Size is one
of the most important biological aspects of an organism. Therefore, an accurate
substitute for the aurochs should also match the bodily dimensions of wild
aurochs, apart from all the other features. In the past a lot of over- and
underestimations on the true size of the aurochs have been made, so let’s have
a look at how large the aurochs really was, and in which way its size was
variable. Note that when I speak of size, I refer to the height at the withers
and not the weight.
In the past
the size of the aurochs has been broadly exaggerated, some authors suggested
huge heights such as 230 cm at the shoulders, which lack supporting skeletal data and therefore
are baseless. Also the hypothesis of an alleged “dwarf aurochs” on the mainland
has been discarded long ago, since it was based on a misinterpretation of the
large size difference between female and male aurochs [1]. On Sicily, however,
aurochs which became isolated because of the rising sea level after the
Pleistocene seemingly were 20% smaller than on the mainland [1].
Since no
living aurochs were measured by contemporaneous people, we can only rely on
skeletal remains for reconstructing the average size. Using single elements to
extrapolate the withers height of the living animal can be problematic (usually
the metapodials are used for this purpose), but the humerus was shown to be a somewhat
useful tool for this [1]. Without doubt, near-complete, articulated skeletons
are the best way to infer the shoulder height of the living animal, but there
also are several problems that I’ll discuss later on.
The data
provided by various authors concerning the size of aurochs specimen are very
variable, also depending on the respective period and region of the skeletal
material. Especially the data given for bulls is very diverse, ranging from 145
cm to 200 cm [1]. Cis van Vuure summed up all credible measurements of aurochs
shoulder heights and concluded that the average for Holocene aurochs bulls was
160-180 cm and cows 150 cm. The Indian aurochs seemingly was smaller than the
Eurasian subspecies, and Eurasian aurochs during the Pleistocene were larger on
average [1]. This size certainly makes the aurochs an impressive animal and
significantly larger than domestic cattle, but related members of Bos and Bison are of a similar size.
Some
authors suggested a dramatic and continuous size drop during the Holocene,
making the last existing aurochs about the size of domestic cattle [2]. It
seems, however, that the difference between Pleistocene and Holocene aurochs
has been exaggerated, mostly because the Pleistocene specimen show considerably
larger horns on average. Cis van Vuure estimates that the size difference
between Pleistocene and Holocene aurochs might have been about 10 cm in both
sexes on average, and indeed there are several Holocene aurochs specimen that
exceeded a height of 170 and 180 cm [5]. In my opinion, a slight size decrease for
Holocene primigenius members is
plausible nevertheless, because of the absence of hyenas and big cats in Europe,
what also offers an explanation why the horn size got reduced (the same trend
is visible in American bison and their ancestors). However, we should not
forget that aurochs belonging to other subspecies still shared their habitat with these
predators in North Africa and India during the Holocene. In my opinion, the shift to a warmer climate at the beginning of the
Holocene probably was not relevant for the observed size decrease, because the aurochs’ range retreated
southwards during the glacials where the climate still suited the species, and
spread northwards again when climate warmed again, so that the global climate
change probably influenced only the occurrence of the species but did not force
them to increase or decrease in size. Habitat disruption in historic times and
hunting may have plaid a role [3]. But considering that
the same also applied to the Wisent, which still measures about 180 cm at the
withers in bulls, a dramatic drop in size for the historic aurochs seems
unlikely to me and I don’t know of any data from actual bones of historic age supporting
this. The claim that historic aurochs were just as big as modern domestic
cattle seems definitely exaggerated to me, especially because historic
references still describe the animal as being of impressive size and way taller
than domestic cattle (even though cattle were smaller in previous millennia)
[1]. Male specimens of a shoulder height not taller than 150 cm from historic
times would be needed to verify this statement.
Holocene
southern aurochs remains usually show animals that are smaller than Northern
aurochs specimens, what is accordant to Bergmann’s rule [1]. And interestingly,
northern and southern Europe was seemingly inhabited by aurochs populations
that were genetically distinct from each other. The Southern European aurochs
belonged to the same genetic lineage as the near eastern populations, from
which cattle were domesticated [4]. I suppose this lineage might have measured
150-160 cm at the shoulders in bulls, based on data [5] from Hungary. There are
not many available measurements for the africanus
subspecies, but it seemingly was as big as or a little smaller than the
southern European aurochs [1].
My reconstruction of the Lund bull and the Cambridge cow. Bull and cow are shown with a shoulder height of 170 and 146 cm, respectively (Human=180 cm). All rights reserved. |
This is as
far as the skeletal remains go. But the problem is, skeletons often are mounted
incorrectly, with their limbs bent too much and/or their shoulder blade in a
wrong position, resulting in the skeleton appearing smaller than it really was.
I once took a photo of a mounted bull skeleton from Braunschweig, Germany, and
corrected its posture on the photo via GIMP. The skeleton in a corrected stance
turned out to be 5% taller than the incorrect mount – what would increase a
size of, for example, 165 cm to 173.25 cm. This shows that shoulder heights
given from mounted skeletons have to be viewed with caution. Furthermore, we
should not forget that mounted skeletons lack the connective tissue between the
bones and the skin and flesh surrounding them, as well as the hooves. So we can
add 5-10 cm to the height data from mounted skeletons to approach the size of
the animals in life.
Something
that seemingly isn’t considered by most of the authors referring to the
aurochs’ size is the fact that most likely not all aurochs remains stem from
fully grown individuals. The age of the actual specimen can be indicated by
tooth wear, cranial sutures or the epiphysal plate. It is well possible that
the smaller bull remains with a reconstructed height of only 145 or 150 cm were
subadult individuals, therefore the ontogenetic age of the specimen should also
be taken into account.
Numerous
references give information on the observed size difference between bull and
cow within the respective sample. I am also a bit sceptical on that because only
the skull and pelvis give clear information on the sex of the individual. And even
the skulls can be ambiguous in some cases. For example, the Vig specimen has
not very prominent eye sockets and also the horns are less thick, less
inwards-curving and more upright than in usual bulls, yet it is tall overall
and has tall neural spines in the shoulder area, and therefore likely was a
bull. But again, Cis van Vuure’s estimate (see above) sounds plausible and is
comparable to what is displayed by Gaurs and Bantengs.
All in all
it seems that the aurochs was indeed variable in size. Pleistocene aurochs
probably were larger on average than Holocene populations, but not as
significantly as it has been proposed by some authors. The average size of the
Holocene aurochs probably was around 170 cm height at the withers in bulls and
150 cm in cows, with northern aurochs populations being on the larger end of
the bell curve and southern ones (including the subspecies namadicus and africanus)
on the smaller end. This accords to the controversial Bergmann’s rule and is
found a number of other large mammal species as well. The claim that historic
aurochs were only as tall as domestic cattle very likely is an exaggeration,
although habitat destruction and hunting perhaps led to another size decrease
during the very end of their existence, what are certainly anthropogenic causes.
What does
this tell us for breeding-back? Usual “un-improved” Heck cattle (which
unfortunately often are promoted as a “rebred” aurochs, what is a blatantly
wrong statement) are way too small to fit their ancestor, reaching only 140-145
cm on average. Although domestic cattle were derived from near eastern aurochs,
which likely were somewhat smaller than Northern aurochs but still impressive
and taller than domestic cattle, there are indeed some modern cattle breeds
that exhibit the size of impressive European aurochs. Uncastrated Chianina
bulls from Italy can reach up to 180 or more on occasion, and cows about 150
cm. The Maltese ox is a breed that seems to be about the same size. Large
Maremmana bulls grow very tall as well, the largest bull I know of reached 182
cm, and the related Podolica and Boskarin are just as big. These tall and
slender breeds surely give an impression of what an awesome animal the aurochs
was. Some Holstein cattle grow big as well, but this breed is very derived
overall.
So, using
these very large and more or less primitive breeds, breeding-back can achieve
the size of wild aurochs. I think that cattle with a size of 160 cm in bulls in
a breeding-back project are satisfying already (and maybe 150 cm for southern
Europe), but more size is desirable in any case. 170 cm would be very good and
probably authentic; animals even larger than that still can be tolerated or
even wanted. In the end, nature will refine the size of a variable cattle
population to the amount of space and food that is available.
Most of the
Heck cattle breeders do not show great intentions to improve the size of their
cattle. But Taurus cattle, which also have a much better overall resemblance to
the aurochs than usual Heck cattle, have some bulls ranging between 160-165
already. A further size increase of Taurus cattle (at least in the Lippeaue) is
to be expected because of selection and further crossing-in of Chianina and
Sayaguesa. Also Tauros Project wants large cattle that appreciate the impressive
animal that the aurochs was, using at least Maremmana, Podolica and Boskarin.
Literature
[1] van Vuure, Cis: Retracing the Aurochs - History, Morphology
and Ecology of an extinct wild Ox. 2005.
[2] Claude
Guintard: On the size of the ure-ox or aurochs (Bos primigenius Bojanus 1827)
[3] Frisch,
Walter: Der Auerochs – das europäische Rind. 2010.
[4] Albano
Beja-Pereira et al. The origin of European cattle: Evidence from modern and
ancient DNA. 2006
[5] Rene
Kysely: Aurochs and potential crossbreeding
with domestic cattle in Central Europe in the Eneolithic period: A metric
analysis of bones from the archaeological site of Kutna Hora-Denemark (Czech
Republic). 2008.