地球磁极偏移：可能帮助智人在 41,000 年前生存下来的要素

Ancient Homo sapiens may have benefited from sunscreen, tailored clothes and the use of caves during the shifting of the magnetic North Pole over Europe about 41,000 years ago, new University of Michigan research shows.

密歇根大学（University of Michigan）的一项新研究表明，大约41,000年前，磁北极在欧洲上空移动期间，古代智人可能受益于防晒霜、量身定制的衣服和洞穴的使用。

These technologies could have protected Homo sapiens living in Europe from harmful solar radiation. Neanderthals, on the other hand, appear to have lacked these technologies and disappeared around 40,000 years ago, according to the study, publishedin Science Advances and led by researchers at Michigan Engineering and the U-M Department of Anthropology.

这些技术可以保护生活在欧洲的智人免受有害的太阳辐射。另一方面，尼安德特人似乎缺乏这些技术，并在大约 40,000 年前消失了，该研究发表在《科学进展》上，由密歇根工程学院和密歇根大学人类学系的研究人员领导。

The team found that the North Pole wandered over Europe when the magnetic field's poles started to flip positions, a natural process that has happened around 180 times over Earth's geological history. While the magnetic reversal didn't complete at the time, the magnetic field weakened to cause aurora to occur over most of the globe, and allowed more harmful UV light to come in from space.

该团队发现，当磁场的磁极开始翻转位置时，北极在欧洲上空徘徊，这一自然过程在地球地质史上已经发生了大约 180 次。虽然当时磁反转没有完成，但磁场减弱，导致极光出现在全球大部分地区，并允许更多有害的紫外线从太空进入。

Around the same time, Homo sapiens appear to have started making tailored clothing and using ochre, a mineral that has sun-protective properties when applied to the skin, with greater frequency. These behaviors could have contributed to their spread throughout Europe and Asia at a time when the Neanderthal population was declining.

大约在同一时间，智人似乎开始制作量身定制的衣服，并更频繁地使用赭石，赭石是一种涂抹在皮肤上具有防晒特性的矿物质。这些行为可能有助于它们在尼安德特人人口下降时在欧洲和亚洲传播。

"In the study, we combined all of the regions where the magnetic field would not have been connected, allowing cosmic radiation, or any kind of energetic particles from the sun, to seep all the way in to the ground," said Agnit Mukhopadhyay, lead author and U-M research affiliate in climate and space sciences and engineering.

“在这项研究中，我们结合了所有磁场不会连接的区域，允许宇宙辐射或来自太阳的任何类型的高能粒子一直渗入地面，”主要作者、密歇根大学气候和空间科学与工程研究附属机构 Agnit Mukhopadhyay 说。

"We found that many of those regions actually match pretty closely with early human activity from 41,000 years ago, specifically an increase in the use of caves and an increase in the use of prehistoric sunscreen."

“我们发现，其中许多地区实际上与 41,000 年前的早期人类活动非常吻合，特别是洞穴使用的增加和史前防晒霜使用的增加。”

Wandering poles 流浪杆

Earth's magnetic field is created by its rotation, and by extension, the rotation of its core. The core, which is composed of molten iron, generates electrical currents, which extend in a halo around the globe. This halo helps protect Earth from cosmic radiation—the stuff that thins Earth's ozone layer and lets in more UV light. The interaction of these particles with Earth's magnetic field results in aurora as well.

地球的磁场是由其旋转产生的，进而是由其核心的旋转产生的。核心由熔融铁组成，产生电流，电流以光晕的形式延伸到地球周围。这个光晕有助于保护地球免受宇宙辐射的侵害，宇宙辐射使地球的臭氧层变薄，并允许更多的紫外线进入。这些粒子与地球磁场的相互作用也会产生极光。

Mukhopadhyay began building models of this interaction using the Space Weather Modeling Framework, a versatile numerical tool developed and maintained by the U-M Center for Space Environment Modeling, to study the sun, heliosphere and planetary space environments, including that of Earth.

Mukhopadhyay 开始使用空间天气建模框架构建这种相互作用的模型，该框架是由 UM 空间环境建模中心开发和维护的多功能数值工具，用于研究太阳、日球层和行星空间环境，包括地球的环境。

The sun continually throws hot gases and charged particles toward Earth, which, because of their extremely high temperatures, act as a plasma system. Mukhopadhyay developed a model that predicts how this plasma system interacts with Earth's magnetic field, ultimately driving the formation of the aurora.

太阳不断向地球抛出热气体和带电粒子，由于地球的温度极高，地球充当等离子体系统。Mukhopadhyay 开发了一个模型，可以预测这个等离子体系统如何与地球磁场相互作用，最终驱动极光的形成。

This magnetic field has a north and south orientation: the North and South poles. The orientation of the magnetic field is why you typically only see aurora at the North and South poles, where magnetic fields are the strongest. But occasionally throughout history, these poles wander from their traditional geographic positions.

这个磁场有南北两个方向：北极和南极。磁场的方向是您通常只在磁场最强的北极和南极看到极光的原因。但纵观历史，这些磁极偶尔会偏离其传统的地理位置。

These are called "geomagnetic excursions," says Mukhopadhyay. The most recent event is called the Laschamps excursion, which occurred about 41,000 years ago.

这些被称为“地磁游览”，Mukhopadhyay 说。最近的事件被称为拉尚游览，发生在大约 41,000 年前。

Working with Sanja Panovska, a researcher at Germany's GFZ Helmholtz Center for Geosciences, Mukhopadhyay created a 3D reconstruction of Earth's geospace system.

Mukhopadhyay 与德国 GFZ 亥姆霍兹地球科学中心的研究员 Sanja Panovska 合作，创建了地球地球空间系统的 3D 重建。

To do this, the researchers combined three separate models: one global model that reconstructs the geomagnetic field during the Laschamps excursion, a model of the space plasma environment around Earth, and a model that predicted what Earth's aurora looked like at the time. The resulting 3D model showed where charged particles were able to slip through Earth's geomagnetic field.

为此，研究人员结合了三个独立的模型：一个重建拉尚游览期间地磁场的全局模型，一个地球周围的空间等离子体环境模型，以及一个预测当时地球极光样子的模型。由此产生的 3D 模型显示了带电粒子能够穿过地球地磁场的位置。

The researchers found that during the Laschamps excursion, Earth's magnetic field reduced in size to about 10% of its current strength. This allowed Earth's magnetic poles to droop down near the equator and for its magnetic field lines to expand. This would have also allowed aurora to be seen all over Europe and into northern Africa.

研究人员发现，在拉尚游览期间，地球的磁场大小减小到当前强度的 10% 左右。这使得地球的磁极在赤道附近下垂，并使它的磁力线扩大。这也将使极光遍布欧洲和北非。

The researchers then laid their 3D map of Earth's space system over the world, and found that the time period of the Laschamps excursion—which lasted from about 41,000 to 39,000 BP—coincided with periods of change for groups of humans living on the planet.

然后，研究人员将地球空间系统的 3D 地图绘制到世界各地，发现拉尚游览的时间段（持续约 41,000 至 39,000 BP）与生活在地球上的人类群体的变化时期相吻合。

Cosmic rays, radiation and survival

宇宙射线、辐射和生存

Neanderthals and Homo sapiens coexisted in Europe, with Homo sapiens—often called anatomically modern humans—arriving roughly 56,000 years ago, says Raven Garvey, U-M associate professor of anthropology. By about 40,000 years ago, Neanderthals were no longer identified as a species in Europe.

尼安德特人和智人在欧洲共存，密歇根大学人类学副教授 Raven Garvey 说，智人——通常被称为解剖学上的现代人——大约在 56,000 年前到达。到大约 40,000 年前，尼安德特人在欧洲不再被确定为一个物种。

"What some of the differences are between these species, between Neanderthals and anatomically modern humans, that might account for that disappearance has been a major anthropological question for decades," Garvey said.

“这些物种之间、尼安德特人和解剖学上的现代人之间的一些差异可能解释了这种消失，几十年来一直是人类学的一个主要问题，”加维说。

Clothing may have been a contributing factor, she said. The technological means of producing clothing that fitted to the body has been discovered at archaeological sitesassociated with anatomically modern humans, but not necessarily Neanderthals.

她说，服装可能是一个促成因素。在与解剖学上的现代人有关的考古遗址中发现了生产合身衣服的技术手段，但不一定是尼安德特人。

However, at sites associated with anatomically modern humans, archaeologists have found not only scrapers used in hide production, but also needles and awls—items associated with sewing. According to Garvey, tailored clothing has a twofold benefit: it was significantly warmer and the added warmth meant that people could travel farther from their hearths and shelters in search of food.

然而，在与解剖学现代人相关的遗址中，考古学家不仅发现了用于生产皮革的刮刀，还发现了与缝纫相关的针和锥子。根据 Garvey 的说法，量身定制的服装有双重好处：它明显更暖和，而且增加的保暖性意味着人们可以离壁炉和避难所更远的地方寻找食物。

Tailored clothing could have also provided another unintended benefit—protection from sun damage, she said.

她说，量身定制的服装还可以提供另一个意想不到的好处——防止阳光伤害。

There are multiple detrimental effects of solar radiation, including ocular pathologies and folate depletion (which can lead to birth defects and increased infant mortality), "so having protection against solar radiation would also have conferred significant advantage to anyone who possessed it," Garvey said.

太阳辐射有多种有害影响，包括眼部病变和叶酸耗竭（这可能导致出生缺陷和婴儿死亡率增加），“因此，拥有太阳辐射保护也会给任何拥有它的人带来显着的好处，”加维说。

Homo sapiens may have also ramped up their use of ochre, a naturally occurring pigment composed of iron oxide, clay and silica that has been used by many species of hominins for a very long time. People used it to paint objects, cave walls and even to decorate their bodies.

智人可能也增加了对赭石的使用，赭石是一种由氧化铁、粘土和二氧化硅组成的天然色素，许多种类的古人类已经使用了很长时间。人们用它来画物体、洞穴墙壁，甚至装饰他们的身体。

"There have been some experimental tests that show it has sunscreen-like properties. It's a pretty effective sunscreen, and there are also ethnographic populations that have used it primarily for that purpose," Garvey said. "Its increased production and its association primarily with anatomically modern humans (during the Laschamps) is also suggestive of peoples having used it for this purpose as well."

“有一些实验测试表明它具有类似防晒霜的特性。这是一种非常有效的防晒霜，也有人种学人群主要将其用于此目的，”加维说。“它的产量增加以及它主要与解剖学现代人的联系（在 Laschamps 期间）也表明人们也将其用于此目的。”

Finding caution in the (solar) wind

在（太阳能）风能中寻找谨慎

The researchers are careful to underscore that their findings aren't definitive. However, they are a new way to look at already existing data.

研究人员小心翼翼地强调，他们的发现并不是确定的。然而，它们是查看现有数据的一种新方法。

"I think it's important to note that these findings are correlational and (ours is a) meta analysis, if you will," Garvey said. "But I think it is a fresh perspective on these data in light of the Laschamps excursion."

“我认为重要的是要注意这些发现是相关的，如果你愿意的话，（我们的是）荟萃分析，”Garvey 说。“但我认为，鉴于 Laschamps 的短途旅行，这是对这些数据的新视角。”

In addition to examining how previous excursions might have affected humans long ago, Mukhopadhyay said the 3D model offers people a way to predict how excursions might affect us in the future.

Mukhopadhyay 说，除了研究以前的短途旅行在很久以前可能如何影响人类之外，3D 模型还为人们提供了一种预测短途旅行在未来可能如何影响我们的方法。

"If such an event were to happen today, we would see a complete blackout in several different sectors," he said.

“如果今天发生这样的事件，我们将看到几个不同的行业完全停电，”他说。

"Our communication satellites would not work. Many of our telecommunication arrays, which are on the ground, would be severely affected by the smallest of space weather events, not to mention the human impacts which would also play a pretty massive role in our day-to-day lives."

“我们的通信卫星将无法工作。我们在地面上的许多电信阵列都会受到最小的太空天气事件的严重影响，更不用说人类影响了，这些影响也将在我们的日常生活中发挥相当大的作用。

Mukhopadhyay also pointed out that their work also highlights that people were still able to survive on a planet whose atmosphere looked a lot different than ours does today, and this has implications for the search for life on planets other than Earth.

Mukhopadhyay 还指出，他们的工作还强调，人们仍然能够在一个大气层看起来与我们今天的大气层大不相同的星球上生存，这对在地球以外的行星上寻找生命有影响。

"Many people say that a planet cannot sustain life without a strong magnetic field," he said. "Looking at prehistoric Earth, and especially at events like this, helps us study exoplanetary physics from a very different vantage point. Life did exist back then. But it was a little bit different than it is today."

“许多人说，没有强磁场，行星就无法维持生命，”他说。“观察史前地球，尤其是像这样的事件，有助于我们从非常不同的有利位置研究系外行星物理学。生命在那时确实存在。但它与今天略有不同。

Study co-authors also include Michael Liemohn, Daniel Welling and Austin Brenner of Michigan Engineering, Natalia Ganjushkina of both Michigan Engineering and the Finnish Meteorological Institute, Ilya Usoskin of the University of Oulu and Mikhail Balikhin of the University of Sheffield.

该研究的合著者还包括密歇根工程学院的 Michael Liemohn、Daniel Welling 和 Austin Brenner，密歇根工程学院和芬兰气象研究所的 Natalia Ganjushkina，奥卢大学的 Ilya Usoskin 和谢菲尔德大学的 Mikhail Balikhin。

论文地址：https://www.science.org/doi/10.1126/sciadv.adq7275