Unlocking the rainbow: The science of human diversity
By Paul Salopek
CHICAGO TRIBUNE STAFF WRITER
Web-posted: Saturday, April 26, 1997
First in a two-part series
UNIVERSITY PARK, Pa. -- In a beat-up refrigerator humming away in his
laboratory storeroom, Ken Weiss is storing vials of
human blood: the largest gene pool left of a tribe
of people inexorably vanishing from the Earth.
The insides of the freezer, not much different from ones used by many
people to store groceries, hold the DNA of 12,000 Yanomamo
Indians, a fierce Amazonian tribe that lives in Brazil near the
watershed of the Orinoco River. The blood samples were
collected by anthropogists a generation ago, and there are now
more vials in the nondescript room at Pennsylvania State University
where Weiss is a researcher than there are Yanomamos still alive.
Like many remote populations, the Yanomamo have been ravaged by
Western diseases and, in this case, the shotguns of invading gold
prospectors. Their rain forest home is scarred by airstrips and mines.
Of a population numbering in the tens of thousands at the turn of the
century, fewer than 10,000 remain.
So it is that Weiss' storehouse has become one obscure if vivid
example of a genetic quest so vast, controversial and unprecedented
that even those who know of its existence can't agree on its principal
goal.
It is the Human Genome Diversity Project, a title that has proved
confusing because it is so close to the more famous Human Genome
Project that is mapping the entire code of human DNA.
By contrast, the Human Genome Diversity Project, over five years and
at a cost of $25 million, calls on geneticists at universities worldwide
to collect 10,000 blood samples from at least 400 ethnic groups ranging
from Afghans to Apaches, from Basques to African Bushmen.
In short, it is the first genetic survey of humankind, a painstaking
portrait of how and why members of the human species duplicate or
differ from one another.
Weiss is the North American coordinator of the project, which is
awaiting approval by the National Academy of Sciences, a step that
would open it to government funding and increase its public profile. If
approved as expected this summer, the project would serve as an
official institutional umbrella for research that has been going on
unofficially for decades by a scattered group of scientists and
commercial researchers.
Which human tissue samples will come under the project's aegis --
those of the Yonomamo included -- is just one of the complicated
ethical and logistical questions that will have to be resolved.
To some, the project is a scramble to salvage the fading biodiversity of
our species -- a genetic inheritance that shrinks with the demise of
every tribe such as the Yanomamo. Moreover, by collecting and
comparing the DNA from the far-flung populations, scientists say they
will at last be able to sketch a global family tree and "read" the tale
of human evolution, how our ancestors populated the
Earth.
Still others call the diversity project a medical bonanza that, by
exploring why some groups resist certain diseases, might lead to
breakthroughs in the treatments of ailments ranging from Alzheimer's
disease to diabetes.
But it is the project's revelations about race that promise to rattle
our perceptions of identity the most and ignite debate
in classrooms, taverns and homes across the world.
Indeed, the father of the project, Luigi Luca Cavalli-Sforza, an eminent
Stanford University professor who has slogged the globe collecting
blood samples from Italian villages to sweltering rain forests, has
received an incongruous trickle of hate mail:
How dare Cavalli-Sforza suggest, the obscenity-spattered missives
read, that our notions of race are irrelevant and that groups such as
blacks and whites -- or anybody else for that matter -- are basically
the same.
"Outward appearances tell almost nothing about our roots -- the
shapes of our noses, the color of our skins change with climate," said
Cavalli-Sforza, a reserved, silver-haired academic with an elegant
Mediterranean accent, impatiently waving off the racist attacks. "It's
our genes that tell our story best."
Meanwhile, a vocal, angry minority see the project as something
altogether different: a cultural ripoff or at least a callous abuse of
aboriginal rights.
As the debate escalates, the vast store of human tissue that
Cavalli-Sforza and others have collected will be carefully cultured in
labs so that the cells live on for decades -- a biotech process called
"immortalization." In a final, Dr. Strangelovian twist, the cell lines
-- a cross-section of humanity kept alive in petri dishes -- would be
stored in genetic repositories around the world.
Some of the preliminary findings have proved controversial:
After analyzing thousands of DNA samples collected in smaller studies,
experts are amazed at the genetic unity that binds our diverse, polyglot
species. Any two people, regardless of geography or ethnicity, share at
least 99.99 percent of their genetic makeups -- a deep sameness that
makes a mockery of racist ideologies such as Nazism.
Paradoxically, the minuscule .01 percent of our genome that does
make people different doesn't shake out along visible racial lines.
Instead, some 85 percent of human genetic diversity occurs within
ethnic groups, not between them. The traits that so polarize our culture
-- the shade of our skin, the shape of an eye, hair texture -- actually
hide a dazzling and unexpected molecular tapestry that reflects our true
origins. The European gene pool, for example, carries the story of
where its members came from -- and where they later migrated. It is a
swirl of 35 percent African genes and 65 percent Asian genes.
In a development that enthralls medical researchers, a global genetic
survey will tap the "healthy genes" locked away in the nuclei of
different ethnic groups. With the marvels of genetic medicine, disease
resistance unique to one population might soon be shared by all.
"This project is going to infuriate bigots," declared Kenneth Kidd a
project planner at Yale University. "It peels away our cultural bias
with molecular data."