By Paul Rincon Science reporter, BBC News

Neanderthals probably made this hand axe from Swanscombe in Kent

Scientists are to begin work on the second phase of a project aimed at piecing together the history of human colonisation in Britain.

Phase one of the Ancient Human Occupation of Britain project (AHOB) discovered people were here 200,000 years earlier than previously thought.

Phase two has now secured funds to the tune of £1m and will run until 2010.

Team members hope to find out more about Britain's earliest settlers and perhaps unearth their fossil remains.

How far back could human occupation go in Britain? We just don't know; but we are certainly going to be looking Prof Chris Stringer, AHOB Project

They will also compare the animals and plants of Britain with those of nearby continental Europe. This will establish similarities and differences to determine how distinctive British wildlife was in the distant past.

Studies of prehistoric mammals suggest there were filters operating in the distant past that allowed some animals in from mainland Europe, but not others.

These filters may have been physical barriers such as the English Channel, or the narrowness of a land bridge that once connected Britain to Europe, or they may included climatic factors.

See some of the most important prehistoric sites in Britain More details

Dr Nick Ashton, from the British Museum, said "AHOB2" would investigate the absence of humans in Britain between 180,000 and 60,000 years ago: "The new project will test the idea that this was due to the creation of the English Channel just prior to this time," he said.

The first year of the project will include an attempt to recover DNA from a fragment of human jawbone discovered at Kents Cavern in Devon. Recent re-dating of the specimen shows it is older than previously thought.

If the jawbone is from a modern human (Homo sapiens), as it was long thought to be, it would be amongst the earliest fossils from our species known from Europe; but the early date suggests it could also be from a late Neanderthal (Homo neanderthalensis).

Warm periods

A see-sawing climate and the presence of intermittent land access between Britain and what is now continental Europe allowed only stuttering waves of immigration.

Humans came to try to live in Britain eight times and on at least seven occasions they failed - beaten back by freezing conditions.

A dig at Lynford revealed mammoth remains and signs of human activity

Phase one of AHOB extended the timing of the earliest known influx by 200,000 years. More than 30 flint tools unearthed in a fossil-rich seam at Pakefield, near Lowestoft, on the east coast, represent the oldest, unequivocal evidence of humans in northern Europe.

But project scientists now plan to hunt for even older evidence of occupation than this.

"The conditions that brought people to Pakefield were Mediterranean; there were warm summers and mild winters. Those conditions were there even earlier than Pakefield," said Chris Stringer, the project's director and head of human origins at London's Natural History Museum.

"How far back could human occupation go in Britain? We just don't know; but we are certainly going to be looking."

Burial practices

Professor Stringer said the discovery of a well-preserved fossil hominid, or early human, continues to be a "personal dream".

While the ancient settlers of Britain left an evidence trail in the form of stone artefacts and butchered animal bones, their fossil remains are vanishingly rare.

The Swanscombe skull may belong to an early Neanderthal

Early Neanderthals are known from teeth discovered at Pontnewydd in Wales and a partial skull unearthed at Swanscombe in Kent. Late Neanderthal remains have been found on Jersey.

An earlier species, Homo heidelbergensis, is represented at the 500,000-year-old site of Boxgrove, West Sussex, by a shinbone and two teeth.

"The problem is that humans were always thin on the ground in the distant past. They were competing with the lions, the hyenas and the wolves, so the environment could not support large numbers of humans," said Professor Stringer.

"They didn't bury their dead, they don't seem to use caves as much as they did later on and we don't have good cave sites in Britain with deposits from the right time, except perhaps Kents Cavern.

"But with the sites in East Anglia, we have other mammals preserved there; we have stone tools, so at least there's a chance - we just have to get lucky."

Buried landscape

Dramatic coastal erosion in some parts of East Anglia has forced many people to leave homes that are collapsing into the sea.

It is also exposing a buried landscape beneath the cliffs that is over half a million years old. The potential for uncovering fossils and artefacts will ensure the region is a major focus for AHOB's next phase.

DNA may shed light on the owner of the Kents Cavern jawbone

Quarrying at gravel pits is also exposing ancient sites, such as Lynford in Norfolk, which contains possible evidence of Neanderthals butchering mammoths.

"We're hoping to foster closer relations with the aggregates industry because unless they dig holes, we're not going to see the right sediments exposed," said Danielle Schreve, a palaeontologist from Royal Holloway, University of London.

"They're after sand and gravel which were laid down by ancient rivers and that's a prime place to find bones and stones together. That stuff needs to be recorded because there's an enormous amount of it being lost."

Dr Schreve is working with colleagues to refine a dating method for ancient archaeological finds in Britain based on evolutionary changes in the teeth of water voles.

The AHOB project involves researchers from the Natural History Museum, the British Museum, Royal Holloway and other institutes and is funded by the Leverhulme Trust.

Paul.Rincon-INTERNET@bbc.co.uk