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By comparing the specimens' ages and degrees of DNA degradation, the researchers calculated that DNA has a half-life of 521 years. That means that after 521 years, half of the bonds between nucleotides in the backbone of a sample would have broken; after another 521 years half of the remaining bonds would have gone; and so on. The team predicts that even in a bone at an ideal preservation temperature of -5 °C, effectively every bond would be destroyed after a maximum of 6.8 million years. The DNA would cease to be readable much earlier -- perhaps after roughly 1.5...

When scientists first decoded the human genome in 2000, they were quick to portray it as proof of humankind’s remarkable similarity. The DNA of any two people, they emphasized, is at least 99 percent identical. But new research is exploring the remaining fraction to explain differences between people of different continental origins. Scientists, for instance, have recently identified small changes in DNA that account for the pale skin of Europeans, the tendency of Asians to sweat less and West Africans’ resistance to certain diseases. At the same time, genetic information is slipping out of the laboratory and into everyday life,...

Seven of the largest pharmaceutical companies have formed a group to develop genetic tests to determine which patients would be at risk from dangerous drug side effects. The new group, the International Serious Adverse Events Consortium, is one of a wave of cooperative research efforts sweeping the drug industry, as companies come under pressure to cut costs and increase their success rates in developing medications. The Food and Drug Administration has encouraged the formation of such groups. If drugs could be withheld from patients who have a genetic risk for serious side effects, it could not only protect the patients...

IN one sense we know much less about Earth than we do about Mars. The vast majority of life forms on our planet are still undiscovered, and their significance for our own species remains unknown. This gap in knowledge is a serious matter: we will never completely understand and preserve the living world around us at our present level of ignorance. We are flying blind into our environmental future. Since the Swedish naturalist Carl Linnaeus inaugurated the modern system of classification two and a half centuries ago, biologists have found and given Latinized names to about 1.8 million species of...

Scientists at the institute directed by J. Craig Venter, a pioneer in sequencing the human genome, are reporting that they have successfully transplanted the genome of one species of bacteria into another, an achievement they see as a major step toward creating synthetic forms of life. Other scientists who did not participate in the research praised the achievement, published yesterday on the Web site of the journal Science. But some expressed skepticism that it was as significant as Dr. Venter said. His goal is to make cells that might take carbon dioxide out of the atmosphere and produce methane, used...

Gov. Eliot Spitzer is proposing a major expansion of New York’s database of DNA samples to include people convicted of most crimes, while making it easier for prisoners to use DNA to try to establish their innocence. Currently, New York State collects DNA from those convicted of about half of all crimes, typically the most serious. The governor’s proposal would order DNA taken from those found guilty of any misdemeanor, including minor drug offenses, harassment or unauthorized use of a credit card, according to a draft of his bill. It would not cover offenses considered violations, like disorderly conduct. In...

Geneticists re-examining the first settlement of Australia and Papua-New Guinea by modern humans have concluded that the two islands were reached some 50,000 years ago by a single group of people who remained in substantial or total isolation until recent times. The finding, if upheld, would undermine assumptions that there have been subsequent waves of migration into Australia. Analyzing old and new samples of Aborigine DNA, which are hard to obtain because of governmental restrictions, the geneticists developed a detailed picture of the aborigines’ ancestry, as reflected in their Y chromosomes, found just in men, and their mitochondrial DNA, a...

As May dawns and the mothers among us excitedly anticipate the clever e-cards that we soon will be linking to and the overpriced brunches that we will somehow end up paying for, the following job description may ring a familiar note: Must be exceptionally stable yet ridiculously responsive to the needs of those around you; must be willing to trail after your loved ones, cleaning up their messes and compensating for their deficiencies and selfishness; must work twice as hard as everybody else; must accept blame for a long list of the world’s illnesses; must have a knack for shaping...

WASHINGTON, Oct. 4 — Following a kind of family tradition, Dr. Roger D. Kornberg of Stanford University School of Medicine won this year’s Nobel Prize in Chemistry on Wednesday for showing how genes convey their messages in cells to copy functions like making proteins. The Nobel Prize committee cited Dr. Kornberg, 59, for visually showing how information encoded in a cell’s DNA blueprint is read and duplicated into what is called messenger RNA. This messenger RNA, in turn, takes the information out of the nucleus to outer areas of the cell where it is used to construct proteins that control...

As part of an intensive effort to develop a new generation of machines that will sequence DNA at a vastly reduced cost, scientists are decoding a new human genome — that of James D. Watson, the co-discoverer of the structure of DNA and the first director of the National Institutes of Health’s human genome project. Decoding a person’s genome is at present far too costly to be a feasible medical procedure. But the goal now being pursued by the N.I.H. and by several manufacturers, including the company decoding Dr. Watson’s DNA, is to drive the costs of decoding a human...

A push to require all convicted criminals in New York to submit their DNA to a central database is gaining crucial support in Albany, where officials say it could create the most comprehensive DNA collection system in the nation. If the proposal becomes law, it would make New York the only state to require collecting DNA from everyone convicted of felonies and misdemeanors, including youthful offenders convicted in criminal court, officials said. Currently, 43 states require that people convicted of all felonies submit DNA, but none require samples from those convicted of all misdemeanors, and New York has required those...

For three billion years, life on earth consisted of single-celled organisms like bacteria or algae. Only 600 million years ago did evolution hit on a system for making multicellular organisms like animals and plants. The key to the system is to give the cells that make up an organism a variety of different identities so that they can perform many different roles. So even though all the cells carry the same genome, each type of cell must be granted access to only a few of the genes in the genome, with all the others permanently denied to it. People, for...

Researchers have now decoded the dog genome to a high degree of accuracy, allowing deep insights into the evolutionary history not only of Canis familiaris but also of its devoted companion species, Homo sapiens. The dog whose genome has been sequenced is Tasha, a female boxer, said Kerstin Lindblad-Toh, a biologist at the Broad Institute in Cambridge, Mass., who led a large group of colleagues in the DNA sequencing effort. Their findings are reported in today's issue of the journal Nature. The world's dog population numbers some 400 million, divided into some 350 breeds. The researchers chose to sequence Tasha's...

Some male prairie voles are devoted fathers and faithful partners, while others are less satisfactory on both counts. The spectrum of behavior is shaped by a genetic mechanism that allows for quick evolutionary changes, two researchers from Emory University report in today's issue of Science. The mechanism depends on a highly variable section of DNA involved in controlling a gene. The Emory researchers who found it, Elizabeth A. D. Hammock and Larry J. Young, say they have detected the same mechanism embedded in the sequence of human DNA but do not yet know how it may influence people's behavior. Voles,...

May 13, 2005 DNA Study Yields Clues on Early Humans' First Migration By NICHOLAS WADE By studying the DNA of an ancient people in Malaysia, a team of geneticists says it has illuminated many aspects of how modern humans migrated from Africa. The geneticists say there was only one migration of modern humans out of Africa; that it took a southern route to India, Southeast Asia and Australia; and that it consisted of a single band of hunter-gatherers, probably just a few hundred people strong. Because these events occurred in the last Ice Age, when Europe was at first too...

WASHINGTON, May 6 - A sharply critical independent audit found Friday that Virginia's nationally recognized central crime laboratory had botched DNA tests in a leading capital murder case. The findings prompted Gov. Mark Warner to order a review of the lab's handling of testing in 150 other cases as well. Among the auditors' eight recommendations, all of which were accepted by Mr. Warner, were that the governor restrict the work of the lab's chief DNA scientist, Jeffrey Ban; review 40 cases that Mr. Ban has handled in recent years, along with a sample totaling 110 additional cases; and develop procedures...

Again and again, the standard DNA tests came up negative on a three-inch-by-two-inch piece of muscle recovered from the World Trade Center site, and just a year after the 2001 attacks, forensics experts were stymied. Yet now, the scrap has been linked to a firefighter from Midtown Manhattan, allowing his death to be confirmed and giving his wife and two children some sense of finality. Solving brutally difficult cases like that one required an investment of two extra years and millions of dollars by the medical examiner's office in New York, which sought out and used DNA identification technologies that...

Opening a new front in the battle against cancer, federal officials are planning to compile a complete catalog of the genetic abnormalities that characterize it. The proposed Human Cancer Genome Project, as it is being called for now, would be greater in scale than the Human Genome Project, which mapped the human genetic blueprint. It would seek to determine the DNA sequence of thousands of tumor samples, looking for mutations that give rise to cancer or sustain it. Proponents say a databank of all such mutations, which would be freely available to researchers, would provide invaluable clues for developing new...

Filed at 5:18 p.m. ET Women get more work out of hundreds of genes on the X chromosome than men do, and that could help explain biological differences between the sexes, a new study says. The results imply that women make higher doses of certain proteins than men do, which could play out in gender differences in both normal life and disease, researchers said. So far, however, none of the genes identified in the study has been linked to any such observable differences, said senior study author Huntington Willard of Duke University. He and Laura Carrel of Pennsylvania State University...