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24.05.2023
THEME: WORLD

A New Perspective on Human Evolution: Multiple African Populations Gave Rise to Homo Sapiens

A groundbreaking study published in the journal Nature on May 17, 2023, challenges previous theories on human evolution by suggesting that Homo sapiens arose from multiple closely related populations across Africa. This new model has significant implications for the interpretation of the fossil record.

Using genetic data from present-day African populations, including 44 newly sequenced genomes from the Nama group of southern Africa, researchers found that the earliest detectable split in early human populations occurred between 120,000 and 135,000 years ago, after prolonged periods of genetic intermixing. The study also discovered that contributions from archaic hominins were unlikely to have significantly affected Homo sapiens' evolution.

The origin of Homo sapiens has been a topic of debate among scientists, with Africa widely accepted as the birthplace of our species. However, uncertainty surrounded specific models of divergence and migration. This study employed linkage disequilibrium and diversity-based statistics for demographic inference, allowing researchers to evaluate a wide range of alternative models.

The 44 new genomes from the Nama people provided valuable data for the study, revealing weakly structured stem models that explained patterns of polymorphism previously attributed to contributions from archaic hominins in Africa. Consequently, fossil remains from coexisting ancestral populations should be genetically and morphologically similar. The study also found that only 1-4% of genetic differentiation among contemporary human populations could be attributed to genetic drift between stem populations, making it difficult to reconcile the tree-like model of recent population divergence from a single ancestral population in Africa with the fossil and archaeological records.

Researchers used geographically and genetically diverse populations across Africa to infer demographic models, confirming the inadequacy of tree-like models and allowing for the evaluation of alternative models. Demographic histories were inferred from 4x-8x whole-genome sequencing data for four diverse African populations.

The earliest divergence among contemporary human populations differentiates the southern African Nama population from other African groups at 110-135 thousand years ago. The study also found high gene flow between eastern and western Africa, as well as back-to-Africa gene flow at the beginning of the Holocene epoch, primarily affecting ancestors of Ethiopian agricultural populations.

Models allowing for migration between stem populations outperformed those without migration between stems, providing further evidence for the new model of human evolution. The study also suggests that population structure extends back to more than 1 million years ago.

In conclusion, this groundbreaking research offers a new perspective on human evolution, suggesting that Homo sapiens arose from multiple closely related populations across Africa. The findings challenge previous theories and have significant implications for the interpretation of the fossil record. As our understanding of human evolution continues to grow, it becomes increasingly clear that the story of our species is a complex and fascinating one, with many more discoveries yet to be made.

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24.05.2023
THEME: HEALTH

Recycling Plants Unknowingly Unleash Microplastics: A Hidden Danger

Recycling is an essential practice to save our planet. However, a recent study reveals that recycling plants may inadvertently release large amounts of hazardous microplastics. These tiny plastic particles, less than 5 millimeters in size, pose a significant threat to both the environment and human health, as they can enter the food chain and accumulate in living organisms.

Led by Erina Brown from the University of Strathclyde in Glasgow, an international team of scientists sampled wastewater from a UK recycling plant and discovered that microplastics in the water amounted to 13% of the plastic processed. This means the facility could release up to 75 billion plastic particles per cubic meter of wastewater. The findings were published in the Journal of Hazardous Material Advances.

The plant's water filtration system managed to reduce the microplastic concentration from 13% to 6%. However, the majority of the particles were smaller than 10 microns, with 80% being smaller than 5 microns. These tiny particles can easily infiltrate the environment and pose a risk to human health, as particulate matter less than 10 microns has been linked to various human illnesses.

High levels of microplastics were also found in the air around the recycling facility, emphasizing the potential dangers of these particles. The recycling plant discharged up to 2,933 metric tonnes of microplastics per year before the water filtration system was implemented. After its installation, this number was reduced to 1,366 metric tonnes per year, highlighting the need for better management and monitoring of microplastic pollution in recycling facilities.

Globally, only 9% of the 370 million metric tonnes of plastic produced gets recycled, with the majority of plastic waste ending up in landfills or the environment, where it can take hundreds of years to decompose. Recycling is a crucial component of waste management, but this study reveals that even recycling facilities can contribute to the growing microplastic pollution problem.

Judith Enck, a former US Environmental Protection Agency (EPA) official and current leader of the Beyond Plastics lobby group, emphasizes the importance of addressing this issue. With growing awareness of microplastics' harmful effects on the environment and human health, it's essential for recycling facilities to minimize their release of these particles.

In conclusion, while recycling is a vital practice in our fight against plastic pollution, this study sheds light on the hidden dangers of microplastics generated during the process. It serves as a reminder that there's still much work to be done to improve recycling processes and minimize the release of hazardous microplastics. Addressing this lesser-known threat within our recycling plants is crucial as we strive for a greener future.

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24.05.2023
THEME: ENVIRONMENT

The Sinking City: New York's Battle with Climate Change and Heavy Buildings

New York City is sinking under the weight of its own buildings while simultaneously grappling with the climate crisis that leads to more frequent and extreme rainfall events, according to a new study published in the journal Earth's Future. With sea levels around NYC rising more than twice as fast as the global rate, projected to rise between 8 inches and 30 inches by 2050, the city faces a daunting challenge.

The study, led by Tom Parsons, a research geophysicist at the US Geological Survey, calculated the mass of 1,084,954 buildings in NYC, weighing about 1.68 trillion pounds (762 billion kilograms). Using simulations and satellite data, they discovered that the city is sinking at an average rate of 1 to 2 millimeters a year, with some areas sinking up to 4.5 millimeters a year. Subsidence, the sinking or settling of Earth's surface, is a global issue affecting 44 of the 48 most populous coastal cities, including lower Manhattan, Brooklyn, Queens, and Staten Island, which are sinking at a faster than average rate.

Sophie Coulson, a geophysicist, emphasizes the importance of understanding landscape changes and identifying vulnerable areas for flood mitigation and sea level rise preparation. The study suggests that subsidence can pose an earlier flooding threat than sea level rise, not just in NYC but globally.

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