When a fly's smell is bad, its life stinks.

Is the system by which humans detect odors, olfaction, as deeply conserved through evolution as we've long assumed?  Olfaction presents ...

olfaction

I still smell a rat! (Episode II)

So each olfactory neuron (ON) expresses only one of its 2000 olfactory receptor (OR) genes on its surface and hence can only react (bind to)...

developmentolfaction

I smell a rat! (but how do I know it's a rat?)

There's a very fine review in the current issue of Nature Neuroscience , by Zou et al.; "How the olfactory bulb got its glomeruli: ...

genetic plasticityneural developmentodorsolfactionsensory developmentsmell