*Yoruba still carry ‘beneficial’ genes from mystery ancient human ancestor that guards them against tumours
*Huge plate tectonics crack in Kenya growing, could mean African continent will break up soon, researchers find
*Sahara desert has expanded by more than 10 per cent over last century due to climate change, scientists say
Scientists have provided explanation why more West Africans especially Nigerians unlike other races are better protected from developing cancers.Evidence of an unknown species of human ancestor has been found hiding in the Deoxy ribonucleic Acid (DNA)/genetic material of West African people.
Experts made the finding by analysing the human genome, looking for strings of genetic information that were out of place.This revealed an inheritance of markers from an unidentified human-like species, some of which may be of benefit to their descendants – including one, which suppresses the development of tumours.
Researchers believe an ancient species of hominin, known as Homo heidelbergensis, may be the most likely candidate for the ‘ghost’ species.The full findings of the study are available in a paper published in the online print repository bioRxiv.
Arun Durvasula and Sriram Sankararaman, researchers at the University of California, Los Angeles, United States (U.S.), made the finding. They devised a statistical method able to highlight abnormal genetic code without needing the genome of the species it was inherited from.This bypasses the need for DNA extracted from extinct African hominins as a basis of comparison.
The hotter and wetter climate on the African continent tends to destroy any preserved DNA, unlike samples of human-like species the Neanderthals and Densiovans uncovered in Europe and Asia.The statistical technique was applied to the DNA of 50 modern Yoruba who had their genetic information sequenced as part of the 1,000 Genomes Project. This established that roughly eight per cent of their DNA comes from a yet unknown ‘ghost’ species.
The Yoruba tribe of West Africa is found predominantly in Nigeria, Benin, Togo and Ghana.While Homo sapiens may be the only hominin species alive today, tens of thousands of years ago the planet was home to a variety of human and protohuman species.
As the result of interspecies breeding, some of these species’ DNA has been passed down to modern humans.Traces of Neanderthal DNA are still found in people of non-African descent and Denisovan DNA lives on in people of Asian heritage.
Researchers also learned in 2016 that the DNA of an unknown population of archaic hominins continues to exist in Pacific Island peoples.The Neanderthals and Denisovans have been ruled out of the equation, as we already have their DNA and there is no evidence to suggest they lived in Africa.
Homo heidelbergensis was a more advanced hominin living in Africa around 200,000 years ago and a more probable candidate. It could also be that the mystery DNA came from an isolated group of Homo sapiens or population of hominins that are as yet unknown to researchers.Also, a large crack, stretching several miles, made a sudden appearance recently in south-western Kenya.The tear, which continues to grow, caused part of the Nairobi-Narok highway to collapse and was accompanied by seismic activity in the area.
Now researchers are claiming that in millions of years the African continent could split two.In an article for the Conversation, Lucia Perez Diaz, Postdoctoral Researcher at the Fault Dynamics Research Group, London’s Royal Holloway, explains how this could happen.
The Earth is an ever-changing planet, even though in some respects change might be almost unnoticeable to us.Plate tectonics is a good example of this. But every now and again something dramatic happens and leads to renewed questions about the African continent splitting in two.
Scientists believe that East Africa is breaking up. A huge tectonic plate boundary 3,100 miles (5,000km) long is running up along the eastern section of the continent.
This can be seen the surface as the East African Rift System (EARS). The African plate has split into the Somalian and Nubian tectonic plates, which are pulling away from each other. This active rift zone is currently spreading at few millimeters per year. This means that in around 10 million years, a new ocean will emerge as the EARS continues to tear East Africa apart.
Also, new research suggests global warming is causing the Sahara desert to grow.Scientists have found that the world’s largest desert has expanded by more than ten per cent over the last 100 years.The study suggests the rest of the world’s deserts could be expanding too as widespread climate change continues to heat up the planet.
“Our results are specific to the Sahara, but they likely have implications for the world’s other deserts,” said Sumant Nigam, a professor of atmospheric and oceanic science at the University of Maryland. The researchers analysed seasonal rainfall data throughout Africa from 1920 to 2013.
The team found that areas around the Sahara that were once non-desert regions could now be classified as deserts.The East African Rift is described as an active type of rift, in which the source of these stresses lies in the circulation of the underlying mantle.
Beneath this rift, the rise of a large mantle plume is doming the lithosphere upwards, causing it to weaken as a result of the increase in temperature, undergo stretching and breaking by faulting.Evidence for the existence of this hotter-than-normal mantle plume has been found in geophysical data and is often referred to as the ‘African Superswell’.
Activity along the eastern branch of the rift valley, running along Ethiopia, Kenya and Tanzania, became evident when the large crack suddenly appeared in south-western Kenya.
This superplume is not only a widely-accepted source of the pull-apart forces that are resulting in the formation of the rift valley but has also been used to explain the anomalously high topography of the Southern and Eastern African Plateaus.Rifts exhibit a very distinctive topography, characterised by a series of fault-bounded depressions surrounded by higher terrain.In the East African system, a series of aligned rift valleys separated from each other by large bounding faults can be clearly seen from space.
Not all of these fractures formed at the same time, but followed a sequence starting in the Afar region in northern Ethiopia at around 30m years ago and propagating southwards towards Zimbabwe at a mean rate of between 2.5-5cm a year.Although most of the time rifting is unnoticeable to us, the formation of new faults, fissures and cracks or renewed movement along old faults as the Nubian and Somali plates continue moving apart can result in earthquakes.
Deserts are defined as places with a very low average rainfall, usually four inches (100 mm) or less, and many areas around the Sahara now fall below this threshold.During the summer months, the expansion of the Sahara was most noticeable, researchers found.
In these months, it resulted in a nearly 16 per cent increase in the desert’s average area over the 93-year span covered by the study.The senior author of this study, Professor Nigam added: ‘”Deserts generally form in the subtropics because of the Hadley circulation, through which air rises at the equator and descends in the subtropics.
“Climate change is likely to widen the Hadley circulation, causing northward advance of the subtropical deserts. The southward creep of the Sahara however suggests that additional mechanisms are at work as well, including climate cycles such as the AMO.” Researchers claim that the reason for the expansion of the Sahara is a combination of human-influenced factors and natural change.The Atlantic Multidecadal Oscillation (AMO), which alters climate patterns in the region, works on a 50- to 70-year cycle.
The Pacific Decadal Oscillation (PDO), marked by temperature fluctuations in the northern Pacific Ocean on a scale of 40 to 60 years, also plays a role in changing temperatures.Although the pattern varied seasonally, the expansion was steady and undeniable, researchers found. The southern edge of the Sahara borders the Sahel region, the semi-arid transition zone that lies south of the Sahara.
Researchers found the Sahara expands as the Sahel retreats, disrupting the region’s fragile grassland ecosystems and human societies.Lake Chad, which sits in the centre of this conflicted transition zone, is used to judge the changing conditions in the Sahel.“The Chad Basin falls in the region where the Sahara has crept southward. And the lake is drying out,” Professor Nigam explained.
The town of Diakhao, Senegal in March of 2018 illustrates the conditions of the Sahel during the dry season. The Sahel is the transition zone that lies south of the Sahara Desert, and fluctuates between very dry, desert-like conditions and wetter, more temperate conditions every year. Expansion of the Sahara is putting pressure on Sahel communities, such as Diakhao, that rely on seasonal increases in rainfall during the wet season.
Researchers used statistical methods to remove the effects of the AMO and PDO in order to look at direct human influences.These natural climate cycles accounted for about two-thirds of the total observed expansion of the Sahara. The remaining one-third can be attributed to climate change.