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Global population plummeted after Younger Dryas comet impact


The Cosmic Tusk
Sat, 07 Aug 2021 19:24 UTC
Comet impact
© ShutterstockAn artist's conception shows an impact event on Earth.
It is commonly thought that human genetic diversity in non-African populations was shaped primarily by an out-of-Africa dispersal 50-100 thousand yr ago (kya). Here, we present a study of 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples. Applying ancient DNA calibration, we date the Y-chromosomal most recent common ancestor (MRCA) in Africa at 254 (95% CI 192-307) kya and detect a cluster of major non-African founder haplogroups in a narrow time interval at 47-52 kya, consistent with a rapid initial colonization model of Eurasia and Oceania after the out-of-Africa bottleneck. In contrast to demographic reconstructions based on mtDNA, we infer a second strong bottleneck in Y-chromosome lineages dating to the last 10 ky. We hypothesize that this bottleneck is caused by cultural changes affecting variance of reproductive success among males.



Full paper: Karmin et al. 2020 A recent bottleneck of Y chromosome diversity coincides with a global change in culture
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Info

Light pollution is making it harder for animals to navigate at night

Scott Alan Johnston
Universe Today
Sat, 07 Aug 2021 19:01 UTC
Dung Beetle
© Chris CollingridgeA nocturnal dung beetle climbing atop its dung ball to survey the stars before starting to roll.
Ah, the majestic dung beetle. The pinnacle of evolution. In all seriousness, these little critters are incredibly sophisticated navigators who have, for millennia, used the night sky to guide them about their business. But light pollution is making their lives more difficult by limiting their ability to navigate by the stars. Other nocturnal creatures, including some birds and moths, may be facing similar challenges.

Dung beetles are known for their penchant for rolling dung into balls, then pushing their prize away from competing beetles as quickly as possible. To swiftly escape the competition, they need to be able to travel in straight lines away from a dung pile, putting as much distance as they can between them and their rivals. The stars provide these rushing beetles with a compass, acting as directional cues in the sky with which the beetles are able to orient themselves. When they reach a safe distance, the beetles then bury the dung and proceed to consume it in relative safety.

Researchers at the University of Würzburg in Germany, Lund University in Sweden, and the University of the Witwatersrand in South Africa set out to examine how light pollution affects the beetles' ability to travel by starlight.

Their results, published in the journal Current Biology, show that the beetles become disoriented in different lighting conditions. For example, in the presence of bright city lights, the beetles have a tendency to travel directly towards the nearest, brightest light source. Instead of dispersing away from a dung pile, the beetles are all drawn in one direction. This makes conflict and competition more likely as individuals encounter each other more frequently.
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SOTT Focus: MindMatters: Cliodynamics and the Secular Cycles of History

Harrison Koehli, Elan Martin, Adam Daniels
Sott.net
Sat, 07 Aug 2021 00:00 UTC
cliodynamics
Does history really repeat? If so, how, and why? We discussed the "fourth turning" on a previous episode of MindMatters. According to Strauss and Howe, the United States has entered a time of crisis which could see societal collapse, revolution, or war. However, their theory has its problems. While suggestive on the descriptive level, it has not been scientifically supported. Enter Peter Turchin.

Today we continue our discussion of historical cycles by looking at cliodynamics, a field of study pioneered by Turchin. Turchin's work gives scientific support to the idea that cycles are an essential feature of civilization. Empires rise and fall. Periods of stagnation and crisis end in war, revolution, and collapse. These trends, and the factors that determine them, can be measured and modeled. And all the indicators show that the U.S. has indeed entered a time of crisis, along with Europe - on par with the conditions that led to the American Civil War.

Today on MindMatters we discuss the outlines of Turchin's work, how it applies to American history, and what it might mean for the future.


Running Time: 01:20:48

Download: MP3 — 64.2 MB


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Chalkboard

Physicists discover simple propulsion mechanism for bodies in dense fluids


PhysOrg
Sat, 07 Aug 2021 18:10 UTC
scallops seashells graphic
© redit: Pixabay/CC0 Public Domain
A team of researchers from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), the University of Liège and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy have developed a micro-swimmer that appears to defy the laws of fluid dynamics: Their model, consisting of two beads connected by a linear spring, is propelled by completely symmetrical oscillations. The scallop theorem states that this cannot be achieved in fluid microsystems. The findings have now been published in the academic journal Physical Review Letters.

Scallops can swim in water by quickly clapping their shells together. They are large enough to still be able to move forwards through the moment of inertia while the scallop is opening its shell for the next stroke. However, the Scallop theorem applies more or less depending on the density and viscosity of the fluid: A swimmer that makes symmetrical or reciprocal forward or backward motions similar to the opening and closing of the scallop shell will not move an inch. "Swimming through water is as tough for microscopic organisms as swimming through tar would be for humans," says Dr. Maxime Hubert. "This is why single-cell organisms have comparatively complex means of propulsion such as vibrating hairs or rotating flagella."
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Red Pill

Flashback Best of the Web: Dead scientists, genetically engineered viruses and government pandemics: Conspiracy theorists were so right


Jolly Roger
Sun, 26 Apr 2009 18:44 UTC

Comment: This is an old one from our archives, an anonymous blogpost from 2009. While it remains to be seen whether 'culling the population' is an intended outcome of Covid-1984, 'conspiracy theorists' like this were remarkably accurate in most of their predictions...


puppet masters economist
© The Economist'Conspiracy theory' in 2009, acknowledged mainstream fact in 2020
If you sell crack, join a gang, or rob the mob you can expect to die a violent death, but if you listen to your mother, eat all the right foods, and study hard in college to become a microbiologist, you should expect to live to a ripe old age and die peacefully.

That being the case, a few eyebrows were raised when five microbiologists either disappeared or died mysteriously violent deaths in 2001. A short time later the number rose to 19, and then 29.

They were found stabbed to death in the trunks of cars, thrown off bridges, or they wrapped their cars around trees after their brake fluid disappeared. Once again, this is the stuff of Hollywood spy stories, and not the way you would expect a microbiologist to give up the ghost.
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Blue Planet

How supereruption of Toba volcanoe 74,000 years ago disrupted climate

Rutgers University
Source
Tue, 27 Jul 2021 12:00 UTC
Toba
© Landsat satellite photoLake Toba, Sumatra, Indonesia
A massive volcanic eruption in Indonesia about 74,000 years ago likely caused severe climate disruption in many areas of the globe, but early human populations were sheltered from the worst effects, according to a Rutgers-led study.

The findings appear in the journal PNAS.

The eruption of the Toba volcano was the largest volcanic eruption in the past two million years, but its impacts on climate and human evolution have been unclear. Resolving this debate is important for understanding environmental changes during a key interval in human evolution.

"We were able to use a large number of climate model simulations to resolve what seemed like a paradox," said lead author Benjamin Black, an assistant professor in the Department of Earth and Planetary Sciences at Rutgers University-New Brunswick. "We know this eruption happened and that past climate modeling has suggested the climate consequences could have been severe, but archaeological and paleoclimate records from Africa don't show such a dramatic response.

Comment: And it's possible that what caused the eruption was an encounter with a cometary body: Volcanoes, Earthquakes And The 3,600 Year Comet Cycle

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Magnify

Flashback Best of the Web: Scientists' suspicious deaths are under the microscope

Alanna Mitchell, Simon Cooper & Carolyn Abraham
Globe and Mail
Sat, 04 May 2002 06:52 UTC
don wiley
'Superstar scientist' Don Wiley
It's a tale only the best conspiracy theorist could dream up.

Eleven microbiologists mysteriously dead over the span of just five months. Some of them world leaders in developing weapons-grade biological plagues. Others the best in figuring out how to stop millions from dying because of biological weapons. Still others, experts in the theory of bioterrorism.

Throw in a few Russian defectors, a few nervy U.S. biotech companies, a deranged assassin or two, a bit of Elvis, a couple of Satanists, a subtle hint of espionage, a big whack of imagination, and the plot is complete, if a bit reminiscent of James Bond.


Comment: Notice how the authors are trivializing the murders with multiple allusions to fictional and stereotypical notions in an attempt to preemptively allay readers' suspicions. In all likelihood, these scientists' deaths - and the dark underbelly of Western military intelligence networks that connect them - could not be matched by anything in Hollywood fiction.


The first three died in the space of just over a week in November. Benito Que, 52, was an expert in infectious diseases and cellular biology at the Miami Medical School. Police originally suspected that he had been beaten on Nov. 12 in a carjacking in the medical school's parking lot. Strangely enough, though, his body showed no signs of a beating. Doctors then began to suspect a stroke.

Just four days after Dr. Que fell unconscious came the mysterious disappearance of Don Wiley, 57, one of the foremost microbiologists in the United States. Dr. Wiley, of the Howard Hughes Medical Institute at Harvard University, was an expert on how the immune system responds to viral attacks such as the classic doomsday plagues of HIV, ebola and influenza.
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Gem

Emerging secrets of the Alps: algae causing strange red snow

Dhananjay Khadilkar
BBC
Fri, 30 Jul 2021 12:00 UTC
alps red snow algae
It is a shocking, garish sight to come across on a peaceful mountainside. Hike high enough in the French alps during the late spring and early summer, and there is a good chance that you will come across some rather strange patches of snow among the grey limestone and stunted clumps of vegetation. This snow isn't white - it's blood red.

The peculiar phenomenon - sometimes known as blood snow - is the result of a defence mechanism produced by microscopic algae that grow in the Alpine snow. Normally these microalgae have a green colour as they contain chlorophyll, the family of pigments produced by most plants to help them absorb energy from sunlight. However, when the snow algae grow prolifically and are exposed to strong solar radiation, they produce red-coloured pigment molecules known as carotenoids, which act as a sunshield to protect their chlorophyll.

Comment: It's notable that elsewhere on the planet algae blooms in bodies of water also appear to be on the increase: See also: And check out SOTT radio's:

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Gem

NIST's quantum crystal could be a new dark matter sensor


NIST
Thu, 05 Aug 2021 09:49 UTC
John Bollinger NIST
© R. Jacobson/NISTNIST physicists John Bollinger (left) and Matt Affolter adjust the laser and optics array used to trap and probe beryllium ions in the large magnetic chamber (white pillar at left). The ion crystal may help detect mysterious dark matter.
Physicists at the National Institute of Standards and Technology (NIST) have linked together, or "entangled," the mechanical motion and electronic properties of a tiny blue crystal, giving it a quantum edge in measuring electric fields with record sensitivity that may enhance understanding of the universe.

The quantum sensor consists of 150 beryllium ions (electrically charged atoms) confined in a magnetic field, so they self-arrange into a flat 2D crystal just 200 millionths of a meter in diameter. Quantum sensors such as this have the potential to detect signals from dark matter — a mysterious substance that might turn out to be, among other theories, subatomic particles that interact with normal matter through a weak electromagnetic field. The presence of dark matter could cause the crystal to wiggle in telltale ways, revealed by collective changes among the crystal's ions in one of their electronic properties, known as spin.

As described in the Aug. 6 issue of Science, researchers can measure the vibrational excitation of the crystal — the flat plane moving up and down like the head of a drum — by monitoring changes in the collective spin. Measuring the spin indicates the extent of the vibrational excitation, referred to as displacement.

This sensor can measure external electric fields that have the same vibration frequency as the crystal with more than 10 times the sensitivity of any previously demonstrated atomic sensor. (Technically, the sensor can measure 240 nanovolts per meter in one second.) In the experiments, researchers apply a weak electric field to excite and test the crystal sensor. A dark matter search would look for such a signal.
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Solar Flares

Minor CME leads to geomagnetic storm: Grid failure all but guaranteed by 2024

Cap Allon
Electroverse
Wed, 04 Aug 2021 06:49 UTC
Solar grid fires


The sun may have been quiet over the past week or so, but that didn't stop our planet's magnetic field allowing a minor CME to break its defenses and push the indexes into geomagnetic storm territory.

A minor coronal mass ejection (CME) erupted on the sun a few days ago, and, as expected, it impacted Earth on August 3; however, what wasn't forecast by the observers at NOAA and NASA was the event sparking a geomagnetic storm.

The event was barely a blip as far the telemetry was concerned:

Comment: See also:

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