In order to breathe in, we must
flatten the dome-shaped diaphragm; to breath out, we let it relax again. The
diaphragm delivers oxygen to us a dozen times or more each minute, a
half-billion times during an 80-year life.
Before the evolution of a diaphragm,
our reptilelike ancestors probably breathed the way many reptiles do today.
They used a jacket of muscles to squeeze the rib cage.
Scientists
suspect that the diaphragm evolved through some change in the way mammal
embryos develop: Mutations caused certain embryonic cells to grow into an
entirely new muscle. Dr. Kardon and other researchers are trying to understand
that shift and why the muscle sometimes fails to develop, with catastrophic
consequences.
Original Article:http://www.nytimes.com/2015/04/07/science/behind-each-breath-an-underappreciated-muscle-the-diaphragm.html?rref=collection%2Fsectioncollection%2Fscience&action=click&contentCollection=science®ion=stream&module=stream_unit&version=search&contentPlacement=10&pgtype=sectionfront
After taking Biodiversity and Evolution 2, this post does not surprise me at all. i remember looking at diaphragm bones in lab and comparing them to mammals and reptiles. This actually very interesting to find out more about evolution and how the diaphragm has evolved and mutated to change in the way mammal embryos develop.
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