New Historian

Multi-cellular Life Evolved 60 Million Years Earlier, Says New Study

cells before Cambrian Explosion lived in colonies

<![CDATA[According to a new study published in the journal, Nature, some spherical fossils in China have been found that are 60 million years older than the date the Cambrian Explosion began, 542 million years ago. The study was conducted by Virginia Tech geobiologist Shuhai Xiao, in collaboration with researchers from the Chinese Academy of Sciences. This new find could help scientists understand when and how single-celled organisms evolved into multi-cellular organisms. It has long been taught that the Cambrian Explosion took place around 540 million years ago. During this period of time, most of the animal phyla in existence today appeared. It lasted only for a short time, about 20 million years. Before the Cambrian Explosion, most living organisms on Earth were simple-celled, and some of these simple-celled organisms lived together in colonies. Xiao and his Chinese colleagues were seeking an explanation as to why and when multi-cellularity started to occur. In seeking out answers, the scientists observed phosphorite rocks from the Doushantuo Formation, which is located in the central Guizhou Province of South China. In order to see what was inside these rocks, the researchers cut them into thin slices, which enabled them to shine light through them, like looking through stained glass. They observed the rock slices through a microscope, where they observed multiple cells joined together into circular clusters. No two cells looked the same, as they differed in shape and size, which may suggest that they developed from different tissue types. This is known as cell differentiation, a characteristic seen in multi-cellular plants and animals in order for stem cells to grow into specific types of cells for specific uses in the organism. These fossils could have been mistaken for colonies of bacteria, but the scientists concluded that they were far too complex for this to be the case. They realized the fossils contained signs of differentiation, cell-to-cell adhesion, and programmed cell death, which are all characteristics of modern multi-cellular life. They surmised that the fossils may be embryos of a still unknown ancient creature. The strange fossils, also known as "Megasphaera", were first studied by Xiao over fifteen years ago, at a time when it was still uncertain what they were. He speculated, however, that they may have been fossils. Because no adult animals have been found that could have produced these embryos, the identity of these fossils is still open to scrutiny. Each of these fossils is very small, measuring just 0.03 inches (0.7 millimetres) in diameter. They were found in an area which would have been a marine environment during that time. The scientists are not ruling out that these fossils could be from a plant, as their make-up is similar to algae. Xiao and his colleagues are now looking for more "Megasphaera", but most importantly, they hope to find the organisms that produced these embryos. Their task is rather difficult, as the animals (or plants) that produced these embryos could very well be extinct, and there are only a few living animals that they could be related to.]]>

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