How far can a human shrink before he suffocates?

[Radrook]

How far can a human shrink before he suffocates?

In the film The Shrinking Man the protagonist continues to shrink until he is the size of an ant and beyond. Of course as he shrinks the lungs become smaller. At exactly what sizs does breathing become impossible?

 

[JD16]

At the point when the size of the oxygen molecule exceeds the capacity of the lungs?

 

[Radrook]

At the point when the size of the oxygen molecule exceeds the capacity of the lungs?

Yes, I know that such a level would be reached. But prior to that, how far can you shrink without suffocating?

 

[JD16]

Yes, I know that such a level would be reached. But prior to that, how far can you shrink without suffocating?

Since its Sci-fi that we're discussing, everything is hypothetical,....I would assumed that as a person shrink, his/her internal organs shrink accordingly, thus the amount of oxygen required would drop accordingly as well,...who knows?

 

[jayem]

How far can a human shrink before he suffocates?

In the film The Shrinking Man the protagonist continues to shrink until he is the size of an ant and beyond. Of course as he shrinks the lungs become smaller. At exactly what sizs does breathing become impossible?

I don't think respiration would be the primary factor setting the lower limit of size. For any mammal, I think it might be heat loss. Which would occur much more rapidly if body size is very small. Most small isothermic animals, like shrews and hummingbirds must compensate by having high metabolic rates. They eat frequently, and have very fast heart rates. Human physiology would have to be radically different at the scale of a tiny insect.

 

[Radrook]

I don't think respiration would be the primary factor setting the lower limit of size. For any mammal, I think it might be heat loss. Which would occur much more rapidly if body size is very small. Most small isothermic animals, like shrews and hummingbirds must compensate by having high metabolic rates. They eat frequently, and have very fast heart rates. Human physiology would have to be radically different at the scale of a tiny insect.

How about these?


Rodents


The smallest member of the rodent order is the Baluchistan pygmy jerboa, with an average body length of only 4.4 cm (1.7 in). [36]

Carnivorans

The smallest member of the order Carnivora is the least weasel (Mustela nivalis), with an average body length of (4.5-10.2 in). It weighs between 29.5 – 250 grams with females being lighter.

Marsupials

The smallest marsupial is the Long-tailed planigale from Australia. It has a body length of (4.3–5.1 in) (including tail) and weigh 4.3 grams (0.15 oz) on average.

Pilbara ningaui is considered to be of similar size and weight.

Primates

The smallest member of the primate order is Madame Berthe's mouse lemur (Microcebus berthae), found in Madagascar,[37] with an average body length of 92 mm (3.6 in).


https://en.wikipedia.org/wiki/Smallest_organisms#Rodents[/quote]


Assuming that we are of the primate category then the smallest human can be 3.6 inches tall?

If so, how far below that can we feasibly go before we croak?

 

[jayem]

How about these?


Rodents


The smallest member of the rodent order is the Baluchistan pygmy jerboa, with an average body length of only 4.4 cm (1.7 in). [36]

Carnivorans

The smallest member of the order Carnivora is the least weasel (Mustela nivalis), with an average body length of (4.5-10.2 in). It weighs between 29.5 – 250 grams with females being lighter.

Marsupials

The smallest marsupial is the Long-tailed planigale from Australia. It has a body length of (4.3–5.1 in) (including tail) and weigh 4.3 grams (0.15 oz) on average.

Pilbara ningaui is considered to be of similar size and weight.

Primates

The smallest member of the primate order is Madame Berthe's mouse lemur (Microcebus berthae), found in Madagascar,[37] with an average body length of 92 mm (3.6 in).


https://en.wikipedia.org/wiki/Smallest_organisms#Rodents[/quote]


Assuming that we are of the primate category then the smallest human can be 3.6 inches tall?

If so, how far below that can we feasibly go before we croak?

I'll bet they all have high metabolic rates, and rapid cardiac action. And they all have fur to help retain body heat.

I don't know what the lower limit of human size would be assuming our physiology is unchanged. There are numerous physiologic differences just between babies and adults. You mentioned respiration. Having a smaller diameter trachea means there is greater resistance to air flow. Babies compensate by breathing faster, and the diaphragm and respiratory muscles have a relatively greater work load. The cardiovascular system also works differently to accommodate this. That's one consequence of a smaller body. According to this, the smallest man ever definitely documented was 1' 10'' tall. I'm pretty sure that survival of an adult human who was smaller than a newborn would require major anatomic and physiologic changes.

 

[Radrook]

This is the shortest height recorded for a man.

Chandra Bahadur Dangi

(30 November 1939 – 3 September 2015) (Nepali: was the shortest man in recorded history for whom there is irrefutable evidence, measuring 54.6 cm (1 ft 9 1⁄2 in).[2]

Dangi was a primordial dwarf. He broke the record of Gul Mohammed (1957–97), whose height was 57 cm (1 ft 10 in). Chandra came to the attention of the media when a wood contractor saw him in his village in the Dang district of Nepal, and he was awarded the title of shortest adult human ever recorded after his height was measured in February 2012.[3] He was subsequently included in the Guinness World Records. Three of his five brothers were less than 1.22 m (four feet) tall, while his two sisters and two other brothers are of average height.[4]
Chandra Bahadur Dangi - Wikipedia

Of course shortness is just a measure of height and not overall smallness.

 

[Radrook]

Since its Sci-fi that we're discussing, everything is hypothetical,....I would assumed that as a person shrink, his/her internal organs shrink accordingly, thus the amount of oxygen required would drop accordingly as well,...who knows?

In the Shrinking Man film they have the man smaller than a spider and using a matchbox as a shelter after the housecat cat attacked him at his the doll-house and chased him into the house basement.

BTW
Not all sci fi is the same. Some sci fi is a mix of fantasy and science and often disregards reality in for the sake of entertainment. For example, the maneuverability of spacecraft in space battles mimics the dynamics of how such machines would behave in an atmosphere instead of how they would perform in a vacuum of space where lift provided by wings or air foiled structures would be irrelevant.

In contrast, hard science fiction, as it is referred to and as was written by such writers as Isaac Asimov, strives to adhere to the laws of physics. It's within the parameters of the latter type of sci-fi that the question is being asked.

 

[Jimmy D]

You've been starting some unusual threads recently Rad. I may not have participated in them all but I have enjoyed reading them.

You gotta love those tiny animals!

 

[Radrook]

You've been starting some unusual threads recently Rad. I may not have participated in them all but I have enjoyed reading them.

You gotta love those tiny animals!

Yes, their smallness does make them cute-especially if they are mammals. That's why many people prefer them as pets as opposed to larger ones. As long as they don't bite or sting me or try to set up residence inside my body, like that Amazon fish that supposedly tries to swim up the urinal tract, they are OK by me.

The only trouble I had with a small mammal was with a Chihuahua which took a deep dislike to me as soon as he saw me. Permitted me to go into the store which he was guarding on the porch entrance but chose to attack when I came out.

I was approx eleven years old then and had seen how long the teeth of little dogs were because I had previously owned one. So when he threatened to sink them into one of my ankles, I bolted and the chase was on.

Back and forth we went down that scorching hot street with him almost catching me and I sliding to a stop and letting his momentum carry him past me. Finally, after several repetitions of this embarrassing public display, I was provided with a semi-face-saving way out when my cousin opened the door to the car and I desperately dived in head first.

So yes, tiny can be cute. But sometimes....


BTW
Thanx for the positive statement about the threads.

The reason I posted this question is because I have read numerous sci fi short stories and watched various films, starting with the classic The Shrinking Man, based on the novel which uses this man's physical shrinking experience as an extended metaphor of how modern man becomes less and less a unique individual as technological progress gradually pushes his importance into the faceless societal background, and wondered about the actual limits that would apply if such a phenomenon were to occur.

For example, one short story had a creature, what turned out to be an alien scientist actually, shrinking into the subatomic realm and infinitely beyond it. Can't recall whether he had some type of protective suit on but one would assume that it would be essential.

​

 

[Radrook]

I don't think respiration would be the primary factor setting the lower limit of size. For any mammal, I think it might be heat loss. Which would occur much more rapidly if body size is very small. Most small isothermic animals, like shrews and hummingbirds must compensate by having high metabolic rates. They eat frequently, and have very fast heart rates. Human physiology would have to be radically different at the scale of a tiny insect.

Here are other obstacles that were mentioned concerning a human shrinking in size:
How small could a person be shrunk? [Archive] - Straight Dope Message Board

 

[Radrook]

There are numerous physiologic differences just between babies and adults. major anatomic and physiologic changes.

Is that why babies sound like veritable fire-engine sirens at unholy hours of the night? Because they are trying to get oxygen into their lungs?

 

[Hammster]

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