# @science on Instagram

- **Type:** Image
- **Original URL:** https://www.instagram.com/p/DOGV1E-k_no
- **Gondola URL:** https://gondola.cc/posts/34058355-science-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/f8c6c03b07.jpg
- **Posted:** 2025-09-02T12:00:41.000+00:00
- **Account Owner:** Science 🧬 (@science) — https://gondola.cc/science

## Caption

Some 4.2 billion years ago, Earth was a hostile world of searing volcanoes and constant asteroid strikes. Yet in that chaos, scientists now believe our Last Universal Common Ancestor (LUCA) was already alive, thriving only a few hundred million years after the planet formed. LUCA was not the very first life, but the ancient ancestor from which every organism, bacteria, trees, whales, and humans, ultimately descends.⁠
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By comparing the genomes of hundreds of microbes, researchers reconstructed LUCA’s traits. Far from a primitive spark, this single-celled organism was surprisingly sophisticated. Its genome likely encoded around 2,600 proteins, and it fueled itself with hydrogen and carbon dioxide. Even more striking, LUCA appears to have carried a rudimentary immune system, an early CRISPR-like defense, showing that even at this primordial stage, viruses were already a force shaping life.⁠
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The findings place LUCA in the Hadean Eon, a time once thought too extreme for biology. With Earth still reeling from the impact that created the Moon, days lasted only 12 hours and tides ran higher under a closer lunar pull. LUCA may have lived at hydrothermal vents or in surface waters, drawing on CO₂ and H₂ and participating in a recycling ecosystem where one microbe’s waste became another’s fuel.⁠
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To date LUCA, scientists used a molecular clock built from ancient duplicated genes, tracing mutation patterns backward to the root of the tree of life. The picture that emerges is a communal early biosphere, gene sharing abetted by viruses, and metabolism robust enough to endure planetary turmoil.⁠
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This ancient complexity challenges the idea that life needs eons to organize. If LUCA arose so quickly on a hostile early Earth, life may emerge readily wherever chemistry, water, and time align, and perhaps far beyond our planet.⁠
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#science #biology #evolution #origins #microbiology #genetics #life #earth #cosmos #research #astrobiology #earlyearth #luca #viruses #hadean

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## Tags

evolution, earth, research, astrobiology, viruses, microbiology, origins, cosmos, science, genetics, life, hadean, biology, luca, earlyearth

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