Beach-side property might be a luxury today, but living by the seaside may have helped modern humans in South Africa survive the biggest supervolcano eruption of the past 2.5 million years. The Toba supervolcano, on what is now Sumatra, Indonesia, spewed about 3,000 cubic kilometres of ash, rock and glass in a cataclysmic eruption around 74,000 years ago.
Toba eruption shards are a handy signpost of time, according to Kira Westaway, a luminescence dating expert at Macquarie University. "They have a very distinct geochemical fingerprint," Dr Westaway, who was not involved in the research, said. "If you can find it in your sediment, you have what's called a 'marker horizon' where you know it's 74,000 years."