For decades, researchers have observed that rates of evolution seem to accelerate over short time periods—say five million years versus fifty million years. This broad pattern has suggested that “younger” groups of organisms, in evolutionary terms, have higher rates of speciation, extinction and body size evolution, among other differences from older ones. For decades, researchers have observed that rates of evolution seem to accelerate over short time periods—say five million years versus fifty million years. This broad pattern has suggested that “younger” groups of organisms, in evolutionary terms, have higher rates of speciation, extinction and body size evolution, among other differences from older ones. Evolution Molecular & Computational biology Phys.org – latest science and technology news stories