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Politics : Evolution -- Ignore unavailable to you. Want to Upgrade?

To: mel221 who wrote (21088)	2/10/2012 9:04:27 AM
From: Brumar89	Respond to of 69300

So clay molecules evolved into lipids .... Or mythical cells with clay cell walls (????) produced lipids, then other cells began using them as cell walls instead of the clay walls? This is just a fairy tale. Why aren't there such life forms now that use clay cell walls? Did you know there likely wasn't much clay, if any, on earth when life appeared? newsroom.ucr.edu (note: this article is talking about ANIMAL life, not life. Life precedes animal life by billions of years.) ... “Our study shows for the first time that the initial soils covering the terrestrial surface of Earth increased the production of clay minerals and provided the critical geochemical processes necessary to oxygenate the atmosphere and support multicellular animal life,” .... Analyzing old sedimentary rocks, the researchers found evidence of an increase in clay mineral deposition in the oceans during a 200 million year period that fell between 1.1 to 0.54 billion years ago — a stretch of time known as the late Precambrian when oxygen suddenly increased in the Earth’s atmosphere. The increases in clay formation and oxygen shortly preceded — in geological time — the first animal fossils about 600 million years ago. .... Clay minerals form in soils through biological interactions with weathering rocks and are then eroded and flushed to the sea, where they are deposited as mud. Because clay minerals are chemically reactive, they attract and absorb organic matter in ocean water, and physically shelter and preserve it. The UCR-led study emphasizes the possibility that colonization of the land surface by a primitive terrestrial ecosystem (possibly involving fungi) accelerated clay formation, as happens in modern soils. Upon being washed down to the sea, the clay minerals were responsible for preserving more organic matter in marine sediments than had been the case in the absence of clays. Organic matter preservation results in an equal portion of oxygen released to the atmosphere through the chemical reaction of photosynthesis. Thus an increase in the burial of organic carbon made it possible for more oxygen to escape into the atmosphere, the researchers posit. “One of the things we least understand is why animals evolved so late in Earth history,” Kennedy said. “Why did animals wait until the eleventh hour, whereas evidence for more primitive life dates back to billions of years? One of the best bets to explain the difference is an increase in oxygen concentration in the atmosphere, which is necessary for animal life and was likely too low through most of Earth’s history.” To establish a change in clay abundance during the late Precambrian, the researchers studied thick sections of ancient sedimentary rocks in Australia, China and Scandinavia, representing a history of hundreds of millions of years, to identify when clay minerals increased in the sediment from almost nothing to modern depositional levels. ...