The fruit of a narrow-leaved campion, buried in permafrost by a
ground squirrel 32,000 years ago on the banks of the Kolyma river
in Siberia, has been coaxed into growing into a new plant, which
then successfully set seed itself in a Moscow laboratory. Although
this plant species was not extinct, inch by inch scientists seem to
be closing in on the outrageous goal of bringing a species back
from the dead. I don't expect to live to see a herd of resurrected
mammoths roaming the Siberian steppe, but I think my grandchildren
just might.
The mammoth is the best candidate for resurrection mainly
because flash-frozen ones with well-preserved tissues are regularly
found in the Siberian permafrost. Occasionally these have been
fresh enough to tempt scientists to cook and eat them, usually with
disappointing results. Just last week a Chinese paleontologist in
Canada, Xing Lida, filmed himself frying and eating what he said
was a small mammoth steak. Cells from such carcasses have been
recovered, encouraging a rivalry between Japanese and Russian
scientists to be the first to revive one of these huge,
elephant-like mammals by cloning. Four years ago the mammoth genome
was sequenced, so we at least now know the genetic recipe.
The news of the resurrected flower does, apparently, remove one
obstacle. After 32,000 years the plant's DNA had not been so
damaged by natural radioactivity in the soil as to make it
unviable, which is a surprise. Mammoth carcasses are often much
younger - the youngest, on Wrangel Island, being about 4,700 years
old, contemporary with the Pharoahs. So the DNA should be in even
better shape.
However, plants are much better at cloning themselves from any
old cutting. Coaxing an elephant cell into becoming an embryo is
not at all easy; though, as Dolly the sheep showed, not impossible.
To do the same for a mammoth cell would be harder still. And then
there is the problem of how to get the embryo to grow. Implanting
it into the womb of an Indian elephant (its closest living
relative) is the best bet, but experiments with implanting rare
embryos into other species' wombs have been mostly unsuccessful.
For example, a rare form of wild ox, the gaur, was going to have
its embryos reared in cattle wombs, but it did not work.
So do not book the Siberian mammoth safari trip just yet.
Equally, don't bet against it eventually coming off.
Which other species might follow? One that only recently went
extinct (last seen in 1936) is the marsupial carnivore called the
thylacine, or "Tasmanian tiger". A few years ago, genes from a dead
thylacine were injected into a mouse and "expressed" in its tissue.
The great auk, the dodo and other creatures that died out before
the invention of refrigeration are going to be much harder to
revive.
Perhaps fortunately, Neanderthals, dead for 28,000 years,
unfrozen and not very closely related to their likely surrogate
parent (you and me), would be harder still, though their DNA
sequence is now known. And as for the dinosaurs - 65 million years
dead - forget it. Although come to think of it, re-engineering a
chicken until it looks like a dinosaur cannot be ruled out, once
people learn to play genetics well enough.
The real significance of the Siberian flower, though, is that it
makes future extinctions potentially reversible. So long as we can
flash-freeze seeds and tissues from threatened species (a disused
mine in a frozen mountain in Spitsbergen already holds a seedbank
of rare plant varieties), then we can give posterity the chance to
resurrect them. Combine this with the news that extinction rates,
at least of birds and mammals, have been falling in recent decades,
and there are grounds for a glimmer of ecological optimism. The
great spasm of extinction caused by humans - mainly when we spread
our rats, weeds and bugs to oceanic islands - may be coming to an
end.
Far more significant than the reversal of extinction, however,
is the revival of wild ecosystems. Ecologists are finding that wild
habitats can be put back together more easily than they thought. A
marine reserve off Mexico is now teeming with large fish again.
Yellowstone Park's ecological revival following the introduction of
the wolf is remarkable: by cutting the numbers of elk, wolves have
brought back aspen trees and long grass and hence beavers, rodents
and hawks.
In Costa Rica, a rainforest rich in tree species is now thriving
on what was, in 1993, exhausted farmland. Once a canopy of
sun-loving trees was planted, hundreds of other tree species moved
in naturally. One commentator says: "The accepted belief is that
once destroyed, tropical rainforests could never be restored. But
is that really the case or just a myth?"
Environmentalists will worry that such optimism breeds
complacency about habitat destruction. But it might instead breed
ambition to restore habitats and revive rare species. Over the past
50 years, agricultural yields have risen and, in real terms, food
prices have fallen, with the result that marginal land has been
released from growing food worldwide. Forest cover has increased in
most of Europe and North America; nature reserves have expanded
even in the tropics.
So here's an image of the future. With much of the world's meat
grown, brain-free and legless, in factories, and much of its fruit
and vegetables in multi-storey urban farms lit with cheap fusion
power, there will again be vast steppes, savannahs, prairies and
rain forests, teeming with herds of wild game. Perhaps even a few
woolly mammoths among them.
