Monthly Archives: May 2016

Historic genetic ‘picture’ of Arabian camel revealed

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Camels blogpost

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An analysis of the ancient and modern DNA of the single-humped ‘Arabian’ camel or dromedary reveals how human societies have influenced the animal’s genetic diversity.

Long-distance and back-and-forth movements in ancient camel caravan routes are one way this has happened.

The camels have long been a source of food and transport for desert communities, and a vital resource in trade and agriculture in hot, arid regions. That’s why the scientists responsible for this study believe that in the context of climate change and advancing desert landscapes, scrutinizing dromedary’s biology, reproduction and adaptation to hostile terrain has acquired a new level of importance.

“The dromedary has out-performed all other domesticated mammals, including the donkey, in arid environments and continues to provide essential commodities to millions of people living in marginal agro-ecological areas,” says lead author Faisal Almathen from the Department of Veterinary Health and Animal Husbandry at King Faisal University.

“There is very little defined population structure in modern dromedaries. We believe this is a consequence of cross-continental back and forth movements along historic trading routes,” he adds. “Our results point to extensive gene flow which affects all regions except East Africa where dromedary populations have remained relatively isolated.”

For this study, the researchers collected and analysed genetic information from a sample of 1,083 living dromedaries from 21 countries across the world. The team also examined ancient DNA sequences from bone samples from early-domesticated dromedaries from 400-1870 AD and wild ones from 5,000-1,000 BC.

The international team of scientists was led by geneticists from The University of Nottingham, the University of Veterinary Medicine in Vienna and King Faisal University in Saudi Arabia. The research itself is published in the Proceedings of the National Academy of Sciences of USA.

The ancient refuge of southern Arabia

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It seems that southern Arabia has provided shelter to people, 20,000 years earlier, following an ice age that made much of the Earth uninhabitable, according to new evidence provided by University of Huddersfield researchers this week.

Once the Ice Age receded, the Red Sea plains of what we know now as southern Arabia in addition to the far side of the Bab el-Mandeb strait and the Horn of Africa were among glacial sanctuaries where people were able to cluster and survive.

This has been hypothesized before by scientists but never confirmed until this study.

It defies what was commonly thought of Arabia; that humans did not settle there in large numbers until the development of agriculture, roughly 10,000 years earlier.

Analyzing mitochondrial DNA for a lineage that’s common in Arabia and the horn of Africa, the researchers discovered that the lineage, named R0a, is more ancient than what was thought.

The ancient gene flow infiltrated the horn, well before the spread of agriculture into that region. It seeped into the rest of the Middle East (present day Iran, Pakistan and India) and other territories, like Europe through the movement of people and the development of trading networks.

The study mapping human dispersals, post the Ice Age, and deep ancestry was published in Scientific Reports. The DNA analyzed was extracted from living people, since to date this couldn’t be recovered from prehistoric remains. So the scientists had to rely on modern diversity to draw conclusions about the history of the DNA lineage.

Future climate projections for MENA: A dark scenario

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Heat waves expected to be long and intolerable in the region.

Heat waves expected to be long and intolerable in the region.{credit}GETTY{/credit}

A new study is warning against a climate scenario that could see large populations in the Middle East and North Africa region become forcibly displaced because of extreme weather conditions.

“Climate change will significantly worsen the living conditions in the Middle East and in North Africa,” says the study’s lead researcher Jos Lelieveld of the Max Planck Institute for Chemistry, Mainz, Germany. “Prolonged heat waves and desert dust storms can render some regions uninhabitable, which will surely contribute to the pressure to migrate.”

The hot desert climate [will] intensify and become more extreme if global greenhouse gas emissions continue to increase, states the study. The number of warm days and nights may increase sharply. And on average, the maximum temperature in the hottest days will rise from its current level of 43 °C to 50 °C by the end of the century.

Heat waves will occur more frequently, and last significantly longer, according to the study. At present day, it’s extremely hot for an average of 16 days. But by mid-century, the number of hot days will spike, reaching 80 per year. And by the century’s end, the region will go through an 118-day-long extreme heat wave, as per Lelieveld et al.

The extreme heat might also cause higher rates of premature mortality, and a range of cerebrovascular and heart diseases. Combined with increasing air pollution by windblown desert dust, “the environmental conditions could become intolerable,” says Lelieveld.

Last October, Lelieveld and colleagues proposed another chilling vision of the Gulf countries predicting a heat wave so extreme that it could render some major cities like Dubai and Doha uninhabitable by the turn of this century. They also recently published findings that showed that desert dust in the atmosphere over Saudi Arabia, Iraq and Syria has increased up to 70% since the beginning of this century, as a result of prolonged droughts and an increase in sand storms.

The new study, published in the Springer journal Climatic Change, is an extension of Lelieveld and colleagues’ work into how different regions are affected by climate warming.

In the Middle East, the unrelenting rise in global temperatures will “enhance the already hot and dry environmental conditions,” states the study, which followed efforts to improve data access and analyze climate indices in a region that has typically suffered from restricted availability of meteorological data sets.

The study considers two scenarios: one that saw greenhouse gas emissions decreasing and the other (a business as usual scenario) saw no change. Under both scenarios, the heat levels in the Middle East would increase; four folds and two folds respectively.

“Even if climate change in the 21st century will be limited to a global mean temperature increase of 2 °C relative to pre-industrial times, warming over land is typically stronger than over the oceans and extreme temperatures in many regions can increase well beyond 2 °C,” says the study.

Sooner or later, many people will have to leave, the researchers predict.