Why are some organs duplicated?

[derek10]

Why do we have two lungs, two kidneys instead of one bigger one but one liver, heart, pancreas?
I can understand the ears and eyes' cases, to see in 3D and hear better but not in the lungs and kidneys ones
I've googled but couldn't find a definite answer to this.

Is it due to need for a "spare" organ upon failure? (even I don't know if you can live with one lung and the lack of a second heart)
Is it because two smaller lungs/kidney work better than a single bigger one?

Is there a explanation for this?
Thanks!

 

[jedishrfu]

This article may help to explain it:

http://health.howstuffworks.com/human-body/systems/circulatory/two-lungs-one-heart.htm

 

[DaveC426913]

Bilateral symmetry. A very common trait established in the deep past of life.

 

[DaveC426913]

This article may help to explain it:

http://health.howstuffworks.com/human-body/systems/circulatory/two-lungs-one-heart.htm

That's a really disappointing article. It essentially says 'we developed two lungs because we need them to survive.'

 

[Evo]

You can live with one lung, one kidney very well, they have donor surgeries now where they will take part of a person's liver to donate because the liver will regenerate, people even have lived with part of their brain removed (the brain in some instances rewired itself).

What Organs Can You Live Without?

http://www.livescience.com/27896-pope-one-lung-organs-you-can-live-without.html

Did you know that some people are born with their organs reversed? They are on the wrong side of the body.

http://health.howstuffworks.com/human-body/parts/reversal-of-organ.htm

 

[jedishrfu]

That's a really disappointing article. It essentially says 'we developed two lungs because we need them to survive.'

Yes, however barring our modern technology two lungs may have allowed us to survive to have kids.

 

[Andy Resnick]

Why do we have two lungs, two kidneys instead of one bigger one but one liver, heart, pancreas?
<snip>

I wasn't a fan of jedishrfu's article either, but your question only makes sense in terms of comparative anatomy and comparative physiology:

http://en.wikipedia.org/wiki/Comparative_physiology
http://en.wikipedia.org/wiki/Comparative_anatomy

Different organisms have evolved different approaches to solve the same problem (adaptation). I'm not expert enough to say much more than that.

 

[derek10]

Thank you for your replies and links
The human body is not perfectly bilateral simmetric. (usually) heart on left side, liver on the right, off center stomach, etc..
But two almost identical lungs, kidneys, one bladder at center, etc
Why is that?
Interesting the reversed organ placement, diagnostics would be so awkward (pains on the other side, surgery...)