Addomesticamento del Micio: indizi dal Genoma.

Genome reveals clues to cat domestication 

 Cats and humans have shared the same households for at least 9,000 years, but we still know very little about how our feline friends became domesticated. 
An analysis of the cat genome led by researchers at Washington University School of Medicine in St. Louis reveals some surprising clues. 

Researchers at Washington University School of Medicine in St. Louis led an international  team that sequenced and analyzed the cat genome to better understand the animal's  domestication. Pictured is a blue Abyssinian [Credit: WikiCommons] 

Cats have a relatively recent history of domestication compared with dogs; canines arose from wolves over 30,000 years ago. 
"Cats, unlike dogs, are really only semidomesticated," said senior author Wes Warren, PhD, associate professor of genetics at The Genome Institute at Washington University. "They only recently split off from wild cats, and some even still breed with their wild relatives. So we were surprised to find DNA evidence of their domestication." 
One way scientists can understand the genetics of domestication is to look at what parts of the genome are altered in response to living together with humans, Warren added.

The researchers compared the genomes of domestic cats and wild cats, finding specific regions of the domestic cat genome that differed significantly. 
The scientists found changes in the domestic cat's genes that other studies have shown are involved in behaviors such as memory, fear and reward-seeking. 
These types of behaviors -- particularly those when an animal seeks a reward -- generally are thought to be important in the domestication process. 

"Humans most likely welcomed cats because they controlled rodents that consumed their grain harvests," said Warren. "We hypothesized that humans would offer cats food as a reward to stick around." 
This meant that certain cats that would normally prefer to lead solitary lives in the wild had an additional incentive to stay with humans. 
Over time, humans preferred to keep cats that were more docile. 

Cat genome project 
The cat genome sequencing project, funded by the National Human Genome Research Institute, part of the National Institutes of Health (NIH), began in 2007.
 The project's initial goal was to study hereditary diseases in domestic cats, which are similar in some cases to those that afflict humans, including neurological disorders, and infectious and metabolic diseases. 
To obtain the high-quality reference genome needed for this research, the team sequenced a domestic female Abyssinian cat named Cinnamon. 
They chose this particular cat because they could trace its lineage back several generations. This cat's family also had a particular degenerative eye disorder the researchers wanted to study. 
To better understand characteristics of domestication, the researchers sequenced the genomes of select purebred domestic cats.

Hallmarks of their domestication include features such as hair color, texture and patterns, as well as facial structure and how docile a cat is. 
Cats are bred for many of these types of characteristics. 
In fact, most modern breeds are the result of humans breeding cats for their favorite hair patterns. 
The team also looked at a breed called Birman, which has characteristic white paws. The researchers traced the white pattern to just two small changes in a gene associated with hair color. 
They found that this genetic signature appears in all Birmans, likely showing that humans selectively bred these cats for their white paws and that the change to their genome happened in a remarkably short period of time. 
The group also compared the cat genome with those of other mammals -- including a tiger, cow, dog and human -- to understand more about the genetics of cat biology. 
"We looked at the underlying genetics to understand why certain abilities to survive in the wild evolved in cats and other carnivores," said Michael Montague, PhD, the study's first author and a postdoctoral research associate at The Genome Institute.
 The differences they found in the cat genome help explain characteristics such as why cats are almost exclusively carnivorous and how their vision and sense of smell differ from other animals like dogs.

Solitary carnivores 
To digest their fatty, meat-heavy meals, cats need genes to efficiently break down fats. The team found particular fat-metabolizing genes in carnivores such as cats and tigers that changed faster than can be explained by chance. 
This more rapid change generally means these genes provide some sort of digestive advantage to carnivores that only consume animal proteins. 
The researchers did not find such changes in the same genes of the cow and human, who eat more varied diets and would not need such enhancements. 
Cats also rely less on smell to hunt than dogs.

So it is not surprising that the researchers found fewer genes for smell in cats than dogs.

 But they did find more genes related to an alternate form of smell that detects chemicals called pheromones, which allow cats to monitor their social environment, including seeking out the opposite sex. 
This ability is not as important to dogs, which tend to travel in packs. 

But it is crucial in cats, which are more solitary and may have more difficulty finding mates. 
Cats also have better hearing than most other carnivores, including an ability to hear in the ultrasonic range to better track prey. 
Their vision is also exceptional in low light. 
"Cats tend to be more active at dawn and dusk," said Montague, "so they need to be able to detect movement in low light." 
Accordingly, the team identified specific genes that likely evolved to expand cats' hearing range and their vision in low light. 
Even though the genomes of domestic cats have changed little since their split from wild cats, the new work shows that it is still possible to see evidence of the species' more recent domestication. 
"Using advanced genome sequencing technology, we were able to shed light on the genetic signatures of cats' unique biology and survival skills," said Warren. "And we were able to significantly jump start our knowledge about the evolution of cat domestication." 

The research appears Nov. 10 in the Proceedings of the National Academy of Sciences Early Edition. 


Author: Gaia Remerowski 


| Source: Washington University in St. Louis [November 10, 2014]

DOVE i pastori incontrarono gli agricoltori

Interessante. Si conosce già per sommi capi la sequenza dei fatti. Ma le stratigrafie ci offrono brevi serie d'immagini ravvicinate estremamente 
coinvolgenti e soprattutto ci indicano il dove e suggeriscono il come.
Il quando è circa 5.000 anni fa.
Il luogo è il Kazakhstan, in un corridoio Est-Ovest nel quale si svilupperà la storica Via della Seta.
Il ruolo dei pastori nomadi fu un punto chiave dell'espansione dell'agricoltura. 
Il grano, coltivato 6.000 anni fa nell'Asia sud occidentale, era assente in  Cina prima del 2.500 a.C. mentre il miglio - coltivato in cina nell'8.000 a.C. 
era assente nell'Asia sud occidentale prima del 2000 a.C.

Questo studio documenta la trasmissione attraverso il Kazakhstan di queste coltivazioni nel 2.700/2500 a.C (circa 5.000 anni fa).  

Ancient nomads 

spread earliest domestic grains 

along Silk Road 






 Charred grains of barley, millet and wheat deposited nearly 5,000 years ago at campsites in the high plains of Kazakhstan show that nomadic sheepherders played a surprisingly important role in the early spread of domesticated crops throughout a mountainous east-west corridor along the historic Silk Road, suggests new research from Washington University in St. Louis. This is a photo of the long-term settlement stratigraphy at the site of Tasbas.  

Un forno di mattoni di argilla/fango (visibile in basso a destra) che conteneva le più antiche prove di coltivazione del grano
Mudbrick/clay oven (visible on right lower portion) contained earliest evidence for grain farming [Credit: Paula Doumani/ Washington University in St. Louis]


 "Our findings indicate that ancient nomadic pastoralists were key players in an east-west network that linked innovations and commodities between present-day China and southwest Asia," said study co-author Michael Frachetti, PhD, an associate professor of archaeology in Arts & Sciences at Washington University and principal investigator on the research project. "Ancient wheat and broomcorn millet, recovered in nomadic campsites in Kazakhstan, show that prehistoric herders in Central Eurasia had incorporated both regional crops into their economy and rituals nearly 5,000 years ago, pushing back the chronology of interaction along the territory of the 'Silk Road' more than 2,000 years," Frachetti said. 
The study, to be published April 2 in the Proceedings of the Royal Society B, establishes that several strains of ancient grains and peas had made their way across Eurasia thousands of years earlier than previously documented. 
While these crops have been known to exist much earlier in ancient China and Southwest Asia, finding them intermingled in the Bronze Age burials and households of nomadic pastoralists provides some of the earliest concrete signs for east-west interaction in the vast expanse of Eurasian mountains and the first botanical evidence for farming among Bronze Age nomads. 


This is a panoramic view of the Byan Zhurek valley and setting near Tasbas  [Credit: Michael Frachetti/Washington University in St. Louis] 


Bread wheat, cultivated at least 6,000 years ago in Southwest Asia, was absent in China before 2500 B.C. while broomcorn millet, domesticated 8,000 years ago in China, is missing in southwest Asia before 2000 B.C. 
This study documents that ancient grains from eastern China and soutwest Asia had made their way to Kazakhstan in the center of the continent by 2700-2500 B.C. (nearly 5,000 years ago). 
"This study starts to rewrite the model for economic change across Eurasia," said first author Robert Spengler, PhD, a paleoethnobotanist and research associate in Arts & Sciences at WUSTL. "It illustrates that nomads had diverse economic systems and were important for reshaping economic spheres more generally." Findings are based on archaeobotanical data collected from four Bronze Age pastoralist campsites in Central Eurasian steppe/mountains: Tasbas and Begash in the highlands of Kazakhstan and Ojakly and Site 1211/1219 in Turkmenistan. 

"This is one of the first systematic applications of archaeobotany in the region, making the potential for further future discovery very exciting," Spengler said. Frachetti and a team of WUSTL researchers led the on-site excavations, working closely with archaeologists based in Turkmenistan, Kazakhstan and Italy. Spengler conducted the paleoethnobotany laboratory work at WUSTL, under the directorship of Gayle J. Fritz, PhD, professor of archaeology and expert in human-plant relationships. "Finding this diverse crop assemblage at Tasbas and Begash illustrates first evidence for the westward spread of East Asian and Southwest Asian crops eastward, and the surprise is that it is nomads who are the agents of change," Frachetti said. 


Source: Washington University in St. Louis [April 01, 2014]

Where pastoralist met farmer and East met West (Spengler et al. 2014)

The paper's conclusion:

Archaeobotanical data from Central Eurasian pastoralist campsites have major implications for our understanding of late prehistoric agriculture across Asia.Sites like Tasbas and Begash illustrate the earliest acquisition of domesticated crops by mobile pastoralists and illustrate their capacity to participate in exchanges that bridged East Asian and Central Asian farming cultures by the early third millennium BC. Mobile pastoralists living in (southern) Central Asian alluvial fans and along the mountainous spine of Central Eurasia also integrated farming into their own domestic strategies (at least) by the mid second millenniumBC. Their pastoral mobility and the formation of extensive networks throughout the IAMC helped spread particular grain morphotypes and a mixed plant cohort of wheat, barley, millet and green peas through the mountains between Xinjiang, China and southwest Asia in the second millennium BC. The seasonal campsites of Begash, Tasbas, Ojakly and Site 1211/1219 are the earliest sites thus far reported to break down the strict polarization between nomads and farmers in prehistoric Central Eurasia. They also transform our comprehension of the vast arena of interaction that defines this region in ancient times. 

Related:

• Frachetti on the multiregional emergence of mobile pastoralism
• Horse not important for the emergence of steppe pastoralism
• Michael Frachetti on the Inner Asian Mountain Corridor

Proc. R. Soc. B doi:10.1098/rspb.2013.3382

Early agriculture and crop transmission among Bronze Age mobile pastoralists of Central Eurasia 

Robert Spengler et al.

Archaeological research in Central Eurasia is exposing unprecedented scales of trans-regional interaction and technology transfer between East Asia and southwest Asia deep into the prehistoric past. This article presents a new archaeobotanical analysis from pastoralist campsites in the mountain and desert regions of Central Eurasia that documents the oldest known evidence for domesticated grains and farming among seasonally mobile herders. Carbonized grains from the sites of Tasbas and Begash illustrate the first transmission of southwest Asian and East Asian domesticated grains into the mountains of Inner Asia in the early third millennium BC. By the middle second millennium BC, seasonal camps in the mountains and deserts illustrate that Eurasian herders incorporated the cultivation of millet, wheat, barley and legumes into their subsistence strategy. These findings push back the chronology for domesticated plant use among Central Eurasian pastoralists by approximately 2000 years. Given the geography, chronology and seed morphology of these data, we argue that mobile pastoralists were key agents in the spread of crop repertoires and the transformation of agricultural economies across Asia from the third to the second millennium BC.

Link