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A new study reveals that humans were extensively using fire to modify landscapes as far back as 50,000 years ago. That’s at least 10,000 years earlier than previously believed. Scientists uncovered this clue in a 300,000-year-old sediment core extracted from the East China Sea.

The core contained fossilized charcoal, microscopic remnants of plant matter burned but not fully consumed. Known as pyrogenic carbon, these particles drifted into the sea via rivers over tens of thousands of years. They serve as an enduring record of fire on land.

A Fire Signature That Outpaced Climate

The research team, led by Dr. Debo Zhao from the Institute of Oceanology at the Chinese Academy of Sciences, found something unexpected. Around 50,000 years ago, levels of pyrogenic carbon suddenly spiked. The timing didn’t line up with known climate patterns. It suggested something new was at play.

“Our findings challenge the widely held belief that humans only began influencing geological processes in the recent past—during the last Ice Age and the ensuing Holocene,” said Dr. Zhao.

Instead, the evidence points to humans (modern Homo sapiens) as the likely culprits. This timeline aligns with archaeological records showing a rapid expansion of Homo sapiens across Eurasia, Southeast Asia, and into Australia between 70,000 and 50,000 years ago.

In each of these regions, fire activity began to rise dramatically. But this wasn’t wildfire season. These were intentional flames.

A Record of Ice and Fire

As the climate cooled during glacial periods, fire became indispensable. It helped early humans cook food, stay warm, fend off predators, and migrate into colder, more challenging landscapes. But it also transformed those landscapes.

“Humans likely began shaping ecosystems and the global carbon cycle through their use of fire even before the Last Ice Age,” said Dr. Stefanie Kaboth-Bahr, a paleontologist at Freie Universität Berlin and coauthor of the study.

The fire’s effects were lasting. Burning vegetation releases carbon into the atmosphere. Doing this repeatedly over large areas eventually warms the planet, albeit by a very tiny amount compared to present-day industrial activity.

The discovery suggests that humans began influencing the Earth’s carbon cycle tens of thousands of years earlier than scientists had assumed. “Even during the Last Glaciation, the use of fire had probably started to reshape ecosystems and carbon fluxes,” added Professor Wan Shiming, another corresponding author.

The Global Signature of Humanity’s First Flames

The researchers compared the East Asia findings with data from Europe, Southeast Asia, and Papua New Guinea–Australia. The same pattern emerged in each region: a sudden uptick in fire activity starting roughly 50,000 years ago.

Crucially, this fire surge appeared even where natural conditions—like rainfall or lightning—wouldn’t account for such increases. Something else had to be driving it. The clearest candidate: humans.

The study also suggests that this early fire use was systematic enough to leave a lasting mark on Earth’s geological record—what some scientists refer to as the pyroscape, the legacy of fire through time.

This study underscores how early and profoundly humans began altering the planet. It challenges the idea that the Anthropocene (our proposed new geological epoch) begins with agriculture or the Industrial Revolution. Instead, the spark might have been struck much earlier, with the simple but powerful act of lighting a fire.

Kaboth-Bahr’s research is part of a larger initiative called The Burning Question, which investigates the role of fire in shaping ecosystems across Eastern Africa. Supported by the German Research Foundation and partners in Ethiopia, the project seeks to understand fire’s ecological, climatic, and cultural significance over the last 600,000 years.

The findings appeared in the Proceedings of the National Academy of Sciences.

An international research team led by scientists from the University of Vienna has uncovered new insights into how specialized cell types and communication networks at the interface between mother and fetus evolved over millions of years. These discoveries shed light on one of nature’s most remarkable innovations – the ability to sustain a successful pregnancy. The findings have just been published in Nature Ecology & Evolution.

Pregnancy that lasts long enough to support full fetal development is a hallmark evolutionary breakthrough of placental mammals – a group that includes humans. At the center of this is the fetal-maternal interface: the site in the womb where a baby’s placenta meets the mother’s uterus, and where two genetically distinct organisms – mother and fetus – are in intimate contact and constant interaction. This interface has to strike a delicate balance: intimate enough to exchange nutrients and signals, but protected enough to prevent the maternal immune system from rejecting the genetically “foreign” fetus.

To uncover the origins and mechanisms behind this intricate structure, the team analyzed single-cell transcriptomes – snapshots of active genes in individual cells – from six mammalian species representing key branches of the mammalian evolutionary tree. These included mice and guinea pigs (rodents), macaques and humans (primates), and two more unusual mammals: the tenrec (an early placental mammal) and the opossum (a marsupial that split off from placental mammals before they evolved complex placentas).

A cellular “atlas of mammal pregnancy”

By analyzing cells at the fetal-maternal interface, the researchers were able to trace the evolutionary origin and diversification of the key cell types involved. Their focus was on two main players: placenta cells, which originate from the fetus and invade maternal tissue, and uterine stromal cells, which are of maternal origin and respond to this invasion.

Using molecular biology tools, the team identified distinct genetic signatures – patterns of gene activity unique to specific cell types and their specialized functions. Notably, they discovered a genetic signature associated with the invasive behavior of fetal placenta cells that has been conserved in mammals for over 100 million years. This finding challenges the traditional view that invasive placenta cells are unique to humans, and reveals instead that they are a deeply conserved feature of mammalian evolution. During this time, the maternal cells weren’t static, either. Placental mammals, but not marsupials, were found to have acquired new forms of hormone production, a pivotal step toward prolonged pregnancies and complex gestation, and a sign that the fetus and the mother could be driving each other’s evolution.

Cellular dialogue: Between cooperation and conflict

To better understand how the fetal-maternal interface functions, the study tested two influential theories about the evolution of cellular communication between mother and fetus.

The first, the “Disambiguation Hypothesis,” predicts that over evolutionary time, hormonal signals became clearly assigned to either the fetus or the mother – a possible safeguard to ensure clarity and prevent manipulation. The results confirmed this idea: certain signals, including WNT proteins, immune modulators, and steroid hormones, could be clearly traced back to one source tissue.

The second, the “Escalation Hypothesis” (or “genomic Conflict”), suggests an evolutionary arms race between maternal and fetal genes – with, for example, the fetus boosting growth signals while the maternal side tries to dampen them. This pattern was observed in a small number of genes, notably IGF2, which regulates growth. On the whole, evidence pointed to fine-tuned cooperative signaling.

These findings suggest that evolution may have favored more coordination between mother and fetus than previously assumed. The so-called mother-fetus power struggle appears to be limited to specific genetic regions. Rather than asking whether pregnancy as a whole is conflict or cooperation, a more useful question may be: where is the conflict?”

Daniel J. Stadtmauer, lead author of the study and researcher at the Department of Evolutionary Biology, University of Vienna

Single-cell analysis: A key to evolutionary discovery

The team’s discoveries were made possible by combining two powerful tools: single-cell transcriptomics – which captures the activity of genes in individual cells – and evolutionary modeling techniques that help scientists reconstruct how traits might have looked in long-extinct ancestors. By applying these methods to cell types and their gene activity, the researchers could simulate how cells communicate in different species, and even glimpse how this dialogue has evolved over millions of years.

“Our approach opens a new window into the evolution of complex biological systems – from individual cells to entire tissues,” says Silvia Basanta, co–first author and researcher at the University of Vienna. The study not only sheds light on how pregnancy evolved, but also offers a new framework for tracking evolutionary innovations at the cellular level – insights that could one day improve how we understand, diagnose, or treat pregnancy-related complications.

The research was conducted in the labs of Mihaela Pavličev at the Department of Evolutionary Biology, University of Vienna, and Günter Wagner at Yale University. Wagner is Professor Emeritus at Yale and a Senior Research Fellow at the University of Vienna. The study was supported by the John Templeton Foundation and the Austrian Science Fund (FWF).