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DNA clocks

As DNA passes from one generation to the next, it acquires small changes, known as mutations. Scientists estimate that after a million years, 2-4 per cent of any stretch of animal DNA will have changed. By measuring the number of DNA changes between peoples from different parts of the world, scientists can calculate when they separated. This 'DNA clock' also tells us that the last common ancestor between chimps and humans lived about 350,000 generations ago: about 5 million years.

Lucy lived 3-5 million years ago and may have been our ancestor.
Lucy lived 3-5 million years ago and may have been our ancestor.
The Natural History Museum London

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