Lewontin: THE PROBLEM FOR EVOLUTIONISTS AND POPULATION GENETICISTS WAS ALWAYS TO TRY TO ACTUALLY CHARACTERIZE HOW MUCH GENETIC VARIATION THERE WAS BETWEEN INDIVIDUALS AND GROUPS. AND I SPENT A LOT OF TIME WORRYING ABOUT THAT, LIKE OTHER PEOPLE IN MY PROFESSION. Narrator: IN THE 1960s, RICHARD LEWONTIN DECIDED TO FIND OUT JUST HOW MUCH GENETIC VARIATION FELL WITHIN, AND HOW MUCH BETWEEN, THE GROUPS WE REGARD AS RACES. A NEW TECHNOLOGY ENABLED HIM TO DO PIONEERING WORK. AND THAT METHOD, WHICH WAS CALLED GEL ELECTROPHORESIS -- A VERY FANCY NAME -- WE WERE ABLE TO USE ON ANY ORGANISM AT ALL. IF YOU COULD GRIND IT UP, YOU COULD DO IT. THAT INCLUDED PEOPLE. YOU DIDN'T HAVE TO GRIND THE WHOLE PERSON, BUT YOU COULD TAKE A LITTLE BIT OF TISSUE OR BLOOD. OVER THE YEARS, A LOT OF DATA WERE GATHERED BY ANTHROPOLOGISTS AND GENETICISTS, LOOKING AT BLOOD GROUP GENES AND PROTEIN GENES AND OTHER KINDS OF GENES FROM ALL OVER THE WORLD. ANTHROPOLOGISTS JUST WENT AROUND TAKING BLOOD OUT OF EVERYBODY. I MUST SAY, IF I WERE A SOUTH AMERICAN INDIAN, I WOULDN'T HAVE LET THEM TAKE MY BLOOD, BUT THEY DID. AND SO I THOUGHT, WELL, WE'VE GOT ENOUGH OF THESE DATA. LET'S SEE WHAT IT TELLS US ABOUT THE DIFFERENCES BETWEEN HUMAN GROUPS. Narrator: LEWONTIN'S FINDINGS WERE A MILESTONE IN THE STUDY OF RACE AND BIOLOGY. Lewontin: IF YOU PUT IT ALL TOGETHER -- AND WE'VE NOW GOT THAT FOR PROTEINS, FOR BLOOD GROUPS, AND NOW WITH DNA SEQUENCING, WE HAVE IT FOR DNA SEQUENCE DIFFERENCES -- IT ALWAYS COMES OUT THE SAME. 85% OF ALL THE VARIATION AMONG HUMAN BEINGS IS BETWEEN ANY TWO INDIVIDUALS WITHIN ANY LOCAL POPULATION, BETWEEN INDIVIDUALS WITHIN SWEDEN OR WITHIN THE CHINESE, OR THE KUIKURU, OR THE ICELANDERS. Narrator: TO PUT IT ANOTHER WAY, OF THE SMALL AMOUNT OF VARIATION IN OUR GENES, THERE IS APT TO BE AS MUCH DIFFERENCE BETWEEN GORGEOUS AND HER TEAMMATE CHRISTINE AS THERE IS BETWEEN GORGEOUS AND HER OPPONENT KAOLIN. ANY TWO INDIVIDUALS WITHIN ANY SO-CALLED RACE MAY BE AS DIFFERENT FROM EACH OTHER AS THEY ARE FROM ANY INDIVIDUAL IN ANOTHER SO-CALLED RACE. ARE THE PEOPLE WHO WE CALL BLACK MORE LIKE EACH OTHER THAN THEY ARE LIKE PEOPLE WHO WE CALL WHITE, GENETICALLY SPEAKING? THE ANSWER IS NO. THERE'S AS MUCH OR MORE DIVERSITY AND GENETIC DIFFERENCE WITHIN ANY RACIAL GROUP AS THERE IS BETWEEN PEOPLE OF DIFFERENT RACIAL GROUPS. Narrator: STILL, WE KNOW THAT SOME GENES ARE FOUND WITH GREATER FREQUENCY IN SOME POPULATIONS. Goodman: AND GEOGRAPHY IS THE BETTER WAY TO EXPLAIN THAT, MORE THAN RACE OR ANYTHING ELSE. THERE CAN BE ACCUMULATIONS OF GENES IN ONE PLACE OF THE GLOBE AND NOT ANOTHER. RACE DOES NOT ACCOUNT FOR PATTERNS OF GENETIC VARIATION. OUR RECENCY AS A SPECIES AND THE WAY WE HAVE MOVED AND MATED THROUGHOUT OUR HISTORY DOES. OUR HUMAN LINEAGE ORIGINATED IN AFRICA. ABOUT TWO MILLION YEARS AGO, SMALL GROUPS OF EARLY HOMINIDS, NOT MODERN HUMANS, BEGAN A FIRST MIGRATION OUT OF AFRICA TO THE FAR REACHES OF THE GLOBE, BREEDING ISOLATED LINEAGES. IT WAS LONG THOUGHT -- AND IS STILL BELIEVED BY SOME -- THAT THOSE FIRST LINEAGES LED TO GENETICALLY DISTINCT RACES THAT ARE WITH US TODAY. IT TURNS OUT THAT'S NOT TRUE. I THINK THERE'S ALMOST GENETIC PROOF NOW -- I WOULDN'T SAY THE ISSUE IS TOTALLY RESOLVED -- THAT THOSE LINEAGES JUST DIED OUT, THAT NEANDERTHALS IN EUROPE DIED, THAT HOMO ERECTUS IN ASIA DIED, THAT THERE WAS A SECOND MIGRATION OF OUR MODERN SPECIES, HOMO SAPIENS, AND THAT ALL MODERN HUMANS ARE PRODUCTS OF THE SECOND MIGRATION, WHICH IS PROBABLY LESS THAN 100,000 YEARS OLD, BY THE BEST CURRENT EVIDENCE. Goodman: SOME OF THOSE MOVEMENTS MAY FOLLOW MAJOR MIGRATIONS AS AGRICULTURAL PEOPLE CAME INTO EUROPE, AS PEOPLE CROSSED THE BERING STRAIT AND CAME INTO THE AMERICAS. BUT OTHER MOVEMENTS ARE MUCH MORE SUBTLE. THERE ARE SMALLER GROUPS OF INDIVIDUALS THAT MOVED OR THEIR GENES MOVED FROM PLACE TO PLACE AND TIME TO TIME. WE'VE HAD MAYBE 100,000 YEARS OF HAVING GENES MOVE OUT AND MIX AND RE-ASSORT IN COUNTLESS DIFFERENT WAYS. Narrator: A HUNDRED THOUSAND YEARS MAY SEEM LIKE A LONG TIME, BUT IN EVOLUTIONARY TERMS, IT IS A BLINK OF THE EYE. HUMAN POPULATIONS HAVE NOT BEEN ISOLATED FROM EACH OTHER LONG ENOUGH TO EVOLVE INTO SEPARATE SUBSPECIES. THERE JUST HASN'T BEEN TIME FOR THE DEVELOPMENT OF MUCH GENETIC VARIATION, EXCEPT THAT WHICH REGULATES SOME VERY SUPERFICIAL FEATURES LIKE SKIN COLOR AND HAIR FORM. FOR ONCE THE OLD CLICHE IS TRUE -- UNDER THE SKIN, WE REALLY ARE EFFECTIVELY THE SAME, AND WE GET FOOLED BECAUSE SOME OF THE VISUAL DIFFERENCES ARE QUITE NOTICEABLE.