Introduction to the Special Collection: Early Earth Environments and the Origins of Life

The intent of this collection is to build on the momentum spawned by a new generation of creative, compelling, and often controversial and highly debated research across a vastly interdisciplinary landscape. Our specific goal as guest editors was to invite articles that, as a group, would bridge origins of life research with a rigorous environmental context grounded in next-generation studies of the earliest Earth; our solar system neighborhood, far and wide; and our relationship with the early and evolving Sun. The initial inspiration behind this design was the launch in 2019 of the Prebiotic Chemistry and Early Earth Environments (PCE₃) Research Coordination Network (RCN) within the NASA Astrobiology Program. As the inaugural co-leads of that RCN, we as editors have purposely aligned the thematic arc of this collection with PCE₃’s mission:

To investigate the delivery, synthesis, and fate of small molecules under the conditions of Early Earth and the subsequent formation of proto-biological molecules and pathways that lead to systems harboring the potential for life.

The structure of this collection follows from the first PCE₃ workshop, held in 2021 and organized by Ulrich Müller, Jamie Elsila Cook, and Dustin Trail. The associated plenary talks surveyed life’s origins across a wide array of related topics: earliest planetary formation; evolution of the near surface; inventories, geological settings, and building blocks; prebiotic complexity; and peering into the past with today’s biochemistry.

The timing of this collection is easily justified given the astonishing array of advances over the past few decades, which include the likelihood of clement temperatures and very early oceans. It seems that Earth’s earliest chapter (the Hadean) was far less hellish than previously thought. The catalog of possible products of abiotic organic synthesis and the implicit pathways to their formation has grown impressively, thanks to remarkable discoveries that include recent windfalls from the Bennu and Ryugu asteroids. Revelations about atmospheric compositions have shaped thinking about early redox conditions and their controls; associated greenhouse warming scenarios; and the nature of incoming solar radiation, related atmospheric photochemistry, and the essential prebiotic building blocks that resulted. These studies, like most explorations of early Earth, draw strongly on established connections between deep and surface Earth processes, including early core formation and the concomitant consequences for atmospheric redox.

At the same time, we have learned that large and frequent impacts can trigger the reducing conditions needed to synthesize the complex building blocks of life, while also initiating hydrothermal activity that can further spark in situ production of building-block molecules. Also on the list of the positive impacts of impacts is exogenous delivery of key materials, think, for example, of phosphorous and potential foundational organics. Moreover, models are emerging for an early generation of land masses that rose above the ocean surface via impact cratering, mantle plumes, or incipient plate tectonics. Early land areas might have fostered the essential wet-dry cycles known from experiments to drive organic polymerization. Emergent land would also have allowed for the alkaline lakes and hot springs that are woven into certain origin models.

Other research points to low pH conditions in early oceans, assumed from the high levels of warming atmospheric CO₂ required to explain voluminous liquid water beneath a faint young Sun. On the plus side, relatively low seawater pH would have sustained steep proton gradients at deep, alkaline seafloor vents, thus fueling optimism for those preferring vents as the optimal sites for early prebiotic pathways. On the other side of the coin, however, the high dissolved CO₂ might have limited the supplies of pH-sensitive compounds important in some origin models.

We have included these examples to highlight why origins of life research is operating more and more at the intersection between environmental evolution and prebiotic chemistry. Not surprisingly, the first half of the volume is centered mostly on geology, geochemistry, astronomy, and astrophysics as the backdrop for the many details about organic production, polymerization, and ultimately complexification and functionality that follow. We begin with the article by Segura et al. (2026, this volume), which examines the beginnings of our solar system, including the formation of fundamental elements and molecules potentially involved in the initial building blocks (the “raw materials” of life) and the reduced overall luminosity but active flaring of the early Sun. These stellar properties had profound consequences for early climate and crucial photochemical reactions.

We move then to Pathak and Dasgupta (2026, this volume), who explore in detail the early delivery of “life-essential volatile elements” to Earth, first reviewing the range of prevailing views and then exploring in detail one option related to the processes and products of Mars-mass embryos. The authors speculate on specific volatile inventories and distributions for such embryos and possible links to major volatile contributions to proto-Earth, our overall bulk silicate properties, and related controls on Earth’s life-essential elements. Moving further on the theme of impacts on early Earth, Black and Bermingham (2025, reprinted at the end of this issue) emphasize the large and frequent events predicted for the Hadean and Archean, showcasing the cumulative benefits of such exogenous delivery, which include the ingredients of life and processes that overall favored habitability and set the stage for the development of life. Their conclusions also emphasize that the relationship between life and impacts was a double-edged sword, with individual events often leading to transient but significant ecological disruptions that challenged early life and the persistence of oceans.

Next, Chowdhury et al. (2026, this volume) narrow the focus a bit by writing on the topographic and chemical details of Earth’s early crust, emphasizing the progression from an initial planet hostile to life to one with stable crust far more favorable to its emergence. Highlights include discussions of early planetary differentiation; interactions between the deep and surface Earth; rock recycling; development of oceans; evolution of tectonics culminating in a mobile-lid regime; and, critically, evolution of crustal settings that ultimately favored life’s beginnings. Korenaga (2026, this volume) carries the important and controversial theme of early tectonics further, challenging the popular notion of an early, long-lived stagnant lid. The author instead suggests an early Hadean onset of plate tectonics triggered by early differentiation in a magma ocean, further asserting that this landmark catalyzed a concomitant transformation to a habitable planet. In the process, surface environments may have emerged that supported key prebiotic processes through generation of hydrothermal vents on the seafloor and continental crust above the seas that hosted “warm little ponds,” both of which factor prominently in origin of life discussions.

The articles that follow this environmental setup comprise a sequence that explores the synthesis of precursor molecules from the simple to complex. Camprubi et al. (2026, this volume) begin this journey with a discussion of abiotic synthesis of simple building blocks, highlighting two approaches that explore pathways either (1) linked to processes known from extant life or (2) those unleashed from the constraints of the modern system paradigm. In the process, they find that despite the many differences to emerge from these “historically divided hypotheses,” carbon reduction remains the common denominator. Menor-Salván and Ruiz-Bermejo (2026, this volume) take us further along the prebiotic path by reviewing both classical and recent alternative experimental approaches to understanding how and where prebiotic biopolymer building blocks may have formed through, for example, wet-dry and freeze-thaw cycling. Collectively, these two chapters emphasize the limitations of both classical and alternative prebiotic models that must be considered when reconciling the reality of messy chemistry with the “desire” for the emergence of self-sustaining and evolvable systems within the context of an early Earth environment.

Next, Edri et al. (2026, this volume) move us further along by discussing chemical and geological processes on prebiotic Earth that may have increased the complexity of organic molecules, highlighting important chemical and physical processes, such as polymerization, assembly, and selection, that could have favored increased function during the early stages of life’s development. With Bowman et al. (2026, this volume), we continue with the theme of progressive advances in molecular complexity by challenging the notion of a single origin of life and instead adopting a novel alternative. In this new view, life “arose across diverse planetary environments” that spawned wide-ranging biochemistry. The resulting products both competed and cooperated, with an eventual network convergence. In the process, the authors also questioned the traditional underpinnings of models forLUCA (the Last Universal Common Ancestor).

We end this march toward life with Bell and Fournier (2026, this volume), an important reminder of what we actually do (and don’t) know about the earliest records of life based on geologic, geochemical, and genomic arguments. This timeline, still very much a work in progress, defines something of an endpoint marking the culmination of the myriad antecedent geologic, geochemical, astronomical, astrophysical, and biochemical steps ably reviewed in these collected articles. Last, but certainly not least, Steele et al. (2026, this volume) ask us to think more broadly, highlighting the impressive and still growing record of organic molecules on Mars. By extrapolation, these data, as the “oldest planetary record of organic and prebiotic chemical synthesis pathways that could have led to life,” give us novel insights into plausible abiotic mechanisms that may have operated on early Earth and perhaps even contributed to life’s beginnings on Mars.

Indeed, beyond arguments for present and past habitability and potential biosignature detection, astrobiologists are now also asking questions more specific to whether and how life might have begun on a moon or planet elsewhere in the solar system or far beyond. In this regard, lessons from Earth as captured in this collection of articles move that ball substantially down court. The unprecedented marriage of vastly diverse disciplines and discoveries now mixed and tuned toward questions of life’s origins has made for a very exciting time for those asking where we come from and whether we are alone.