16 | New Scientist | 15 January 2022
NEW research in bottlenose
dolphins shows that the females
have clitorises that evolved for
pleasure. Biologist Patricia
Brennan tells New Scientist how
she and her colleagues carried
out this study, why it is so vital
to study female genitalia and
her response to naysayers who
question the value of her work.Jessica Hamzelou: How did
you come to study this subject?
Patricia Brennan: I have been
collaborating with a researcher
studying vaginas in dolphins.
When we dissected the vaginas,
I would look at these clitorises
and be just amazed. I was like:
“Oh my gosh, these are pretty
big, well-developed clitorises.”
We know that dolphins have
sex all the time, not just for
reproduction. It makes sense
that the clitoris would be
functional [and give pleasure
when stimulated].Are dolphins really having
sex all the time?
Bottlenose dolphins live close to
the shore, where scientists can
go out on their boats and study
them. They see them having
sex year-round, even when the
females are not receptive, so
not ready to get pregnant.
Not only do they have sex
all the time, they have a lot of
homosexual sex. The females
will rub each other’s clitorises
with their snouts and their
flippers really often. It’s not
like every once in a blue moon,
it’s actually pretty common.
Females also masturbate.
If they’re out there seeking
all these sexual experiences,
it’s likely that it’s feeling good.What are you looking for
in the dolphin clitorises?
We were particularly interested
in the erectile tissue. We looked
at the nerves, too – we were
shocked by how big they were.
We were also able to see free
nerve endings right underneath
the skin. These are known to
increase sensitivity. We have
these in great abundance in our
fingertips, and in the human
clitoris and the glans penis.
And then we found that the
skin itself in the clitoris is about
a third of the thickness of the
adjacent skin. Once we put all of
those things together, we werepretty certain that this is
functioning in pleasure, just
like in humans. It’s providing the
morphological evidence that
we need to say, yes, this is what
a functional clitoris looks like
(Current Biology, doi.org/hcfk).Is this controversial?
There is this hypothesis
that, because penises and
clitorises share the same
developmental pathway,
the clitoris is just a mini penis,
it doesn’t necessarily have
a function. There is debate
whether even human female
orgasms are functional or just a
by-product. It just refuses to die.
We can show that this is
actually a fully functional organ
that’s serving a purpose. It’s
probably evolutionarily a good
idea because it makes you seek
out sex more often.Critics have questioned the
importance of your research in
the past. What is your response?
We’re trying to describe natural
phenomena. There are people
who are uncomfortable with
studies of sexual behaviour, in
humans or other animals. I’m a
scientist. I ask questions where
I think there are interesting
questions to be asked. ❚Profile
Patricia Brennan is a biologist
who studies sexual behaviour and
evolution. She is based at Mount
Holyoke College in MassachusettsEvolution of the clitoris
Interview: Patricia BrennanIM
AGEB
ROKE
R/ALA
MYA study of dolphin genitalia should end any notion that
the clitoris is just a “mini penis”, finds Jessica HamzelouNews
MicrobiologyBACTERIAL biofilms contain a
level of structural organisation
that we thought was unique to
plants and animals.
Biofilms, slimy clumps of
microorganisms, were long
considered to be biologically
simple, with no more than a
primitive level of structural
organisation. This contrasts with
many multicellular organisms,
including animals, in which cells
can grow into different forms at
different times and places during
the body’s development to
produce complex structures.Now, Gürol Süel at the University
of California, San Diego, and his
colleagues have discovered that
bacterial biofilms aren’t as simple
as we thought. They explored the
response of a Bacillus subtilis biofilm
to being starved of vital nitrogen.
This typically causes bacterial cells
to change and become more resilient
in an adaptation called sporulation.
But rather than all the cells
adapting in the same way, the
researchers could demonstrate
that stress-mitigating genes
produced by the bacteria caused
only some cells to adapt, creating
concentric rings through the roughly
circular biofilm. This tree ring-like
pattern is consistent with a “clock
and wavefront” mechanism, a
more complex structure previously
seen only in animals and plants
(Cell, doi. org/gn2rq7).
“If we just think of [biofilms]
as globs of bacterial cells... we’re
mistaken,” says Süel. “They’re
highly organised.” ❚Alex WilkinsBacteria can form
complex structures
like those of animalsKWANG-TAOCHOUTree ring-like
structures in a
bacterial biofilmBottlenose dolphins
have sex even when
reproduction isn’t possibleLISA^ QUINONES