==============================
Remaking Eden: Cloning and Beyond in a Brave New World
By Lee M. Silver, Weidenfeld & Nicolson, 315 pages, $39.95
I thought I knew about the birds and bees, but Lee Silver, molecular
biology professor at Princeton, taught me otherwise. It turns out my
mother didn't have just one brother, my uncle, but several other siblings
just as close - because her father was a clone.
I've been vaguely aware of this since childhood, when I first met
grandfather Chris's identical twin brother. I'd never heard of Dan, who
lived interstate, until the creepy day I greeted a familiar, beloved man
who didn't know me. Laughter from the adults - but I howled at this
uncanny duplication.
Maybe just such unease is what makes people nervous, even revolted, by the
prospect of human cloning and other disturbing feats of what Silver dubs
`reprogenetics'. When identity itself is up for grabs, what's to hold onto
in an uncertain world?
Such anxieties fuel the persistent anger and alarm in the abortion debate.
Does human personhood begin when parental DNA strands fuse into a unique
living being? Or is an embryo, or even a two-trimester foetus, not yet
sufficiently complex or aware to be deemed a person? In light of genetic
profiling, bio-engineering, and now cloning (very soon, surely, of humans
as well as other mammals), can science help us unpick these ethical issues?
Yes and no. Our received values often derive from the best available
scientific opinion - of the fourth century BC. Is abortion murder?
Adapting Aristotle, Thomas Aquinas taught that the male embryo only becomes
a human being at six weeks, when God infuses a soul into the developing
flesh. Females have to wait until 13 weeks.
More recent Christian theologians update their science to about the middle
of this century. Human life, many hold, starts precisely at conception (a
distressing opinion, given that at least 75 percent of all pregnancies
abort spontaneously without benefit of baptism). Silver, drawing upon
molecular biology and IVF evidence, shows this can't be correct. Indeed,
an embryo doesn't even blend its parents' DNA until the two-cell stage, on
the second day. Even then, each cell in the replicating ball of tissue is
identical until the fourth cycle of doubling. Then the 16-cell clump
splits into a core that will specialise into a baby and an outer shell
growing into a disposable placenta.
This developing tissue with its unique DNA pattern usually goes astray in
various ways, most of them lethal. Sometimes it splits, yielding twins or
quins - natural clones. Hence, the children of Chris and Dan shared
exactly the same paternal inheritance: not cousins, but genetic brothers
and sisters with different mothers.
Twenty years ago, Dr Sherman Silber transplanted a testicle from Terry
Twomey into his sterile identical twin, Tim, afflicted with a rare
developmental disorder. Weird hi-tech incest? Tim and Jannie's child
can't be distinguished genetically from any that Tim might have fathered if
he'd been born whole. Yet Tim's son is also plainly the brother of Terry's
three kids.
Modern reprogenetics multiplies such conundrums dizzyingly. What's a
father and mother, and who's their child? An unethical scientist might
take 10 very early embryos prepared for 10 random IVF couples, and tease
apart the eight cells of each. Implanted into surrogate mothers, each of
the 80 cells could now grow into a healthy baby. We'd end up with 10 sets
of octuplets.
Go back a step. While the 80 cells are segregated, pick one cell from each
of the ten Petri dishes and fuse them together into 10 entirely new
eight-cell mosaic embryos. This is not fantasy - using mice and other
mammals, it's common lab procedure. Now you might have 10 babies born,
each with numerous parents.
Here's the puzzle for theologians - if each original embryo has its soul
divinely infused at conception, how are the souls reassigned when the cells
get randomly recombined? This is not a blasphemous thought-experiment -
every year, natural errors cause twin eggs to merge into mosaic
individuals, or chimeras. Usually they grow up without special problems,
though some intersex chimeras (boy and girl twins fused into one
individuals) have ambiguous genitalia. Do they have a double helping of
souls? How do such facts bias our moral evaluation of abortion?
These are just the simplest starting points in Silver's astonishing,
elaborate examination of next century's molecular revolution. He helps us
think through the facts and ethics of many wilder possibilities - children
for gay couples sharing the heritage of both, detailed genetic scanning
allowing parents to learn broadly how any given embryo would develop, so
they might launch the life of one potential infant instead of another.
Eugenics? Perhaps - but not, Silver argues, as stigmatised by association
with Nazism and other abominations. Yet the outcome might be a swelling
genetic apartheid of rich and poor - enhanced GenRich with extended
longevity and other gifts, resolute or desperate Naturals. Silver blithely
embraces this fate as the fruit of the American dream of consumer
capitalism.
I don't expect this split to happen, actually, since other technologies
like intelligent computers and molecular manufacturing - necessary anyway
to foster advanced reprogenetics - will spread these options cheaply to
everyone who chooses them. It's likely, though, that humanity will
speciate explosively - branching into something old, something wonderfully
new, something borrowed and, by today's standards, something bleugh.
============================
Damien Broderick