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Do animals only breathe through one nostril at a time like humans?

Do animals only breathe through one nostril at a time like humans?


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Humans breathe through one nostril at a time.

Do non-human animals also do so, or do they breathe through both nostrils at once? Has any actual study been conducted on this topic?


The post linked by @Remi.b says

The nasal cycle is a natural ultradian cycle (see here and here. Not only is it present in humans, the nasal cycle has been observed in rats, rabbits, domestic pigs, cats and dogs (see references in Eccles 1996).

Proceeding to Eccles 1996 (p. 372):

The nasal cycle is not only limited to the human nose, as it has been found in the rat and rabbit [31], the domestic pig [32, 33], the cat [34] and the dog [35], and appears to be a universal phenomenon at least in all mammals and possibly other animals…

  1. Bojsen-Moller F, Fahrenkrug J. Nasal swell bodies and cyclic changes in the air passages of the rat and rabbit nose. Anat 1971; 110: 25-37.
  2. Eccles R. The domestic pig as an experimental animal for studies on the nasal cycle. Acta Otolaryngol (Stockh) 1978; 85: 431-436.
  3. Campbell WM, Kern EB. The nasal cycle in swine. Rhinology 1981; 19: 127-148.
  4. Bamford OS, Eccles R. The central reciprocal control of nasal vasomotor oscillations. Pflügers Arch 1982; 394: 139-143.
  5. Webber RL, Jeffcoat MK, Harman JT, Ruttimann UE. Demonstration of the nasal cycle in the beagle dog. J Comput Assist Tomogr 1987; 11: 869-871.

A Pubmed search for '"nasal cycle" animal' gets a total of 18 hits, including refs 32 and 35 above, as well as

  • Spontaneous nasal oscillations in dog. A mucosal expression of the respiration-related activities of cervical sympathetic nerve. Asakura K, Hoki K, Kataura A, Kasaba T, Aoki M. Acta Otolaryngol. 1987 Nov-Dec;104(5-6):533-8.
  • Proceedings: Studies on the nasal cycle in the immobilized pig. Eccles R, Maynard RL. J Physiol. 1975 May;247(1):1P.

A bit more digging forward & backward through citations finds the article on cats (also by Eccles):

R. Eccles & R. L. Lee (1981) Nasal Vasomotor Oscillations in the Cat Associated with the Respiratory Rhythm, Acta Oto-Laryngologica, 92:1-6, 357-361, DOI: 10.3109/00016488109133272

You might find more if you poke around (Google scholar/Pubmed, look at citations backward & forward, try search terms like "'nasal cycle' bird" or "'nasal cycle' reptile"), but at this point I doubt that anyone's bothered to check this in non-mammalian animals…


Surprising Facts About Your Nose

Our noses are generally the subject of both admiration and criticism. Some love their nose, others would change it if they could.

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But it’s easy to forget that your nose, along with your eyes and mouth, don’t just make up your visual identity. And there may be an argument for loving it the way it is.

According to ear, nose and throat specialist Michael Benninger, MD, your nose in particular is one of the most complex and elegant organs in your body. It performs critical life functions and really deserves huge props for its role in keeping you alive and safe — and quite often satisfied.

It’s even responsible for your sex life. (It’s true).

“Your nose is the first organ in your upper respiratory system and one of the main reasons you both survive and thrive,” he says.

Here Dr. Benninger points out several surprising facts about your nose that you might not know.

1. Your nose contains your breath

You’re likely already appreciative of your breath, but it’s kind of a big deal as your nose and mouth are the pathway of air entering and exiting your lungs. In normal everyday breathing your nose is the primary pathway.

Even during exercise where mouth breathing becomes more dominant, some air also still passes through your nose.

“It’s always interesting that although your mouth is a bigger tube, people feel more uncomfortable if their noses are plugged or congested,” Dr. Benninger notes. “That’s how important your nose really is.”

Nasal breathing is also most critical in newborns who breathe through their noses almost all the time. Dr. Benninger adds, “It’s a unique feature related to the configuration of their throats that allows them to breathe and suckle at the same time, without choking.”

“This doesn’t happen in older children or adults,” he adds. “We have to stop breathing to swallow. Something to appreciate next time you aren’t getting air in your nose for a few seconds.”

2. Your nose humidifies the air you breathe

Your nose processes the air you breathe, preparing it for your lungs and throat which do not tolerate dry air well.

As inhaled air passes through your nose, it’s moisturized and humidified thanks to a multiple-layer air pathway with three sets of turbinates (called upper, middle and lower conchae). These are long bony structures covered with a layer of tissue that expand and contract.

This path is where drainage and moisture is regulated. If you have a dry throat, it means the air in this passageway may not have been humidified.

This is also the place where the tone of your voice is shaped as air passes through and the passage expands or contracts.

3. Your nose cleans the air you breathe

The air we breathe has all kinds of stuff in it – from oxygen and nitrogen to dust, pollution, allergens, smoke, bacteria, viruses, small bugs and countless other things. Your nose helps clean it.

On the surface of the nasal tissues in your turbinates, there are cells with tiny hair-like appendages called cilia that trap the bad debris in the air so it doesn’t get into your lungs. Instead, the debris sits in the mucous and is eventually pushed into your throat and swallowed.

“This is extremely beneficial since our stomachs tolerate handling bad debris much better than our lungs do,” Dr. Benninger says.

4. Your nose regulates the temperature of your breath

In the same way your throat and lungs don’t like dirty air, they also don’t like air that’s too cold or too hot.

According to Dr. Benninger, the passing of the air through your nose allows the air to become more like your body temperature, which is better tolerated by your tissues.

Warming cool air in your nose is more common than cooling warm air. That’s because humans spend much more of their time in environments below body temperature — 98.6° — than above it.

“That runny nose you get in cold weather is the best example of this warming and humidifying effect,” he says. “It comes from the condensation of the moisture in your nose when the cold air goes in.”

5. Your nose protects you through smell

High in your nose are a large number of nerve cells that detect odors. In order to smell, the air we breathe must be pulled all the way up to come in contact with these nerves.

Smell plays a key role in taste. We have four primary tastes: bitter, sour, sweet and salty. All of the refinements in taste are related to smell. That’s why people feel that food is tasteless when their ability to smell is decreased.

“Smell and taste are necessary for safety. We need our smell to detect smoke, spoiled food, and some toxic poisons or gases,” Dr. Benninger says.

When we have a cold or allergies, it’s hard for the air to get to these receptors, so people notice a decreased ability to smell.

Those who have completely lost their sense of smell need to have alarms for these gases and must be pay closer attention to what they eat.

6. Smell is important in identification, memory and emotion

Smell partners with your olfactory bulb located in the front part of your brain, just above your nasal cavity. It’s the part of your brain’s limbic system and is associated with memory. We identify other people by the memory of what their personal smell is.

Dr. Benninger points out how this works. “You might remember someone specifically when you smell a certain perfume, soap or similar body odor. If it triggers your memory and you get nostalgic and emotional, that’s also because the limbic system is associated with the control of the emotional part of your brain.”

7. Your nose helps you find a mate

“It’s amazing how many of our body functions are directed toward sexual activity and reproduction,” Dr. Benninger says.

Not only does your olfactory system trigger memory, but your nose plays a critical role when paired with your olfactory system in your perception of sex.

That characteristic smell of a person’s perfume, cologne or the scent of their shampoo or soap is important to sexual arousal. The smell of human perspiration also has a direct effect on sexual receptors in the brain. And loss of smell correlates with decreased sexual drive.

Another interesting and widely debated area is the impact of pheromones. These are very important to reproduction in animals, as well as on human sexuality and stimulation.

A small accessory organ in the nose – the vomeronasal organ (VNO) – is related to the olfactory system. Some refer to it as the sixth sense. The VNO is located at the base of your nasal septum (in the roof of your mouth) and almost all animals, including amphibians, have it.

“In humans, the VNO is largely vestigial or non-functional, acting as an old remnant like your appendix. But some researchers believe that it still plays a role in pheromone and other chemical communication,” Dr. Benninger says.

8. Your nose shapes the sound of your voice

What we hear when people speak and sing is in large part related to the resonating structures of the throat and nose.

Your voice is produced in the larynx but that sound is really a buzzing sound. The richness of the sound is determined by how the sound is processed above the larynx, which occurs in your nose and throat.

According to Dr. Benninger, this is the same principle that separates a grand piano from a child’s toy piano. The nasal voice we hear in someone with a cold and allergies is due to a loss of this nasal resonation since air can’t pass through the nose.

9. Your nose and sinuses are a powerful duo

Sinuses also play a part of the resonance in your voice.

It’s hard to talk about the nose without mentioning the sinuses, which have a number of important and positive roles, according to Dr. Benninger.

Your sinuses are air-filled structures in your head that make your head lighter and probably played an important role in allowing us to become upright. They also serve as air cushion shock absorbers that help protect your brain and eyes.

The partnership between your nose and sinuses help control the amount of nitric oxide in your body and in your lungs. They also play a huge role in your immune functionality.

“When it comes to your nose, there’s a lot of amazing information to think about,” Dr. Benninger says, “But next time you look in a mirror, you may want to consider a new respect for the incredible – and only one – you’ve got.”

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy


Mammals can breathe through anus in emergencies

Two pygmy pigs run around at the 10th Thailand international Pet Variety Exhibition in Bangkok

Rodents and pigs share with certain aquatic organisms the ability to use their intestines for respiration, finds a study publishing May 14th in the journal Med. The researchers demonstrated that the delivery of oxygen gas or oxygenated liquid through the rectum provided vital rescue to two mammalian models of respiratory failure.

"Artificial respiratory support plays a vital role in the clinical management of respiratory failure due to severe illnesses such as pneumonia or acute respiratory distress syndrome," says senior study author Takanori Takebe of the Tokyo Medical and Dental University and the Cincinnati Children's Hospital Medical Center. "Although the side effects and safety need to be thoroughly evaluated in humans, our approach may offer a new paradigm to support critically ill patients with respiratory failure."

Several aquatic organisms have evolved unique intestinal breathing mechanisms to survive under low-oxygen conditions using organs other than lungs or gills. For example, sea cucumbers, freshwater fish called loaches, and certain freshwater catfish use their intestines for respiration. But it has been heavily debated whether mammals have similar capabilities.

In the new study, Takebe and his collaborators provide evidence for intestinal breathing in rats, mice, and pigs. First, they designed an intestinal gas ventilation system to administer pure oxygen through the rectum of mice. They showed that without the system, no mice survived 11 minutes of extremely low-oxygen conditions. With intestinal gas ventilation, more oxygen reached the heart, and 75% of mice survived 50 minutes of normally lethal low-oxygen conditions.

Because the intestinal gas ventilation system requires abrasion of the intestinal muscosa, it is unlikely to be clinically feasible, especially in severely ill patients—so the researchers also developed a liquid-based alternative using oxygenated perfluorochemicals. These chemicals have already been shown clinically to be biocompatible and safe in humans.

The intestinal liquid ventilation system provided therapeutic benefits to rodents and pigs exposed to non-lethal low-oxygen conditions. Mice receiving intestinal ventilation could walk farther in a 10% oxygen chamber, and more oxygen reached their heart, compared to mice that did not receive intestinal ventilation. Similar results were evident in pigs. Intestinal liquid ventilation reversed skin pallor and coldness and increased their levels of oxygen, without producing obvious side effects. Taken together, the results show that this strategy is effective in providing oxygen that reaches circulation and alleviates respiratory failure symptoms in two mammalian model systems.

With support from the Japan Agency for Medical Research and Development to combat the coronavirus disease 2019 (COVID-19) pandemic, the researchers plan to expand their preclinical studies and pursue regulatory steps to accelerate the path to clinical translation.

"The recent SARS-CoV-2 pandemic is overwhelming the clinical need for ventilators and artificial lungs, resulting in a critical shortage of available devices, and endangering patients' lives worldwide," Takebe says. "The level of arterial oxygenation provided by our ventilation system, if scaled for human application, is likely sufficient to treat patients with severe respiratory failure, potentially providing life-saving oxygenation."


5 Types of Respiratory Systems in Spiders

  1. A single pair of book lungs, as within the suborder Pholcidae.
  2. Two pairs of book lungs, as within the suborder Mesothelae and the infra-order Mygalomorphae
  3. One pair of tubular trachea only, or sieve trachea to some spiders, such as the Symphytognathidae spider family.
  4. Two pairs of tubular tracheae, or sieve trachea, as in the Caponiidae family of spiders.
  5. A pair of tracheae and a pair of book lungs, as in wolf spiders and orb weavers. This is also apparent in a majority of spider species.

Please Note: Some scientists do not believe there is much of a difference between tubular tracheae and sieve tracheae to classify them differently. However, you will find that other scientists do make the distinction between the tubular and sieve tracheae.

Spiders have four respiratory functions that work together to enable the spider to breathe. The book lungs and the spiracle of the book lungs are located at the anterior end, which is the front end of the spider. For spiders with a trachea, the trachea is located at the posterior end, which is toward the back end of the spider. These two sets of respiratory organs vary from one individual spider species to another. Some spiders have two sets of book lungs while other spiders have two sets of tracheae. Even still, some spiders have a combination of both where the trachea is at the anterior end, and the book lungs are located at the posterior end.

Book lungs are stacks of ten to eighty hollow, leafy disks. The number of hollow disks stacked depends on the species of spider. Spiders, such as tarantulas, in the Mygalomorphae infra-order and Mesothelae suborder, have two pairs of book lungs. Scientists have found that many primitive spider species have the feature of a set of book lungs compared to just one pair.

The book lungs are saturated in light blue haemolymph. Haemolymph is similar to blood for a spider. Then the book lungs or trachea, depending on the spider, filters the oxygen for absorption and releases carbon dioxide into the air through a process called diffusion.

Haemolymph is very similar to the hemoglobin that carries iron-rich nutrients. In the case of spiders, hemocyanin, which is a protein-rich respiratory pigment, carries oxygen and carbon dioxide within haemolymph instead. Haemolymph is a light blue color due to the copper atoms it carries as well.

The Trachea

The tracheae are long tubes that start at small holes on the underside of the exoskeleton and extend through the body of the spider providing oxygen to internal organs. Air is absorbed through the skin or very small trachea holes located on the underside of the spider&aposs abdomen. It is a common belief of arachnologists and entomologists that the trachea is a new feature that was integrated with genetic adaptation. Some species with this trachea feature include wolf spiders, orb spiders, and daddy longlegs.

The spider must move to allow the book lungs to work. The movement of a spider provides the necessary energy for air to be pushed in and out of the book lungs or trachea. However, spiders require less oxygen than people do. Therefore they can go hours to even days without breathing. This is why they can stay so still in their web waiting for their next meal or why you can capture a spider in a jar without holes and they can be still alive days later. So be careful the next time you choose to capture a spider specimen. It may still be alive when you open the jar days later.

Although the respiratory system of a spider is much simpler compared to mammals, the inner workings of a spider are amazing. They are very resilient creatures, so don&apost underestimate the survival rate of spiders. They are equipped to survive the toughest of times and circumstances. One way this is evident is in the way they breathe, and yet can go for hours without breathing at all.

For each question, choose the best answer. The answer key is below.

  1. Where are the book lungs located?
    • anterior end
    • posterior end
  2. Where are the trachae located?
    • anterior end
    • posterior end
  3. What color is the haemolymph?
    • red
    • yellow
    • light blue
    • dark blue
  4. What is carried within the haemolymph?
    • Only oxygen and carbon dioxide
    • oxygen, carbon dioxide, and copper
    • oxygen, carbon dioxide, copper, and iron
    • oxygen, carbon dioxide, copper, and protein
  5. How many types of respiratory systems do arachnids have?
    • 3
    • 4
    • 5
  6. In order for the book lungs to work, spiders must do what?
    • stay still
    • move
    • make a web
  7. True or False: Spiders can go a few weeks without breathing.
    • True
    • False

Answer Key

  1. anterior end
  2. posterior end
  3. light blue
  4. oxygen, carbon dioxide, copper, and protein
  5. 5
  6. move
  7. True

Interpreting Your Score

If you got between 0 and 2 correct answers: You may want to consider reading the material again.

If you got between 3 and 4 correct answers: Oops! Spider physiology can be hard sometimes. Read through the material to learn and understand the information you missed.

If you got 5 correct answers: Almost! You may have overlooked some details. Consider studying the material again so you can have a greater understanding of the spider respiratory system.

If you got 6 correct answers: Good Job! You are on your way to becoming an arachnologist!

If you got 7 correct answers: Way to go!! Have you ever considered becoming an arachnologist? You may be good at it.

© 2014 Linda Sarhan


Do animals only breathe through one nostril at a time like humans? - Biology

New International Version
Stop trusting in mere humans, who have but a breath in their nostrils. Why hold them in esteem?

New Living Translation
Don’t put your trust in mere humans. They are as frail as breath. What good are they?

English Standard Version
Stop regarding man in whose nostrils is breath, for of what account is he?

Berean Study Bible
Put no more trust in man, who has only the breath in his nostrils. Of what account is he?

King James Bible
Cease ye from man, whose breath is in his nostrils: for wherein is he to be accounted of?

New King James Version
Sever yourselves from such a man, Whose breath is in his nostrils For of what account is he?

New American Standard Bible
Take no account of man, whose breath of life is in his nostrils For why should he be esteemed?

NASB 1995
Stop regarding man, whose breath of life is in his nostrils For why should he be esteemed?

NASB 1977
Stop regarding man, whose breath of life is in his nostrils For why should he be esteemed?

Amplified Bible
Stop regarding man, whose breath [of life] is in his nostrils [for so little time] For why should he be esteemed?

Christian Standard Bible
Put no more trust in a mere human, who has only the breath in his nostrils. What is he really worth?

Holman Christian Standard Bible
Put no more trust in man, who has only the breath in his nostrils. What is he really worth?

American Standard Version
Cease ye from man, whose breath is in his nostrils for wherein is he to be accounted of?

Aramaic Bible in Plain English
Withdraw yourselves from man whose breath is in his nostrils, for as what is he esteemed?

Contemporary English Version
Stop trusting the power of humans. They are all going to die, so how can they help?

Douay-Rheims Bible
Cease ye therefore from the man, whose breath is in his nostrils, for he is reputed high.

English Revised Version
Cease ye from man, whose breath is in his nostrils: for wherein is he to be accounted of?

Good News Translation
Put no more confidence in mortals. What are they worth?

GOD'S WORD® Translation
Stop trusting people. Their life is in their nostrils. How can they be worth anything?

International Standard Version
"Stop trusting in human beings, whose life breath is in their nostrils, for what are they really worth?"

JPS Tanakh 1917
Cease ye from man, in whose nostrils is a breath For how little is he to be accounted!

Literal Standard Version
Cease yourselves from man, Whose breath [is] in his nostrils, For—in what is he esteemed?

NET Bible
Stop trusting in human beings, whose life's breath is in their nostrils. For why should they be given special consideration?

New Heart English Bible
Stop trusting in man, whose breath is in his nostrils for of what account is he?

World English Bible
Stop trusting in man, whose breath is in his nostrils for of what account is he?

Young's Literal Translation
Cease for you from man, Whose breath is in his nostrils, For -- in what is he esteemed?

James 4:14
You do not even know what will happen tomorrow! What is your life? You are a mist that appears for a little while and then vanishes.

Psalm 8:4
what is man that You are mindful of him, or the son of man that You care for him?

Psalm 144:3
O LORD, what is man, that You regard him, the son of man that You think of him?

Psalm 144:4
Man is like a breath his days are like a passing shadow.

Psalm 146:3
Put not your trust in princes, in mortal man, who cannot save.

Isaiah 40:15
Surely the nations are like a drop in a bucket they are considered a speck of dust on the scales He lifts up the islands like fine dust.

Isaiah 40:17
All the nations are as nothing before Him He regards them as nothingness and emptiness.

Cease you from man, whose breath is in his nostrils: for wherein is he to be accounted of ?

Psalm 62:9 Surely men of low degree are vanity, and men of high degree are a lie: to be laid in the balance, they are altogether lighter than vanity.

Psalm 146:3 Put not your trust in princes, nor in the son of man, in whom there is no help.

Jeremiah 17:5 Thus saith the LORD Cursed be the man that trusteth in man, and maketh flesh his arm, and whose heart departeth from the LORD.

Genesis 2:7 And the LORD God formed man of the dust of the ground, and breathed into his nostrils the breath of life and man became a living soul.

Genesis 7:22 All in whose nostrils was the breath of life, of all that was in the dry land, died.

Job 27:3 All the while my breath is in me, and the spirit of God is in my nostrils

Job 7:15-21 So that my soul chooseth strangling, and death rather than my life…

Psalm 8:4 What is man, that thou art mindful of him? and the son of man, that thou visitest him?

Psalm 144:3,4 LORD, what is man, that thou takest knowledge of him! or the son of man, that thou makest account of him! …


A more efficient system

Birds employ a more efficient system, one in which thin-walled air sacs are connected to the lungs. As shown in the illustration of the cardinal, the air sacs fill the body cavity. They are not involved directly in gas exchange but function as bellows to direct airflow through the lungs in one direction, from back to front. This increases lung efficiency.

Another major difference between mammals and birds is that the grape-like alveoli are replaced by thin-walled, tubular structures called parabronchi (shown at lower right in the diagram). Like human alveoli, avian parabronchi are covered by a rich supply of capillaries and are the sites for gas exchange. Parabronchi are located throughout the lungs between secondary bronchi. Just as air moves in one direction through the lungs, it also flows in one direction through the parabronchi, from one secondary bronchus into another.

The genius of the air sacs is that they allow continuous, one-way flow during both inspiration and expiration. The air sacs are arranged in two groups: one coming off the front of the lungs (anterior) and the other off the back of the lungs (posterior). Here’s how the system works:

During inspiration, the posterior air sacs expand, pulling air into the primary bronchi, which terminate near the far end of the lungs. While some of the air is diverted through secondary bronchi near the back of the lungs and into parabronchi, most of it passes directly into the posterior group of air sacs. At the same time, the anterior air sacs expand, pulling air from the parabronchi through the secondary bronchi. This creates the one-way back-to-front flow through the lungs.


Why does shape matter?

The nose's purpose goes beyond smelling and breathing. It also helps warm and moisten the air before it reaches the lungs. The right temperature and humidity levels are important throughout the respiratory tract, because they help the tiny, hair-like cells that line the tract to keep out germs and allergens.

In fact, the nose is so good at regulating air temperature and humidity levels that the air is already 90 of the way to its ideal temperature and moisture level by the time the air reaches the back of the throat, the researchers wrote. [Gasp! 11 Surprising Facts About the Respiratory System]

Air that is already hot and humid doesn't need to change much as it flows through the nostrils. Cool and dry air, on the other hand, needs to be warmed, and moisture must be added. Narrower nostrils could help facilitate this, as they make the air flow in more turbulently and come into greater contact with the warm, moist mucus in the nose, the researchers wrote. Indeed, it was probably more helpful for humans in cold and dry climates to have a narrower nose, senior study Mark Shriver, a professor of anthropology at Pennsylvania State University, said in statement.

The new study's findings appear to support "Thomson's Rule," an idea put forth by the British anatomist Arthur Thomson in the late 1800s, Shriver said. Thomson "said that long and thin noses occurred in dry, cold areas, while short and wide noses occurred in hot, humid areas," Shriver said. People have tested this rule by measuring skulls however, no one had done the measurements on living people, Shriver added.

He noted that natural selection isn't the only possible explanation for nose differences. Another explanation could be sexual dimorphism, in other words, differences between males and females, the study said. The researchers did note that there were differences between men's noses and women's in their findings, for example, men's noses were larger, on average, than women's noses.

The findings could also have medical implications, particularly as people travel more around the world, the study said. For example, the researchers asked if someone with a narrow nose could have an increased risk for respiratory problems if he or she lived in a hot and humid climate.

In future studies, the researchers hope to also look at people who live at high altitudes, such as people in the Andes, Tibet and Ethiopia, to learn if low atmospheric-oxygen levels also play a role in nose shape, the researchers said.


New study says mammals can breathe through *checks notes* their butts?

I breathe through my nose and, when I have a cold, my mouth. You probably do the same. It works well and it’s kept me alive for over 35 years, so I really can’t complain. But what if we were totally missing out on a novel way of breathing that nobody ever told us about? What if our bodies &mdash and those of other mammals like pigs and rodents &mdash were capable of breathing through a different, but also familiar orifice? I’m talking of course about our butts.

No, this isn’t a painfully late April Fools’ joke Scientists from the U.S. and Japan have penned a very interesting paper based on their experiments with multiple mammal species. The researchers say that while it’s not exactly the most efficient way to get oxygen into the body, mammals appear to possess the ability to “breathe” through their butts. Yeah, you read that correctly, and I’m sorry.

As food moves through the intestines, it is broken down and its nutrients are absorbed by the body. Knowing that some organisms like aquatic loaches can absorb air through the gut, the scientists wanted to see if the same would be true for mammals. They used oxygen in its gas form and in a liquid form called conjugated perfluorocarbon. The compound has been used in medicine for some time, but it’s applied to the airways and obviously not the intestines. As it turns out, the gut is also receptive to oxygen, and it could be a game-changer for patients that are in serious respiratory distress.

After artificially inducing respiratory failure in the animals, the researchers pumped either gas or liquid oxygen into their rectums. Both the gas and liquid forms raised oxygen levels and aided in the recovery of respiratory failure. The researchers suggest that these findings could be used to create an enema-like oxygen supplementation system to save human lives if similar results are seen in humans. This would be particularly useful in situations where a person’s airway is blocked or has sustained severe damage and can no longer provide enough oxygen for survival.

“Artificial respiratory support plays a vital role in the clinical management of respiratory failure due to severe illnesses such as pneumonia or acute respiratory distress syndrome,” Takanori Takebe, senior author of the study, said in a statement. “Although the side effects and safety need to be thoroughly evaluated in humans, our approach may offer a new paradigm to support critically ill patients with respiratory failure.”

Obviously, this entire thing would need to be tested in a wide range of scenarios before it could be deemed safe for humans, but the idea is interesting and potentially life-saving. Perhaps your butt will one day save your butt, so to speak.

Mike Wehner has reported on technology and video games for the past decade, covering breaking news and trends in VR, wearables, smartphones, and future tech.


Porous Science: How Does a Developing Chick Breathe Inside Its Egg Shell?

Introduction
Have you ever wondered how an unborn chick breathes inside its shell? Every animal needs oxygen to live, so the chick must get air somehow! When an animal&mdashincluding a human&mdashinhales, oxygen enters its lungs and is then distributed to all the different parts of its body. The animal's metabolism converts the oxygen into energy. During this process, a waste gas called carbon dioxide is produced. To get rid of it, the carbon dioxide is carried back to the lungs, where it is collected and exhaled. So not only must the chick have a way to let oxygen in, it also must somehow let carbon dioxide out. How does it do this sealed inside an eggshell?

Background
When oxygen enters an animal's lungs, it is shuttled and distributed by the bloodstream. It is also the bloodstream that carries carbon dioxide back to the lungs to be breathed out. Animals that grow inside their mothers, like humans, get their oxygen from their directly mothers. The blood stream of the baby animal and the mother are connected via an umbilical cord, which allows the baby to collect oxygen that his or her mother breathes in as well as use the mother's lungs to expel the carbon dioxide.

How do animals, such as chickens, which develop inside an egg outside of their mothers' bodies and therefore do not have umbilical cords, take in oxygen and get rid of carbon dioxide? Bird and reptile eggs have a hard shell. Directly under the shell are two membranes. Between the membranes is a small air cell, also called an air sack, filled with oxygen. As the animal develops it uses the oxygen, which must be replenished, and it also has to release carbon dioxide. How does this happen? Well, if you examine a chicken egg carefully with a magnifying glass, you'll see that there are tiny little holes, called pores, in the shell. In this activity, we'll see how those work to let the developing chick breathe.

Materials
&bull Large pot or bowl
&bull Water
&bull Blue food color
&bull Liquid dishwasher detergent
&bull Teaspoon measurers
&bull Three eggs (for best results, do not use freshly laid eggs, rather, use older, commercial eggs)
&bull Tongs or large spoon
&bull Cup
&bull Plate or paper towel
&bull Optional: a sensitive scale, such as a digital kitchen scale or a triple-beam balance that can measure tenths of a gram

Preparation
&bull Pour one and one half cups of water in a large pot or bowl.
&bull Add one quarter teaspoon of liquid dish detergent and one quarter teaspoon of blue food color. Mix well.

Procedure
&bull Carefully put the three eggs in the pot with the water, dish detergent and blue food color.
&bull Make sure that the eggs are submerged in the liquid. If part of the egg is above the surface of the water, mix together liquid dish detergent and blue food color with more water in the same proportions as you did before. Add this to the pot until the eggs are submerged.
&bull Set a timer for one hour or make a note of the time.
&bull After the eggs have soaked in the liquid for at least one hour, carefully lift one of them out of the liquid using the tongs or large spoon. How does the egg look?
&bull Crack the raw egg into a cup, being careful not to damage or crush the shell much.
&bull Set the empty eggshell on a plate or paper towel.
&bull Carefully inspect the inside of the shell. What do you see?
&bull Crack open the other two eggs in the same way. Look all around the inside of their shells, too. What do you see? Do all of the insides of the shells look the same? Are there noticeable differences?
&bull Extra: Do fresh eggs and aged eggs behave similarly? Buy a dozen eggs whose expiration date is at least two weeks away. Try this activity with half of the eggs right away. Let the other six eggs age in the refrigerator for two weeks. Repeat the activity with the aged eggs. How does the data compare between the fresh and the aged eggs?
&bull Extra: If pores in the chicken egg's shell allow materials to cross back and forth between the inside of the egg and the outside environment, then the air inside the egg could be replaced by water, and water is heavier than air. Using a scale that can distinguish changes as small as 0.1 gram, such as a triple-beam balance or high-quality electronic kitchen scale, weigh some eggs, then have an adult help you hard-boil them and weigh the eggs again. Did the eggs change weight? If so, how did they change weight? What does this say about the ability of the chicken egg to allow water to cross its shell?

Observations and results
Did all of the eggs have at least a few small blue dots on the inside of their shells? Were the dots mostly clustered in one or a few areas on the inside of each shell?

Directly under the chicken egg's shell are two membranes. When the eggs are laid by the mother they are warmer than the air, and as they cool the material inside the egg shrinks a little bit. This shrinkage is what pulls the two membranes apart, leaving behind the small air sack that is filled with oxygen. As the developing chick grows it uses the oxygen from the air sack and replaces it with carbon dioxide. The tiny pores in the shell allow the carbon dioxide to escape and fresh air to get in. The chicken egg has more than 7,000 pores in its shell to allow this to happen! These pores also allow water to go through the shell, which is why the dye appears as small dots on the inside of the shell, often clustered in certain areas, and why an egg after being hard-boiled would weigh slightly more than when it was raw. Also, freshly laid eggs do not allow water to penetrate as well as older, commercial eggs do, so fewer blue spots will probably be visible on the inside of fresher eggs compared with older ones.

Cleanup
Dispose of the raw eggs by pouring them down the drain. (The eggs should not be eaten because they were soaked with dishwater detergent.) Thoroughly clean any surface the raw eggs touched because they can carry salmonella.


This activity brought to you in partnership with Science Buddies


Pheromones in Humans: Myth or Reality?

Pheromones are volatile, odorous substances which are released by one animal and detected by another, causing some sort of physiological reaction. These reactions can manifest themselves in a variety of different ways: some pheromones modulate sexual activity, some affect aggression, some play roles in territory marking, and other pheromones have similarly diverse effects on the target animal. Pheromones have been demonstrated in a very large number of organisms ranging from amoebas to fish to mammals, including primates. However, the question of whether human olfactory signals exist has been a question of much debate and few definite conclusions. In this paper I will look at some possible examples of odor signaling in humans.

Mammals of all sorts use olfactory signals to indicate willingness to copulate, define territory, mark their young, and signal aggressive intent. These processes can be seen in many animals used as models for human systems, including rats, monkeys (both Old World and New World), hamsters and mice. The fact that pheromones are important biological signals in a plethora of other species indicates that the possibility of human pheromones should not be discarded lightly.

Although humans generally rate olfaction as their least important sensory modality, we still spend billions of dollars, years of our life, and a considerable amount of effort to modify the way we smell (at least in industrialized countries). These efforts typically include scrubbing with deodorant soaps and scented shampoos, applying deodorants to those parts of our bodies we feel need deodorizing, and finally applying perfumes and sprays to replace those natural odors we just discarded down the shower drain. This points out an obvious contradiction: if olfaction is considered unimportant and possibly even obsolete, why do we work so hard to change the way we smell? The first question to address is where do these odors we produce come from? Whereas animals release pheromones from their skin, urine, feces, and to some extent breath, most research on pheromones in humans indicates that the main odor-producing organ is the skin. For the purposes of this paper, the skin is what I will focus on. These odors are largely produced by the skin's apocrine sebaceous glands, which develop during puberty and are usually associated with sweat glands and tufts of hair. These glands are located everywhere on the body surface, but tend to concentrate in six areas1:

1) The axillae (underarms)

2) The nipples of both sexes2

3) The pubic, genital, and circumanal regions

4) The circumoral region and lips

5) The eyelids

6) The outer ear

The first four of these regions are generally associated with varying amounts of hair growth, which makes perfect sense, as the extremely large surface area of a tuft of hair is a very effective means of spreading an odor by evaporation. The fact that body hair and apocrine glands appear simultaneously at puberty is significant and suggests that body odor and its dispersal may be linked to sexual development. These supposedly non-functional structures, coupled with the olfactory system, would be called part of a pheromonal system in any other mammal.

The substances produced by these glands are relatively imperceptible by the human nose what we smell when we detect skin odor is not the fresh glandular secretions but rather the bacterial breakdown products of these glandular secretions. The sebaceous secretions themselves consist mostly of lipids such as squalene and other esters. When degraded by enzymes of bacteria naturally present on human skin, free fatty acids result, including those that smell hircine and are generally regarded as unpleasant. The most prominent examples of these hircine fatty acids have the general formula (CH3(CH2)nCOOH) and are called butyric acid (n=2), caproic acid (n=4), and caprylic acid (n=6).

The first studies I will discuss relate to evidence for the existence of pheromone signaling in human babies and children. The first interesting studies regarding children come from Michael Kalogerakis and Irving Bieber. They proposed a theory that olfaction is related to sexual identification in young children. Kalogerakis performed a study on young boys, two to four years of age, which strongly indicated that at some point in early childhood, a boy will begin to show an aversion to the odors of their father, and will simultaneously feel attraction to the odors of their mother. According to Bieber, this indicates a shift in sexual interest and acts as a biological trigger for the Oedipus response. Kalogerakis supports this theory with a case study of a boy named Jackie, who originally was closer to his father, but at the age of three years, three months, began to show a distinct preference for his mother's smells, especially at times right after she and Jackie's father had been having intercourse. At four years of age, Jackie would become nauseous at the smell of his father. This behaviour continued, tapering off slowly until Jackie was six, and his sexual identity had presumably been established.

Another intriguing study was carried out by Michael J. Russell of UCSF in 1976. He enlisted the help of ten recent mothers, whom he asked to wear a cotton pad in their bra for three hours before testing. Russell then tested the sleeping babies' ability to differentiate between pads worn by their own mothers and those worn by strange mothers. At the age of two days, only one of the ten babies responded to either type of pad, and he responded to both with a sucking response. At the age of two weeks, eight babies responded by sucking to a stranger's pad, and seven responded to their mother's pad. Also, one child responded only to its mother's pad. At the age of six weeks, however, things had changed. Eight babies responded to their mother's pad, one responded to a stranger's pad, and one did not react to it's mother's pad but did react with a jerk and a cry to the stranger's pad. These results may indicate either that a baby imprints on its mother's odor, or as Russell suggests, that the mother unconsciously marks her baby with a distinctive scent, a phenomenon observed in many other primates. This latter possibility is supported by the common parental observation that a child will reject their favorite blanket or stuffed animal after it has been washed, presumably because it has lost specific odors acquired in previous contacts.

A final childhood phenomenon worth mentioning is one observed by Dr. Alex Comfort. Comfort noticed that in the past three centuries, the age of onset of menstruation for girls has had a direct correlation with the amount of time that young girls spend with boys. In pre-Victorian times, menstruation began at an early age, only slightly above the average age of onset now. However, in Victorian times, when mingling between the sexes was minimized as much as possible, the average age of onset climbed a few years. In post-Victorian times, as boys and girls were allowed to mingle more freely and coeducation appeared, the average age fell once again. Admittedly, this could be due to a number of other factors, but it is Comfort's opinion that it is due to the exposure to odors of the opposite sex. In fact, this phenomenon has been documented in mice and is called the Vandenbergh effect: female mice raised alone in sterile cages have a much higher age of maturation than that of female mice raised alone in cages filled with a male mouse's bedding material. When the bedding belonged to a castrated male mouse, this effect was not observed.

There are variations in odor perception between human adult males and females. Le Magnen and Doty found that this is most evident in the case of women's acute ability to smell musk3, which are steroids, large cycloketone or lactones, often with side chains which are most likely involved with their biological specificity of action. All of these compounds are very similar to the male sex hormone testosterone (see appendix for structures). Whereas women are very sensitive (1 part in 109) to the musky odors of civetone (from the anal glands of the civet cat and used in many perfumes), exaltolide (a synthetic musk), and boar taint substance (a sexual attractant produced in the preputial glands of the boar), men are relatively insensitive (1 part in 106) to these substances. Moreover, women's sensitivity to these substances varies as a function of where they are in their menstrual cycle: during menstruation, women are no more sensitive to musks than men, but about ten days after menstruation (ovulation -- a woman's peak fertility period), women reach their maximum sensitivity. In addition, women on the pill, women who have had ovarectomies, pregnant women, and post-menopausal women are relatively insensitive to these substances. Le Magnen deduced from these results that sensitivity to musk in women is critically defendant on the levels of estrogen in the blood: during ovulation, serum estrogen is at a peak, whereas serum levels of estrogen are low during menstruation, pregnancy, in post-menopausal women, women who have had ovarectomies, and birth-control pill users. Further, it is the action of progesterone which causes nasal congestion during menstruation and pregnancy4, and might be responsible for the reduced sensitivity at these times.

Why is this relevant? Men secrete musky odorants in abundance. The -3-ol precursor of boar taint substance is found in male urine, and substances similar to testosterone, such as androstenone, are secreted in the smegma and from the apocrine glands of the underarms5 and pubic area of males. As is usually the case, bacterial action may be necessary for the release of the odorants. The fact that men's bodies secrete these substances and that women are maximally sensitive to them when they are most fertile indicates that there may be a olfactory-sexual role for these substances in human sexuality.

Indeed, a study performed by J. Richard Udry at the University of North Carolina attempted to delineate the relationship between coitus, orgasm and position in the menstrual cycle. He found that women do indeed engage in sexual intercourse about six times more frequently at about the time of ovulation, when women's sensitivity to the male musk odor is highest. In addition, the women are much more likely to have an orgasm at these times. Further, the women Udry studied women were several times less likely to have sexual intercourse or have an orgasm during and two to three days after menstruation, which is when women's sensitivity to the musky smell of men is lowest. Coupled with women's odor sensitivity, these results could indicate a possible pheromonal trigger for sexual behaviour.

There are several other effects in adult humans which might hinge on pheromones. Some of the most interesting results come from work done by Martha McClintock at Harvard. She performed a study on menstrual cycles in women who lived together in dormitories and found that when women are housed together, their menstrual cycles tend to synchronize and lengthen. She also found that the lengthening effect was attenuated in direct relation to the amount of time these women spent with men. In one woman's case, her regular cycle was six months long, but when she started seeing a man, it dropped to four and a half weeks. After she stopped seeing this man, her cycle once again lengthened. Of course, in an experiment like this, it is difficult to eliminate diet, work and sleep habits as factors, but the fact that this is such a widespread phenomenon indicates that something more basic is probably at work here. It is to be stressed that airborne odors or pheromones were not directly demonstrated in this study, but there is an identical phenomenon in mice that has been shown to be pheromonal in nature. This effect is called the Lee-Boot phenomenon, in which groups of female mice housed together experience increases and synchrony in their estrus cycles. When a female mouse is housed alone, this effect does not occur, but when a solitary female mouse is kept in a cage supplied with bedding from a cage full of female mice, the Lee-Boot effect is once again observed, indicating that the cues are chemosensory in nature. The attenuation of cycle elongation in women in response to male contact is also echoed in mice, and is called the Whitten effect. Once again this effect has been shown to be due to olfactory signals.

Michael Russell provided some more insight on the phenomenon of menstrual synchrony. A colleague of his, on reading McClintock's paper, mentioned that she too had noticed the same phenomenon among her friends, except that in every case, it was her own menstrual cycle which determined the synchronization of her friends'. Upon hearing this, Russell asked his colleague if he could use her underarm scent to help confirm and extend McClintock's findings. She consented, and proceeded to wear sterile cotton pads under her arms regularly. Russell the recruited sixteen female volunteers, each of whom came in three times a week for four months to have a liquid applied to her upper lip. One group of women had pure alcohol applied to their lips, and the other group had a mixture of alcohol and Russell's colleague's underarm scent from the previous day applied. The group which received pure alcohol did not experience changes in their menstrual cycle, but those that had the mix of alcohol and underarm scent applied showed a radical change in their cycles: The average time lag between cycles had been 9.3 days, but after four months, this had decreased to 3.4 days, and fully half the women were in exact synchrony with Russell's colleague, discounting the the aforementioned one day time lag. None of these women had ever even met Russell's colleague. McClintock's study showed that women who lived together reported menstrual synchronization, and Russell's study provided a likely mechanism: underarm scent. Another possible interpretation of this study leads to the conclusion that there may be dominant women with regard to menstrual synchrony, a phenomenon observed in many animals.

Dr. Russell provided yet another interesting result. At the same time he was performing his experiments on babies' ability to discriminate between their own mothers and strange mothers, he performed another experiment on whether young adults could discriminate between their odors and others' and between male and female odors. Twenty-nine college age students, 16 male and 13 female, were asked to wear a clean undershirt for twenty-four hours without using soap, deodorants, or perfumes. After twenty-four hours passed, the shirts were collected and put in buckets with the armpit right above a strategically placed sniffing hole. Two tests were then performed: the subjects were presented with three shirts, one theirs, one from a strange female and one from a strange male. The subjects were then asked to identify which shirt was theirs, taking as much time as needed. The subjects were then asked to identify which shirt belonged to the strange male and which shirt belonged to the strange female. The subjects generally sniffed each bucket once in succession, and then repeated the process. The results were impressive: 81% of the males and 69% of the females identified their own shirts correctly, for an average success rate of 75%, which is highly significant when compared to the chance percentage of 33%. In the second sex-identifying test, the subjects performed just as well: 81% of the males and 69% of the females were correct, for an average of 75%. Once again, this result was very significant, as chance would dictate a 50% success rate. When asked to characterize the odors of the shirts, the subjects generally said the males' shirts smelled musky and the females' shirts smelled sweet. This observation jibes well with the previous discussion of variations in odor perception.

One final effect needs to be mentioned due to large amount of research on it. There have been many studies on whether or not human vaginal secretions might contain some kind of sex pheromone (or "copulin", as one researcher calls them). Several researchers have found that human vaginal secretions contain various small (C2 to C6) fatty acids, with acetic acid predominating. Richard P. Michael found that about 30% of the women (he called them 'producers') produced a significant amount of those small fatty acids (not including acetic acid) that induce copulatory behaviour in infra-human monkeys. In addition, these "copulins" increased up until ovulation, and then decreased as menstruation approached. Michael also noted that women on birth-control pills did not show this mid-cycle increase, and had a lower overall fatty acid content. Michael theorized that these fatty acids or "copulins" were a sexual trigger in humans, but this has never been demonstrated, although the producers' secretions did increase copulatory behaviour in rhesus monkeys. When David Goldfoot's group in Wisconsin tried to confirm these results, however, they were unsuccessful.

Are pheromones in humans a myth or are they real? At this point, it is difficult to say either a definite yes or a definite no. The field is obviously very confused, and for every paper one finds that seems to demonstrate the existence of human pheromones, one can find another equally compelling study refuting their existence. In this paper I have tried to consider a few compelling bits of evidence, but it should be noted that none of these results are yet widely accepted, and no pheromone has yet been isolated and conclusively linked to a physiological effect in humans. Further, much of the work in this field is of a qualitative nature, without adequate controls or firm statistical basis.

However, some of the results mentioned above are quite compelling. McClintock's study and Russell's extension seem to strongly indicate there is some odorant that affects women's menstrual cycles. The fact that men secrete musk-like substances that women are maximally sensitive to during ovulation coupled with the finding that there is a demonstrated increase in coitus during this period is also very intriguing. "Copulins" may or may not be human sexual releasers, and they seem to stimulate copulatory behavior in monkeys, although this result has not been confirmed.

To close, I would like to propose a new way of looking at pheromones, specifically in humans. With our highly developed intellect and rich compliment of emotions, ambitions, motivations and desires, it may not be profitable to look at human pheromones the same way we look at animal pheromones. Instead of looking for odorants that cause a definite physiological response, it may behoove us to look at how possible pheromones affect our attitudes. We are not machines that blindly fall into some stereotyped behaviour in response to an odor, but we may be machines that are nudged towards a type of behaviour by pheromones in concert with our higher intellect.

1. This is an overgeneralization there are substantial differences in apocrine gland distribution and quantity between the various races. The six areas outlined here are generally found in caucasians, but blacks and Aborigines tend to have more and larger glands, with a higher number on the chest and abdomen than is found in an average caucasian. In addition, Aborigines have a much more powerful scent gland in the circumanal region. Asians, on the other hand, tend to have smaller and far fewer apocrine glands than either Caucasians or blacks, and many have none at all. In fact, only about 10% of Japanese people have any underarm odor at all, and at one point having scent glands in the underarms qualified a Japanese male for a military exemption and a free ticket to a medical center where they could receive treatment.

2. Interestingly, the mammary glands themselves are highly modified apocrine glands

3. Musk is a basic ingredient of all perfumes and colognes.

4 . This phenomenon might be responsible for womens' reputed proclivity for unusual foods during pregnancy and menstruation.

5. A note about underarms: many of the authors of the references for this paper have pointed out that underarms are the ideal location for the dispersion of odors and /or pheromones. This is because 1) They are among the warmest parts of the body, and are among the first parts to perspire. 2) They are amply endowed with apocrine and sweat glands. 3) There is usually a strong growth of hair, which is a very effective means of dispersing an odor (as noted above). 4) Underarms are high on the torso and thus well-situated to disperse odors in the region of other people's noses. 5) Finally, being under the arms, armpits are protected from excessive evaporation. To release odors, the arms must be raised or in motion. Comfort speculates that underarms may even be specialized for this purpose.

1. Hopson, Janet. Scent signals: The Silent Language of Sex. New York: William Morrow and Company, 1979

2. Stoddart, D. Michael. Mammalian Odours and Pheromones. London: Edward Arnold Ltd., 1976

3. Shorey, H.H. Animal Communication by Pheromones. New York: Academic Press, 1976

4. Vandenbergh, John G. (ed). Pheromones and Reproduction in Animals. New York: Academic Press, 1983

5. Doty, Richard L. (Ed). Mammalian Olfaction, Reproductive Processes, and Behavior. New York: Academic Press, 1976

6. Theimer, Ernst T. (Ed). Fragrance Chemistry: The Science of the Sense of Smell. New York: Academic Press, 1982

7. Wells, F. V. and Marcel Billot. Perfumery Technology Art: Science: Industry. Chichester: Ellis Horwood Ltd, 1981

8. Comfort, Alex. "Likelihood of Human Pheromones." Nature, vol. 220, pp. 432-479

9. McClintock, Martha K. "Menstrual Synchrony and Suppression." Nature, vol. 229, pp. 244-245

10. Russell, Michael J. "Human Olfactory Communication." Nature, vol 260, pp.520-522

11. Udry, J. Richard and Naomi M. Morris. "Distribution of Coitus in the Menstrual Cycle." Nature, vol. 220, pp. 593-596

12. Michael, Richard P. et al. "Volatile Fatty Acids, 'Copulins', in Human Vaginal Secretions." Psychoneuroendocrinology, vol. 1, pp. 153-163

13. Huggins, George P and George Preti. "Volatile Constituents of Human Vaginal Secretions." American Journal of Obstetrics and Gynecology, vol. 126, pp. 129-136

14. Kalogerakis, Michael G. "The Role of Olfaction in Sexual Development." Psychosomatic Medicine, vol. 25, pp. 420-432

15. Bieber, Irving. "Olfaction in Sexual Development and Adult Sexual Organization." American Journal of Psychotherapy, vol. 13, pp. 851-859

16. Michael, Richard P. et al. "Human Vaginal Secretions: Volatile Fatty Acid Content." Science, vol. 186, pp. 1217-1219.

www.anapsid.org/ pheromones.html

© 1994-2014 Melissa Kaplan or as otherwise noted by other authors of articles on this site


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