# What is the history of breathing? **URL:** \ **Category:** Factual Questions\ **Created:** [September 4, 2023, 6:00pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598 "2023-09-04T18:00:46Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [September 4, 2023, 6:00pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598/1 "2023-09-04T18:00:46Z")
Humans can breathe either through the nose or the mouth. Tradeoffs ensue. A clogged nose, say from a cold, doesn’t turn off life, but food can easily slip into the windpipe and choke a person. How did this develop? Do other mammals all have two air entrances? If so, what earlier classes have a combined breathing apparatus? If none do, when did it start in mammals? ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [September 4, 2023, 6:09pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598/2 "2023-09-04T18:09:54Z")
Mouth breathing came first. The nostrils were just depressions with smellifying sensors. They became connected in the lobe-fin fishes that were our ancestors. > > **[Choana](https://en.wikipedia.org/wiki/Choana)** > > The choanae (SG: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They are considered one of the most important synapomorphies of tetrapodomorphs, that allowed the passage from water to land. > In animals with secondary palates, they allow breathing when the mouth is closed. In tetrapods without secondary palates their func... ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [September 4, 2023, 6:18pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598/3 "2023-09-04T18:18:27Z")
The jaw evolved as a modification of the first set of gills which was initially used to force water through for breathing and only later coopted into a feeding structure. If you want to trace the history back even further. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 4, 2023, 8:41pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598/4 "2023-09-04T20:41:51Z")
According to this article, [Evolution of the Mammalian Nose](https://crompton.oeb.harvard.edu/evolution-mammalian-nose-presentation), breathing through the nose while sleeping is highly beneficial to mammals, and found across all mammals. > [@](#): > > All mammals at rest preferentially breath in and out through the nose. One role of the respiratory turbinates and an essential requirement for endothermy is the prevention of loss of heat and water in the expired air. The airflow to the lungs bypasses the oral cavity because the larynx is held in an intranarial position by the palatopharyngeal muscles (shown in red). These originate medial to the pterygoid hamulus and form a soft extension to the hard palate as well as a sphincter that grips the larynx. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [September 4, 2023, 9:37pm UTC](https://boards.straightdope.com/t/what-is-the-history-of-breathing/989598/5 "2023-09-04T21:37:26Z")
Looks like a number of adaptations were needed to get the current design. They apparently appear in cynodonts, from the above link. > It is not until the early Triassic that the first steps leading to a mammalian type nose appear. … > > The next advance in nasal structure occurred in an ill defined and paraphyletic group referred here to simply as mammaliforms, that existed at the beginning of the end of the Triassic and beginning of the Jurassic. But then it gets murky, because no early mammal fossils include well-preserved nasal functions. > This break in the fossil record begs the obvious question, when did these final steps take place?