Advanced tools and expanded fossil datasets have painted a clearer picture of the eukaryotic diversity of the Proterozoic eon, which has been hard to quantify. The findings show that Earth's severe Cryogenian glaciations catalyzed a pivotal shift in the evolution and diversity of early eukaryotes during this eon, 2500 to 538 million years ago. This work underscores the interplay between Earth’s environmental perturbations and the evolutionary trajectories of early life. Quantifying global fossil diversity provides valuable insights into the evolutionary history of life on Earth and its relationship with environmental changes. This is exemplified by the well-known mass extinction events and associated environmental perturbations during the Phanerozoic Eon (538 Ma – present day). The Proterozoic Eon also saw significant tectonic and environmental shifts on Earth – from the formation and disassembly of supercontinents to an extensive and severe glaciation that froze nearly the entire planet solid. However, our understanding of global fossil diversity of Proterozoic life, particularly for eukaryotes, has been limited by inconsistent fossil data and poorly defined age constraints. This has hindered efforts to unravel the evolutionary trajectories of early eukaryotes. Recent advancements in paleontological and geochronological datasets, along with the application of new tools like the Constrained Optimization (CONOP) algorithm, have enabled more precise reconstructions of fossil diversity; these methods help integrate diverse stratigraphic data and circumvent the limitations of undated fossiliferous sections. Using the CONOP program and a global compilation of fossil eukaryotes, Qing Tang and colleagues constructed a high-resolution diversity curve of Proterozoic and early Cambrian eukaryotic fossil species. The findings revealed a gradual increase in species richness during the “Boring Billion” – a period marked by stable Earth system conditions with very little biological innovation. However, the Cryogenian glaciations that followed profoundly influenced eukaryotic life. According to the findings, the Cryogenian was a key driver of biodiversity shifts and marked a pivotal transition to the Ediacaran period, which saw greater diversity, more rapid turnover, and multiple radiations and extinctions.

 

For reporters interested in research integrity issues, the authors note, “In [the] field of paleontology, transparency data sharing is a key priority. Because paleontology is largely a specimen-based science, reproducibility is critically dependent on accessibility of specimens and data (CT data, images, databases, etc.). Thus, a detailed protocol for specimen and data repository is of paramount importance. Most journals… have requirements for specimen and data availability. Such practice should become universal for all peer-reviewed journals.”

New findings in mice have uncovered a crucial mechanism linking neuronal activity to mitochondrial function, researchers report, revealing a potential pathway to combat age-related cognitive decline. Mitochondria play a pivotal role in meeting the dynamic energy demands of neuronal activity, producing adenosine triphosphate (ATP) primarily via oxidative phosphorylation (OXPHOS). However, in the aging mammalian brain, mitochondrial metabolism deteriorates, leading to profound effects on neuronal and circuit functionality. The breakdown of the OXPHOS pathway contributes to oxidative stress and mitochondrial dysfunction. However, the mechanisms underlying the decline in OXPHOS activity and its impact on mitochondrial efficiency in aging neurons remain poorly understood, which, by extension, has limited the development of targeted interventions for age-related cognitive decline. To address this, Wenwen Li and colleagues investigated the role of mitochondrial transcription in cognition in the hippocampus of young and aged mice. Li et al. identified a novel coupling mechanism, which they dubbed excitation-mitochondrial DNA transcription coupling (E-TC_mito), that connects neuronal excitation with mitochondrial DNA transcription. This coupling, distinct from the traditional excitation-transcription coupling in the nucleus, is essential for maintaining synaptic and mitochondrial health. In aging brains, the effectiveness of E-TC_mito declines, leading to cognitive deficits. Notably, by enhancing E-TC_mito in aged mice, the authors observed improved cognitive function, highlighting its potential as a therapeutic target for counteracting cognitive decline associated with aging. “Through an impressive combination of innovative tools, innovative physiology, and behavior experiments, Li et al. provide key insights into mitochondrial biology in the aging mammalian brain,” write Deniz Bingul and Scott Owen in a related Perspective. “The findings raise the possibility of identifying targets for age-related neurocognitive disorders associated with mitochondrial dysfunction, including Alzheimer’s and Parkinson’s diseases.”

The Buck Institute for Research on Aging and strategic partner Phenome Health today announced a four-year award of up to $52M from the Advanced Research Projects Agency for Health (ARPA-H) to support its groundbreaking research project, “Personalized Analytics for Transforming Health (PATH): A PATH Toward Proactive Health.” The project aims to revolutionize healthcare by harnessing the power of advanced analytics and AI to predict and prevent diseases with the goal of increasing individual healthspan.