Russell's Teapot issue 4

The Resurrection of the Christmas
Island Rat
Approximately 120 years ago, a disease brought
by European ships led to the demise of Australia’s
Christmas Island rats; Rattus Macleari
is the scientific name for these species of mammal.
However, scientists are now investigating
whether this extinct creature could possibly be
resurrected.
Resurrecting mammals that died millions of
years ago, like dinosaurs, may seem like something
far from reality, however the examination
of resurrecting a more recently extinct creature
offers insight into the extent to which this is
possible.
A team of palaeontologists researching the
limitations of what technique is possible to
resurrect the Christmas Island rat, said that the
whole point of de-extinction work is defined by
the vast unknown out there. This ensures the
process works and it is very much dependent
on how degraded DNA is rebuilt. A characteristic
of degraded DNA is that it do not contain
all the genetic material required to reconstruct
the full animal genome. An example would be
the carcasses of mammoths found underneath
layers of ice in Siberia – as the freezing of the
ice has usually damaged the DNA. Fortunately,
with the Christian Island rat, which became
extinct in the early 20th century, the team said
they “lucked out”, as they had managed to obtain
all of the rodent’s genome. This is a critical
step in ensuring the possibility of resurrection
of these rats remain promising. As 95% of its
genome is identical to the Norway brown rat,
this provides the perfect case of genome sequencing
as a really good modern reference
comparison was needed.
While the sequencing of the Christmas Island
rat was mostly successful, a few key genes were
missing. These genes oversaw the olfactory system,
which allows the sense of smell, meaning
that without these crucial genes, a resurrected
Christmas Island rat would likely not smell in
the way that it had done originally. Professor
Gilbert from Copenhagen University in Denmark
said that “with current technology, it may
be completely impossible to ever recover the
full sequence, and therefore it is impossible to
ever generate a perfect replica of the Christmas
Island rat”. Though a replica may seem like a
long way off, the key is that scientists can edit
the DNA that defined what makes the extinct
animal fundamentally different from the living
rat. Therefore, Professor Gilbert said that purely
editing an elephant’s DNA may lead to them
growing fur and being able to live in a cold
climate.
The only problem is whether this is ethical or
not, which can only be decided when the Professor
Gilbert and the team of palaeontologists
involved in the project discuss it with other
scientists and the ethics committee. A good
step forward would be to take it incrementally.
For example, we could change existing animals’
DNA, like male lions to not have a head so furry,
but to look more like its female counterpart,
or as Professor Gilbert plans to do, changing a
black rat genome to a Norway brown rat. The
professor has raised some doubts as to whether
it is the best use of money to undertake a project
that goes about reviving extinct species,
when more should be placed on keeping existing
animals alive i.e., the snow leopard, sea
turtles, rhinos and saola.
By Kinshing Huo