Image courtesy of Shutterstock.
Joel Kontinen
Evolution has its source of problems. In speculating that humans lived here tens of thousands
years ago, it causes another difficulty.
In evolution, mankind is derived from apelike
creatures over thousands of years, but who designed us humans?
In their view, “around 41,000 years ago, Earth’s
magnetic field weakened to just a fraction of modern levels, leading to a huge
increase in the radiation hitting the surface of the planet. Some researchers
suggest the Laschamps event, as it is known, could have pushed Neanderthals towards extinction,
while modern humans might have protected themselves using tailored clothing and
ochre sunscreen.
Earth’s magnetic field extends into space and acts as
a protective shield against harmful radiation. The magnetic poles usually line
up with the north and south poles, but they occasionally wander due to
changes in the liquid
outer core of the planet. “Fluctuations in this system can lead to
variations in the strength and orientation of Earth’s magnetic field, such as
those observed during the Laschamps event,” says Agnit Mukhopadhyay at the University
of Michigan.
By studying magnetic signatures preserved in volcanic
rocks and sediments, Mukhopadhyay and his colleagues created a detailed 3D
reconstruction of Earth’s magnetic field during the Laschamps event.
They found evidence that the magnetic poles had
shifted towards the equator and that the field strength had weakened to just 10
per cent of today’s levels.
Auroras,
created by charged particles hitting the upper atmosphere, are usually only
visible close to the poles, but this would have changed during the Laschamps
event. “Auroras would have been visible in much wider areas, possibly even near
the equator,” says Mukhopadhyay.
A weakened magnetic field would have allowed more
solar and cosmic radiation to reach Earth’s surface, and may have altered
regional climates. “These environmental changes may have driven adaptive
behaviours in human populations, such as the increased use of protective
clothing and ochre for UV shielding,” says Mukhopadhyay.
The researchers argue that the production of tailored clothing and
the use of the reddish mineral ochre as a sunscreen may have given Homo
sapiens an advantage over Neanderthals, who are thought to have become
extinct
Veronica Waweru at
Yale University says there is evidence for ancient humans using ochre around this time. For
example, the Porc-Epic site in Ethiopia records ochre use at 45,000 years ago,
but this intensified 40,000 years ago, she says. They may have used it for
sunscreen or other reasons such as making artwork or adhesives.”
Ladislav Nejman at
JCMM in the Czech Republic says we don’t know if modern humans used ochre as a
sunscreen. “If they did, it could’ve protected them more, but not necessarily
saved them,” he says. “Humans in Europe really had it stacked against them at
the time.”
He points out that the Laschamps event coincided with
an extremely cold period known as Heinrich event 4, as well as a major volcanic
eruption in Italy called the Campanian Ignimbrite explosion.
“The huge advantage that Homo sapiens had as
a species compared to Neanderthals is that there “were other large populations,
living in Africa and elsewhere, so new Homo
sapiens could move into Europe after these events,” says Nejman.”
Source:
James Woord 2025 Ancient humans may have faced radiation risk 41,000 years ago | New Scientist16 April
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