Otter’s Tell-Tale Tail

This is a little off the usual “inner twin” topic… and then again maybe not when considering the “beach/sea” theme of my previous post.  

Today, Academia sent me a paper that was presented by my friend, Gareth Morgan:  Pachyosteosclerosis in marine mammals.

I decided to write Gareth about it, as well as provide my own take/findings.  This is what I emailed:  

Hi Gareth, 

Hope this finds you well.  

I’ve read your recent paper, and found it very interesting, … as well as raising many questions on my end.  

Have you given consideration to our human bodies having evolved to be suited for both aquatic AND terrestrial environs (swimming and walked/running).  

Something like “river” otters that are both land and water dwellers.  

River otters and sea otters have the same skeletal shape, except the sea otter is much more robust and bones are denser.  When in the water though, they both swim and dive using “undulation” (whip-like motion) which humans also perform well given our ability to mimic the otters tail using our legs (it’s the fastest known swim technique other wise referred to as the “fish kick” and “dolphin kick”).   

It’s interesting to note that modern human legs have grown longer and arms shorter than our ancestors and nearest primate relatives.  

So first question: why did our arms shorten?  Answer: tucks away better for less drag during undulation swimming.  

Second question: why did our legs lengthen? Answer: makes for a longer/stronger “tail-like” appendage.  This is also why our ankles are so flexible— can be brought to an aerodynamic “tippy-toe” point and held there.  

Food for thought,

May

Another thing I didn’t mention to Gareth that we have in common with otters, is that they vocalize loudly in high pitch, both in air and water.  It’s interesting to note that higher-pitched sounds travel faster and reach further under water than low pitch sounds.  That women, girls and young boys tend to have higher pitch voices is likely due to their tendency of  having been the ones watching and/or swimming (as “guard”) in the upper-sea water surface as the “dads” swam and foraged below them.  If the guards saw a predator (ie shark, croc,… ), their warning scream under water would be easily heard by dad.