demo 31

FISH POND/ Tiktaalik: An intermediate stage between fish and reptile had long been hypothesized to have existed during the Late Devonian, some 375 million years ago. In some exposed rocks from the Late Devonian, archeologists discovered a fish with wrists. Inside our bodies are connections to a menagerie of other creatures. Some parts resemble parts of jellyfish, others parts of worms, still others parts of fish. These aren’t haphazard similarities. Looking back through billions of years of change, everything innovative or apparently unique in the history of life is really just old stuff that has been recycled, repurposed, or otherwise modified for new uses. For instance, hiccups are inherited from fish and tadpoles. We hiccup when a nerve spasm causes muscles in the diaphragm, neck and throat to contract. We gasp and take in some air, and the glottis in the back of our throat snaps shut. This tortuous path that nerves take in our body and the brain stem’s response when they spasm are marvelous adaptations for gill-breathers, but not entirely ideal for us.Our ancestry with apes is far more recent than with fish, and as a result, our inner ape dominates our inner fish. This fact is most evident when we consider behavior as well as anatomy.
extract from “Your Inner Fish” by Neil Shubin