Population History of Domestic Sheep Revealed by Paleogenomes | Molecular Biology and Evolution | Oxford Academic
I've previously noted how almost all our domestic animals have been selectively bred to improve upon their wild ancestors, sometimes to the extent that the wild ancestor is hardly recognisable as the same species. Indeed, in some instances, the genetic isolation of the wild and domestic varieties is so wide that they are regarded as different species.
And Bible-literalist creationists believe all animals were magically create out of dirt without ancestors, specifically for the use of man - which begs the question, why have we had to improve on them to make them fit for purpose? Did an omnipotent creator god not know what we would use them for?
In a recent post I describes the domestication of modern cattle from their wild auroch ancestors, which, because of their size and aggressive nature, were too dangerous for herding and milking, and the domestic breeds have evolved from a very small founder population, probably because of that difficulty so animals placid enough were only rarely found.
All that took place thousands of years before creationists believe there was an Earth with life on it, as is usual with almost all of Earth's and human history.
Now, as an added embarrassment to creationists, palaeogeneticists have managed to trace the ancestors (wild mouflons) of modern domestic sheep to discover where they were domesticated and how long ago. It goes without saying that it happened long before creationists believe the god magicked sheep out of dirt, in common with almost all of Earth's history.
The domestication of sheep. The domestication of sheep is one of the earliest in human history, with archaeological evidence tracing it back to around 11,000 years ago in the Fertile Crescent, a region spanning parts of modern-day Türkiye, Syria, Iran, and Iraq. Sheep were initially domesticated for meat and hides, but by around 5,000–6,000 years ago, selective breeding had enhanced wool production, giving rise to one of the first sources of wool for textiles.It is generally accepted that mouflons were first domesticated somewhere in Southwest Asia but exactly where precisely is unknown. As well as the Fertile Crescent running in an arc from Mesopotamia (modern Iraq) across Northern Arabia to the Levant and Türkiye, another possible location is central Anatolia. The other question was which wild mouflon populations were most likely first domesticated
Wild Ancestors of Domestic Sheep
Modern sheep (Ovis aries) are primarily descended from wild ancestors in the Ovis genus, particularly from the Asiatic mouflon (Ovis orientalis) and the Urial (Ovis vignei), both native to Central and Western Asia. Genetic studies suggest that these wild species were integral to the gene pool of early domesticated sheep, contributing specific traits that humans found useful, like docility, smaller body size, and manageable wool and meat qualities.
Contributions to the Modern Sheep Genome
- Asiatic Mouflon (Ovis orientalis): This wild sheep is often considered the primary ancestor of domestic sheep. Mouflons have short, rough coats, and the domestication process gradually favoured sheep with softer, woollier coats.
- Urial (Ovis vignei): Genetic evidence suggests a smaller but notable contribution from the Urial, which is native to mountainous regions from eastern Türkiye through Iran to Central Asia.
The selective breeding of these early domestic sheep gradually led to traits like reduced aggression, more extensive wool cover, and an increased reproductive cycle, which allowed for easier management and higher yields of wool and meat. Over millennia, other selective breeding practices enhanced specific traits, creating the numerous breeds we have today, which vary widely in wool texture, color, size, and adaptability.
Genetic Diversity and Crossbreeding
The modern sheep genome is also influenced by ongoing crossbreeding, particularly in regions like Europe, Asia, and Africa. This has introduced genetic variation that allows sheep to thrive in diverse climates and has expanded the gene pool to create breeds adapted for different agricultural needs, such as dairy, wool, and meat production.
Tell me more about the Urial and how is differs from the Konya sheep, Ovis orientalis anatolica.
The Urial (Ovis vignei) and the Konya sheep (Ovis orientalis anatolica), a subspecies of the Asiatic mouflon (Ovis orientalis), are both wild relatives of modern domestic sheep, but they exhibit differences in appearance, habitat, and genetics that reflect their distinct evolutionary paths.
Urial (Ovis vignei)
Konya Sheep (Ovis orientalis anatolica - Anatolian Mouflon)
- Appearance and Size: Urials are medium-sized sheep with a distinctive reddish-brown coat that changes to a lighter color on the belly, legs, and face. Males are particularly notable for their large, spiralling horns that can be quite long and are a defining characteristic. They also develop a mane of hair along the neck and chest during certain seasons.
- Habitat: Urials are native to the mountainous and hilly regions of Central and Western Asia, including Iran, Afghanistan, Pakistan, and parts of India. They are well adapted to dry, rugged environments and are often found at elevations ranging from 600 to 3,600 meters (about 2,000 to 11,800 feet). Their preferred habitat tends to be more arid and less forested compared to other wild sheep species.
- Behavioural Traits: Urials live in small social groups, usually separated by gender, with larger groups forming during the breeding season. They are generally more adapted to warmer, arid climates compared to the Konya sheep. Unlike some other wild sheep species, Urials tend to stay within a more restricted range, rarely migrating over large distances.
- Contribution to Domestic Sheep Genetics: The Urial has contributed only a limited genetic input to domestic sheep, mainly influencing the adaptability and size of certain regional breeds. While not a primary ancestor of domestic sheep, they are still a part of the broader genetic pool that has influenced the development of certain traits.
Key Differences
- Appearance and Size: The Konya sheep, or Anatolian mouflon, is a subspecies of the Asiatic mouflon. This sheep has a lighter coat, usually a tawny-brown color, with a prominent white saddle patch, which distinguishes it from the Urial. The males have shorter, more crescent-shaped horns compared to the long spirals of the Urial. These features give them a more compact appearance.
- Habitat: The Anatolian mouflon is native to Türkiye, particularly in the central Anatolian region around Konya, which is how it gets its common name. This region is characterized by steppes and semi-arid plateaus, with a climate that includes both hot summers and cold winters. This habitat requires a greater adaptability to seasonal changes in temperature than the regions where Urials are typically found.
- Behavioural Traits: Anatolian mouflons live in social herds that can vary in size depending on the season. They tend to be more nomadic than Urials, with seasonal movements to find food and water. This nomadic behaviour makes them well-adapted to the fluctuating environmental conditions of Central Anatolia.
- Role in Sheep Domestication: The Anatolian mouflon has a stronger genetic link to domestic sheep than the Urial, as it is part of the Ovis orientalis group from which most domesticated sheep are derived. Through early selective breeding, traits of the Anatolian mouflon, such as manageable size, coat color, and a sociable temperament, were passed on to domestic sheep populations.
- Genetic Influence: The Konya sheep (Anatolian mouflon) is a more direct ancestor to domestic sheep, whereas the Urial's influence is secondary.
- Physical Traits: Urials have larger, more spiralled horns and tend to be slightly larger, with reddish-brown colouring, while Anatolian mouflons are tawny with white saddle patches.
- Behavioural and Habitat Adaptations: Urials are more adapted to arid, mountainous regions, whereas the Anatolian mouflon is adapted to the steppe and semi-arid plateaus, showing more adaptability to seasonal climates.
These differences highlight how specific environmental and geographic factors have shaped their evolution, influencing the genetic traits that have been selectively bred into modern domestic sheep.
To address that question, an international team of palaeogeneticists led by Damla Kaptan of the Department of Biological Sciences, Middle East Technical University, Ankara, Türkiye have analysed 24 partial ancient sheep genomes and the genomes of five modern wild mouflons from Central Anatolia and two from Cyprus. The team have recently published their findings, open access in the journal Molecular Biology and Evolution:
Abstract Sheep was one of the first domesticated animals in Neolithic West Eurasia. The zooarchaeological record suggests that domestication first took place in Southwest Asia, although much remains unresolved about the precise location(s) and timing(s) of earliest domestication, or the post-domestication history of sheep. Here, we present 24 new partial sheep paleogenomes, including a 13,000-year-old Epipaleolithic Central Anatolian wild sheep, as well as 14 domestic sheep from Neolithic Anatolia, two from Neolithic Iran, two from Neolithic Iberia, three from Neolithic France, and one each from Late Neolithic/Bronze Age Baltic and South Russia, in addition to five present-day Central Anatolian Mouflons and two present-day Cyprian Mouflons. We find that Neolithic European, as well as domestic sheep breeds, are genetically closer to the Anatolian Epipaleolithic sheep and the present-day Anatolian and Cyprian Mouflon than to the Iranian Mouflon. This supports a Central Anatolian source for domestication, presenting strong evidence for a domestication event in SW Asia outside the Fertile Crescent, although we cannot rule out multiple domestication events also within the Neolithic Fertile Crescent. We further find evidence for multiple admixture and replacement events, including one that parallels the Pontic Steppe-related ancestry expansion in Europe, as well as a post-Bronze Age event that appears to have further spread Asia-related alleles across global sheep breeds. Our findings mark the dynamism of past domestic sheep populations in their potential for dispersal and admixture, sometimes being paralleled by their shepherds and in other cases not.
Introduction
The early Holocene witnessed gradual yet dramatic shifts in human lifeways, as early Neolithic human groups started to cultivate plants and domesticate animals (Harris 1996; Zeder 2008, 2017; Chessa et al. 2009, Arbuckle et al. 2014). Sheep, among the first such herded livestock species, were domesticated in southwest Asia c. 10,000 to 8,000 Before the Common Era (BCE) (Zeder 2008; Vigne 2011). Domestic sheep were eventually transported across the globe by humans, some becoming feral as in the case of the European Mouflon (Poplin 1979; Vigne et al. 2011; Barbato et al. 2017.1). Today, there exist hundreds of commercial domestic sheep breeds, multiple Mouflon lineages (i.e. wild relatives of domesticates, including feral sheep), and five other species of wild sheep (Ovis) worldwide. Despite intense work using genome data from modern-day sheep lineages (Lv et al. 2015, 2022; Barbato et al. 2017.1; Ciani et al. 2020; Deng et al. 2020.1; Li et al. 2020.2; Chen et al. 2021; Her et al. 2022.1; Wang et al. 2023), neither the location of, nor the wild progenitors involved in, the first domestication process, nor the post-Neolithic demographic histories of domestic sheep or Mouflon populations are well-understood.
One open question is the source of the domestic sheep gene pool. Earlier studies pointed out multiple Asiatic sheep species (Ovis ammon, Ovis gmelini, Ovis vignei) as the probable ancestor of domestic sheep (Nadler et al. 1973; Hiendleder et al. 1998; reviewed in Pedrosa et al. 2005). However, subsequent evidence has eliminated O. ammon and O. vignei as potential ancestors (Clutton-Brock 1981; Uerpmann 1987, Hiendleder et al. 1998). Some recent studies have considered the Iranian/Asiatic Mouflon (O. gmelini) from western Iran and easternmost Turkey as the wild population genetically closest to the ancestor of domestic sheep (reviewed in Pedrosa et al. 2005; Chen et al. 2021; Her et al. 2022.1; Cheng et al. 2023.1). However, this has not yet been fully established. The O. gmelini group has five subspecies: the Armenian Mouflon (Ovis gmelini gmelini), the Isfahan Mouflon (Ovis gmelini isphananica), the Laristan Mouflon (O. gmelini laristanica), the Cyprian Mouflon (O. gmelini ophion), and the Anatolian Mouflon (O. gmelini anatolica) (Blyth 1841). These groups are assumed to represent local wild populations since the early Holocene, except for the Cyprian Mouflon that dates back to the ∼12th millennium BCE and was presumably brought from mainland Anatolia/Levant (Zeder 2008; Vigne et al. 2011; Demirci et al. 2013; Sanna et al. 2015.1). Some genetic studies have also suggested that Anatolian and Cyprian Mouflons were subjected to proto/semi-domestication practices in the past (Hadjisterkotis 1992; Vigne 2003, 2011, 2014.1; Demirci et al. 2013; Sanna et al. 2015.1; Barbato et al. 2017.1). However, this is still a speculation, and the genetic relationships between these Mouflons and the ancient and present-day domestic sheep remain unclear.
Another largely unresolved question is the history of domestic sheep breeds (Chessa et al. 2009; Larson et al. 2014.2). Present-day domestic sheep cluster in two main geographic groups, Europe vs. Asia/Africa, based on genome-wide polymorphism data (Kijas et al. 2012; Naval-Sanchez et al. 2018; Li et al. 2020.2). This split is also observed in modern sheep mitochondrial haplotype groups, with European sheep mostly carrying haplotype B and Asian sheep dominantly carrying haplotype A (Bruford and Townsend 2006; Tapio et al. 2006.1; Meadows et al. 2007; Kijas et al. 2009.1; Demirci et al. 2013; Lv et al. 2015; Machová et al. 2022.2). The presence of an east–west genetic structure in modern breeds has previously been dated back to 7,000 to 6,000 BCE using molecular clock approaches (Niemi et al. 2013.1; Cai et al. 2018.1; Taylor et al. 2021.1). Accordingly, using ancient DNA, we recently showed that Anatolian Neolithic sheep (ANS) have a higher affinity to present-day European breeds than to non-European breeds, while Neolithic and Bronze Age Kyrgyzstan sheep show higher affinity to present-day Asian breed, suggesting the early establishment of this split (Yurtman et al. 2021.2). These patterns imply either multiple domestication centers and/or a large heterogeneous progenitor population that went through multiple independent bottlenecks. However, in the study by Yurtman et al. (2021.2), all modern breeds showed higher genetic affinity to each other than to Neolithic sheep. This could imply significant amounts of post-Neolithic admixture among continental sheep populations, including possible introgression from wild sheep into domestic flocks and the dispersal and breeding of sheep with desired traits across continents (Sherratt 1983; Marciniak 2011.1; Schoop 2014.3; Deng et al. 2020.1; Cheng et al. 2023.1). The latter scenario has already been explained using haplotype sharing information, with the most recent common ancestor of domestic breeds having been dated to c. 3,000 years ago (Ezard et al. 2009.2; Kijas et al. 2012).
Hence, paleogenomic data have already started providing clues into sheep demographic history (Taylor et al. 2021.1; Yurtman et al. 2021.2; Larsson et al. 2024). However, the limited spatial and temporal coverage, as well as the quality of the genetic data published, have impeded higher resolution analysis of sheep history, leaving questions as to the origin of domestication and the patterns of post-domestication dispersal open. To address this gap, here we present a comprehensive dataset of ancient and present-day wild and domestic sheep, including a 13,000-year-old Anatolian wild sheep genome, Eurasian domestic sheep paleogenomes, as well as the first genome-wide data from present-day Anatolian Mouflons (Table 1, Fig. 1). Our results identify Anatolian and Cyprian Mouflons and Epipaleolithic Anatolian sheep as better candidates for a domestication source than the Iranian Mouflon. We further confirm the presence of a dual structure of modern sheep diversity during the Neolithic using additional ancient genomes, including those from present-day Türkiye and Iran. We also find multiple instances of population admixture or replacement, including post-Neolithic eastern influence on Baltic ancient sheep. Finally, as a legacy of domestication and recent bottlenecks, we see a depletion in the genetic diversities of present-day domestic and wild sheep.
Other evidence in this study, although not addressed in the report because biologists don't need this stuff pointed out to them like creationists do, is the evidence that the various species and subspecies, such as that on the island of Cyprus had only partially speciates and were still capable of interbreeding with the emerging domestic strain of sheep and so contributing their DNA to the domestic sheep. What this amounts to is allopatric speciation in progress probably driven by fragmentation of an original population by glaciation, just as we saw with the different subspecies aurochs.
The fact that most of that occurred before there was an Earth for it to occur on, according to creationists mythology, probably won't prevent creationists from dismissing this evidence as variations of a 'kind', created apparently before 'Creation Week'.
The blunt instrument of the Bible's crude approach to taxonomy coupled with the ludicrously short timescale which was probably as long as the Bronze Age pastoralists could imagine the past stretching back in time for, means that creationists fail to appreciate how Earth and the life on it acts as a dynamic system forever changing and adjusting, as plate tectonics influences climate which causes speciation and divergence, resulting in the fascinating patterns we see in nature.
It's a measure of the damage religion does that it deprives believers of the opportunity to appreciate the real worder around them which they just dismiss as the result of magic by their special invisible magic friend and feel smugly satified with not knowing or understanding.
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