Scuba diving to the depths of human history

KITTED out with the latest scuba gear, Garry Momber peers through the murky water to the seabed below. It's dark - Momber is 11 metres below the water's surface and the black peat of the seabed absorbs what little light reaches the bottom. Then the tide turns, and as clearer water flows in from the open seas, the decaying remains of an ancient forest emerge from the gloom. Working quickly, he records details of the exposed material before the strengthening current forces him away from the site.

This is all in a day's work for Momber, who is director of the Hampshire and Wight Trust for Maritime Archaeology in Southampton, UK. His job is to search for clues to a prehistoric world lost beneath the waves in the channel that separates the Isle of Wight from the south coast of England - to be precise, at a location 300 metres off the port of Yarmouth.

Momber's work is just part of a growing trend for searching the deep for clues to our distant past. The field of underwater archaeology is perhaps best known for unearthing relics from more recent history, like Henry VIII's ship the Mary Rose, yet the seabed is stuffed with clues to prehistory too - especially a murky period 11,500 years ago, at the end of the last ice age, when early Europeans were slowly changing from being nomadic hunter-gatherers into settled farmers.

Back then, sea levels were 50 metres lower than today, and the vast majority of early societies would have lived on fertile land by the coast. But as the ice sheets melted, millions of square kilometres of coastal territory would have been flooded. By 4000 BC, when the coastline had stabilised to roughly its current form, 40 per cent of prehistoric Europe was submerged - along with much of the evidence for their way of life.

"Anybody who was doing anything on the shore more than 6000 years ago was doing it below present sea levels," says Nic Flemming of the UK's National Oceanography Centre in Southampton.

The result is that remains found on land today are not going to tell you much about these early societies. "If you leave out 40 per cent of the data, you're going to make some serious mistakes," says Flemming.

What's more, finds from the sea floor are well preserved. Indeed they are often in better condition than similar discoveries on land, since the low-oxygen conditions in mud and peat sediments slow the decay of organic material. Underwater sites can therefore provide unparalleled insights into the lifestyles of our ancestors as the ice age ended. "Underwater archaeology can open the door to how societies evolved and developed," says Momber.