Hey everyone!

 

Just a question out of curiosity. Humans (other animals too) appear to be very sensitive to the smell of any thiol compound (some can be detected in parts per billion).

 

I was wondering if there is a biological reason why this is so? Is it intended for something such as a defence mechanism or is it a by product of being able to smell other aromatic compounds and such?

 

Thanks for the information.

 

-- Ryan Jones

Sulphide compounds (hydrogen sulphide and mercaptans/thiols) are produced by bacteria as they break down proteins so the smell warns that meat has gone off. There is also some in faeces from the meat processed in your gut so the smell would warn against that potentially infectious material.

 

NB. Most people have populations of bacteria in their gut that make use of the sulphur in digested proteins but dedicated vegetarians tend to lose these as their diet is low in cysteine and methionine-containing proteins. However, should they eat a hearty plate of, say, baked beans the sulphur in that cannot be processed and is excreted principally as hydrogen sulphide making really smelly farts!

Interesting so it does have an evolutionary purpose! That also explains why they are so provocative, even in low concentrations.

 

Thanks for the information

Gah don't remind me. I just ate asperagus. I can't stand that smell.