The repatriation of human remains currently held in UK museums and universities to indigenous peoples around the world will do immense damage to science.
By Jonathan Amos
BBC News Online science staff
That is the claim of leading researchers who fear many hundreds of specimens that hold vital clues to our evolutionary past could soon be dispersed to be reburied, burnt or even smashed up.
Professor Chris Stringer with a replica of the Cohuna skull from south eastern Australia
The original skull, dating from about 8,000 BC was returned to Aboriginal control by the Australian National Museum 10 years ago
London's Natural History Museum has several hundred specimens that may be claimed by indigenous groups
The scientists have been speaking ahead of a report due to be published this summer by a working group that will recommend changes to the legal status of human material held by UK institutions.
The scientists are campaigning against the adoption of legislation already passed in Australia and the US which has seen thousands of specimens handed over to aboriginal communities.
"These collections are central to what we do; if we have to hand some of this material over it will be tragic," said Dr Robert Foley, an anthropologist from the Leverhulme Centre for Human Evolutionary Studies at Cambridge University.
"There is enormous interest in human evolution; huge interest in how modern humans came out of Africa and spread across the world. These bones help us understand that."
Indigenous groups - principally Aboriginal Australians - believe the collections are an affront to their customs. They say they should have every right - legal and moral - to repossess the material.
"Documentation shows that way back during colonisation, Aboriginal people objected to the removal of much of this material in the first place," Lyndon Ormond-Parker, a researcher on Aboriginal cultural affairs, told BBC News Online.
"A lot of it, they believe, was stolen. As part of their spiritual beliefs, they think this material should now be returned to be laid to rest in peace."
The UK collections - like the 18,000 specimens held in Cambridge - comprise a range of material from locks of hair and individual teeth to whole skeletons.
Most of the remains date back beyond 1850; some are tens of thousands of years old. Although much is of UK origin, a great deal comes from abroad. Several hundred specimens - perhaps a thousand or more - could become the focus for repatriation claims from Australia and the US.
Scientists say that by applying modern analytical techniques, they can use the bones to discern patterns of migration in ancient human communities - who lived where, who mixed with whom and when.
The chemistry of the bones will very often record how an individual lived - and died.
For example, different forms, or isotopes, of carbon and nitrogen atoms in teeth betray the diet of a person, with vegetarians displaying a very different isotopic signature to an individual who eats meat or fish.
But to those who study the evolution of the human species, it is the scale and variation of the collections which allow them to do the all-important comparative research.
Professor Chris Stringer is from the Natural History Museum, which has the largest bone collection in the UK. He told BBC News Online: "I study Neanderthals but to do that I need to know how varied modern humans are.
This canine tooth is from a post medieval adolescent
female, viewed with a scanning electron microscope
The arrows point to defects in the development of enamel caused by "stress" events in the young person's life
Such events may indicate poor diet or illness or perhaps exposure to toxins
"To answer that central question of whether Neanderthals were a separate species from us, I need a measure of how varied the modern human population is."
And this point was echoed by Richard Neave, a medical artist at Manchester University and an expert on facial reconstruction, whose interest concerns applications in modern forensic science.
"These collections give us the opportunity to study a wide range of different ethnic groups," he said.
"One has to look at more than one sample - that's crucial. In the event that you have a decomposed dead body, perhaps in bits, to reconstruct the facial features, the soft tissue features, you have to have a very good understanding of the skull and you only get that from looking at lots and lots of specimens."
In the US, the Native American Graves Protection and Repatriation Act (Nagpra) has seen a steady erosion of collections. Claimants decide the future of the bones, whether to rebury or destroy them, or to keep them available for study.
Rumours and leaks suggest the working group, under the chairmanship of Professor Norman Palmer, will be sympathetic to the idea of repatriation.
Some UK collections have already been returned voluntarily - by the Royal College of Surgeons of England and the Pitt Rivers museum in Oxford, for example.
But the scientific arguments to resist a UK Nagpra may be hard to sell at the moment, especially in the aftermath of the Alder Hey scandal, in which it emerged thousands of children's organs from post mortem examinations had been stored at the Liverpool hospital without the proper authorisation.
The scientific community came out badly from the affair; its arguments about the need to retain body tissues for research appearing cold and aloof.
Nonetheless, the community will be looking to retain as much of the ancient human archive as possible.
"If this material were repatriated and kept available for science - that would at least be something," Dr Foley said.
In the US, scientists and native Americans have battled in the courts over remains
"But the other fear is that even if we don't lose much material we could be tied up in masses of bureaucracy establishing where every single item is. We simply don't have the funding for that."
Professor Stringer added: "This is a complex issue. There are legitimate claims for repatriation. But there is a spectrum - from skeletons that can be linked to living people, to at the other extreme remains that have no kinship links with living people.
"We have to consider whether we need blanket legislation or whether we need to consider each individual case on its merits."
Mr Ormond-Parker says the scientific case has been largely overstated; many of the specimens have very little research value, he argues.
"There is a compromise that will satisfy all parties.
"In some cases where material has been returned, there has been agreement between the community and the institution concerned, and scientists have had to obtain the informed consent of the community before undertaking research.
"This is the way ahead but in the first instance, museums must be open and honest about what they hold in their collections and they must have curatorial polices that give Aboriginal communities the proper respect."