Stone Age beads made from ostrich eggshells formed the earliest known social network

Humans are social creatures, but little is known about when, how, and why different populations connected in the past. Answering these questions is crucial for interpreting the biological and cultural diversity that we see in human populations today. DNA is a powerful tool for studying genetic interactions between populations, but it can’t address any cultural exchanges within these ancient meetings.

Now, scientists from the Max Planck Institute for the Science of Human History have turned to an unexpected source of information—ostrich eggshell beads—to shed light on ancient social networks.

In a new study published in Nature, researchers Drs. Jennifer Miller and Yiming Wang report 50,000-years of population connection and isolation, driven by changing rainfall patterns, in southern and eastern Africa.

Ostrich eggshell beads: a window into the past

Ostrich eggshell (OES) beads are ideal artefacts for understanding ancient social relationships. They are the world’s oldest fully manufactured ornaments, meaning that instead of relying on an item’s natural size or shape, humans completely transformed the shells to produce beads.

This extensive shaping creates ample opportunities for variations in style. Because different cultures produced beads of different styles, the prehistoric accessories provide researchers with a way to trace cultural connections.

“It’s like following a trail of breadcrumbs,” says Miller, lead author of the study. “The beads are clues, scattered across time and space, just waiting to be noticed.”

To search for signs of population connectivity, Miller and Wang assembled the largest ever database of ostrich eggshell beads. It includes data from more than 1500 individual beads unearthed from 31 sites across southern and eastern Africa, encompassing the last 50,000 years. Gathering this data was a painstakingly slow process that took more than a decade. 

Climate change and social networks in the Stone Age

By comparing OES bead characteristics, such as total diameter, aperture diameter and shell thickness, Miller and Wang found that between 50,000 and 33,000 years ago, people in eastern and southern Africa were using nearly identical OES beads.

The finding suggests a long-distance social network spanning more than 3,000 km once connected people in the two regions. 

“The result is surprising, but the pattern is clear,” says Wang, co-corresponding author of the study. “Throughout the 50,000 years we examined, this is the only time period that the bead characteristics are the same.”

This eastern-southern connection at 50-33,000 years ago is the oldest social network ever identified, and it coincides with a particularly wet period in eastern Africa. However, signs of the regional network disappear 33,000 years ago, likely triggered by a major shift in global climates.

Around the same time that the social network breaks down, eastern Africa experienced a dramatic reduction in precipitation as the tropical rain belt shifted southward. This increased rain in the large area connecting eastern and southern Africa (the Zambezi River catchment), periodically flooding riverbanks and perhaps creating a geographic barrier that disrupted regional social networks. 

“Through this combination of paleoenvironmental proxies, climate models, and archaeological data, we can see the connection between climate change and cultural behaviour,” says Wang.

Weaving a story with beads

Together, the results of this working document a 50,000-year-long story about human connections, and the dramatic climate changes that drove people apart.

The data even provides new insight into variable social strategies between eastern and southern Africa by documenting different bead-use trajectories through time. These regional responses highlight the flexibility of human behaviour and show there’s more than one path to our species’ success. 

“These tiny beads have the power to reveal big stories about our past,” says Miller. “We encourage other researchers to build upon this database, and continue exploring the evidence for cultural connection in new regions.”

Researchers discovered a 2 billion year old ancient nuclear reactor in Africa

The Oklo-reactor in Gabon, Africa is one of the most intriguing geological formations found on planet Earth. Here, naturally occurring fissile materials in two billion-year-old rocks have sustained a slow nuclear fission reaction like that found in a modern nuclear reactor.

Uranium-235 is a radioactive element with a half-life of 700 million years.

Traces of it are found in almost all rocks, especially magmatic rocks, and its decay is believed to be one of the sources of Earth’s inner heat. Because it decays over time at a constant rate, its concentration in the Earth’s crust is almost everywhere the same – except in Oklo.

The Oklo-Formation, a succession of sandstone and siltstone, was deposited two billion years ago by a large river. Microbial activity of the first lifeforms caused the element uranium, derived from weathered magmatic rocks, to become concentrated in certain layers of the sediments.

Later tectonic movements buried the layers deep underground.

In 1972, chemical analysis showed an unusually low concentration of uranium-235 in the ore mined in the Oklo open pit mine. However, there were high concentrations of elements like caesium, curium, americium and even plutonium to be found. Such elements are formed today only in nuclear reactors, as the uranium decays during controlled nuclear fission.

When uranium-235 decays, it will emit three neutrons. If one of the emitted neutrons hits another uranium atom, this atom will also decay and a chain reaction will begin. In most rocks, there is either not enough uranium to sustain nuclear fission or it decays too fast to cause a chain reaction.

In the Oklo-reactor, two factors came together to sustain slow nuclear fission for hundreds of thousands of years. Weathering of magmatic rocks and bacterial activity concentrated the uranium enough to start a nuclear chain reaction. Then the water that infiltrated the formation along faults slowed down the emitted neutrons enough to sustain slow and stable nuclear fission. As the uranium decays, it forms other radioactive elements fueling the reactor.

Over time the Oklo-reactor has produced large quantities of toxic plutonium and caesium-isotopes, which have since decayed into stable and harmless barium. During this process, however, no harmful radioactivity has leaked into the environment.

As the planet warms due to our carbon emissions, burning oil and coal is no longer a sustainable way to meet humanity’s hunger for energy.

Many experts believe that nuclear energy could be a temporary solution until renewable energy sources are ready to meet the demand. Unfortunately, nuclear energy comes with radioactive waste.

A permanent repository for nuclear waste must contain toxic elements and radioactivity for at least 100,000 years. The problem is that we don’t know what materials to use for the containers to store the waste.

Steel will rust, concrete can leak and even glass is damaged by the emitted radiation. By studying the Oklo-reactor, scientists hope to find a way to safely dispose of nuclear waste as produced by modern reactors.

Research by a team of scientists of the US Naval Research Laboratory in Washington D. C. and published in the journal PNAS has investigated how the Oklo-reactor was able to work so long and yet not pollute the environment. In rocks recovered from the Oklo mine, barium (the ‘trace’ left by the former radioactive elements) is not found evenly distributed but rather found in nests surrounded by a thin layer of ruthenium compounds.

Native ruthenium is a rare and inert metal often associated with ore of other elements. The scientists believe that the radioactive plutonium and caesium were encapsulated and safely isolated from the environment by a shell of ruthenium-compounds. If so, containers made of ruthenium alloys could be used to safely store radioactive waste for a very long time.

As the Oklo-reactor demonstrates, the ruthenium compounds remain stable even if exposed to radioactivity and corrosion by water over vast geological periods.

A 4.6-billion-year-old meteorite is the oldest volcanic rock ever found

A lonely meteorite that landed in the Sahara Desert in 2020 is older than Earth. The primaeval space rock is about 4.6 billion years old and is the oldest known example of magma from space.

Its age and mineral content hint that the rock originated in our early solar system from the crust of a protoplanet — a large, rocky body in the process of developing into a planet, according to a new study. 

The meteorite, called Erg Chech 002 (EC 002), is likely a rare surviving chunk of a lost baby planet that was destroyed or absorbed by bigger rocky planets during our solar system’s formation. 

Pieces of EC 002 were found in Adrar, Algeria, in May 2020, and the fragments were “relatively coarse-grained, tan and beige,” sporadically studded with crystals that were “larger green, yellow-green and less commonly yellow-brown,” according to a description by the Lunar and Planetary Institute (LPI). 

EC 002 is an achondrite, a type of meteorite that comes from a parent body with a distinct crust and core, and lacks round mineral grains called chondrules, according to the Center for Meteorite Studies at Arizona State University.

Approximately 3,100 known meteorites originated in crust and mantle layers of rocky asteroids, but they reveal little about protoplanet diversity when our solar system was young. About 95% come from just two parent bodies, and around 75% of those originated from one source — possibly the asteroid 4 Vesta, one of the largest objects in the asteroid belt, the researchers reported.

A meteoritic rarity

Among the thousands of rocky meteorites, EC 002 stood out. Radioactive versions, or isotopes, of aluminium and magnesium, indicated that the meteorite’s parent was an ancient body dating to 4.566 billion years ago, and EC 002’s chemical composition revealed that it emerged from a partly-melted magma reservoir in the parent body’s crust.

Most rocky meteorites come from sources with basaltic crusts — rapidly cooled lava that is rich in iron and magnesium — but EC 002’s composition showed that its parent’s crust was made of andesite, which is rich in silica. 

“This meteorite is the oldest magmatic rock analyzed to date and sheds light on the formation of the primordial crusts that covered the oldest protoplanets,” the study authors reported.

While EC 002 is highly unusual, other studies have found that such silica-infused andesite crusts were likely common during our solar system’s protoplanet-forming stage, “contrary to what the meteorite record suggests,” the researchers wrote.

“It is reasonable to assume that many similar chondritic bodies accreted at the same time and were capped by the same type of primordial crust,” the study authors said. Yet, when the scientists peered at distant cosmic objects’ spectral “fingerprints” — wavelength patterns in the light they emit or reflect — and compared them to EC 002, they found no matches.

Even after comparison with 10,000 objects in the Sloan Digital Sky Survey database, EC 002 was “clearly distinguishable from all asteroid groups,” the scientists reported. “No object with spectral characteristics similar to EC 002 has been identified to date.”

Where are all the protoplanets with andesite crusts today? During our solar system’s volatile period of planetary birth, most of these protoplanets likely didn’t make it past infancy, according to the study.

Either they were smashed to bits in collisions with other rocky bodies, or they were absorbed by bigger and more successful rocky planets, such as Earth, Mars, Venus and Mercury, leaving few traces behind to spawn meteorites such as EC 002. 

“Remains of primordial andesitic crust are therefore not only rare in the meteorite record, but they are also rare today in the asteroid belt,” the scientists wrote.