Abstract
The Niata was a cattle variety from South America that figured prominently in writings on evolution by Charles Darwin. Its shortened head and other aspects of its unusual morphology have been subject of unsettled discussions since Darwin’s time. Here, we examine the anatomy, cranial shape, skull biomechanics, and population genetics of the Niata. Our results show that the Niata was a viable variety of cattle and exhibited anatomical differences to known chondrodysplastic forms. In cranial shape and genetic analysis, the Niata occupies an isolated position clearly separated from other cattle. Computational biomechanical model comparison reveals that the shorter face of the Niata resulted in a restricted distribution and lower magnitude of stress during biting. Morphological and genetic data illustrate the acquisition of novelty in the domestication process and confirm the distinct nature of the Niata cattle, validating Darwin’s view that it was a true breed.
Highlights
The change in skull shape towards a short and stout appearance is an independently reappearing trait during domestication and is considered a breed-defining characteristic in some dogs, cats, and pigs[1] (Fig. 1)
Mutations in genes associated with chondrodysplasia can be important drivers in the appearance of breeds[20] and in dogs different genes are related to chondrodysplasia and brachycephaly, respectively[20,21,22]
Several genes such as ACAN, PRKG2, and EVC2 are considered to be related to so-called snorter dwarf-like chondrodysplasia[6,23,24], which is even breed defining in Dexter cattle[6]
Summary
The change in skull shape towards a short and stout appearance (brachycephaly) is an independently reappearing trait during domestication and is considered a breed-defining characteristic in some dogs, cats, and pigs[1] (Fig. 1). Extreme brachycephaly was described in the Niata cow from South America[2]. In the Niata, brachycephaly was considered breed defining[2] even though heavily shortened skulls have been observed in several cattle breeds as a form of malformation[2,3,4,5,6]. We use geometric morphometrics of the skull and genetic data to place the Niata within the context of other cattle breeds. Our anatomical study will serve to evaluate the claims that the morphology of the Niata is tied to disease and malformations[14]. We examine the cranial and postcranial morphology of the Niata to compare it with anatomical markers for chondrodysplasia in cattle. We extracted DNA from Niata specimens in museum collections and genotyped single nucleotide polymorphisms (SNPs) to study the relationship between the Niata and other cattle breeds such as indicine Zebu breeds, taurine European breeds, hybrids, as well as Bos javanicus[25]
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