circumstances, ideally with natural and sexual selection, and also pressure from predators. 

 

5. Are modern breeding-back cattle “ready to be released”?

 

This brings us to the next question, namely if modern “breeding-back” cattle are already suited for such an endeavour. My answer is a clear and strong yes. I think that modern “breeding-back” is very close to the pinnacle of what can be achieved with domestic cattle, apart from the fact that they are still very heterogeneous. But stabilizing the phenotype might actually take centuries, considering the large number of genes involved and the slow reproduction of cattle. From the ecological standpoint, I think the cattle are very fit – cattle tend to feralize rather easy, and so should “breeding-back” cattle, which descend from hardy and robust landraces. Of course, the currently running projects can still strive for even better animals, but I am very satisfied with the current results. I think it is time to look for an area large enough and isolated from humans enough so that the cattle can develop freely and unhindered from any human interference – at the same time, it would be very interesting to document phenotypic changes of these released cattle over decades in a long-term study.

 

6. Conclusion: Will the aurochs ever come back?

 

If you strictly mean the original animal in all aspects like it was 100.000, 10.000 or 1000 years ago, we can effectively almost rule that out with certainty. No matter which route we take, there will be genetic and phenotypic differences. But in a more sensu lato way of the term, we can produce a type of bovine that is barely distinguishable from the aurochs (apart from vestiges of domestication that will appear in several individuals for a very long time, such as small white spots, recessive diluted coat colours etc.) that also functions ecologically the same way, shows the same social behaviour patterns (as all domestic cattle do) and is also at least partly shaped by natural selection, by taking the best of the best of “breeding-back” cattle and releasing them into a suitable area.

 

Two new aurochs head busts based on actual skulls

Recently I finished two aurochs head busts I have been working on over the last couple of weeks. They represent the Ilford (= London) skull and a skull from the Natural history Museum whose age and location I do not know. Both skulls are available as 3d scans on sketchfab, which was great for my reconstructions.

 

based on the NHM skull

based on the Ilford skull

How I reconstructed them

 

As usual, I started with trying to accurately reproduce the skulls. I decided to make the skull 20 cm long, which is quite a handy size for the busts that still enables much detail. Then I started sculpting the eyes, nasal cartilage, lips and facial muscles around the skulls. Next step was to accurately reproduce the shape of the horn cores, and then adding the keratinous sheaths, which involves guesswork. While the horn sheaths of the Ilford skull were pretty straightforward to infer from the cores, that of the NHM skull was more tricky because the tips of the cores face forwards, not inwards as usual in aurochs. It could be the case that the keratinous sheaths were not long and did not create inwards-curving horn shapes in life, or that the sheaths were rather long, long enough to create the inwards curve. I chose latter option because the relation between the solidly keratinous part of the horn and the horn core seems to have been highly variable in aurochs and seems to be generally that way in bovines.

After sculpting the horns, the next step was to sculpt the skin and fur.

 

Why two of them

 

I chose to reconstruct two aurochs bulls to show the intraspecific variation. The Ilford skull is very massive and robust in morphology, perhaps from a very old bull, while the NHM skull is more filigree in comparison. It shows that the aurochs was quite variable in some aspects of its morphology and by fabricating two busts I wanted to show that. To add a female, I am going to make a bust based on the Sassenberg cow in the future.

 

 

How did the results work out?

 

I am quite satisfied with the results. I think I did not underestimate the soft tissue this time, in the case of the nose of the Ilford specimen I might even have overestimated it. The Ilford reconstruction has eyes that appear surprisingly large compared to one would guess from the skull alone. I think the curly hair on the forehead turned out to be quite realistic, although I could have made the hair even longer and shaggier in at least one of them considering what historic texts say.

 

What remains a speculation

 

The exact extent of the keratinous sheath in life cannot be derived from the bones and therefore remains a speculation. The extent of the white muzzle ring probably also varied among aurochs bulls, with some having virtually none and some having it fully expressed as in my reconstruction of the NHM skull.

 

Here are my head busts next to each other:

 

 

I call them Ozzy and Lemmy.

 

 

 

 

The wisent hybrid origin hypothesis is outdated

Traces of hybridization among closely related species have been found everywhere it was looked for, including the genus Homo. Bovines are no exception to this. About ten years ago, it was proposed that the wisent, which I refer to as Bos bison bonasus here, originated as a hybrid of aurochs and steppe bison, Bos bison priscus, and inherited around 10% of its nuclear genome from aurochs. Now, ten years later, it has been demonstrated that this hypothesis was based on premature conclusions and partly also the result of methodological problems. However, the rebuttal of the hybrid origin hypothesis did not nearly attract as much attention as the paper by Soubrier et al., 2016, so that many still think this is the current state of research. Considering that I wrote a post when the paper came out titled “Confirmed: the wisent is an aurochs hybrid” back then in 2016 that is still online, I feel obliged to present a (hopefully) up-to-date picture of the current research on the origin of the European bison. Let’s dive into the literature.

 

A possible hybrid origin for the wisent was first proposed in 2004 by Verkaar et al., when it was surprisingly revealed that the wisent does not cluster with American bison and yak on the mitochondrial genome but with taurine and indicine cattle instead [1]. This would have suggested that bison bulls repeatedly mated with cows of the cattle lineage, which, given the time and region, would have been aurochs, giving rise to a bison that has “cattle-line mitochondria”. Then, more than ten years later, this hypothesis was endorsed by Soubrier et al., who executed a test of 10.000 single nucleotide polymorphisms and concluded that 10,9% of the nuclear genome of the wisent stem from aurochs [2]. At that time, I found that convincing, given that wisent sometimes clearly show the primigenius spiral in their horns and have a shorter body length than American bison, traits that I associated with the aurochs. But, as we will see, the results of Soubrier et al., did not remain uncontested for long.

 

The first critical response to mention would be Wang et al from two years later [3]. They find no evidence of 10% nuclear aurochs ancestry, and also found that parts of the nuclear genome show a similar phylogeny as the mitochondrial genome. The authors consider it more likely that the evolutionary phenomenon called incomplete lineage sorting is responsible for the weird mitogenomic position of the wisent on the phylogenetic tree.

ILS is a rather cool phenomenon. It happens when there are polymorphic genes (with more than one allele) in an ancestral population and the population splits up and undergoes cladogenesis. One branch would inherit only one allele of the polymorphic gene (let’s call it “A”), while the other population still has the alleles A and B. Then, this other population splits up too and one filial population retains only A, and the other one only B. What would the result on a phylogenic tree be if you look at this gene? The population that branched off first would group together with the population that retained A, while B would result as the outgroup to the other two – although this is not what happened in reality. This is incomplete lineage sorting. In fact, it is not rare that mitogenomes show phylogenies that are inconsistent with those inferred from nuclear DNA [3]. Wang et al. find that ILS is a more plausible explanation for the mitochondrial position of the wisent and more consistent with the genomic structure of the bovine [3]. The authors also caution that phylogenies based on single genes can be misleading because of ILS [3].

 

What about the 10% aurochs ancestry on the mitochondrial genome? It seems that this number is erroneous because an inadequate method was used [4]. Soubrier et al. looked at fewer than 10.000 SNP, which is a rather scarce sample, and did an f4-statistics analysis with them, which is how they arrived at the 10,9% aurochs ancestry. Grange et al. point out that this might be problematic because f4-statistics assume an ancestral population that is polymorphic for the SNPs, while the sample the authors used were from the BovineSNP50 chip that contains SNPs for differentiating individuals of modern cattle breeds [4]. With another approach, namely the Approximate Bayesian Computation (ABC), Grange et al. arrive at a 97,2% probability that there is at least one percent aurochs ancestry in the wisent genome, which is significantly lower than the results of Soubrier et al. [4]. The method employed by Soubrier et al. also results in ancient wisents, wisents from 1911 and Pleistocene priscus being closer to each other than the wisent from 1911 to modern wisents, indicating that something is methodologically wrong here [4].

Weçek et al. did a whole genome sequence analysis with modern wisent genomes as well as four historical samples and found that only 2,4 to 3,2% of the wisent genome seem to come from the aurochs/cattle lineage and the genomic structure suggests that it occurred a long time ago, therefore they consider it possible that this reflects aurochs introgression but they note it requires more research [5].

 

If the wisent is not an aurochs hybrid, where does it come from? One hypothesis that was postulated is that it is a descendant of late surviving B. b. schoetensacki. Bone remains from the Sirejol cave from the Upper Pleistocene have been tentatively morphologically assigned to this form previously, and a phylogenetic analysis revealed that the material belonged to the Clade X proposed by Soubrier et al. and Bb1 proposed by Massilani et al. (2016) [6]. The authors of Palacio et al. therefore conclude that schoetensacki corresponds with this mitochondrial clade [6]. The presence of schoetensacki in the Late Pleistocene would imply a ghost lineage spanning over a 500.000-year period, since this variant disappears from the fossil record shortly after aurochs enter the European continent in the Middle Pleistocene.

However, the morphological assignment of the Sirejol material to schoetensacki was likely premature, as a morphometric analysis taking sexual dimorphism into account rejects that this material was of a late surviving schoetensacki bison [4]. The much more basal B. b. schoetensacki clusters morphologically with the earlier B. b. menneri, but not with steppe bison and wisent.

 

So the wisent is not a descendant of the European Bos bison schoetensacki either. What we can say is that molecular clock data suggests that the lineages of B. b. bonasus and B. b. bison diverged around 215kya (roughly the same time when B. b. priscus first entered America) and gene flow ceased at 102kya [4]. 57 ancient genomes suggest that late Pleistocene steppe bison originated from the north while wisent originate from a refuge in the southern Caucasus after the most recent glacial maximum [7]. The American bison is nested in the priscus tree on the mitogenome [4], so we can be rather confident that B. b. bison descends from B. p. priscus in some way (either directly or over B. b. latifrons).

 

The two mitochondrial clades Bb1 and Bb2 are present in the late Pleistocene in Western Europe and the Caucasus, they are sister clades to the modern wisent clade [7,8]. It seems that while aurochs retreated southwards during glacial periods, ancient bison stayed in refuges dispersed over Europe [7,8]. This fragmentation and isolation could explain how the ancestors of the wisent split off from the rest of late Pleistocene bison around 215kya. While the more cold-adapted ancestors of the steppe bison/American bison clade probably remained in the north, the ancestors of the wisent might have stayed in their refuges in the Caucasus and parts of Europe.

 

As you see, the situation is much more nuanced than my post from 2016 suggests. It is a reminder for me that the last word is never spoken in science, contrary to what the title of my 2016 post suggests (“confirmed”, a word I should not have used).

If I missed any relevant papers in this post, I'd be grateful if it could be pointed out to me. 

 

Literature

 

[1] Verkaar et al.: Maternal and paternal lineages in cross-breeding bovine species. Has wisent a hybrid origin? 2004.

[2] Soubrier et al.: Early cave art and ancient DNA record the origin of European bison. 2016.

[3] Wang et al.: Incomplete lineage sorting rather than hybridization explains the inconsistent phylogeny of the wisent. 2018.

[4] Grange et al.: The evolution and population diversity of bison in Pleistocene and Holocene Eurasia: sex matters. 2018.

[5] Weçek et al.: Complex admixture preceded and followed the extinction of wisent in the wild. 2016.

[6] Palacio et al.: Genome data on the extinct Bison schoetensacki establish it as a sister species of the extant European bison (Bison bonasus). 2017.

[7] Massilani et al.: Past climate changes, population dynamics and the origin of Bison in Europe. 2016.

[8] wisenthybrid3

[9] Zver et al.: Phylogeny of Late Plesitocene and Holocene Bison species in Europe and North America. 2021.

 

Did the wisent evolve because of humans?

For this post, I created the new post category “wild speculations”, because it is indeed a wild speculation. Some species even evolved as a result of human activities. One example for human-induced speciation would be the plant Erythranthe peregrina, which is a hybrid of two species introduced to Britain, E. guttata and E. lutea, which hybridized, created a sterile hybrid which experienced allopolyploidization (doubling of the genome) and produced a fertile hybridogeneous species. It was discovered relatively recently (2011). Without human intervention, this species would not exist. It is also possible that other kinds of human intervention, such as wiping out species, can result in a speciation event over a longer period of time in evolutionary terms because the niches that become vacant have potential for the evolution of new species. I have the suspicion that it is possible that the wisent might be such a case.

The story begins around 600kya, when there was only one Bos species in Europe, Bos (bison) schoetensacki. Around that time, a second bovine species migrated to Europe, either by island hopping from Africa or via the continental route from western Asia, the aurochs. Only a few millennia after the aurochs arrived in Europe, B. schoetensacki disappeared from the fossil record. I think it is quite possible that B. schoetensacki was outcompeted by the newly arrived aurochs as both bovines must have occupied a similar niche and the extinction shortly after the arrival of the aurochs is just as suspicious as the fact that bison subsequently were absent from interglacial faunal assemblages of Europe until the very late Pleistocene around 13kya, when bison (now in the form of the wisent) re-entered the interglacial megafauna assemblage. I call that the “bison gap” (roughly 600kya-13kya). If the aurochs outcompeted bison in Europe, why did they rejoin the interglacial fauna and why only so recently? B. bison priscus, which was most likely the ancestral form of the wisent, was present in Europe during all of the recent glacial periods. So, it could have evolved into an interglacial bison type much earlier, right after the extinction of B. schoetensacki if the aurochs did not outcompete bison in Europe – if it did, it is an open question why this competition was not a factor anymore at the end of the Pleistocene and during the Holocene.

Several thousand years earlier, there was another event that had an impact on the European megafauna: Palaeoloxodon antiquus and Stephanorhinus hemitoechus died out, most likely because of hunting from humans. Elephant extinction reduced competition for other grazers, at the same time forest growth became more common. Aurochs could not invade denser forest while bison are adapted to consume more wooden vegetation and can invade denser forest. This might have created new ecological space for bison to re-enter the interglacial faunal assemblage.

 

This guess is impossible to verify, but I think it must have one or several reasons why bison were absent from the European interglacial faunal assemblages for over 500.000 years.

 

If this guess is true, it would illustrate how nature is dynamic and might respond to anthropogenic impacts not necessarily always in a diversity-reducing way but sometimes also in a diversity-increasing way.

 

Aurochs anatomy revisited

In the latest post, I reviewed much of the ancient and historical aurochs depictions and what they tell us.

Here are some conclusions in this regard:

 

A shoulder hump present and visible, more so bulls than in cows but present in both sexes, but not nearly as prominent as in bison – this is also in line with the fact that the shoulder spines are not as high in the aurochs as in bison.

The dewlap likely had almost a gap in the throat region, similar to what we see in banteng.

The pelvis was probably slanted to some degree; we see this also in other wild bovines and this is likely basal for Bos.

Adult bulls probably made a massive and somewhat hefty impression as they are often portrayed in that fashion. Likely there was no edge between the neck and the hump in bulls in the “default position” of the neck.

 

With this information, I attempted some new reconstructions, also trying to avoid my common mistakes I tend to make when I reconstruct the aurochs.

 

Most puzzling to me is the length and shape of the trunk. Let us look at the length first.

When I do my reconstructions, I always consider the cartilage between the leg elements that is missing in the skeletons. This makes the legs longer in life than what they appear in the skeleton. There were of course also the intervertebral discs between the vertebrae, which I also considered but assumed that most mounts take them into account. Looking at dissected cattle, I think, however, that some skeletal mounts might underestimate the amount of cartilage between the vertebrae. This means that the ratio between shoulder height and trunk length was certainly not exactly as in the skeletons. The exact ratio in life is, however, hard to determine without accessing the skeleton directly. Some guesswork is involved, and this is where aurochs depictions can be helpful. Not in detail, but they do transport the overall impression the animals must have made. And if the artwork is bulky, the animal certainly was not gracile.

There is also one sentence in Schneeberger’s report from Jaktorow that provides a clue. He writes that bulls were not as long as the cows, which is the only written account of the body morphology of the aurochs that I am aware of. The fact that he wrote cows being “not as long as the bulls” could indicate that he found the bulls to be somewhat longish. But not necessarily. However, the way the remark is put is interesting.

 

The same goes for the shape of the trunk. With the exception of the Siga verde bull engraving, none of them show bulls with an overly slender waist as in young fighting bulls.

 

Putting the evidence together, I made three sketches based on three different approaches.

This one is based on the photo of a Holstein bull. I manipulated the proportions of the bull on the photo in order to make it fit the Store-damme skeleton:

 

This one is based on the Torsac-dirac skeleton, using ancient depictions such as the one from the Romito cave, Siga verde or Dordogne as a guidance:

 

The last one is based on the Store-damme skeleton:

 

 

While the results are not all too different from each other, I think the lower sketch is the most plausible one, it resembles the Lascaux cave paintings quite well while also matching the anatomy of extant wild bovines. It also resembles the reconstruction of the Sassenberg bull by Tom Hammond in overall morphology. If two artists come to the same result with different skeletons and methods, we might be on the right track. 

 

 

 

What ancient and historical depictions of the aurochs tell us

When trying to infer the morphology of the aurochs from all available evidence, we do reach a point where comparisons with living relatives (wild bovines and domestic cattle) will not get us any further because there are limits to what the skeletal morphology tells us about the surrounding soft tissue. This is where ancient and historical depictions made by people who actually encountered the living animals become helpful. With this post, I want to do a review of what I think these depictions tell us about the morphology of the wild bovine.

 

This post features some images; if you are the copyright holder of these images (in those where the copyright is not yet expired) please notify me if you want me to remove the images in question.

 

-) Cave paintings and prehistoric engravings

 

All prehistoric depictions show a rather short dewlap in both sexes that becomes very short in the throat region. This shape of the dewlap is similar to what we see in banteng. The backline is almost always slightly depressed in the middle of the trunk, creating an S-shape. Bulls are often shown with a rather massive and sometimes longish morphology, most notably the engravings at the Grotta de Romito and Dordogne.

The hump is indicated in most ancient depictions, but not nearly as prominent as in depictions of steppe bison. There is mostly no edge between the neck and the shoulder hump in the bulls, similar to what we see f.e. in Sayaguesa but unlike what we see in Lidia and most other domestic bulls.

 

-) The Zliten mosaic

 

It shows a rather athletic bull that might be an aurochs with a morphology similar to young Lidia bulls.

 

-) The Vapheio cup

 

The bulls on the Vapheio cup from ancient Greece show curly hair between the horns and rather longish trunks. The waist is not as slender as in young Lidia bulls and the dewlap is again very short.

 

-) Bestiary of the British Library 12F XIII

 

This is the only depiction showing what might be a “mane” like in Lidia, Chillingham and some OVP Heck bulls. The trunk is rather short and narrowing towards the hips and the dewlap is short.

 

-) Aurochs hunt depiction from 16^th century of Nuremberg

 

It shows a bull with an athletic body with a narrow waist and a short trunk.

 

-) von Herberstein’s taxidermy

 

There are two contemporaneous drawings showing Sigismund von Herberstein’s aurochs taxidermy, one from 1556 and one from 1557. These drawings, however, have to be viewed with caution; not because they are stylized, all contemporaneous aurochs depictions are, but because it is based on a taxidermy and we do not know how authentic this taxidermy was. Von Herberstein was also in possession of a wisent taxidermy that was drawn by the same artist at the same time, and the wisent drawing is rather accurate, so the taxidermies might have been quite authentic and so might be the drawings.  

 

 

The 1556 drawing shows a massive body, short dewlap with a similar shape as in cave paintings,a hump not discernable (while illustrated very clearly in the wisent drawing), curly hair on the forehead, a slightly slanted pelvis as in banteng and gaur, which I believe to be the basal condition within the Bos clade.  

 

The 1557 coloured drawing shows a short but massive trunk, slightly slanted pelvis, a hump that is slightly indicated, dewlap short but more than one “flap” under the throat (more like domestic cattle) and the same curly hair as in the older drawing.

 

-) Charles Hamilton Smith’s aurochs

 

CHS’s copy of the lost “Augsburg painting” shows a very short dewlap with two indicated flaps in the throat region, a deep chest and relatively trunk narrowing towards the hip, a hump that is only indicated and neck muscles set apart from the hump. The original is said to have shown a coarse black coat.

 

I leave this analysis as it is for this post, my conclusions for the aurochs’ anatomy will be covered in an upcoming post that will also include some new reconstructions avoiding my old mistakes. Stay tuned.