E*****o
发帖数: 2 | 1 Hi, guys! Is it really feasible in a reasonable-distant future?
http://www.nytimes.com/2012/12/02/magazine/can-a-jellyfish-unlo
After more than 4,000 years — almost since the dawn of recorded time, when
Utnapishtim told Gilgamesh that the secret to immortality lay in a coral
found on the ocean floor — man finally discovered eternal life in 1988. He
found it, in fact, on the ocean floor. The discovery was made unwittingly by
Christian Sommer, a German marine-biology student in his early 20s. He was
spending the summer in Rapallo, a small city on the Italian Riviera, where
exactly one century earlier Friedrich Nietzsche conceived “Thus Spoke
Zarathustra”: “Everything goes, everything comes back; eternally rolls the
wheel of being. Everything dies, everything blossoms again. . . .”
Sommer was conducting research on hydrozoans, small invertebrates that,
depending on their stage in the life cycle, resemble either a jellyfish or a
soft coral. Every morning, Sommer went snorkeling in the turquoise water
off the cliffs of Portofino. He scanned the ocean floor for hydrozoans,
gathering them with plankton nets. Among the hundreds of organisms he
collected was a tiny, relatively obscure species known to biologists as
Turritopsis dohrnii. Today it is more commonly known as the immortal
jellyfish.
Sommer kept his hydrozoans in petri dishes and observed their reproduction
habits. After several days he noticed that his Turritopsis dohrnii was
behaving in a very peculiar manner, for which he could hypothesize no
earthly explanation. Plainly speaking, it refused to die. It appeared to age
in reverse, growing younger and younger until it reached its earliest stage
of development, at which point it began its life cycle anew.
Sommer was baffled by this development but didn’t immediately grasp its
significance. (It was nearly a decade before the word “immortal” was first
used to describe the species.) But several biologists in Genoa, fascinated
by Sommer’s finding, continued to study the species, and in 1996 they
published a paper called “Reversing the Life Cycle.” The scientists
described how the species — at any stage of its development — could
transform itself back to a polyp, the organism’s earliest stage of life, “
thus escaping death and achieving potential immortality.” This finding
appeared to debunk the most fundamental law of the natural world — you are
born, and then you die.
One of the paper’s authors, Ferdinando Boero, likened the Turritopsis to a
butterfly that, instead of dying, turns back into a caterpillar. Another
metaphor is a chicken that transforms into an egg, which gives birth to
another chicken. The anthropomorphic analogy is that of an old man who grows
younger and younger until he is again a fetus. For this reason Turritopsis
dohrnii is often referred to as the Benjamin Button jellyfish.
Yet the publication of “Reversing the Life Cycle” barely registered
outside the academic world. You might expect that, having learned of the
existence of immortal life, man would dedicate colossal resources to
learning how the immortal jellyfish performs its trick. You might expect
that biotech multinationals would vie to copyright its genome; that a vast
coalition of research scientists would seek to determine the mechanisms by
which its cells aged in reverse; that pharmaceutical firms would try to
appropriate its lessons for the purposes of human medicine; that governments
would broker international accords to govern the future use of rejuvenating
technology. But none of this happened.
Some progress has been made, however, in the quarter-century since Christian
Sommer’s discovery. We now know, for instance, that the rejuvenation of
Turritopsis dohrnii and some other members of the genus is caused by
environmental stress or physical assault. We know that, during rejuvenation,
it undergoes cellular transdifferentiation, an unusual process by which one
type of cell is converted into another — a skin cell into a nerve cell,
for instance. (The same process occurs in human stem cells.) We also know
that, in recent decades, the immortal jellyfish has rapidly spread
throughout the world’s oceans in what Maria Pia Miglietta, a biology
professor at Notre Dame, calls “a silent invasion.” The jellyfish has been
“hitchhiking” on cargo ships that use seawater for ballast. Turritopsis
has now been observed not only in the Mediterranean but also off the coasts
of Panama, Spain, Florida and Japan. The jellyfish seems able to survive,
and proliferate, in every ocean in the world. It is possible to imagine a
distant future in which most other species of life are extinct but the ocean
will consist overwhelmingly of immortal jellyfish, a great gelatin
consciousness everlasting. |
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