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Original photo by Jani
Mahkonen/Photomosaic ® by Robert Silvers
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On
Westwood Boulevard in Los Angeles, just off the
University of California campus, the street is jammed at
lunchtime. The tones of all humanity flow past, faces from
Santa Monica, Singapore, and Senegal, a stroboscopic stream of
light and dark. Notwithstanding such contrasts in appearance,
comparisons of our DNA show that human populations are
continuous, one blending into the next, like the spectrum of
our skin coloring. We all carry the same genes for skin color,
but our genes responded differently to changes in solar
intensity as bands of Homo sapiens migrated away from
the unrelenting sun of the equator.
Still, it seems to be human nature to assign types to our
fellow humans and then make judgments based on those types.
Take this tall woman coming along the sidewalk and entering an
Italian restaurant. Blond, but not California blond. In her
early fifties, wearing a stylish suit and elegant shoes—a
European. Physically she belongs to what one observer has
called “the fair-skinned, fair-haired, gray-to-blue-eyed,
long-limbed, relatively narrow-faced individuals that
constitute a substantial portion of the population of Sweden,
Denmark, Iceland, Norway, western Finland.” That is, the
Nordic type.
Leena Peltonen is one of the world’s leading medical
geneticists. In 1998 she was recruited from Helsinki
University to become the founding chairwoman of the Department
of Human Genetics at UCLA’s medical school. Trained as both a
physician and a molecular biologist, she has discovered the
genetic sources for many rare diseases, such as Marfan
syndrome, a connective-tissue disorder. She has also found
hereditary links to more prevalent conditions, such as
multiple sclerosis, schizophrenia, osteoarthritis, and
migraine.
The raw material for her investigations is DNA collected
from people in Finland. Research by Peltonen and by her
compatriots Juha Kere, Jukka Salonen, Albert de la Chapelle,
and Jaakko Tuomilehto have made Finland into a sort of DNA
laboratory for mankind. Now its scientists are detecting the
heritable imprints of heart disease, diabetes, and asthma. The
country’s contributions to medicine and genetics are far out
of proportion to its size and population of 5 million.
As research subjects the Finns are an agreeable lot. When
asked to participate in studies, Peltonen noted, three out of
four will say yes. Access to clinical records is much easier
in Finland than in the United States because the health care
system is streamlined, centralized, and computerized. Foreign
collaborators may tap into the resource as well. The U.S.
National Institutes of Health has helped fund a dozen
biomedical projects in Finland in the last decade.
But even more important for a geneticist, “the genealogies
are already built,” said Peltonen, referring to the family
pedigrees through which diseases can be tracked. “The setting
of a limited number of ancestors and hundreds of years of
isolation make Finns good study subjects.”
The genetic homogeneity, or sameness, of the Finns makes
them easier to study than Californians, say, who hail from all
over. To illustrate, Peltonen drew two pairs of human
chromosomes, which were shaped something like swallowtail
butterflies. Symbolizing two Finnish people, the four
chromosomes were similar—banded horizontally with the same
light-and-dark patterns. “These guys are the boring Finns,”
she said with a trace of irony.
She drew another set of chromosomes representing a pair of
Californians, and the banding patterns were quite dissimilar.
The variance shows up better at the group level. Think of the
human genome as a very large deck of cards, each card bearing
a gene variant. The number of cards in the Finnish deck is
fewer than the number of cards in the California deck because
the Finns have fewer gene variants, or alleles, to play with.
When scientists look for variants that cause diseases, they’re
easier to spot in the Finnish deck because so many cards are
similar.
The uniformity of Finns, created by several centuries of
isolation and intermarriage, results in a large set of
hereditary disorders. So far researchers have identified 39
such genetic diseases, many of them fatal, that crop up in the
unlucky children of unwary carriers. Peltonen, who began her
career as a pediatrician, said: “Genetic diseases transform
the family. You know the children won’t get better.” Since
switching her focus to research, Peltonen and her associates
have identified 18 of the 39 endemic conditions.
Although far less common than cardiovascular ailments and
much less of a drain on the health-care system, the hereditary
disorders identified so far are so well known to Finns that
they are part of the lore of the nation. The Finnish Disease
Heritage has its own Web site.
“In school, children are taught that Finnish genes are
slightly different,” Peltonen explained. “The textbooks and
public press contain significant information about them. The
search for the special selection of genes—actually they are
alleles—is considered as a cause for pride.”
Clearly the Finns were an exceptional bunch, wedged at the
top of the world between Sweden and Russia and speaking an odd
tongue that is unrelated to other languages of Scandinavia.
Does all of this make Finns a race?
“How do you genetically define race?” Peltonen answered,
shaking her head. Race is used in biology for birds and
animals—the term is tantamount to subspecies—but her studies
had no use for it. Patterns of human variation can be linked
to geography, and geographic ancestry can be linked to health
risks. As a genetic explorer Peltonen has followed the
movement of populations in history, knowing that genes had
diversified during the moves, but in Finland as elsewhere only
a tiny fraction of the alleles and health risks are
distinctive. “Race may fade away once we understand all the
variants,” she said. “But for diagnostic purposes it will be
useful to know where your roots are. That’s the value of the
Finnish Disease Heritage. The story of these genes helps us
visualize how Finland was settled.”
By convention the Finns are white or Caucasian. Peltonen
was probably the palest person on Westwood Boulevard.
Nevertheless, in the 19th century she would have been classed
with the Mongol race because anthropologists of that day
lumped Finns with the Laplanders, or Sami, as they call
themselves—the nomadic, faintly Asiatic people who roam the
Scandinavian Arctic. That’s how arbitrary “race” can be.
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