Home' Trinidad and Tobago Guardian : December 24th 2016 Contents Why does sex exist when organ-
isms that clone themselves use less
time and energy, and do not need
a mate to produce offspring? Re-
searchers at the University of Stir-
ling aiming to answer this age-old
question have discovered that sex
can help the next generation resist
Populations that clone themselves are
entirely female and do not need sex to
As sex requires males, and males do
not produce offspring themselves, an
entirely clonal population should always
reproduce faster than a sexual one.
Yet while some animal and plant spe-
cies can reproduce without sex, such as
komodo dragons, starfish and bananas,
sex is still the dominant mode of repro-
duction in the natural world.
Scientists know that sex allows genes
to mix, allowing populations to quick-
ly evolve and adapt to changing envi-
ronments, including rapidly evolving
However, for sex to beat cloning as
a reproduction strategy, there must be
large-scale benefits that make a differ-
ence to the next generation.
The theory has been difficulty to test
as most organisms are either wholly
sexual or clonal so cannot be compared
A team of experts from the Universi-
ty of Stirling have taken an innovative
approach to test the costs and benefits
Using an organism that can reproduce
both ways, the waterflea, researchers
found sexually produced offspring were
more than twice as resistant to infec-
tious disease as their clonal sisters.
Dr Stuart Auld of the Faculty of Nat-
ural Sciences, said: "One of the oldest
questions in evolutionary biology is,
why does sex exist when it uses up so
much time and energy?
"Sex explains the presence of the
peacock's tail, the stag's antlers and the
male bird of paradise's elaborate dance.
"But if a female of any of these species
produced offspring on her own, without
sex, her offspring should come to dom-
inate, while the other females watch the
redundant males fighting and dancing.
So, why are we not surrounded by clonal
A26 body & soul
guardian.co.tt Saturday, December 24, 2016
The scientists examined 6,000 Daphnia, waterflea, as part of the
study. PHOTO: UNIVERSITY OF STIRLING
Sex evolved to help
future generations fight
infection, scientists show
YOUR DAILY HEALTH
News and advice
A drug that alters the immune
system has been described as
"big news" and a "landmark"
in treating multiple sclerosis,
doctors and charities say. Trials,
published in the New England
Journal of Medicine, suggest
the drug can slow damage to the
brain in two forms of MS.
Ocrelizumab is the first drug
shown to work in the primary pro-
gressive form of the disease. The
drug is being reviewed for use in
the US and Europe.
MS is caused by a rogue immune
system mistaking part of the brain
for a hostile invader and attacking
it. It destroys the protective coating
that wraps round nerves called the
myelin sheath. The sheath also acts
like wire insulation to help electrical
signals travel down the nerve.
Damage to the sheath prevents
nerves from working correctly and
means messages struggle to get from
the brain to the body.
This leads to symptoms like hav-
ing difficulty walking, fatigue and
The disease can either just get
worse, known as primary progres-
sive MS, or come in waves of disease
and recovery, known as relapsing
Both are incurable, although there
are treatments for the second state.
Ocrelizumab kills a part of the im-
mune system---called B cells---which
are involved in the assault on the
In 732 patients with progressive
MS, the percentage of patients that
had deteriorated fell from 39 per
cent without treatment to 33 per
cent with ocrelizumab.
Patients taking the drug also
scored better on the time needed
to walk 25 feet and had less brain
loss detected on scans.
In 1,656 patients with relapsing
remitting, the relapse rate with
ocrelizumab was half that of using
Prof Gavin Giovannoni, from
Barts and The London School of
Medicine and Dentistry, was in-
volved in the trials and said: "The
results shown by these studies have
the potential to change how we ap-
proach treating both relapsing and
primary progressive MS."
He told the BBC: "It's very signif-
icant because this is the first time a
phase three trial has been positive
in primary progressive MS."
More than 100,000 people are
diagnosed with MS in the UK, and
around one-in-five are progressive.
Dr Aisling McMahon, the head
of clinical trials at the MS Socie-
ty, commented: "This is really big
news for people with the primary
progressive form of multiple scle-
rosis. It's the first time a treatment
has shown the potential to reduce
disability progression for this type
of MS, which offers a lot of hope for
The drug is being considered by
the European Medicines Agency and
the US Food and Drug Administra-
"By comparing clonal and sexual
daughters from the same mothers,
we found sexually produced off-
spring get less sick than offspring
that were produced clonally. The
ever-present need to evade disease
can explain why sex persists in the
natural world in spite of the costs."
The waterfleas and their par-
asites were collected from the
wild. Sexual and clonally pro-
duced daughters were harvested
from the wild waterfleas and these
offspring were exposed to the par-
asites under controlled laboratory
The study is published in Royal
Society Proceedings B.
(University of Stirling)
Multiple sclerosis drug 'a landmark'
"By comparing clonal and
sexual daughters from
the same mothers, we
found sexually produced
offspring get less sick
than offspring that were
produced clonally. The
ever-present need to
evade disease can explain
why sex persists in the
natural world in spite of
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