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The theory of evolution by natural selection explains how species change over time. The core mechanism: within any population, individuals vary in traits. Some traits improve survival and reproduction in the current environment. Those individuals pass more genes to the next generation. Over many generations, the population shifts.
This isn't random chance. Natural selection is a sorting mechanism — it consistently favours traits that improve fitness in a given environment. But which traits help depends entirely on the environment. In a changing environment, evolution can happen surprisingly fast.
Evolution is supported by multiple independent lines of evidence: the fossil record showing gradual changes over time, genetic analysis showing shared ancestry, direct observation of evolution happening (bacteria developing antibiotic resistance, for example), and comparative anatomy showing homologous structures across species.
Humans share about 99% of our DNA with chimpanzees, about 85% with mice, and even about 60% with banana plants — we're not descended from chimps but share a common ancestor from about 6-7 million years ago.
by lungelondlovu5604
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Earthquakes occur when stress accumulated along geological fault lines is suddenly released. Tectonic plates — the massive sections of Earth's crust — are constantly moving, typically a few centimetres per year. Where plates meet, they grind against each other. Friction prevents smooth sliding, so stress builds up over decades or centuries until it releases catastrophically.
The point underground where the earthquake originates is the hypocentre (or focus). The point on the surface directly above is the epicentre, which is what news reports refer to. Seismic waves radiate outward in all directions from the hypocentre.
The Richter scale and more modern moment magnitude scale measure energy released. The scale is logarithmic — a magnitude 7 is about 32 times more energy than a magnitude 6. A magnitude 9 releases about 1,000 times more energy than a magnitude 7.
Earthquakes are concentrated along plate boundaries: the Pacific Ring of Fire (Japan, Indonesia, Chile), the Alpine-Himalayan belt, and mid-ocean ridges. But intraplate earthquakes can occur far from boundaries and are often harder to predict.
by nikhilshukla8968