We all have two of certain organs, like kidneys and lungs, but why not multiple hearts, livers or brains? Read More: Bilaterial Symmetry http://www.nhm.ac.uk/nature-online/evolution/what-is-the-evidence/morphology/bilateralism/ “Humans have body plans that are bilaterally symmetrical. This means that if you draw a line down the centre of the human body, from the middle of the head to the feet, the same features appear on either side.� Why do you have two lungs but only one heart? http://health.howstuffworks.com/human-body/systems/circulatory/two-lungs-one-heart1.htm “Your vital organs -- like your lungs, your heart, your pancreas, brain and liver -- are just that, vital. Not only are they vital to life, they are also vital to one another.� Why have one heart but two kidneys? http://www.thenakedscientists.com/HTML/questions/question/3091/ “It’s not just us that are bilaterally symmetrical. All vertebrates are – be they birds, reptiles, frogs, or fish. In fact, not just vertebrates but almost all other animals are bilaterally symmetrical as well.� ____________________ DNews is dedicated to satisfying your curiosity and to bringing you mind-bending stories & perspectives you won't find anywhere else! New videos twice daily. Watch More DNews on TestTube http://testtube.com/dnews Subscribe now! http://www.youtube.com/subscription_center?add_user=dnewschannel DNews on Twitter http://twitter.com/dnews Trace Dominguez on Twitter https://twitter.com/tracedominguez Julia Wilde on Twitter https://twitter.com/julia_sci DNews on Facebook https://facebook.com/DiscoveryNews DNews on Google+ http://gplus.to/dnews Discovery News http://discoverynews.com Download the TestTube App: http://testu.be/1ndmmMq

• published: 27 Jul 2015
• views: 115338