WASHINGTON – Scientists examining the genomes of West Africans have detected signs that a mysterious extinct human species interbred with our own species tens of thousands of years ago in Africa, the latest evidence of humankind’s complicated genetic ancestry.
The study indicated that present-day West Africans can trace a substantial proportion, about 2 to 19 percent, of their genetic ancestry to an extinct human species — what the researchers called a “ghost population.”
“We estimate interbreeding occurred approximately 43,000 years ago, with large intervals of uncertainty,” said University of California, Los Angeles human genetics and computer science professor Sriram Sankararaman, who led the study, published this week in the journal Science Advances.
Homo sapiens first appeared a bit more than 300,000 years ago in Africa and later spread worldwide, encountering other human species in Eurasia that have since gone extinct, including the Neanderthals and the lesser-known Denisovans.
Previous genetic research showed that our species interbred with both the Neanderthals and Denisovans, with modern human populations outside of Africa still carrying DNA from both. But while there is an ample fossil record of the Neanderthals and a few fossils of Denisovans, the newly identified “ghost population” is more enigmatic.
Asked what details are known about this population, Sankararaman said, “Not much at this stage.”
“We don’t know where this population might have lived, whether it corresponds to known fossils, and what its ultimate fate was,” Sankararaman added.
Sankararaman said this extinct species seems to have diverged roughly 650,000 years ago from the evolutionary line that led to Homo sapiens, before the evolutionary split between the lineages that led to our species and to the Neanderthals.
The researchers examined genomic data from hundreds of West Africans, including the Yoruba people of Nigeria and Benin and the Mende people of Sierra Leone, and then compared that with Neanderthal and Denisovan genomes. They found DNA segments in the West Africans that could best be explained by ancestral interbreeding with an unknown member of the human family tree that led to what is called genetic “introgression.”
It is unclear if West Africans derived any genetic benefits from this long-ago gene flow.
“We are beginning to learn more about the impact of DNA from archaic hominins on human biology,” Sankararaman said, using a term referring to extinct human species. “We now know that both Neanderthal and Denisovan DNA was deleterious in general but there were some genes where this DNA had an adaptive impact. For example, altitude adaptation in Tibetans was likely facilitated by a Denisovan introgressed gene.”
Impact of space station spin requires study, official says – CTV News
Space engineers will analyze whether a glitch that caused the International Space Station to spin out of its normal orientation could have impacted any of its systems, a Russian space official said Wednesday.
Sergei Krikalev, the director of crewed space programs at the Russian space corporation Roscosmos, emphasized that last week’s incident did not inflict any observable damage to the space station but he said that experts would need to study its potential implications.
“It appears there is no damage,” Krikalev said in an interview broadcast by Russian state television. “But it’s up to specialists to assess how we have stressed the station and what the consequences are.”
NASA emphasized Wednesday that the station was operating normally and noted that the spin was within safety limits for its systems.
Thrusters on Russia’s Nauka laboratory module fired shortly after the module arrived at the International Space Station on Thursday, making the orbiting outpost slowly spin about one-and-a-half revolutions. Russia’s mission controllers fired thrusters on another Russian module and a Russian cargo ship attached to the space station to stop rotation and then push the station back to its normal position.
Both U.S. and Russian space officials said the station’s seven-person crew wasn’t in danger during the incident.
The station needs to be properly aligned to get the maximum power from solar panels and to maintain communications with space support teams back on Earth. The space station’s communications with ground controllers blipped out twice for a few minutes on Thursday.
NASA said in a tweet Tuesday that the station was 45 degrees out of alignment when Nauka’s thrusters were still firing and the loss of control was discussed with the crew. “Further analysis showed total attitude change before regaining normal attitude control was (tilde)540 degrees,” NASA said.
On Wednesday, NASA noted that “continued analysis following last week’s event with unplanned thruster firings on Nauka has shown the space station remains in good shape with systems performing normally.”
“Most importantly, the maximum rate and acceleration of the attitude change did not approach safety limits for station systems and normal operations resumed once attitude control was regained,” it said.
Roscosmos’ Krikalev, a veteran of six space missions who spent a total of 803 days in orbit, noted Wednesday that firing orientation engines created a dynamic load on the station’s components, making a thorough analysis of whether some of them could be overstressed necessary.
“The station is a rather delicate structure, and both the Russian and the U.S. segments are built as light as possible,” he said. “An additional load stresses the drivers of solar batteries and the frames they are mounted on. Specialists will analyze the consequences. It is too early to talk about how serious it was, but it was an unforeseen situation that requires a detailed study.”
Krikalev said Nauka’s engines fired because a glitch in the control system mistakenly assumed that the lab module hadn’t yet docked at the station and activated the thrusters to pull it away.
The launch of the 22-ton (20-metric-ton) module has been repeatedly delayed by technical problems. It was initially scheduled to go up in 2007, but funding problems pushed the launch back, and in 2013 experts found contamination in its fuel system, resulting in a long and costly replacement. Other Nauka systems also underwent modernization or repairs.
Nauka is the first new compartment for the Russian segment of the International Space Station since 2010, offering more space for scientific experiments and room for the crew. Russian crew members will have to conduct up to 11 spacewalks beginning in early September to prepare it for operation.
The space station is currently operated by NASA astronauts Mark Vande Hei, Shane Kimbrough and Megan McArthur; Oleg Novitsky and Pyotr Dubrov of Roscosmos; Japan Aerospace Exploration Agency astronaut Akihiko Hoshide and European Space Agency astronaut Thomas Pesquet.
In 1998, Russia launched the station’s first compartment, Zarya, which was followed in 2000 by another big piece, Zvezda, and three smaller modules in the following years. The last of them, Rassvet, arrived at the station in 2010.
Perseid Shower season | 96.1 Renfrew Today – renfrewtoday.ca
If you’ve been looking to the night skies on clear occasions of late, you may have been seeing quite the show.
Backyard Astronomer Gary Boyle says it’s Perseid (Per-say-id) Meteor Shower Season.
The natural phenomenon began July 14th, and is on-going.
Boyle says two nights next week (this week) will provide optimal viewing opportunities.
The event is great for the naked eye, but it’s an impossible challenge for cellphones- you’ll need a 35mm camera, and best, one with a time-lapse feature.
The Backyard Astronomer says that this year, the crescent moon sets within a couple of hours after sunset leaving us with a dark sky.
By contrast, next year’s Perseids takes place under a full moon, drastically reducing the hourly rate.
The Perseid Meteor Shower activity comes to an end August 24th.
Browns Socialhouse in Kamloops temporarily closed because of COVID-19 – radionl.com
A Kamloops restaurant has temporarily closed its doors because of COVID-19.
In a post online, Browns Socialhouse says the closure is “in the best interest of our guest and staff health and safety.”
“We are working closely with the Interior Health Authority and will update you when we will be re-opening,” the statement said. “These are extremely difficult and unprecedented times, but we stand strong and are determined to be a thriving business in the Kamloops and surrounding region community.”
As this time, there is no indication who might have tested positive for the virus at the restaurant or if there was transmission reported there. The exposure is not yet listed on Interior Health’s public exposure list.
Health officials are encouraging people to get vaccinated as most new cases are in people who are not vaccinated or not yet fully vaccinated.
For now, a COVID-19 outbreak remains in the Central Okanagan – which includes Kelowna, West Kelowna, Lake Country, and Peachland and other nearby communities – because of a recent spike in cases. Masks are mandatory there, while people are also being told not to travel to those communities, especially if they’re not yet fully vaccinated.
Several restaurants in the Kelowna-area have been forced to temporarily close in the past few weeks because of positive COVID-19 tests.
Provincial Health Officer, Dr. Bonnie Henry, has so for said vaccines are not mandatory for people to attend events or travel, but she’s also in support of groups and businesses that make it mandatory.
“We do recommend people take precautions, but we’re not, at this point, going to be requiring people [to be immunized],” Henry said. “There are some businesses and some groups making requirements that I think are perfectly valid for their own situations, where they have required that only people who are immunized are allowed to attend.”
“We’ve talked about not having vaccine passports for things like having access to public services, but there are some things that are not essential services, where it is important that only immunized people get together. Especially if it’s in a situation where we have more of the virus transmitted, and in settings like indoor crowded settings.”
COVID-19: Delta variant driving fourth wave in B.C. – Vancouver Sun
N.W.T. Métis activist remembered as unfiltered politician, caring friend – CBC.ca
The cost of down payments in Canadian cities skyrocketed in 2021, new data shows – CTV News
Silver investment demand jumped 12% in 2019
Europe kicks off vaccination programs | All media content | DW | 27.12.2020 – Deutsche Welle
Iran anticipates renewed protests amid social media shutdown
Health13 hours ago
How safe is it for fully vaccinated people to return to in-person work? One expert weighs in – CP24 Toronto's Breaking News
Sports11 hours ago
Gold for Andre De Grasse, another huge 400m hurdles record
News11 hours ago
U.S. to outfit border agents with body cameras in major oversight move
Tech17 hours ago
Facebook's WhatsApp rolls out option for disappearing photos, videos to take on Snapchat – Yahoo News Canada
Sports11 hours ago
TOKYO OLYMPICS Update
Sports11 hours ago
Another record on track, Belarus sprinter heads for Poland
Sports20 hours ago
Canada start time women's Olympic soccer final – TSN
Sports4 hours ago
Toronto Raptors Pascal Siakam and Fred VanVleet pen emotional farewell messages to Kyle Lowry – NBA CA