Science
Humans in America 30000 years ago, far earlier than thought – CTV News
PARIS, FRANCE —
Tools excavated from a cave in central Mexico are strong evidence that humans were living in North America at least 30,000 years ago, some 15,000 years earlier than previously thought, scientists said Wednesday.
Artifacts, including 1,900 stone tools, showed human occupation of the high-altitude Chiquihuite Cave over a roughly 20,000 year period, they reported in two studies, published in Nature.
“Our results provide new evidence for the antiquity of humans in the Americas,” Ciprian Ardelean, an archeologist at the Universidad Autonoma de Zacatecas and lead author of one of the studies, told AFP.
“There are only a few artefacts and a couple of dates from that range,” he said, referring radiocarbon dating results putting the oldest samples at 33,000 to 31,000 years ago.
“However, the presence is there.”
No traces of human bones or DNA were found at the site.
“It is likely that humans used this site on a relatively constant basis, perhaps in recurrent seasonal episodes part of larger migratory cycles,” the study concluded.
The stone tools — unique in the Americas — revealed a “mature technology” which the authors speculate was brought in from elsewhere.
The saga of how and when Homo sapiens arrived in the Americas — the last major land mass to be populated by our species — is fiercly debated among experts, and the new findings will likely be contested.
‘CLOVIS-FIRST’ DEBUNKED
“That happens every time that anybody finds sites older than 16,000 years — the first reaction is denial or hard acceptance,” said Ardelean, who first excavated the cave in 2012 but did not discover the oldest items until 2017.
Until recently, the widely accepted storyline was that the first humans to set foot in the Americas crossed a land bridge from present-day Russia to Alaska some 13,500 years ago and moved south through a corridor between two massive ice sheets.
Archeological evidence — including uniquely crafted spear points used to slay mammoths and other prehistoric megafauna — suggested this founding population, known as Clovis Culture, spread across North America, giving rise to distinct native American populations.
But the so-called Clovis-first model has fallen apart over the last two decades with the discovery of several ancient human settlements dating back two or three thousand years before earlier.
Moreover, the tool and weapon remnants at these sites were not the same, showing distinct origins.
“Clearly, people were in the Americas long before the development of Clovis technology in North America,” said Gruhn, an anthropology professor emerita at the University of Alberta, in commenting on the new findings.
In a second study, Lorena Becerra-Valdivia and Thomas Higham, researchers at the University of Oxford’s Radiocarbon Accelerator Unit, used radiocarbon — backed up by another technique based on luminescence — to date samples from 42 sites across North America.
Using a statistical model, they showed widespread human presence “before, during and immediately after the Last Glacial Maximum” (LGM), which lasted from 27,000 to 19,000 years ago.
MEGAFAUNA WIPED OUT
The timing of this deep chill is crucial because it is widely agreed that humans migrating from Asia could not have penetrated the massive icesheets that covered much of the continent during this period.
“So if humans were here DURING the Last Glacial Maximum, that’s because they had already arrived BEFORE it,” Ardelean noted in an email.
Human populations scattered across the continent during an earlier period also coincide with the disappearance of once abundant megafauna, including mammoths and extinct species of camels and horses.
“Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals,” the second study concluded.
Many key questions remain unanswered, including whether the first of our species to wander across the frozen tundra of Beringia made their way south via an interior route or — as recent research suggests — by moving along the coast, either on foot or in boats of some kind.
It is also a mystery as to “why no archeological site of equivalent age to Chiquihuite Cave has been recognized in the continental United States,” said Gruhn.
“With a Bering Straits entry point, the earliest people expanding south must have passed through that area.”
Science
Nasa's Hubble marks 34th anniversary with stunning view of Little Dumbbell Nebula – The Times of India
In celebration of its 34th anniversary, Nasa‘s Hubble Space Telescope has once again wowed astronomers and space enthusiasts alike by capturing an extraordinary image of the Little Dumbbell Nebula. This latest image offers a vivid glimpse into the complexities of a planetary nebula, demonstrating Hubble’s enduring capabilities in its extended mission.
The Little Dumbbell Nebula, also known as Messier 76, is one of the faintest objects in the Messier catalog and has intrigued astronomers for its intricate structure and dual-lobed shape. This planetary nebula, located approximately 2,500 light-years away in the constellation Perseus, represents a brief stage in the life cycle of a moderate-sized star like our sun.
Dr. Jennifer Wiseman, a senior scientist at Nasa’s Goddard Space Flight Center, expressed her admiration for the new imagery: “This beautiful nebula is what remains after a star like our own sun has exhausted the bulk of its nuclear fuel and shed its outer layers. The vibrant colors and intricate structures visible in the nebula are a telescope’s way of painting the portrait of the final stages of stellar evolution.”
The Little Dumbbell Nebula, despite its faintness, shines brightly in the detailed images provided by Hubble, allowing scientists to study aspects of the nebula that are rarely visible. The images highlight the dense, glowing gas and complex layers of material expelled from the dying star at the center of the nebula.
According to Dr. Wiseman, “Hubble’s high-resolution capabilities allow us to examine the fine details within the nebula, helping us understand how stars expel their material and the dynamics of this expulsion process. This image is more than just a picture; it’s a deep dive into the life of stars.”
Since its launch on April 24, 1990, Hubble has revolutionized our understanding of the universe, from the dynamics of galaxies to the atmospheres of exoplanets and the distribution of dark matter. Its contributions continue to support and complement data gathered by newer space observatories.
As Hubble continues its journey in space, the scientific community remains enthusiastic about the ongoing contributions it will bring to our understanding of the cosmos. Dr. Wiseman remarked, “Every image from Hubble is a new lesson in our cosmic curriculum.”
These observations not only contribute significantly to our knowledge of the life cycle of stars but also continue to highlight the critical role of Hubble in the exploration and understanding of our universe. As Hubble enters another year in orbit, its legacy of discoveries promises to keep inspiring both the scientific community and the public.
SpaceX sent up the 30th launch from the Space Coast for the year on the evening of April 23, a mission that also featured the company’s 300th successful booster recovery.
A Falcon 9 rocket carrying 23 of SpaceX’s Starlink internet satellites blasted off at 6:17 p.m. Eastern time from Cape Canaveral Space Force Station’s Space Launch Complex 40.
The first-stage booster set a milestone of the 300th time a Falcon 9 or Falcon Heavy booster made a successful recovery landing, and the 270th time SpaceX has reflown a booster.
This particular booster made its ninth trip to space, a resume that includes one human spaceflight, Crew-6. It made its latest recovery landing downrange on the droneship Just Read the Instructions in the Atlantic Ocean.
The company’s first successful booster recovery came in December 2015, and it has not had a failed booster landing since February 2021.
The current record holder for flights flew 11 days ago making its 20th trip off the launch pad.
SpaceX has been responsible for all but two of the launches this year from either Kennedy Space Center or Cape Canaveral with United Launch Alliance having launched the other two.
SpaceX could knock out more launches before the end of the month, putting the Space Coast on pace to hit more than 90 by the end of the year, but the rate of launches by SpaceX is also set to pick up for the remainder of the year with some turnaround times at the Cape’s SLC-40 coming in less than three days.
That could amp up frequency so the Space Coast could surpass 100 launches before the end of the year, with the majority coming from SpaceX. It hosted 72 launches in 2023.
More launches from ULA are on tap as well, though, including the May 6 launch atop an Atlas V rocket of the Boeing CST-100 Starliner with a pair of NASA astronauts to the International Space Station.
ULA is also preparing for the second launch ever of its new Vulcan Centaur rocket, which recently received its second Blue Origin BE-4 engine and is just waiting on the payload, Sierra Space’s Dream Chaser spacecraft, to make its way to the Space Coast.
Blue Origin has its own rocket it wants to launch this year as well, with New Glenn making its debut as early as September, according to SLD 45’s range manifest.
2024 Orlando Sentinel. Distributed by Tribune Content Agency, LLC.
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The common loon, that icon of northern wilderness, is under threat from climate change due to declining water clarity. Published earlier this month in the journal Ecology, a study conducted by biologists from Chapman University and Rensselaer Polytechnic Institute in the U.S. has demonstrated the first clear evidence of an effect of climate change on this species whose distinct call is so tied to the soundscape of Canada’s lakes and wetlands.
Through the course of their research, the scientists found that July rainfall results in reduced July water clarify in loon territories in Northern Wisconsin. In turn, this makes it difficult for adult loons to find and capture their prey — mainly small fish — underwater, meaning they are unable to meet their chicks’ metabolic needs. Undernourished, the chicks face higher mortality rates. The consistent foraging techniques used by loons across their range means this impact is likely echoed wherever they are found — from Alaska to Canada to Iceland.
The researchers used Landsat imagery to find that there has been a 25-year consistent decline in water clarity, and during this period, body weights of adult loon and chicks alike have also declined. With July being the month of most rapid growth in young loons, the study also pinpointed water clarity in July as being the greatest predictor of loon body weight.
One explanation for why heavier rainfall leads to reduced water clarity is the rain might carry dissolved organic matter into lakes from adjacent streams and shoreline areas. Lawn fertilizers, pet waste and septic system leaks may also be to blame.
The researchers, led by Chapman University professor Walter Piper, hope to use these insights to further conservation efforts for this bird Piper describes as both “so beloved and so poorly understood.”
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