</p> If we only need one kidney how come we've got two? I'm usually ok on this sort of thing but I'm a bit stumped.</p>
Do we need two of anything? No. Two eyes? One will do. Two nostrils? One will do. Two legs? One WILL do. Two arms? One will do. Two ears? One will do. Two testicles? One does do. Just the bodies way of backing up, so if disaster was to strike i.e you lost an eye, you would still be able to go on.
because these are part of necessery vital organ system. if we had only one kidney and if that one were to pack in we would die so, by having two , if one was to perish we could still survive. best I can do I'm afraid.
Another useless bit of info: If you have a kidney transplant, unless it's necessary, they don't take away your old kidney. So in most cases, you'd end up with 3 kidneys.
Only certain people have two sperm glands, Peter North - the pornstar does for example. His tagline is 'He leaves womens faces looking like a glazed cream donut'...
We have two kidneys in order to balance the load placed upon them by the body. In 24 hours the kidneys reclaim about 1,300 g of sodium, 400 g of sodium bicarbonate, and 180 g of glucose. With one kidney only half this amount would be processed. The body can manage with only one kidney but the job is faster and easier with two doing the work.
Interesting one. I don't buy the – it's a back-up argument, because the brain a heart would seem better candidates for a back up. I would argue, it's a developmental constraint resulting from symmetry of body parts. Plus we have a basic ancestral design which is modifies by evolution to fit different life histories. Thus we have two arms and two legs because our ancestral fish predecessors had 2 pairs of fins. Not that 4 limbs is better than 6 or 5 or 8. Its just an accident of history. Actually you can remove the spleen from adults so why have one at all, because our ancestors had one. Similarly, why do many have nipples?
May be a bit late but: What I've found out over the years is because of all the work the kidneys do it is better to have two to share the work, but not exactly necessary as one can do the work but it does put a little more strain on your system. Why Doctors say we need two: Quick answer: So we don’t die of dehydration, (usually a cause of renal failure) longer answer: To enable the body to cope with cleansing the blood and getting rid of all the waste products they consider harmful to our body. The kidneys have to be able to excrete anything and everything from the blood and turn it to urine, whilst being able to balance the minerals/vitamins and water etc. that our body needs to function correctly. The kidneys have to filter over 200 litres of fluid daily. On top of this they need to produce hormones to regulate blood pressure, produce an active form of vitamin D that promotes strong, healthy bones and control the production of red blood cells. Unfortunately mine filter everything out and don’t retain what my body needs, that’s why I have to take so many drugs per day to make up for the loss. Also mine aren’t doing a good job of producing the hormones etc. which is why my bones are soft, I need regular iron infusions and my blood pressure is higher than normal.
to filter twice as much stella are you daft if the asda keep the 3 for £20 further generations could have 3 kidneys and livers the size of a mini