Sweet Smell of Success
Two papers were published this week on the brains of early mammals – of our mouse-like ancestors. CT scans revealed the exciting development of the sections of the brain that we associate with the smelling of roses.
The thesis is that as our odorant receptors improved, we required bigger brains to process the data efficiently. So to enhance the olfaction satisfaction of noseworthy information, the head cases had to become bigger to house the fast growing data storage and faster processing equipment.
Dr. Rowe put it more eloquently: "The origin of crown Mammalia saw a third pulse of olfactory enhancement, with ossified ethmoid turbinals supporting an expansive olfactory epithelium in the nasal cavity, allowing full expression of a huge odorant receptor genome."
It is important to remember that these were small creatures who had to share the planet with lots of carnivores and herbivores with large feet. Hence, it was much better to be on the night shift to avoid being eaten or stepped on.
Sensitive whiskers may help to find food when you are very close to it, but a good odorant receptor is a longer range device. Of course, its not just food that is important to young creatures. It is also finding a mate, and if you have chosen to have four little legs instead of wings, screeching and making a spectacle of yourself in order to advertise to your partner, is not a good idea. A good nose means that a stealth approach is possible under cover of darkness, almost as good as a smart phone.
When I look at my dog and see the size of her nose, I can know see why she thinks that she is brighter than I am as I run to the store for dog-food and after her in the park with a plastic bag.
- T.B.Rowe, T.E.Macrini & Z-X Luo, Science, 332, 955, (2011)
- R. Glenn Northcutt, Science, 332, 926, (2011)
