BY LISA M. KRIEGER Mercury News

Deep down, we are all very much alike.

New data confirms what scientists have long suspected: The DNA of human beings is 99.9 percent identical. This finding, reported in Friday's issue of Science, is a powerful statement about the relatedness of all humans.

``Traditional ways of distinguishing populations are irrelevant in terms of genetic code,'' said Craig Venter, head of Celera Genomics Corp., the private company that joined with a public consortium of scientists to map the human genome. ``You cannot look at a person's genes and say with any accuracy whether they are from one racial group or another.''

In fact, the variation between any two individuals in the same racial group could be greater than that between two different groups, Venter said at a recent Washington, D.C., press briefing where he unveiled the data behind his company's map of the human genome.

Many Africans or people of recent African descent are more closely related to Caucasians than they are to other Africans, according to Venter. Likewise, distinctions between Chinese people and Caucasians are virtually insignificant when compared with those between groups from, say, parts of east and west Africa, he said.

``Mapping the DNA sequence variation in the human genome holds the potential for promoting the fundamental unity of all humankind,'' according to Dr. Harold P. Freeman, a member of Celera's Institutional Review Board.

``The power of science can be used to eliminate public perceptions of racial superiority and inferiority, which are the basis of racism itself,'' said Freeman, president and director of surgery at North General Hospital in New York City and a leading authority on the inter-relationships between race, poverty and cancer.

``In this way,'' he said, ``the mapping of the human genome could be pivotal in promoting the concept of one race, the human race.''

The mapping of the human genome was launched in 1989 by an international consortium of federally funded researchers and accelerated when Celera Genomics joined the effort in 1998. The most recent findings on the genome were published in last week's issues of the journals Nature and Science.

On average, two unrelated people differ at just one of every 1,000 sites in their DNA -- and no genes, by themselves or together, are able to predict a person's race, according to Venter.

But these tiny variations add up to roughly 3 million places where two people may differ, creating traits such as hair color, eye color or shade of skin. The variations occur more in some races than others, he added.

Such disparities can also predispose clusters of people to ailments such as heart disease, cancer or depression. They could also help explain the mystery of why some racial and ethnic groups tend to dominate certain activities -- such as Jews and Asians on stringed instruments, Russians in chess, and Africans and African-Americans in track events.

One of the major goals of researchers studying the human genome is to measure precise patterns of genetic differences among human populations, revealing the history, journeys, fluctuations in population size and mixing that occurred among neighboring groups of humans.

Such studies are based on the premise that some forms of genetic material are rigidly passed down from parents to children, weaving an unbroken line of ancestry that researchers can trace.

Nobody knows the identities of the people who donated their DNA for the publicly funded genome team. But Venter said Celera's studies deliberately selected DNA from five individuals: one Asian-American, one African-American, one Latino and two others, unidentified. He found no way of telling which was which.

``No serious scholar in this field considers race to be a scientific concept,'' Venter said.

``We all evolved out of the same three or four groups in Africa, as black Africans,'' he said. With migrations, he said, groups began to form and stabilize over time, and slight differences began to emerge.

While the gene mapping showed no genetic identifiers for races, it did show a spectrum of subtle genetic differences within races.

A trait such as athletic ability is not directly linked to a gene for skin color, the characteristic traditionally used to define race, scientists note.

Instead, it is probably linked to subtle physiological characteristics that have been acquired over the course of evolution -- and may have concentrated in specific populations adapted to different environments.

Tiny variations called single nucleotide polymorphisms (SNPs), the most common type of variation in the genome, may underlie differences in traits such as muscle composition, the body's response to exercise and metabolic efficiency -- traits which seem to be linked to success in certain sports. The genetics of these traits are under study by doctors Jesper L. Andersen and Peter Schjerling of the Copenhagen Muscle Research Center, affiliated with the University of Copenhagen.

The challenge now is to understand how these and other variations affect human health or disease.

Though people cannot be clearly divided into ``races,'' scientists can still detect certain patterns of SNPs that crop up more in some parts of the world than others. This should give researchers clues to the movements of different peoples during history.

For instance, genetic research has revealed ancient connections between men in the western Irish province of Connaught and the Basque region of Spain.

Such findings, however, only show where people may have moved. There is no basis to use genetics to support racist doctrines, the scientists said.

``Throughout recorded history and up to the present time, countless human conflicts have occurred based on how groups of people have seen, classified and behaved toward another group,'' said Celera's Freeman.

``The biological concept of race . . . has no basis in science,'' he said.