Science in the News Article: How corkscrew vaginas and female penises evolved

Menno Schilthuizen, author of "Nature's Nether Regions" (Viking, 2014), looks at saki monkeys at the Prospect Park Zoo.

Menno Schilthuizen, author of “Nature’s Nether Regions” (Viking, 2014), looks at saki monkeys at the Prospect Park Zoo.
Credit: Megan Gannon for Live Science

BROOKLYN, N.Y. — A male ruddy duck with a sky-blue beak coasted across a pond here at the Prospect Park Zoo, brightening a rudely cold spring day.

“There’s a very nice sexually selected bill color,” Dutch biologist Menno Schilthuizen said, poking his head over the wooden-post fence.

At some point in the species’ history, female ruddy ducks decided blue bills were sexy, and evolution favored the flamboyant feature. But evolution just as carefully selected another extravagant male trait, which, at the time, was hidden: a long, corkscrew-shaped penis. [The 7 Weirdest Animal Penises]

In his new book, “Nature’s Nether Regions” (Viking, 2014), Schilthuizen takes a sweeping look across the animal kingdom — from ducks tohermaphroditic snails that have sex all day to sharks that use one of their penises, or “claspers,” (they have two) to flush rival sperm out of the female’s vagina — to illustrate an amazing diversity of genitalia that has been largely unappreciated, even among scientists.

A sluggish start

“I think a lot of evolutionary biologists and people working on sexual selection were not fully aware of the genital diversity that exists,” Schilthuizen told Live Science in an interview at the zoo, commenting on the study of the evolution of sex parts, which has only taken off in the last 25 to 30 years. “The information was there, but it was contained within the field of taxonomy, where it was used extensively for identifying and circumscribing species.”

Many bumblebee species, for example, share the same wardrobe, and the only way for taxonomists to tell them apart was to capture a male and examine its penis, Schilthuizen explained in his book. But it took decades for scientists to realize that species-specific sex parts weren’t part of some lock-and-key design, but rather something more complex.

Back to the ruddy duck: While most birds don’t have any penis whatsoever, ducks do, and these prodigious members unfurl explosively when it’s time to mate. Only recently did scientists discover that some female ducks have long, corkscrew-shapedmenno-schilthuizen-zoo vaginas that spiral in the opposite direction as the male’s member. This allows the female to fight back against undesirable, notoriously aggressive males, since the duck’s penis won’t fit so easily. In this way, duck genitals look less like the byproducts of choosy females than the consequences of a sexual arms race, where male and female parts have evolved in response to each other’s ever-advancing equipment.

Charles Darwin might bear some of the blame for this tunnel vision. For all his contributions to the study of evolution, Darwin’s focus on secondary features unconnected to sex organs may have limited how biologists began investigating sexual selection.

“Because Darwin had paved the way with colorful feathers, rather than genitals, people who work on sexual selection had immediately started working on bird plumage and external features of precopulatory sexual selection, things like these colorful furs,” Schilthuizen said, this time pointing at the orange coats of the perky marmosets hopping between branches behind the glass of an indoor display. And sexual selection of bright colors and bizarre nether regions are not simply special cases of natural selection. [Why So Many Animals Evolved to Masturbate]

“It’s really sort of like chasing a moving target,” Schilthuizen said. “It’s not a kind of evolution that has an optimum or an end point, which adaptation to the environment often does have. The environment is usually much more static than the other half of the same species that co-evolves in response. That’s, by definition, a very dynamic kind of evolution.”

Female penises, male vaginas

When talking about genitals, scientists risk wading into a “semantic morass,” as Schilthuizen calls it in his book. That was perhaps apparent in April when a group of researchers announced the discovery of four news species of cave insects in which the females have a penis — or technically, an organ called a “gynosome,” which acts like a penis — and the male organ more closely resembles a vagina with valuable packets of sperm.

Shown here, the female penis structure of the cave insect Neotrogla aurora.
Shown here, the female penis structure of the cave insect Neotrogla aurora.
Credit: Current Biology, Yoshizawa et al.

“It’s such a good way of illustrating that sexual roles are not about whatsex chromosomes you have or what kind of sex cells you produce, but it’s really about how much you invest in the offspring, and that is what drives not only the intensity but also the direction of sexual selection,” Schilthuizen said.

For the role-reversing cave insects of the genus Neotrogla, the males’ sperm packets, or spermatophores, offer hard-to-come-by nutrients to the females to produce eggs and nourish their offspring. [See Photos of the Genital-Reversed Cave Insects]

“The male has become the sex which invests most nutrients in the offspring, so the male has become the choosy sex, and the females compete over access to the males with their large nutrient spermatophore,” Schilthuizen said. “That has set in motion the evolution of an intermittent organ in the females to either forcefully or otherwise persuade the male to give up that spermatophore.”

Human bias

Perhaps our tendency to anthropomorphize even tiny cave insects makes Neotrogla‘s gender-reversed arrangement seem bizarre. But if human bias distorts the way we look at animals, it also distorts the way we view ourselves.

As recently as the 1960s, many people — biologists even — held on to the rather romantic notion that the female orgasm was unique to humans and perhaps functioned as a way to promote bonding between couples. But for many animals, courtship extends beyond flaunting a flashy coat. Most female mammals have a clitoris, and likely experience orgasms during sex, though the organ might take on a shape wildly different from the human variety. Female spotted hyenas, for example, give birth through their 7-inch-long (18 centimeters) clitoris that looks more like a pseudopenis.

So what sets humans apart? Human males don’t have spines on their penises as chimpanzees (humans’ closest living relatives) and other large primates do, and females don’t experience conspicuous swelling of the vagina when they are fertile and ready to mate, Schilthuizen said, giving two examples. But one could revert the argument and find features on any animal that make it special.

“When everything is bizarre, then nothing is bizarre,” Schilthuizen said. “We have a tendency to still use what is familiar as the norm, and we need to realize that very few animals, because of this diversity, can be directly compared to humans or other animals that we are familiar with. And at a certain point, I wouldn’t say you become blasé, but you become aware that this unpredictably is more characteristic of sexual evolution than anything else. When you realize this, you stop being surprised.”

At the same time, with more knowledge about the multitude of intimate arrangements in the animal world, the most mundane creatures seem more fascinating.

“Even the chipmunks and squirrels that you see in the park here — once you know that they have sperm plugs and asymmetric penises and things like that, you look at them in a very different way,” Schilthuizen said.

The Cosmos Documentary E2 Reflection-Nathalie

COSMOS: Episode 2

Posted by Nathalie Istanto in Biology SL on Tuesday, April 29th, 2014 at 3:49 pm

The second episode of Cosmos talked about the evolution of species. This relates back to the option chosen for our IBDP Biology course, Option D: Evolution. The episode begins by talking about artificial selection in wolves and continued on to talk about natural selection in polar bears. Finally, the episode shows extinctions of animals.

I was interested in the way the wolves evolved into domesticated dogs. It was interesting that the less violent wolves were the ones more likely to survive alongside humans, and evolved into domesticated dogs. I always thought that evolution was the “survival of the fittest”, which I always interpreted as the strongest and largest animals. However, after watching this episode, I found out that smaller animals can also survive, as long as they have a certain characteristic which benefits them.

I knew that polar bears evolved from normal bears, but I didn’t know that their fur color were a simple accidental gene mutation. It’s interesting to think that simple accidents can affect the survival of a whole population. Just from a small accident, the polar bears were able to catch their preys easily compared to the brown bears. I was also able to review a bit on genetics from the small section on the gene mutation in the polar bear’s egg.


Water Bear

The most interesting part of the whole episode for me would be the part where the host talks about how eyes evolve. I find it really interesting that our eyes aren’t as “perfect” as I expected. It turns out, our eyes were originally made to work underwater. As we evolved into land animals, our eyes were slowly adjusting, but wouldn’t work as great as it would underwater. This was because evolution didn’t start over. Instead, it changes bit by bit in our gene. I think that this part is really important as it shows that all living beings adapt. We are probably still evolving at this moment without realizing it.

There has been 5 mass extinctions in the history of the Earth. Apparently, one tiny animal known as the tardigrade was able to survive all this. The tardigrade can survive in many different conditions, from the cold ice to hot lava to even outer space. I find this creature quite cute but also interesting. This tardigrade is proof that with the right genes and characteristics, living things can survive in many different conditions.

The Cosmos Documentary E1Reflection-Nathalie

COSMOS: Episode 1

Posted by Nathalie Istanto in Biology SL on Tuesday, April 29th, 2014 at 3:19 pm

We began watching part of the Cosmos: A Spacetime Odyssey in biology class. The first episode begins with how the universe was formed and how small the earth is compared to the rest of the universe. It also talks about Giordano Bruno, who stood up against the Catholic Church on his theory that the Earth wasn’t the center of everything.

I think that the whole episode was done so beautifully, and the shots were artistic. I find that the whole episode was informative and that I learned quite a bit on how the whole universe. I find it interesting how Bruno was able to think of his theory on the rest of the universe without any scientific training. It’s such a shame that he was killed before people began to prove his idea.

I find this episode fascinating, especially the way they presented the age of the universe with a cosmic calendar. I am astonished to find out how old the universe is compared to us, and that we humans are only found at the very end of the cosmic calendar. It was also interesting to find out how small we humans are when compared to the rest of the universe. We live in the planet Earth, which is located in the solar system. The solar system is located in the Milky Way Galaxy, which in turn is located in the Local Group. The Local Group is then located in the Virgo Supercluster. This shows we are compared to the rest of the world, which shows that we are quite insignificant when compared to the whole universe.

The Cosmos Documentary E1 Reflection -Nabilia

Cosmos: Space Time Odyssey #1 Posted by Nabilla Gunawan in Biology HL on Wednesday, April 30th, 2014 at 06:45 My first impression after watching “The Cosmos” is: beautiful. I awed several times throughout the movie, I just simply think that the visuals this movie presented are beautiful. Watching this movie made me realize how grand the universe is. It is always interesting to explore the past and the beginning of life. Knowledge can be perceived as something dangerous back then. I was a little bit appalled by the narrowmindedness of people towards Bruno – the man who disagrees with the church’s persepctive about earth is the center of universe. Throughout the time, more and more things are discovered, such as Earth, Solar System, Milky Way Galaxy, Virgo Supercluster and The Cosmos.

The Cosmos Documentary E1 Reflection-Geun Myo

Cosmos documentary

Posted by Geun Kim in Biology HL on Wednesday, April 30th, 2014 at 6:08 am

An episode on how lead was taken out of the environment told about how people now know that the Earth is 4.5 billion years old, and explored but shoots down the possibility of the Earth being 6,000 years old.Cosmos also explored a fight that lasted decades between scientists, the government, and big corporations about the hazards of lead emissions in the environment. By telling the story of a scientist who stood up against corporations to defend his views on the dangers of lead emissions, the corporations looked greedy and selfish on the show, and Cosmos opened up a controversial topic; one that could potentially make big companies look bad.

The Cosmos Documentary E1 Reflection – Christy

Biology: “Cosmos” Reflection

Posted by Christy Zakarias in Science on Tuesday, April 29th, 2014 at 8:49 pm



  • The structure of our cosmos: Earth – Solar System – Milky Way Galaxy – Virgo Supercluster – The Cosmos.
  • Our cosmos was created through a Big Bang.
  • The Sun doesn’t exist for the first few months of the Cosmic Calendar.
  • Comets shower abolished the existence of dinosaurs on Earth.
  • Humans have only started to evolve within the last seconds of the Cosmic Calendar.


  • The Earth’s early conditions (atmosphere, diversity, topography, and so on) when humans first evolved.
  • The effects of human evolution on other living things.
  • The process scientists went through to map out our cosmos.


  • I love the concept of the Space Odyssey, and am definitely keen on the style of narration. The special effects and photos of outer space are out of this world (pun intended!). I am excited to continue watching!



  • Factors affecting evolution includes inter-species relation, natural selection and artificial selection.
  • Artificial selection is when human interference contributes to the resulting mutation – which ultimately leads to evolution. Meanwhile, natural selection is when the mutation that leads to evolution is utterly caused by natural factors. Natural selection ensures that only the strongest, better-adapted species survive.
  • Mutation due to transcription and translation is entirely random.
  • The genetic code is universal, hence all living things shares a common ancestor.
  • Evolution reshapes species by little tweaks in the genetic code over generations, but it can’t start over and create entirely new species.
  • Evolution is “blind” to catastrophes, this leads to extinctions.


  • Same as episode one.

Darwin & Natural Selection

Evolution by Natural Selection

Posted by Nabilla Gunawan in Biology HL on Tuesday, May 6th, 2014 at 16:30

Charles Darwin

Portrait of Charles Darwin (“Charles Darwin”)

Charles Darwin (12 February 1809 – 19 April 1882) was a British Scientist who formulate the “Evolution by Natural Selection” Theory. He was born in a wealthy family. Darwin planned to follow a medical career during his studies in Edinburgh University, however switched to Cambridge in the latter of his university years. He went to a voyage that aims to conduct a survey on a ship called HMS Beagle.

During this era, European was still strongly driven and controlled by religion, Christianity in particular. They believed that the world was created by God in seven days, according to bible. Darwin’s ideas on evolution were sparked after reading a book called “Principles of Geology”, which suggested that the fossils found in rocks were actually evidence of animals that had lived millions years ago. Darwin’s thoughts were augmented during his voyage as he saw himself the the variety of animal life and geological features. Darwin was much convinced after he visited Galapagos Islands. Darwin noticed that the Finch were closely related, but different in some ways; the birds have different shapes of beak.

Evolution of “Human”

Darwin wrote his theory based on his observations and come up with an idea on how species evolve. He proposed a theory or evolution, stating that evolution occurs by the process of natural selection, stated below:

The animals (or plants) best suited to their environment are more likely to survive and reproduce, passing on the characteristics which helped them survive to their offspring. Gradually, the species evolve over time.

He published his discoveries on 1859, after helding back his theory for almost 20 years. He immediately published his theory “On the Origin of Species by means of Natural Selection” after learning that another naturalist – Alfred Russell Wallace – developed a similar idea. Due to his theory, Darwin was forcefully attacked by the public and the churh. How theory was extremely controverial during that era. But now, majority are able to accept his theory, and in fact some are investigating in more depth.

To see further on Evolution by Natural Selection or Charles Darwin, view the Evolution video Crash Course below:



“Charles Darwin (1809 – 1882).” BBC News. BBC, n.d. Web. 05 May 2014 <>.

“Charles Darwin.” Panjury. N.p., n.d. Web. <>.

Article Reflection-How to bring back extinct animals-Nathalie

Bringing Back Extinct Animals

Posted by Nathalie Istanto in Biology SL on Tuesday, April 8th, 2014 at 11:06 am


Scientists are able to resurrect animals which have gone extinct. This is important as some animals who are now extinct could have provided scientists with a better understanding on evolution or other scientific knowledge. Some of these animals are also extinct because of human activity. Since it was our fault in the first place, we should try to fix it.

I personally think that cloning animals that are already extinct is a great idea. We can learn more about them from observations instead of relying on past information. However, I also feel that there are some things scientists need to consider before they begin cloning these animals. Firstly, the process itself is quite hard. Scientists dream of cloning a wooly mammoth, but where are they going to find a mammoth’s egg to transfer the nucleus into? Not only that, obtaining the somatic cells of the extinct species can also be challenging.

Scientists also have to think of the environment these cloned animals are going to live in. Some animals are extinct because their natural habitat is destroyed. They might not survive living out in the wild now, so what is the use of cloning these animals if they are just going to die anyway? The money and manpower could have gone into genetic research on a genetic disease instead of cloning animals that could not live in the wild nowadays.

People are also afraid that cloning extinct animals will make the conservation of animals harder. Many people will not want to help conserve habitats of near-extinct animals because they think that these animals can be cloned in a lab. They will continue doing more harm to the environment than good. However, governments are able to create laws to protect the spaces before any of the extinct animals are cloned so that people will still protect that space.

Cloning extinct animals have both advantages and disadvantages, but I think that with proper rules and regulations, the disadvantages can be eliminated.

Article Reflection: The Magical Stem Cell-Nabila

The “Magical” Stem Cell

Posted by Nabilla Gunawan in Biology HL on Tuesday, April 8th, 2014 at 12:59

Infographic: How cloning produces stem cells that can be used to create organs or other body parts as needed.


What if we can regrow our amputated hand back?  Or recreate our broken kidney? Or save someone’s life through medical process. Most of you would say yes wouldn’t you? Thanks to science, particularly biology, allows us to do such thing. This “magical” cell is called stem cell. Stem cell is an undifferentiated cell of a multicellular organism that is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation. Instead of cloning the whole individual, its organs are the one that is cloned.

Stem cell can be obtained from two sources, human’s bone marrow and embryo. So far, embryotic stem cell is proven to be more versatile than adult stem-cell. It is due to the undifferentiated beginning of embyotic stem cell, embryotic stem cell has far greater potential to develop into any human organs.

I’m personally in favour of this stem cells idea. Embyonic stem cells can be use to renew our organ an it might as well increase human’s life expectancy. Not only “normal” organs that can be obtained from donors, but less common organ such as brain or spinal cord, or even the heart. Althoug this has brought up a lot of ethical discussion, such as the process of acquiring the stem cell. It is taken from an embryo, an unborn fertilized cells that is soon to be developed as a baby. If stem cell cloning goes public, there might be a possibility that illegal market on human embryo increase to fullfill the demand of patient that needs stem cell. Acquiring stem cell from embryo can be considered as murdering, although I these embryos have not been through any experience form life or experience what so called “life”.

It is also a possibility that peole in authority will have greater possibility to receive stem cell treatment, there will always be these conspiracy that puts the less privileged people in a harmful position. Issues such as stem cell cloning rose plenty of social issues.

Video Reflection: Ghost in our Genes-Christy

Biology: Ghost In Your Genes

Posted by Christy Zakarias in Science on Monday, February 24th, 2014 at 10:39 am

What is ‘epigenetics’?

Heritable changes in gene expression that does not involve changes to the underlying DNA sequence; a change in phenotype without a change in genotype (“Fundamentals”).

What is the most interesting information you learnt from the documentary?

From the documentary, I learnt that there is another side to genetics aside from the human genome, epigenetics. Dubbed epigenetics are chemical markers along the DNA that control a person’s development by turning genes on and off. These markers vary widely for each person, and are influenced by one’s environment as well as experiences.

What responsibilities do you have to your grandchildren?

Just like genetic information, epigenetics can be passed down from generation to generation. Hence, what I do and experience today can impact the characteristics and health of my future grandchildren. Bearing this in mind, it is then important for me to adopt a healthy lifestyle, one that, for the most part, does not involve starvation, junk food, drinking and smoking. The change in epigenetics might not be immediately apparent in my next generation, however this is only because, as illustrated by the documentary, those changes tend to become increasingly visible two to three generations thereafter.

Works Cited

“Fundamentals.” What Is Epigenetics. N.p., n.d. Web. 23 Feb. 2014. <;.