An interactive NYT article (not paywalled) tests your ability to spot deepfakes generated by AI. I got 7/10 right. This is a useful little exercise because it gives tips about what to look for. It is getting harder to spot deepfakes, but it helps to know what to look for.
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Experts are still intensely interested in how life arose on Earth. If it happened here, it could be a model for the origin of life anywhere in the universe where life might be. A NYT article (not paywalled) discusses some current thinking about this interesting little question:
The rail cars stopped [in the abandoned gold mine shaft]. We stepped out and walked a short distance to a large plastic spigot protruding from the rock. A pearly stream of water trickled from the wall near the faucet’s base, forming rivulets and pools. Wafting from the water was hydrogen sulfide — the source of the chamber’s odor. Kneeling, I realized that the water was teeming with a stringy white material similar to the skin of a poached egg. Caitlin Casar, a geobiologist, explained that the white fibers were microbes in the genus Thiothrix, which join together in long filaments and store sulfur in their cells, giving them a ghostly hue. Here we were, deep within Earth’s crust — a place where, without human intervention, there would be no light and little oxygen — yet life was literally gushing from rock. This particular ecological hot spot had earned the nickname Thiothrix Falls.
Scientists like [Magdalena Osburn, a professor at Northwestern University and a prominent member of the relatively new field known as geomicrobiology] have shown that, contrary to long-held assumptions, Earth’s interior is not barren. In fact, a majority of the planet’s microbes, perhaps more than 90 percent, may live deep underground. These intraterrestrial microbes tend to be quite different from their counterparts on the surface. They are ancient and slow, reproducing infrequently and possibly living for millions of years. They often acquire energy in unusual ways, breathing rock instead of oxygen. And they seem capable of weathering geological cataclysms that would annihilate most creatures. Like the many tiny organisms in the ocean and atmosphere, the unique microbes within Earth’s crust do not simply inhabit their surroundings; they transform them. Subsurface microbes carve vast caverns, concentrate minerals and precious metals and regulate the global cycling of carbon and nutrients. Microbes may even have helped construct the continents, literally laying the groundwork for all other terrestrial life.Like so much about Earth’s earliest history, exactly where and when life first emerged is not definitively known. At some point not long after our planet’s genesis, in some warm, wet pocket with the right chemistry and an adequate flow of free energy — a hot spring, an impact crater, a hydrothermal vent on the ocean floor — bits of Earth rearranged themselves into the first self-replicating entities, which eventually evolved into cells. Evidence from the fossil record and chemical analysis of the oldest rocks ever discovered indicate that microbial life existed at least 3.5 billion years ago and possibly as far back as 4.2 billion years ago.
Among all living creatures, the peculiar microbes that dwell deep within the planet’s crust today may most closely resemble some of the earliest single-celled organisms that ever existed. Collectively, these subsurface microbes make up an estimated 10 to 20 percent of the biomass — that is, all the living matter — on Earth. Yet until the mid-20th century, most scientists did not think subterranean life of any kind was plausible below a few meters.Although these early studies were tantalizing, many scientists remained skeptical because of the possibility that surface microbes had contaminated the samples. In subsequent decades, however, researchers continued to find microbes in rock and water obtained from mines and drill sites all over the world. By the 1980s, attitudes had started to shift. Studies of aquifers clearly indicated that bacteria populated groundwater, even thousands of feet below the surface. And scientists developed more rigorous methods for preventing the accidental introduction of surface microbes, such as disinfecting drill bits and tracking the movement of fluids through the crust to make sure surface water was not mingling with their samples.
“This research really is a form of exploration,” [University of Toronto geologist Barbara Sherwood Lollar] says. “Some of the findings are causing us to rewrite the textbooks about how this planet works. They are changing our understanding of Earth’s habitability. We don’t know where life originated. We don’t know if life arose on the surface and went down or whether life emerged below and went up. There’s a tendency to think about Darwin’s warm little pond, but, as my colleague T. C. Onstott likes to say, it could just as easily have been some warm little fracture.”
The life came from
below hypothesis
Some of the scientists described here work about 4,850 feet underground in an abandoned gold mine in South Dakota. It stinks of brimstone (hydrogen sulfide gas) and is hot and humid (90ᵒ, 100% humidity) down there, even though it is below freezing winter temperature on the surface.
One argument I am aware of against life evolving first on the seafloor at thermal vents is that even thought there is plenty of free energy at those vents, the ocean is simply too big. Biomolecules would be too diluted in an ocean for abiogenesis, i.e., creation of life from non-life. Instead, warm, moist underground pockets or geothermal surface pools with plenty of free energy are plausibly small enough to allow pre-biotic molecules to concentrate in the water there sufficiently to spark non-life into life.
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