The world-renowned bone expert, Sue Black, comes flying out of her office at the University of Dundee, tells me she is starving, and rushes me into the cafe. She manages to simultaneously joke with the waiter, shout advice to two students, and read the menu. Black's face is warm but inscrutable, and her dark green eyes remain steady whether she is talking about rotting corpses or her childhood in Inverness.

For someone whose work includes exhuming mass graves, examining the bones of dead children and studying limbs found on rubbish tips, she is extremely upbeat. "The joke is that they pay me for this," she says. "I love what I do."

Forensic anthropology is the study of the human skeleton in a legal setting, usually in cases where a crime is suspected. Over the past few years it has become increasingly visible through the work of Kathy Reichs, the forensic anthropologist and author, whose heroine, Temperance Brennan, works in the field, and is the central character of the popular television series, Bones. Practitioners are often called on to help identify bodies that are decomposed, burned, mutilated or otherwise unrecognisable, including the victims of natural disasters, such as the 2004 tsunami. (Their work is distinct from that of forensic pathologists, whose job is to examine corpses to determine the cause of death in murder cases.)

Black is full of fascinating detail about what can be gleaned from body parts. For instance, if a person had a tattoo, but the tattooed limb is missing, the different coloured inks will be stored in the lymph nodes. Having been called in to identify a severed leg washed up on a beach recently, Black explains that the chemical composition of the food the man had eaten in his final months led colleagues to where he had lived.

Bones can reveal the best-kept secrets. Black recounts the harrowing story of examining the bones of a nine-year-old boy who hanged himself. The lines of increased density in his legs meant that at regular periods - in this case, every 12 months - his bones had stopped growing for a time. Black told investigators that children stop growing during periods of trauma, and advised them to look into what had affected the victim each year. "They discovered that his parents would go on holiday, and leave the boy with his grandfather," says Black. "The grandfather had been sexually abusing him during that time, which caused the boy to take his life."

I meet Black in the university's department of live sciences, where she divides her time between teaching and laboratory research.

Unlike forensic pathology, forensic anthropology is dominated by women. "My student intake is 95% female," she says. "Boys tend to do the CSI stuff, in the laboratory. Maybe it is because women are better at people-based subjects."

Has Black ever faced obstacles on account of her gender? Laughing, she tells me a favourite story. While she was working at St Thomas's hospital, London, early in her career, some bones were discovered in a rubbish tip. Police needed to check whether they were human or animal. "As soon as I looked at them I knew they weren't human, but the policeman who brought them in was a miserable son-of-a-bitch," says Black. "I could tell he was looking me up and down thinking, 'What can this girl know?'"

Black sealed the bones in a plastic bag and put them on a radiator while they chatted. "When they heated up I gave him the bag and said, 'What can you smell?' He said, 'Roast lamb.' I let him believe he had solved the crime, and the next time bones were discovered, he brought them to me." Soon Black was doing bone work all across London.

I ask her about her most high-profile project, identifying the bodies of Slobodan Milosevic's victims in mass graves in the Balkans - both for public record, and for burial. Black headed a team of anti-terrorist police looking for human remains. "It was horrific," she says. "The first scene we came to was an outhouse in the village of Velika Krusa where 42 men had been killed. We had to try and identify them all." The techniques Black used included comparing dental records with the corpses, and examining markers on the bone to determine age, ethnicity and gender. "People there just wanted to be able to lay their loved ones to rest. We did the best we could to enable them to do that."

I ask whether her work has ever put her in danger, and she reels off various scrapes, such as when the helicopter she was travelling in in Iraq almost crashed; when she was bitten by a venomous snake in Kosovo ("I could see the venom travelling up my leg"); and when her Land Rover was booby-trapped in Bosnia.

"I need to hand over these kinds of trips to others now," says Black, telling me that one of her three young children has begun to worry about her safety when she works away from home.

Black fell into her job, rather than it being a particular ambition. "I was in the wrong place at the wrong time," she laughs. At university, she studied botany and anatomy, and in her third year, she was given a cadaver and told to dissect it. "It was amazing to look inside someone."

Black seemed all set to become a pathologist, but for a woman who appears fearless, it was her phobia of rodents that led her on to a different path. "All the research projects in my fourth year involved experimenting on rodents, such as rats and hamsters," she recalls, shuddering. "I thought to myself, 'There is no way I can work with dead mice.'" The only other available project was a study of human bone, so Black signed up, and eventually devoted her thesis to the topic. "I thought, 'I can do that. Give me dead bodies. Do not give me a rat or a mouse'."

Does her work ever upset her? "No. You do this job because you are there to collect evidence and be an impartial forensic scientist, which is the only right reason to do it." She says that there are those who get into the field because they want to help people identify remains for loved ones, and reduce the suffering of those who are desperate for a relative to be found so that they can have a proper burial. "That is very laudable, but once you start to do that you become personally involved, and once you become personally involved, you can't be objective. I try to retain a clinical detachment." How does she deal with the horrors she sees? "I say to myself, 'I did not cause this, I am not responsible for this, I could not have stopped this.' I am there to find answers."

However, one unsolved case is personal to Black. The disappear-ance of Renee MacRae and her three-year-old son, who went missing in 1976 in Black's home town of Inverness, is Britain's longest-running missing-person case. Black, who was a teenager at the time, remembers the police knocking on doors in her neighbourhood shortly after the disappearances. In 2004, when the case was reopened, Black assisted during the dig for MacRae's remains at Dalmagarry quarry. Sadly, nothing was found.

"To come back almost 30 years later to be a part of a murder inquiry which was so significant to me as a youngster is incredible," she says, and she is "deeply disappointed" that the case remains unsolved. "I want to close it. That one is a little bit personal, and it is dangerous when it is personal, but at least I recognise it is."

How does she relax? "I don't. If I am at home I will find some work to do." What about watching a film, walking, having a meal out? "No, no. I am hyperactive, and a workaholic."

Would she ever turn to writing fiction? "Never," she says, cutting across my question. "I would never make entertainment out of my cases." She tells me that when she needs "moral guidance" she turns to the voice of her grandmother, who died when Black was a child. "When I checked out that question on her, way back, she said, 'Definitely, no.'" Thanks to Black's astounding level of commitment, her grandmother is not the only one with a voice beyond the grave.