Now that we have decoded the human genome, why don't we improve
The question is at present theoretical but could well emerge
as the hardest of all bioethical issues. Biologists routinely
alter the genes of mice, with methods that are not yet acceptable
for making inheritable changes in people, but one day genetic
engineers may figure out how to apply safe patches to the human
Everyone would like to have children who are healthy, beautiful
and gifted. But people vary widely in all these qualities, depending
on their parents' genes, and the pure luck of the draw at conception
when each child gets allotted a random selection of half the
parental gene pool.
Most human genes exist in several different versions in the
population: some of them are great to have, some so-so and some
This month the Icelandic company Decode Genetics found three
quite common versions of a gene called BMP-2, each of which
considerably increases its owner's risk of osteoporosis and
Suppose it were possible to delete any bad version of BMP-2,
and of all other human genes, in a human embryo, and to replace
them with good versions, without any risk to health. Would that
be the right thing to do?
Parents who made such a choice would know they had given their
child the best possible start in life. However expensive the
procedure, it would be cheap in the long run if it saved a lifetime
of medical bills, and therefore could be made available to all.
Life's most serious unfairness, the difference in genetic endowment,
would be erased from birth.
"One day, people may view sex as essentially recreational,
and conception as something best done in the laboratory,"
Dr. Gregory Stock wrote recently in "Redesigning Humans.
" Parents may start to believe it is "reckless and
primitive to conceive a child without prior genetic testing."
Yet there are weighty arguments for not making inheritable
changes to the human genome.
On the practical side, many genes have more than one effect,
and swapping out the bad version of a gene can have unpredictable
complications. The new gene, for example, may interact badly
with the person's other genes.
But if the elimination of disease-causing variants of genes
should prove successful, there might be no holding the line
against parents who wanted to enhance strength or intelligence
Upgrading the imperfect human material is all very well, but
handling the transition between the superpeople and the ordinary
variety promises to be awkward. Social stresses may emerge,
especially if the technology does not trickle down quickly and
Soup up those genes for I.Q.? Altering the genes that shape
human behavior is not to be undertaken lightly. Human nature
is a subtle blend of contrary qualities, the only survivor of
evolution's many disastrous experiments. What could justify
the risk of messing with such a delicate brew? Can't we be happy
as we are, just as nature has shaped us?
"The human body and mind, highly complex and delicately
balanced as a result of eons of gradual and exacting evolution,
are almost certainly at risk from any ill-considered attempt
at `improvement,' " the President's Council on Bioethics
wrote in a report last month on the dangers of enhancing the
body's natural abilities.
As the products of evolution, people may seem churlish if they
challenge evolution's wisdom. But of course, evolution has none.
It is a blind process that depends on constant error to create
occasional lucky accidents.
By culling the unfortunate owners of bad genes, evolution keeps
animals healthy and vigorous until the age of reproduction,
and a bit beyond for species that provide parental care.
But evolution's rigor at favoring good genes that act early
in life is mirrored by a weakness in screening out bad genes
that act after the age of reproduction. Because of this weakness,
evolution has failed to eliminate the bone-fracturing variants
of BMP-2, and the bad, late-acting versions of many other genes
in the human genome. This is the very reason that we age and
If evolution cannot help us after a certain age, why should
we not help ourselves? Should not everyone have a right to the
best versions of the genes in our collective genetic heritage,
or at least to be born free of the worse ones?
And yet, if we reduce genetic differences, we risk turning
the human population into one giant clone, tedious to meet with
and bereft of the variation needed to respond to changing environments.
The pursuit of perfection, if carried to extremes, is a sure
recipe for extinction.
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