Archiv: Homo Neanderthalensis


26.04.2024 - 02:35 [ Smithsonian Magazine ]

An Evolutionary Timeline of Homo Sapiens

(February 2, 2021)

Neanderthals once stretched across Eurasia from Portugal and the British Isles to Siberia. As Homo sapiens became more prevalent across these areas the Neanderthals faded in their turn, being generally consigned to history by some 40,000 years ago. (…)

Despite the bits of genetic ancestry they contributed to living people, all of our close relatives eventually died out, leaving Homo sapiens as the only human species. Their extinctions add one more intriguing, perhaps unanswerable question to the story of our evolution—why were we the only humans to survive?

24.04.2023 - 13:21 [ Science.org ]

A global environmental crisis 42,000 years ago

(19 Feb 2021)

Do terrestrial geomagnetic field reversals have an effect on Earth‘s climate? Cooper et al. created a precisely dated radiocarbon record around the time of the Laschamps geomagnetic reversal about 41,000 years ago from the rings of New Zealand swamp kauri trees. This record reveals a substantial increase in the carbon-14 content of the atmosphere culminating during the period of weakening magnetic field strength preceding the polarity switch. The authors modeled the consequences of this event and concluded that the geomagnetic field minimum caused substantial changes in atmospheric ozone concentration that drove synchronous global climate and environmental shifts.

(…)

We precisely characterize the geomagnetic reversal and perform global chemistry-climate modeling and detailed radiocarbon dating of paleoenvironmental records to investigate impacts. We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

24.04.2023 - 13:16 [ ORF.at ]

Erdmagnetfeld: Polwanderung veränderte das Weltklima

Ungefilterte Strahlung aus dem Weltraum zerriss Luftpartikel in der Erdatmosphäre, trennte Elektronen ab und emittierte Licht. Diese ionisierte Luft brutzelte die Ozonschicht weg, heißt es in einer Presseaussendung zur Studie. In Folge dürften überall auf dem Globus Polarlichter aufgetaucht sein, nicht nur rund um den geographischen Nord- und Südpol wie heute. (…)

Das Erdmagnetfeld schwächelt bereits seit rund 2.000 Jahren wieder. Verglichen mit den ersten direkten Messungen vor 170 Jahren wurde eine Abschwächung um neun Prozent festgestellt, im Bereich des Südatlantiks sogar um dreißig Prozent.

21.02.2021 - 13:05 [ ScienceNews.org ]

50 years ago, scientists named Earth’s magnetic field as a suspect in extinctions

(November 19, 2020)

Effects of Earth’s magnetic field — Science News, November 21, 1970

„Earth’s magnetic field has frequently reversed at intervals of 1 million to 100 million years. A few scientists now suspect that these reversals may have had drastic effects on terrestrial life.… During the past 2.5 million years, eight species of one-cell marine animals called Radiolaria became extinct. Six of these extinctions occurred simultaneously throughout their geographic range immediately following magnetic reversals.“

21.02.2021 - 12:40 [ Science Magazine ]

A global environmental crisis 42,000 years ago

(19.02.2021)

We find that geomagnetic field minima ~42 ka, in combination with Grand Solar Minima, caused substantial changes in atmospheric ozone concentration and circulation, driving synchronous global climate shifts that caused major environmental changes, extinction events, and transformations in the archaeological record.

21.02.2021 - 12:35 [ CNN ]

Reversal of Earth‘s magnetic poles may have triggered Neanderthal extinction — and it could happen again

(19.02.2021)

Some 42,000 years ago, in an event known as the Laschamp Excursion, the poles did just that for around 800 years, before swapping back — but scientists were unsure exactly how or if it impacted the world.

Now, a team of researchers from Sydney‘s University of New South Wales and the South Australian Museum say the flip, along with changing solar winds, could have triggered an array of dramatic climate shifts leading to environmental change and mass extinctions.