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by Daniel Cossins
04 June 2016
doi:10.1016/S0262-4079(16)31003-X
from
SCI-HUB Website
Spanish version
Italian
version
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jasper james/getty
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No disease,
no natural conception,
no mind of your own.
Excited?
Imagine a world without sex and disease,
and where all of our brains are
networked.
It sounds wonderful,
but it will bring
a new set of moral questions...
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Rumors of the end of sex are probably premature.
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It has served us well so far, and
besides, we are biologically programmed to want it. But when it
comes to making babies, it is no longer the only option - and
reproduction without sex looks set to become increasingly common.
Last year, human sperm and egg precursor cells were created by
reprogramming adult skin cells.
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Ethical concerns stopped the researchers
from coaxing those cells into fully functional sperm and eggs, but
the feat seems to have been achieved in mice:
a team in China has reported using
stem-cell- derived sperm to sire healthy mouse pups.
What would happen if the trick could be
safely repeated in humans?
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That would be a genuine cure for
infertility, says reproductive biologist Allan Pacey at the
University of Sheffield, UK. It would also mean same-sex couples
could conceive without the help of donors.
It even raises the prospect of individuals procreating alone, if we
could make sperm from a woman's stem cells and eggs from a man's
stem cells.
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The offspring wouldn't be clones of the
person concerned, since DNA is shuffled every time you create a sex
cell. Even so, it's not a good idea, says Pacey - self-fertilization
is tantamount to inbreeding, because it halves the genetic diversity
available to the child.
Sexless reproduction might also appeal to people who can conceive
naturally, because the random shuffling of DNA when sex cells are
made can lead to problems. Every year millions of babies are born
with a disability caused by genetic defects, and many more inherit
gene variants that predispose them to serious illness.
Parents-to-be can already have embryos, created in vitro, screened
for genetic abnormalities before they are implanted in the uterus.
Using stem cells would make it easier to produce lots of eggs, which
in turn makes pre-implantation checks a more viable option.
But will this application ever be allowed? Pacey suspects not, given
the strength of opposition to destroying embryos.
Henry Greely, director of the Center for Law and the
Biosciences at Stanford University, California, and author of
The End of Sex and the Future of Human
Reproduction, begs to differ.
He anticipates that stem cells will first be used to help people who
are unable to make eggs or sperm.
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Once this is approved, he says, other
applications are likely to follow - particularly in the US, where
"off-label use" of any approved medical product is allowed.
Peer pressure might even persuade people that natural conception is
irresponsible, leading fertility clinics to capitalize by imploring
us to,
"have the best child you can".
"This is going to change humanity," says Greely, "so it's
something people need to pay attention to."
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