The Smell of Love: Dating Sites Match you by Odor

http://dsc.discovery.com/news/2009/05/06/dating-smell-match.html

""The alleles of my Major Histocompatibility Complex are completely opposite from yours," might not sound like pillow talk, but it is the literal basis for the "chemistry" many couples have.

Two companies, Basisnote and Scientific Match, are developing technology to match couples based on the genetic components of the human immune system -- and their odor.

Studies have linked odor to immune systems and shown that people are most likely to be attracted to the smells of those who have different histocompatibility genes than their own. While those who have similar immune systems tend to not be attracted to each others' odors.

"The MHC helps signal whether I find someone attractive or not," said August Hammerli of the Switzerland based Basisnote. "What we have developed is a saliva assay that measures a person's MHC and how they might react to another individual's MHC profile."

It works like this. Clients order a test online and receive it two days later. Then they simply swab their cheeks and put the sample into a machine. Ten minutes later out pops a code of 0's and 1's. Hammerli won't say how many 0's or 1's, or how many different chemicals are being tested.

A client enters their unique code at Basisnote's Web site, and the software matches them to a person with a completely different immune system.

Like the Paula Abdul song, opposite immune systems attract. One person might be easily infected by a particular virus, while the other person easily fights that same virus off.

For the couples, opposite immune systems don't increase their ability to fight off infections. But a 2006 study done by New Mexico State University found that on average, opposite MHC partners engage in more sex, more satisfying sex, and are less likely to cheat in the long term.

The offspring of couples with opposite immune benefit as well. The sons and daughters of these couples, should inherit the best of their parents' immune system, making them better able to fight off a variety of infections.

Since smell is based on a person's immune system, Basisnote identifies the specific chemicals put out by a person's immune system to identify an individual's smell. U.S.-based Scientific Match, meanwhile, matches up its clients by analyzing three genes that largely control an individual's innate immune system -- and smell."