How our sense of smell influenced pig domestication

Giving insight into how our taste for different foods may have been influenced by variation in our ability to smell, researchers have found that inability to detect a particular smell by Asians led to start of pig domestication.

Kara Hoover from University of Alaska Fairbanks in the US and colleagues looked into a smell receptor called OR7D4 that enables us to detect a very specific smell called androstenone, which is produced by pigs and is found in boar meat.

People with different DNA sequences in the gene producing the OR7D4 receptor respond differently to this smell -- some people find it foul, some sweet, and others cannot smell it at all.

The inability to smell androstenone was involved in the domestication of pigs by our ancestors -- andostroneone makes pork from uncastrated boars taste unpleasant to people who can smell it.

Pigs were initially domesticated in Asia, where genes leading to a reduced sensitivity to androstenone have a high frequency, said the study for which the researchers analysed the DNA that codes for OR7D4 from over 2,200 people from 43 populations around the world, many of them from indigenous groups.

We have about four million smell cells in our noses, divided into about 400 different types. There is tremendous genetic variability within and between populations for our ability to detect odours.

Each smell cell carries just one type of receptor or 'lock' on it -- the smell floats through the air, fits into the 'lock' and then activates the cell.

The research was published in the journal Chemical Senses.