Connect with us

Science

'Ghost' human ancestor discovered in West Africa – BBC News

Published

 on


A mysterious “ghost population” of now-extinct ancient human-like creatures may have interbred with early humans living in West Africa, scientists say.

Researchers suggest DNA from this group makes up between 2% and 19% of modern West Africans’ genetic ancestry.

They believe the interbreeding occurred about 43,000 years ago.

Scientists found links to the Mende people of Sierra Leone, Yoruba as well as Esan people in Nigeria, plus other groups in western areas of The Gambia.

The new study was published in Science Advances this week.

It suggests that ancestors of modern West Africans interbred with a yet-undiscovered species of archaic human, similar to how ancient Europeans mated with Neanderthals, and Oceanic populations with Denisovans.

The research sheds more light on how archaic hominins added to the genetic variation of present-day Africans, which has been poorly understood even though it is the most genetically diverse continent.

Hundreds of thousands of years ago there were several different groups of humans including modern humans, Neanderthals and Denisovans.

The newly-discovered “ghost population” of ancient human species seems likely to have diverged from these groups.

Sriram Sankararaman – the computational biologist who led the research at the University of California in Los Angeles – told BBC Newsday he believed more such groups would be found in the future.

His team looked at the genetic make-up of West Africans and found that some of their DNA came from an ancient unexplained source.

“As we get more data from diverse populations – and better quality data – our ability to sift through that data and excavate these ghost populations is going to get better,” Mr Sankararaman said.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

New Methane Discharge Discovered in Russia's Arctic – Guardian – The Moscow Times

Published

 on


A new source of methane discharge has been discovered in the Arctic Ocean near eastern Siberia, raising concerns of a “new tipping point” that could speed up the pace of global warming, The Guardian reported Tuesday. 

Scientists found the potent greenhouse gas bubbling from a depth of 350 meters in the Laptev Sea, with surface-level concentrations that vent into the atmosphere between four and eight times the normal amount. One of the six monitoring points showed methane concentrations 400 times higher than expected under the normal air-sea equilibrium.

“The discovery of actively releasing shelf slope hydrates is very important and unknown until now. This is a new page,” said Igor Semiletov, chief scientist onboard the Akademik M. Keldysh research vessel that’s part of a multi-year Russian-Swedish International Siberian Shelf Study expedition.

The discovery is prompting concerns that a new feedback loop that accelerates climate change may have already been triggered. A recent study co-authored by a member of the expedition found that the loop could be activated if the Arctic warms by just a few degrees.

At this moment, there is unlikely to be any major impact on global warming, but the point is that this process has now been triggered,” Swedish scientist and study co-author Örjan Gustafsson told The Guardian from the vessel.

This East Siberian slope methane hydrate system has been perturbed and the process will be ongoing.” 

The Guardian reported that warm Atlantic currents driven by human-induced climate disruption are the likely cause of the massive methane discharge.  

The Arctic is warming twice as fast as any other place on Earth and The Guardian reported that it is yet to begin freezing for the winter, already surpassing records for the latest date for sea ice formation after melting unusually early this spring. 

This is potentially the third source of methane emissions from the shallower parts of the Laptev Sea and the East Siberian Sea. Semiletov’s expedition released first photos of a massive fountain of methane gas bubbling from the floor of the East Siberian Sea last fall.

The scientists stressed that their findings are considered preliminary until they analyze the data collected on the ground and have their studies peer-reviewed.

The discovery of actively releasing shelf slope hydrates is very important and unknown until now,” Semiletov said. “Potentially they can have serious climate consequences, but we need more study before we can confirm that.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Researchers Worry Methane Discovery in Arctic Ocean Could Signal Dangerous New Climate Feedback Loop – Common Dreams

Published

 on


An international team of researchers aboard a Russian research ship has discovered evidence that frozen methane deposits in the Arctic Ocean have been dispersing over a large area of Siberia, potentially fueling a dangerous new climate feedback loop. 

The Guardian reports the International Siberian Shelf Study (ISSS-2020) found that slope sediments spreading over much of the continental shelf are rich in frozen methane hydrates that have been detected to a depth of 1,150 feet in the Laptev Sea.

Although the scientists said that most of the methane hydrate bubbles are dissolving in the water, methane levels at the sea surface are four to eight times higher than normal and the gas is venting into the atmosphere. What makes methane especially dangerous is that its heating effect is 80 times stronger than CO2 over 20 years. The new discovery has raised serious concerns that a new climate feedback loop may be starting.

According to ISSS-2020:

One of the greatest uncertainties surrounding climate warming [concerns] the emission of naturally accurring greenhouse gases, such as methane, carbon dioxide, and nitrous oxide (N2O) from Arctic thawing permafrost, and collapsing methane hydrates—crystals made of methane gas molecules “caged” between solid water molecules—in the seabed north of Siberia will increase in the future.  

“At this moment, there is unlikely to be any major impact on global warming, but the point is that this process has now been triggered,” Stockholm University researcher Örjan Gustafsson told The Guardian. “This East Siberian slope methane hydrate system has been perturbed and the process will be ongoing.” 

SCROLL TO CONTINUE WITH CONTENT

An existential threat to our democracy. A global pandemic. An unprecedented economic crisis. Our journalism has never been more needed.

Can you pitch in today and help us make our Fall Campaign goal of $80,000 by November 2nd?

Please select a donation method:

<!–
BG Options
/sites/all/modules/custom/ctas/images/june2019/cta-content-mobile-june-2019.jpg (newspaper)
/sites/all/modules/custom/ctas/images/june2019/cta-content-mobile-june-2019_3.jpg (cell)
/sites/all/modules/custom/ctas/images/june2019/cta-content-mobile-june-2019_4.jpg (radio)
/sites/all/modules/custom/ctas/images/august2019/mobile-1.jpg


–>

Gustafsson, a member of the research team, warned last month that “climate warming is awakening the ‘sleeping giants’ of the carbon cycle, namely permafrost and methane hydrates.”

“How much this will lead to added emissions of the strong greenhouse gas methane is poorly understood,” he said. “This is one of the grand challenges in current climate change research and a central goal of the expedition to address.” 

The chief scientist aboard the vessel, Igor Semiletov of the Russian Academy of Sciences, called the hydrate discharges “significantly larger” than anything previously seen. 

“The discovery of actively releasing shelf slope hydrates is very important and unknown until now,” Semiletov told The Guardian. “This is a new page. Potentially they can have serious climate consequences, but we need more study before we can confirm that.” 

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Scientists: 2018 Michigan Meteorite Was Filled With Organic Compounds – Futurism

Published

 on


Clean Look

An unusual meteorite that streaked across the sky of Michigan as a fireball before landing on a frozen lake in 2018 has granted scientists with a peek at the things space rocks can ferry down to Earth.

Namely, the meteorite was chock full of organic compounds — carbon-containing molecules that serve as the building blocks of life on Earth — that had clear extraterrestrial origins, according to research accepted for publication in the journal Meteoritics & Planetary Science. In this case, scientists from Chicago’s Field Museum of Natural History got to it so quickly that they were able to rule out the sorts of contamination that usually impedes meteorite research.

Elbow Grease

Typically meteorites are teeming with life, but only because they were sitting around long enough for Earthly microbes or lichens to move in and colonize them, lead study author Philipp Heck, a Field Museum curator and University of Chicago professor, explained in a press release.

“This meteorite is special because it fell onto a frozen lake and was recovered quickly,” Heck said. “It was very pristine. We could see the minerals weren’t much altered and later found that it contained a rich inventory of extraterrestrial organic compounds.”

Getting Started

It’s compounds like these that some scientists theorize kickstarted life on Earth after they were brought down by a series of ancient meteorite impacts.

“These kinds of organic compounds were likely delivered to the early Earth by meteorites and might have contributed to the ingredients of life,” Heck said in the release.

READ MORE: ‘Fireball’ meteorite contains pristine extraterrestrial organic compounds [Field Museum]

More on meteorites: Scientists: Life on Earth Likely Started in Meteor Craters

Let’s block ads! (Why?)



Source link

Continue Reading

Trending