
Why 'Sexual Mind Control' Is Rare in Nature  - yiedyie
http://news.sciencemag.org/biology/2014/01/why-sexual-mind-control-rare-nature
======
mnw21cam
It's a simulation. In other words, the only conclusions that the scientists
can really draw out are those that were hard-coded into the organism behaviour
to begin with. For instance, they speculate that perhaps it might be a
disadvantage to the parasite to have to generate powerful hormones - yeah,
they would have had to have written that particular parameter into their
simulation. Alter the parameter slightly, and you change the outcome.

~~~
eloff
Most of the simulation results for things like this are dubious at best. Seems
like money better spent to me to focus research energy on more useful
endeavors. However, some simulations are extremely useful and really do
represent reality well.

~~~
mnw21cam
The key is if you can match the simulation parameters to the results, so you
can say "if the disadvantage of having to produce hormones to control the host
becomes less than X, then we see sex mind control appearing - we generally
don't see this in nature, so it must be more disadvantageous than X to produce
hormones". That's a real result.

------
terranstyler
I'd say that it is in the host's own interest to maximize sexual activity
given all other constraints (long term survival and reproduction).

This is why a parasite won't be able to improve (or optimize) it further since
it is fully aligned with the host's incentives.

TLDR: You can't improve what's already optimal

~~~
etiam
I agree with that point with respect to the host's fitness. But the conflict
here stems from the fact that those other constraints (such as the host's long
term survival or reproduction) has little or no value in itself to the
parasite, so there's a chance to have a mismatch of fitness objectives between
the host and the parasite.

~~~
terranstyler
If I understand correctly, you suggest that a parasite would sacrifice "long
term survival" or "offspring adulthood probability" to achieve increased
reproductive success!?

Hmm, the host could for example go on a "raping spree" but it unsure how this
would lead to _significantly_ increased reproduction (I suppose this is an
energetically costly enterprise) and why the raping spree wouldn't be already
an "integrated" behavior if it were so successful.

~~~
etiam
In this case 'a parasite would sacrifice _host_ long term survival or _host_
offspring adulthood probability to achieve increase _it 's own_ reproductive
success'.

The article concerns parasite manipulation of host behaviour, and to the
extent that such manipulation can take control the host will act in the
parasite's genetic interest rather than it's own.

------
dispense
Why have parasites promoting mating success been observed so rarely?

Paywalled article:
[https://www.sciencedirect.com/science/article/pii/S002251931...](https://www.sciencedirect.com/science/article/pii/S0022519313005109)

Abstract:

Host manipulation by sexually transmitted parasites which increases host
mating rate and thus parasite transmission rate has long been viewed as a
plausible parasite adaptation. However, empirical evidence for it is rare.
Here, using an adaptive dynamics approach to evolution, we explore conditions
under which such disease-induced mating enhancement is (or is not) likely to
occur. We find that increased mating success is less likely to evolve if the
host reproduction rate, or the baseline disease transmission rate, is reduced,
and the parasite affects just one sex, compared to when it affects both. We
also find that it is less likely to evolve if the virulence-transmission
trade-off curve is stronger, since we assume that enhanced disease
transmission can only be achieved at the cost of increased virulence and as
this trade-off is concave. In addition, we demonstrate that if disease-induced
mating enhancement is equally acting in both sexes the mating system has no
effect on evolutionary outcomes. On the contrary, if disease-induced mating
enhancement is acting in just one sex, the potential for its evolution
increases with the degree of polygyny in the host population. To study the
examined phenomenon in greater detail we encourage further empirical research
on this apparently less explored impact of sexually transmitted parasites on
host fitness.

------
ytjohn
This is just what the mind controlling parasites want you to think.

------
yiedyie
_«The researchers speculate that sexual mind control either costs too much
energy for the parasite, causes too much harm to the host, or both»_ Judging
by the harm to the host(see Sex and the City) the City has that energy, that
if we see the City as a parasite.

------
mixedbit
Dawkins in "the Extended Phenotype" argues that manipulation such as 'Sexual
Mind Control' is very common in nature. One of examples that he gives is a
female cricket that is 'programmed' to react to a male song. He writes:

'The object's internal chain of command — sense organs, nervous system,
muscles — may be infiltrated and subverted. A male cricket does not physically
roll a female along the ground and into his burrow. He sits and sings, and the
female comes to him under her own power. From his point of view this
communication is energetically more efficient than trying to take her by
force.'

~~~
na85
Dawkins is just describing the mating habits of a very simple organism. It is
not the same as a parasite/virus/whatever causing an increased libido.

------
erikb
I would start with wondering if all STDs have the purpose to be transmitted
sexually. Like aids doesn't look to me like it's purpose is sexual
transmission. Other exchanges of fluids might also result in infection.

------
mattmanser
_The researchers speculate that sexual mind control either costs too much
energy for the parasite, causes too much harm to the host, or both._

Speculate? SPECULATE? How can they not _know_.

It's a simulation for god's sake! How can they not spit out an average for
energy consumed per infected host? How can they not have that data?

Sounds suspiciously like pseudo-science.

~~~
awkward
So you accept that a simulation is a valid experiment, but feel that refusing
to tell science press that natural phenomena fit the exact parameters of the
simulation is pseudo science?

~~~
mattmanser
You completely misunderstood me. What I'm saying is how on earth can it be
valid if they are speculating on the very basic questions.

