"Breeding-back" aims to restore or immitate extinct animals by selective breeding. This blog provides general information, the facts behind myths and news from various projects.

Friday, 29 April 2022
Video of a great Lidia bull
Monday, 11 April 2022
Bos primigenius or Bos taurus?
There is some confusion about which name is the proper scientific name for the aurochs, Bos primigenius or Bos taurus. In this post, I am going to investigate the question which of those names is the legitimate scientific name for the aurochs.
If one considers domestic cattle and aurochs different species because the former has been domesticated, the case is clear which scientific names they should have: the aurochs would be Bos primigenius, described by Bojanus in 1827, and domestic taurine cattle would be Bos taurus, described by Linnaeus in 1758. But there is no scientific consensus on whether domestic animals and their wildtypes should be regarded as one species or separate species. I tend to not regard domestic animals as taxa that need a proper scientific name at all (go here for my post on that).
So, if aurochs and domestic cattle would be one species, with the aurochs being the wildtype and domestic cattle man-made modified versions of the aurochs created by artificial selection, what is the proper scientific name for that species? This is now where it becomes tricky.
Due to the rule of priority of the ICZN, the first name used to describe a species has priority. In this case, Bos taurus would be the proper scientific name of the species containing aurochs and domestic cattle because it is the earlier name. However, in 2003 the ICZN decided that 17 names of wildtypes that are pre-dated by names for domestic forms should be conserved, including Bos primigenius (opinion 2027). However, to complicate the issue, Linnaeus actually referred to the aurochs in his description of Bos taurus from 1758. He mentioned the aurochs as “ferus urus” (= “wild aurochs”) living in Poland. Apparently, he was not aware of the fact that the aurochs probably already had died out when he described the species (go here for the youngest aurochs remains currently known). This is taxonomically not relevant however, Linnaeus definitely described the aurochs and domestic cattle as one species in 1758.
Referring to the aurochs as Bos taurus is therefore definitely legitimate. However, I prefer to follow opinion 2027, also because Bos primigenius at least has a holotype (the Haßleben specimen), while Bos taurus does not. Therefore, it is up to ones’ preference whether to use Bos primigenius or Bos taurus for the species that contains the aurochs, and also depending on your opinion on the taxonomic status of domestic animals in general.
Wednesday, 16 March 2022
The horns of the African aurochs and its evolutionary implications
I did a post on the African aurochs, Bos primigenius mauretanicus, a few years ago. The African aurochs is said to be morphologically very similar if not identical to the European aurochs, so that van Vuure (2005) concludes it might be exclusively geographical [1]. The only difference to the European aurochs mentioned in my old article is the fact that bulls likely had a colour saddle. However, there might be morphological differences in the horns of the African aurochs, which have previously not been recognized in the literature.
In 2015, the oldest aurochs skull found so far was described [2]. It is from Tunisia and is very large-horned. But what was interesting to me about the horns was not their size, but their shape and orientation relative to the skull. They have an angle of 40° relative to the snout, which is narrower than in the European aurochs, where the range of angles of the horns relative to the snout is between 50 and 80° on average, and larger in single exceptions (such as in the skull exhibited at Horsholm). Also, the horns seem to be dorsoventrally compressed at the base or proximal half, while the distal end of the horn seems to be round in cross section.
Due to the age of the skull (700.000 years), I was unsure whether to classify it as a member of B. p. mauretanicus, or maybe as a basal aurochs that lived before subspecies differentiation.
However, I recently found a depiction of another African aurochs skull, that, because of its geologically younger age, certainly is a member of B. p. mauretanicus. The anatomical drawing is from a work from 1931 and is labelled as Bos opisthonomus, which is a junior synonym of B. p. mauretanicus. It shows the same anatomy as the 700.000 years old skull from Tunisia: horns facing forwards in a narrow angle (35°) and dorsoventrally compressed at the base or proximal half. The image is from Duerst (1931) [3].
An anatomical drawing of an African aurochs skull, from Duerst 1931 |
Thus, it seems that these two traits (dorsoventrally compressed horns at the base, horns facing forwards in an angle sharper than in the European aurochs), were general anatomical traits of the African aurochs. That the horns of the African aurochs faced forwards in a sharp angle also fits historic descriptions, because Herodotos describes that in North Africa there were bovines with horns so long and forwards-facing that they had to graze backwards [1]. Likely this referred to the African aurochs. Also ancient depictions of African aurochs show horns growing parallel to the snout, what suggests that the horns were facing forwards in a narrow angle. In European aurochs, and sometimes also domestic cattle, the horns were/are oval in cross section at the base as well (in Pleistocene European aurochs more so than in Holocene ones) [1], but this trait is definitely more expressed in the African aurochs.
Apparently, the aurochs varied in horn orientation from subspecies to subspecies. While the African aurochs had the narrowest angle, the Indian aurochs and possibly B. p. suxianensis had the largest angle, and the European aurochs was in between. Whether the difference in horn orientation has a functional purpose or if the variation was merely a result of genetic drift is unclear to me.
It is interesting to speculate about the evolutionary implications of the horn anatomy of B. p. mauretanicus. There are two conflicting hypotheses on the origin of Bos and the aurochs. One of the hypotheses postulates that Bos and the aurochs in particular evolved in Africa from Pelorovis oldowayensis, the other one suggests that Bos originated from Leptobos in Asia, and the aurochs from the very large-horned Bos acutifrons in India. The fact that the horns of the Indian aurochs are more upright than those of the other aurochs subspecies seems to support the latter hypothesis, as the horns of Leptobos are rather upright. However, the fact that the horns of the African aurochs have such a narrow angle between horns and snout and the dorsoventrally compressed horn bases support the origin from Pelorovis oldowayensis, as this species has horns with a very narrow angle relative to the snout and dorsoventrally compressed horns. Other cranial traits seem to support an origin from Leptobos, on the other hand. The origin of Bos probably can only be resolved by finding more fossils of relevant taxa.
Literature
[1] van Vuure: Retracing the aurochs – history, morphology and ecology of an extinct wild ox. 2005.
[2] Martinez-Navarro et al.: The early middle Pleistocene archaeopaleontological site of Wadi Sarrat (Tunisia) and the earliest record of Bos primigenius. 2014.
[3] Duerst: Grundlagen der Rinderzucht – eine Darstellung der wichtigsten für die Entwicklung der Leistungen und der Körperformen des Rindes ursächlichen, physiologisch-anatomischen, zoologisch-paläontologischen, entwicklungsmechanischen und kulturhistorischen Tatsachen und Lehre. 1931.
Friday, 4 March 2022
Differences between the Quagga Project zebras and the quagga
The Quagga Project likes to call their zebras “Rau quagga”, after the founder of the project Reinhold Rau. That is why I made the post Please don’t call it quagga. The advocates of the name “Rau quagga” state that it is O.K. to call the zebras that way because the “Rau” in “Rau quagga” underlines that they are different animals from the quagga. I, however, think it is not legitimate to call something that is not a quagga a “quagga”, with or without the “Rau” in front of it. Calling those zebras “Rau zebra” would be more adequate if the zebras of the Quagga Project need a name, because they are zebras in any case.
Names aside, I made a post on the differences between the quagga and other zebras not so long ago. I think it is time to have a look at the differences between the zebras of the Quagga Project and the quagga.
The Quagga Project focuses only on the pelage colour characteristics. The coat colour of the Quagga was variable to a certain degree. I tried to capture this diversity in a drawing, using the preserved quagga skins as a reference:
The quagga was variable in the extent of the striping, but there are some general differences between the quagga and the zebras of the Quagga Project.
The striping is supposed to link the zebras of the QP with the quagga, and indeed the amount of reduction of the striping that has been achieved is impressive, but there are some clear differences in the stripe pattern of the quagga and the zebras of the QP.
1) In many of the zebras of the QP the stripes on the neck alternate between broad, solid black stripes and faint, narrow stripes. This was not the case in the quagga. All quagga skins show that the quagga had exclusively broad, solid black stripes on the neck.
2) The stripes on the face of the zebras of the QP are very narrow, producing a broad white space between them. In the case of the quagga, the stripes on the face are rather broad, with only a narrow quite area in between them.
The second clear difference in coat colour between the zebras of the QP and the quagga is the base colour, i.e., the colour between the stripes on the trunk. In the quagga the base colour of the trunk was brown, sometimes more intense sometimes less intense, but always brown. The base colour of the trunk on the zebras of the QP has some brownish shade but is not nearly intense as in the quagga specimen documented. The QP is aware of that and hopes they will achieve that brown base colour in the future.
Another possible difference is the length of the mane. I have the suspicion that the quagga had a shorter mane than other plains zebras, based on the photographs and the preserved skins. The zebras of the QP have rather long manes compared to the documented specimen of quagga. This is only my suspicion; it would have to be verified by measuring the manes of the preserved quagga skins.
Another very important difference between the quagga and the zebras of the quagga project is the fact that the quagga does not share any mitochondrial haplotypes with the living plains zebra subspecies (see my article linked above). There is no reason to assume the case is any different in the zebras of the QP, so therefore the animals are also genetically different.
The quagga and the zebras of the QP are superficially similar because an amount of stripe reduction on leg and trunk has been achieved in the latter, but that is it. There is no justification for calling the zebras of the QP quagga or “Rau quagga”, they are simply plains zebras with a reduced stripe pattern. General differences, such as in the striping on the anterior part of the body or the lack of a brown base colour on the trunk will remain. The project hopes to achieve the brown base colour one day, but I wonder if this is possible without new mutations enabling an increased production of pigment on the trunk area.
I am writing this not in order to criticize the QP, not at all. I just think that we should always stay objective and should not declare the revival of an extinct animal that is still dead as a dodo based on superficial similarity. I am happy that there is the QP, because their zebras could be very useful for outbreeding with quaggas if one individual or a few individuals could be genetically resurrected using genome editing one day.
Tuesday, 22 February 2022
A possible skull of Bos primigenius siciliae
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Uploaded by the user Ghedo on Wikimedia Commons |
Monday, 14 February 2022
Another study debunks the Konik myth
Friday, 11 February 2022
The last aurochs were from Bulgaria, 18th century (!)
Tuesday, 1 February 2022
How the Heck brothers could have done their work better
In a post from 2015, I evaluated the “breeding-back” experiments executed by Heinz and Lutz Heck. I came to the conclusion that they made several technical mistakes and could have done their work better given the circumstances of their time. This post is going to look at how they could have done their experiments better using the possibilities they had when they started in the 1920s.
Step 1: Getting an accurate picture of the aurochs
One of the reasons why the Heck brothers failed at creating a phenotypic copy of the aurochs is that they did not have an accurate, precise picture of the aurochs. They did research, and they also resolved at least some coat colour traits of the animal, but the picture of the aurochs they had included errors and needless speculations such as a red dorsal stripe instead of a grey one as the historic evidence suggest, or a greyish tone in the colour of the cows. The biggest problem was that they failed to recognize the morphology of the aurochs. Apparently, they never saw a mounted aurochs specimen or if they saw one, they did not take a close look at it. Doing so would have told them that the trunk of the aurochs was much shorter than in domestic cattle, that the legs were longer, the head larger and more elongated, and that aurochs had a hump formed by long spinal processes in the shoulder region. Surely, it was not as easy to see a mounted aurochs skeleton as it is today (a quick google search is enough to find photos nowadays), but there were more or less complete aurochs skeletons back this time in Germany (at least the Haßleben specimen which was described in 1827). They did not study the skeletal remains of aurochs, thus the most important part of the aurochs’ life appearance, the morphology, played no role in the projects of the Heck brothers.
They could have done better by looking for a museum that would have had a mounted aurochs specimen and study its differences to modern cattle. Their research on the colour of the aurochs should not have included baseless speculations, but rather they should have strictly followed what the historic evidence that was available to them inferred. Doing that would have enabled them to get a pretty accurate picture of the European aurochs’ morphology and life appearance even back in the 1920s.
Step 2: Creating a strict breeding goal and not ignoring certain traits
Before starting any breeding, it would have been vital to set up breeding criteria that are based on what has been found out about the aurochs’ life appearance. The Heck brothers did not have a clear breeding goal because they did not have a precise picture of the aurochs. Furthermore, they ignored certain traits. Body size was ignored, udder size was ignored, the morphology was not recognized. Thus, anything that roughly met the Heck brothers’ idea of the coat colour of the aurochs and had longer horns would have matched their rather wide selection criteria. Therefore, it is not surprising that they announced success after a few years of breeding, since their breeding goal was not clearly defined. If the Heck brothers had created a clear catalogue of traits the cattle should have that also included all the traits found in the aurochs and not only some, their breeding would have been much more efficient.
Step 3: Finding suitable breeds
This step was without doubt the trickiest of all, because back this time there was much less information available. It was unknown where the aurochs was domesticated, were the most aurochs-like breeds would be found and there were barely any breeding associations to contact and no internet. The brothers, however, did find out that many Iberian breeds show traits of the aurochs. Lutz Heck was particularly impressed by the Spanish fighting bull, which is indeed one of the most aurochs-like breeds that are still around. Heinz Heck, on the other hand, did not use the Spanish fighting bull but included a number of derived breeds, because he hoped that they carry invisible aurochs traits that would surface again when crossed with more primitive breeds. This hope, however, did not fulfil. Retrospectively, it was a mistake to include derived breeds such as Black-pied lowland cattle, Murnau-Werdenfelser and others. The set of breeds selected by the Heck brothers was thus not ideal. The fact that they ignored certain traits (body size, udder size) or did not recognize them (morphology), was another reason why their set of breeds was not ideal. Thus, if the Heck brothers would have known about the morphology of the aurochs and cared about size, they would have looked for breeds that add these traits. If they would have stumbled across Chianina while searching for large breeds, they would have found a breed that adds large size and long legs and to a certain degree small udders. Lutz Heck recognized that Watussi can have aurochs-like horns but did not use that breed. Using it would have considerably increased the size of the horns of their cattle and would have compensated the small horns of other breeds used. Thus, if the Heck brothers would have used a different set of breeds, the result would have been much more aurochs-like. Corsican, Camargue and Lidia are breeds that were used (Lidia only by Lutz Heck), they were valuable because they contributed the right colour (Corsican) or had an athletic morphology (Camargue and Lidia). If they sticked with those three breeds, and maybe also Podolian cattle (for the cold resistance and winter coat), but would not have used the derived ones, and included Watussi and Chianina, the potential for an aurochs-like outcome would have been much larger than it was with the set of breeds they chose. A mix of Corsican, Camargue, Lidia, Chianina, Watussi and perhaps a Podolian breed would have had great potential.
Step 4: Strict selective breeding focusing on the breeding goal
As the Heck brothers did not have a very precise breeding goal, they barely carried out strict selection, leading to a very heterogeneous result. More precise selection criteria and strict selective breeding would have created a more aurochs-like outcome.
Step 5: Setting up a studbook and ensuring that selective breeding is maintained while the breed is expanded to other locations
It was certainly sloppy that the Heck brothers did not set up a studbook for their cattle. Also, the fact that there was no official catalogue containing selection criteria that they themselves and other breeders should have followed created chaos when the population was expanded to other locations. Some breeders selected their cattle for an aurochs-like appearance, such as the Wildgehege Neandertal, others did not, and Heck cattle became a very heterogeneous breed. Creating a catalogue with selection criteria that are based on the aurochs could have prevented this at least to a certain degree.
If the Heck brothers did those five steps, and if the breeders that came after them sticked to the selection criteria, the resulting cattle would not only be better than Heck cattle as they are now, they would even be a lot better. I would even say, we could have the cattle of our dreams now if the Heck brothers would have done their work more thoroughly. Almost 100 years of efficient selective breeding is enough to create a homogeneous but genetically diverse breed of cattle with the right colour, large or even very large size, the right morphology and horns and a sufficient winter coat. Modern “breeding-back” projects are on a good way, but it will take its time until the goal is accomplished. If the Heck brothers did their work more thoroughly, that goal possibly might have been reached now in 2022.
Monday, 24 January 2022
The skull of a Lidia bull
Sunday, 16 January 2022
Does the "Augsburg aurochs" really show an aurochs?
The “Augsburg aurochs” made by Charles Hamilton Smith in 1826 is one of the most famous depictions of an aurochs. It is based on an oil painting which dates to the 16th century and that was purchased by Smith in Augsburg, Germany. The oil painting, which might have been based on a live aurochs, is now lost and there are no photographs of it. The only thing we have is Smith’s copy of the painting, the “Augsburg aurochs”. “Copy” is a bit misleading, as Smith probably did not track out the original work but made his own version of it. For example, the animal on the original painting had an “entirely sooty black” colour, except for a white chin [1], while Smith decided to paint his aurochs in brown for whatever reason. The black and white version of Smith’s artwork is widely publicised, but the original work is coloured and shows a brown animal as you see down below [2].
Wikipedia cites a source which itself cites two sources that the original that Smith’s artwork is based on might not show an aurochs at all: one source claiming the painting might have been based on a hybrid between aurochs and cattle, and another one claiming it might have been based on a Polish steer.
To see if there is anything legitimate behind these ideas, let’s have a look at Smith’s artwork. We do not know what the original looked like, except for the fact that the original bull was entirely black with a white chin. This is a colour that agrees with the other sources for the colour of the aurochs that we have, only the light dorsal stripe was apparently lacking on the original. This does not necessarily have to mean that the animal the painting was based on lacked a dorsal stripe, since this trait is not visible from every perspective.
The animal portrayed by Smith matches an aurochs very well in proportions. The trunk is short, the legs are long, the head is large. The horns have the curvature of an aurochs’ horns and face forwards, and also the size is aurochs-like. The ribcage is deep as in the aurochs, and the waist is slender, creating a triangular shape for the trunk, which was very likely a trait of the aurochs as all wild bovines have that kind of trunk. The head has curly hair on the forehead, which is a trait that is well-documented for the European aurochs [1]. The head looks a bit paedomorphic with its concave snout and large eyes, but Smith tended to stylize his animal depictions. The dewlap is very short, as in the aurochs. The animal seems to have a woolly coat, and historic reports say that aurochs were covered in longer hair than domestic cattle [1], which is plausible for a wild animal living in temperate Europe. All in all, Smith’s depiction looks much like an aurochs, except for the wrong colour, which was aurochs-like in the original. It is most parsimonious to assume that the aurochs-like traits found in Smith’s work were also found in the original oil painting, otherwise it would be a big coincidence that Smith’s work happened to be more aurochs-like, in a time when we did not have a very good picture of the aurochs’ life appearance.
One could argue that the lack of a penis tuft is a hint that the original artwork was based on a domestic steer, as steers usually do not have one. Also, the neck bulge is not very prominent in Smith’s work (steers have none). However, we do not know what the original looked like. Perhaps Smith was not paying attention to these two traits when he did his artwork. Perhaps the artist of the original from the 16th century did not pay attention to them. Smith’s work, however, definitely shows a scrotum.
As for the arguments claiming it was a hybrid between an aurochs and a domestic animal, I don’t know what exactly lead the author to conclude that it was a hybrid as I do not have access to the work in which it is postulated. But I cannot derive any possible reasons that lead to this conclusion based on the artwork, because Smith’s aurochs actually looks much like an aurochs and a wild bovine (the morphology, the dynamic pose and the slender waist suggest a wild animal to me).
Also, the original painting had the word “Thur” written in golden letters on it [1], which is the Polish name of the aurochs. Back in this time, aurochs were only found in Poland [1] and also South-Eastern Europe (Moldavia). The usage of the word “Thur” suggests that the artist had seen an aurochs in Poland, where the last aurochs were found. In Poland, people strictly distinguished between the aurochs and the wisent, because both animals were still found in this country, and they knew what they looked and were like. I see no reason why this word would be used for a domestic steer.
All in all, I think it is highly likely that the original painting Smith’s “Augsburg aurochs” was based on showed an aurochs, that the original probably was a rather accurate depiction of an aurochs because Smith’s work is that too (except for the wrong colour), and that it is well probable that it was painted after a live aurochs. It seems that most authors assume it showed an aurochs, and I see no convincing, compelling reasons to assume otherwise.
Literature
[1] van Vuure: Retracing the aurochs – history, morphology and ecology of an extinct wild ox. 2005.
[2] Frisch: Der Auerochs – das europäische Rind. 2010.
Monday, 10 January 2022
The MAOA gene found to play a role in the aggressive behaviour of Lidia cattle
The monoamine oxidase A gene (MAOA gene) produces the enzyme monoamine oxidase A, which has an important function in the endocrinological metabolism in the brain of mammals. Mutations on this gene cause aggressive behaviour in humans (the Brunner syndrome) and in laboratory mice. These mutations lead to a deficiency of monoamine oxidase A production, causing an excess of serotonin, dopamine and noradrenalin in the brain, which has an impact on behaviour.
A recent study examined the MAOA gene in in cattle. The study tested the MAOA gene in Spanish fighting cattle (Lidia), which is selected for aggression (“fighting spirit”), and breeds that are not selected for aggression and do not display excessively aggressive behaviour (Asturiana de los Valles, Morenas Gallega, Retinta, Rubia Gallega, Avilena, Limousine and Charolaise). They found considerable variation in sequences of the promotor region of the gene between Lidia and the non-aggressive breeds, indicating a possible influence of the gene on the behaviour of the cattle [1].
The million-dollar question now is, what were the sequences of the MAOA gene of the aurochs? Was it more like that of Lidia, or even identical as in Lidia, or more like that of the non-aggressive breed or even identical? As the full genome of the aurochs is resolved, it would be very interesting if someone would examine the MAOA gene of the aurochs. It could tell us if this was one of the many key genes that mutated during the domestication of cattle, and what the behaviour of the aurochs might have been like in terms of aggression, although the MAOA gene is probably not the only gene that is involved in aggressive behaviour.
Literature
[1] Eusebi et al.: Aggressive behaviour in cattle is associated with a polymorphism in the MAOA gene promoter. 2019.
Tuesday, 4 January 2022
Rare aurochs-like traits and the breeds that have them
Some aurochs traits are easy to achieve in “breeding-back”, others are not. For example, it is really easy to breed for a basic aurochs-like colour as this trait is widespread among primitive aurochs-like breeds. Other traits are among the challenges for “breeding back”, also because they are very rare among living cattle. In order to achieve them in “breeding-back”, it is important to visualize where in which breeds these traits can be found. Otherwise the breeding result might not be that convincing in terms of aurochs-likeness. In this post, I mention only the primitive breeds that have some of the desired traits, not the “breeding-back” cattle which already might have some of the traits (f.e. the right body size in the case of Taurus cattle).
Aurochs-like body size. This depends on what you consider an aurochs-like body size. As sexual dimorphism is a factor, I take the withers height of the bulls as a reference. European aurochs bulls varied from 160 to 200 cm or slightly more, therefore they are in the same size class as the wild yak. A number of breeds reach or surpass 160 cm. For example, some Sayaguesa and some Maremmana bulls (such as those acquired for the Auerrind project) reach 170 cm. Chianina and Maltese cattle reach 180 and maybe more in some cases. Modicana from Italy are also said to be 160 cm tall. I know of no confirmed cases, but Podolica and Boskarin might also surpass 160 cm. If one wants to breed for the larger end of the aurochs bull size spectrum, Chianina and Maltese are the only (taurine) options.
Horns with an aurochs-like inwards curve. Horns curving strongly inwards as in the aurochs are found in some individuals of Maronesa, rarely also Sayaguesa. Very rarely, aurochs-like inwards-facing horns are found even in derived breeds such as Holstein (see van Vuure, 2005). Some Lidia also have inwards-curving horns, although their curvature is more two-dimensional compared to that in the aurochs.
Short trunk as in the aurochs. This is a real challenge as this trait is not found in living taurine cattle, at least not in both sexes at the same time. Some Chianina, Maltese and Lidia bulls have an aurochs-like trunk length to leg length ratio, but never the cows. Only in primitive zebus (as outlined in the “challenges” post) have a trunk as short as in the aurochs in both sexes.
Hump as large as in the aurochs. Found in some Lidia and also Corriente individuals.
Elongated skull shape. Found in some Sayaguesa, Lidia, Maltese and Holstein cattle (and possibly others as well).
Well-marked sexual dichromatism. Among the taurine breeds known to me, only Maronesa and the old type of Corsican cattle have a sexual dichromatism as strongly marked as in the aurochs.
Aurochs-like body morphology. Only Lidia has a morphology (in some individuals at least) that looks plausible for a wild bovine, all other breeds have a domestic morphology - some more, others less.
Udder size. The udder should not be visible from the side, as in a wild bovine. This the case in some Lidia and some primitive zebus.
Looking at this list, it appears that for a breeding project that is ought to be successful, well-selected Maronesa, Sayaguesa, Lidia, Chianina/Maltese and primitive zebu are mandatory to achieve a phenotypic match with the aurochs that is as large as possible with domestic cattle. Taurus cattle already achieved many aurochs-like traits such as the right size (cows being 150-155 cm and bulls 155-170 cm tall at the withers), a satisfying sexual dichromatism, aurochs-like horn curvature at least in some cows and the right colour alleles are present (together with undesired alleles). One option would to start from anew with well-selected Maronesa, Sayaguesa, Lidia, Chianina/Maltese and primitive zebu and Watussi for the horn volume. Another option, that might be faster, is to take the best Taurus cattle and breed them for a more homogeneous phenotype, and then cautiously add what may be lacking in the herd, f.e. for the short trunk and small udder adding a F2 individual of (Taurus x primitive zebu) x Taurus that is well-selected, for the horn curvature (if not already achieved by selection with Taurus cattle alone) adding a suitable Maronesa individual, and for the morphology a Lidia individual plus a Watussi or Auerrind crossbreed for horn volume. With consequent breeding, the full potential aurochs-likeness that is achievable with domestic cattle could be seized. One must consider, however, that this would take at least 20 years.
Wednesday, 29 December 2021
Were European wild horses black or black dun?
Coat colour is the only aspect of the life appearance of the Holocene European wild horse that can be determined with a high degree of certainty thanks to studies examining the coat colour genotype of aDNA samples from wild horses.
A 2017 study found that the a allele on the Agouti locus, which originated in Iberia in the late Pleistocene and which causes a black phenotype on an E+/E+ genotype in non-dun horses, became increasingly common among European wild horses in the Holocene until it became the prevalent allele in the later Holocene [1]. This alone does not tell us the phenotype of the animals, because they could have either been black or black dun (also called grullo, mouse dun or blue dun). The question now is: was the late Holocene European wild horse black or black dun?
The Dun locus was resolved in 2015 [2]. It was found that there are three alleles on this locus in horses: dun D, which is wildtype and basal for all living Equus, wildtype non-dun d1 which dates back well into the Pleistocene, and the domestic non-dun d2.
The black allele was restricted to Europe, it was not found in Siberia so far [1]. The wildtype non-dun allele, on the other hand, was so far found only in Siberia [2]. This could lead us to conclude that there were no horses of a genotype a/a d1/d1, therefore being black. However, it must be considered that the Dun locus was so far only tested for Siberian wild horses, and not for European wild horses. I think it is well possible that there were horses with an a/ad1/d1 genotype, because genetics suggest that during the Pleistocene there was one large panmictic population of wild horses from the Pyrenees to Siberia [3], what makes it possible at least that the d1 allele was also found in European Pleistocene wild horses, which were the predecessors of European Holocene wild horses [4]. Furthermore, some cave paintings might depict non-dun wild horses, such as those at Lascaux, which clearly show black and blackish brown or dark brown horses among a large yellowish-brown horse. This must be viewed with caution, however, because the exact shade of a cave painting is always dependent on the pigments available to the artists and may not necessarily reflect the true colour of the animals. But so far, cave paintings proved to be rather accurate on horse colours. F.e. the leopard spotted horses illustrated at Pech Merle were found to be based on horses having that colour [5], and Ekain also shows black dun among bay dun horses. Therefore, I think it is well-possible that there were black wild horses at least during the Pleistocene.
This might have depended on another allele as well. Sponenberg & Bellone (2017) state that seal brown, which is a colour found in Exmoor ponies, can be caused by a black phenotype being diluted by the dominant pangare allele Pa+[6]. Pangare is a basal equine allele because all living wild equines have it, so it must have been the ancestral state in European wild horses as well and some cave paintings illustrate it very clearly. If seal brown is indeed caused by a black phenotype being diluted by pangare, the existence of black wild horses would depend on if the non-pangare allele panp was present in wild horses or not. So far, this has not been tested. I used to think that black suppresses pangare, also because black dun horses always have a dark head while they sometimes may have faint countershading on the body (and as foals sometimes have a white muzzle). The genetic background of seal brown should be tested to be sure.
Another clue could be historic evidence. There are several records describing free-ranging horses in Europe, and until recently it was unclear whether they were truly wild horses, feral horses or hybrids. A recent study confirmed that they were most likely hybrids of feral domestic horses and the native European wild horses. Go here for a summary of those records on these hybrid populations. What is striking is that black dun horses seem to dominate these reports. Black horses are mentioned only very rarely. Of course, the phenotype of hybrids is not very strong evidence, only a hint, as the domestic horse introgression likely has changed the frequency of the colour phenotypes present in the populations. But black dun is not very frequent among domestic horse breeds. Also, dun in general is less frequent than both non-dun alleles in domestic horses, so that it is unlikely that introgression from dun-coloured domestic horses turned an originally black wild population into a black dun hybrid population. Considering that non-dun is more frequent than dun in domestic horses, I do not think that introgression increased the frequency of dun in the wild population and instead assume that the population was originally dun in most of the individuals. If the original wild population was black, this colour probably would be mentioned much more frequently than black dun in those reports on the hybrids.
All in all, I think the evidence for late Holocene European wild horses being mostly black dun outweighs that for them being black. I think it is well possible that there were black wild horses, at least in the Pleistocene, but more research would have to be done. For example, Holocene European wild horse remains could be tested for the dun and non-dun alleles as much as for the pangare and non-pangare alleles, and the genetic background of seal brown should finally be confirmed.
Literature
[1] Sandoval-Castellanos et al.: Coat colour adaptation of post-glacial horses to increasing forest vegetation. 2017.
[2] Imsland et al.: Regulatory mutations in TBX3 disrupt asymmetric hair pigmentation that underlies Dun camouflage color in horses. 2015.
[3] Cieslak et al.: Origin and history of mitochondrial DNA lineages in domestic horses. 2011.
[4] Fages et al.: Tracking five millennia of horse management with extensive ancient genome time series. 2019.
[5] Pruvost et al.: Genotypes of predomestic horses match phenotypes painted in Paleolithic works of cave art. 2011.
[6] Sponenberg & Bellone: Equine color genetics. 2017.
Saturday, 25 December 2021
Taxonomy: how to classify domestic animals?
Back in the time of Linnaeus when modern taxonomy was started in 1758, some domestic animals were classified as the members of the species they were derived from, others as distinct species. Taxonomists have been trying to find a universal standard to handle the naming of domestic animals. The main question is: should they be regarded as members of the species they were derived from, or as distinct species?
Till today, there is no consensus on how to answer this question. Both sides have good arguments for domestic animals either being subspecies of the wild species they derived from or being distinct species.
Arguments for domestic animals being distinct species
Domestic animals have undergone a unique evolutionary path because their evolution is mainly controlled by selective pressures determined by another species, Homo sapiens. Domestic animals have, in contrast to their wild counterparts, experienced a kind of coevolution with humans, and the abiotic and biotic factors of the “natural” (not human-influenced) ecosystem played either only a minor role in the evolution of domestic animals or absolutely none. This is a drastic difference between wild and domestic. Therefore, evolutionary, wild and domestic animals are radically different because the evolution of wild animals is not controlled (influenced, in some cases certainly, but not totally controlled) by humans while that of domestic animals is to a very large extent.
Also, domestic animals differ from their wild counterparts in structure of the genome. The absence of natural selection, the artificial selection executed by humans as well as inbreeding usually leads to a mutation accumulation (often of deleterious alleles) and decrease of genetic diversity, what is called the “costs of domestication”. Thus, domestic animals also differ genetically from their wildtypes.
Morphologically, domestic animals are distinct from their wild ancestors, albeit the degree differs from breed to breed. For example, a Chihuahua differs from a wolf much more dramatically than a German shepherd dog. But general morphological differences between wildtype and domestic are found in any domestic form. In most cases, the difference in morphology between wild and domestic exceed the differences found between wild subspecies of a wild species.
One of the most obvious differences between wild and domestic animals is in the behaviour towards humans. These differences are caused by modifications of the endocrinology and neurology, which probably also cause many of the morphological differences between wild and domestic (for details, see the Dedomestication series).
Due to the absence of natural selection and the more or less intense artificial selection, domestic animals also differ from their wildtypes in physiological aspects. These aspects are directly related to the evolutionary fitness of the animals. I outlined the physiological differences between wild and domestic yaks in this post. A similar reduction of physiological fitness is to be expected in other domestic animals.
Therefore, there are drastic differences between wild and domestic in their evolutionary history and presence, genetics, morphology and physiology. These differences definitely exceed the degree of variation found in wild species that have not been domesticated. Therefore, a status of domestic animals as a distinct species would be justified from an evolutionary, genetic, morphologic and physiologic standpoint.
Arguments for domestic animals being members of the species they were derived from
Domestic animals and their wildtypes are usually able to interbreed without fertility barriers, i.e., they can produce fully fertile offspring. According to Mayer’s species definition, they would be one species because of that. However, Mayer’s species definition does not work universally (for example, wolves, coyotes and golden jackals would be one species because they can interbreed without fertility barriers).
Another argument for domestic animals being members of the wild species they were derived from is that the social behaviour of domestic animals does not differ from that of their wildtype in most cases when given the chance to life under natural circumstances.
Also ecologically, most domestic animals are much like their ancestors in habitat preference, food choice and ecologic niche when living under natural circumstances.
It appears that there are good arguments for both sides. It simply is the case that domestic animals are very different from their wildtype on some aspects, and very similar on other aspects. Because of that, I do not think that there will ever be a consensus on how to classify domestic animals.
Another problem is different domestic animals probably require different solutions. Domestic dogs for example, do not have the same social structure as wolves (as far as I know). Also, ecologically they are not identical. Feral dogs often live as commensals to humans, while wolves do not. So, it might be justified to classify dogs as a distinct species, while many other domesticated animals might be classified as subspecies of their ancestral wildtype. But when not finding a universal standard for all domesticated animals, taxonomy becomes even more arbitrary than it already is. Another problem is that not all domestic breeds/populations are domesticated to the same extent. The differences from the wildtype, be it genomic, ecologic, behavioural, morphologic or physiologic, might be more intense in some breeds than in others. Extreme in some cases, not extreme in others.
This leads to the question if domestic animals should be regarded as taxa at all. Domestic animals are highly heterogeneous, they differ in the extent to which they are domesticated, and often experienced secondary introgression from their wildtype and even other species during their domestication, often only certain populations. In some cases, it even is questionable if all members of a domesticated form can reproduce with each other under natural circumstances due to physical barriers (such as in the case of Chihuahuas and Irish Wolfhound). Maybe it would be better to give domestic animals no taxonomic status at all, but rather regard them as inhomogeneous, artificially created populations of certain wild animals that have been domesticated to a varying extent – varying when comparing different domestic forms to each other (f.e. horses versus dogs) as much as within the domestic forms (f.e. Spanish fighting cattle versus Fleckvieh).
Sunday, 19 December 2021
Who's better: Taurus cattle or Tauros cattle?
Sometimes, Taurus and Tauros cattle get confused. This is not surprising, considering that their name is almost identical. But I think it is important to differentiate between both breeds, because of their different history and also different quality as a “breeding-back” result. This post is going to examinate which breed has so far been more successful in approximating the goal of “breeding-back”.
Some may say it is unfair to compare the two breeds because Taurus cattle were created in 1997 while the TaurOs Project started in 2009. However, I am only comparing individuals of the same crossbreed generation in order to be make it comparable. The youngest Tauros cattle may be of the fourth or fifth generation, the youngest adult ones (only adult cattle can be compared as the traits are not full expressed in juvenile and subadult individuals) may be of the second and third generation. Therefore, I will compare only animals of the first, second and third crossbreed generation of both projects.
I compare them based on the animals that are available to me. The largest Tauros cattle herd is in Keent, Netherlands, but that herd is not very present on the web, only single individuals. The Kettingdijk herd has been documented very well by Geer vanne Smeed (go here for the flickR stream) and there are also many photos and videos of the Milovice herd in the Czech Republic. For a collection of recent photos of several Tauros cattle go here. Regarding Taurus cattle, I only use the Lippeaue and Hortobagyi herds for comparison, because they can be considered the only “true” Taurus cattle herds in the strict sense. Most of the other herds are basically Heck cattle herds that included single Taurus individuals, sometimes as sires (f.e. the Schmidtenhöhe herd, the Cuxhavener Küstenheiden herd). There is a continuum between Heck and Taurus cattle. I only use the “source” of Taurus cattle, Lippeaue and Hortobagyi, for the comparison. Taurus cattle are often labelled as “improved Heck cattle”, but considering that in the Lippeaue there was little to no backcrossing with Heck but they relied heavily on backcrossing with Sayaguesa, and that the portion of Sayaguesa makes up to 50% of the genetic composition of the animals there, the Taurus cattle in the Lippeaue are actually more “improved Sayaguesa” than “improved Heck cattle”. In Hortobagyi, the situation is more diverse as they have more herds and more breeds.
Size
Several Taurus cattle individuals have been measured. The Sayaguesa x Heck bull Lucio was between 160 and 165 cm tall at the withers, the Sayaguesa x (Heck x Chianina) bull “Laokoon’s brother” is about 172 cm tall at the withers. Three cows have been measured, and they ranged between 153 and 155 cm at the withers. Considering that they use Sayaguesa, which can reach up to 170 cm at the withers and Chianina, which even surpass that height, the size of Taurus cattle is what is to be expected.
For Tauros cattle, no measurements have been published so far. But based on the photos and videos available on the web, they cannot be very large. I saw a video that is not online anymore of the Maremmana x Pajuna bull Manolo Uno and he was only insignificantly taller than the Highland crossbreeds (and Highland is a rather small breed). There is also a photo of the Maashorst bull (probably of the same breed combination) which I cannot find anymore that shows it next to a person, and it did not look large either. If Tauros cattle are not that large (not reaching 160 cm, the lower limit of European aurochs bulls), I would not be surprised considering that many of their founding breeds (Pajuna, Highland, Maronesa) are not large. For the size, the Tauros Programme relies on Maremmana, which also may reach 170 cm at least occasionally, but their Maremmana bull at Keent was not that large, it was about the size as the Pajuna bull. We simply need measurements from at least a few bulls to get an idea of Tauros cattle.
Colour
Taurus cattle mostly have the right colour with no domestic colour mutations, except for the recessive dilution allele(s) contributed by Chianina that cause a diluted coat colour in some individuals. Considering that most of the Taurus cattle at the Lippeaue are part Chianina, the allele(s) might be widespread in the population. Small white spots occur rarely in the Lippeaue, and in some Holstein-influenced individuals in Hortobagyi.
Tauros cattle show a wider variation spectrum than Taurus cattle concerning colour. The populations have the recessive dilution allele contributed by Maremmana and Tudanca that removes the red pigment in the coat, and also Simmental dilution contributed by Highland. Several individuals also have the dominant brindle allele, contributed by Highland. White spots seem to be a little bit more common than in Taurus cattle.
Sexual dichromatism
I did a post on the sexual dichromatism found in the Lippeaue for the year 2015. It occurs that more than 80% of the individuals display the right colour for their sex. It is, of course, possible that some black bulls inherit black cows and that some cow-coloured cows inherit bulls with a saddle. But all in all, I think the sexual dichromatism in the Lippeaue is rather good. The dichromatism in Hortobagyi is slightly less good, as dark cows are more common there than in the Lippeaue.
The sexual dichromatism in Tauros cattle is less clear. Bulls with a saddle are not a rare sight, as well as pretty dark cows.
Morphology
The morphology of Taurus cattle is variable. Most individuals are long-legged, but also have a trunk that is longer than in the aurochs (a problem found in most taurine cattle). Most individuals have a comparably long snout, although probably not to the same extent as in the aurochs. A hump is always present. Some individuals are more massive than others, but the body morphology of single individuals such as Lamarck or Lisette is quite good.
Tauros cattle are even more variable concerning body morphology, skull morphology and proportions. Especially the Highland influenced individuals can be rather short-legged and massive (go here). Some bulls resemble Heck cattle in build. Some individuals are comparable to Taurus cattle regarding morphology. What is nice is that some Tauros cattle bulls have rather large humps, but there are also those with a small hump. The skull length varies greatly, some individuals have the same skull shape as Taurus cattle, others can be rather short-faced.
Horn size
The horn size of Taurus cattle is variable. Some individuals in the Lippeaue, such as the bull Lamarck, can have horns that are within the variation range we find in the European aurochs, others have smaller horns than what is average for the European aurochs. Some individuals in the Lippeaue have horns only slightly larger than in Chianina. In Hortobagyi, the average horn volume of Taurus cattle is larger due to the influence of Watussi and Grey cattle. The horn dimensions match those of the European aurochs quite often in Hortobagyi.
Tauros cattle are variable regarding horn size as well. Some individuals can be small-horned too, but on average the horn size in Taurus cattle is larger than in the Lippeaue Taurus cattle, but not larger than in the Hortobagyi Taurus cattle.
Horn curvature
The horn curvature of Taurus cattle is variable, but the horns always face forwards in an aurochs-like angle (the angle should be between 50 and 80°). Some individuals, like Lamarck, Lerida, Loxia and Lisette, have inwards-facing horn tips, sometimes to the same extent as in the aurochs. Other individuals may have outwards-facing horn tips, particularly the cows.
The horn curvature of Tauros cattle is variable as well, more so than in Taurus cattle. The horns of many bulls do not curve inwards, and several cows have lyre-like horn shapes due to influence from Maremmana and Highland. In some bulls, probably the Maronesa-influenced ones, the horn tips face inwards. The horns of some bulls face forwards in an aurochs-like manner, others have too upright horns. Some bulls have horns very reminiscent of those of some Heck or Cachena bulls (go here, for example).
All in all, I think that it would be most fair to conclude that Tauros cattle are somewhere between Heck cattle and Taurus cattle in quality as a “breeding-back” result. Taurus cattle are larger, the horn shape matches the aurochs more often than in Tauros cattle, their sexual dichromatism is clearer, and the Taurus cattle population does not include extremely short-legged chubby individuals that are found in the Tauros cattle population, at least not to the extent found in the Highland crossbreeds. Tauros cattle seem to be more variable on each aspect than Taurus cattle.
So far, Tauros cattle have not reached the quality of Taurus cattle. In order to catch up, the TaurOs Project would need strict selection. Some individuals certainly have potential, that is undoubtedly the case. But based on what the herds currently look like (f.e. their inhomogeneous colours and morphologies), as much as the fact that they have several bulls per herd instead of one quality sire, I wonder if they select their animals at all. Perhaps their plan was simply to crossbreed a number of breeds and then let them breed for themselves rather than strategic selective breeding over several years or decades.