DATING SITES ID THE SMELL OF LOVE
By Eric Bland
Discovery News
May 6, 2009

Original Link

"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.

Environmental factors like hygiene, garlic and other fragrant foods can change some aspects of a person's smell, but the "base note," or the most subtle and persistent smell is the function of the three genes: HLA-A, HLA-B, and HLA-DRB1. Simplified, these three genes control the immune system, which controls which microbes the immune system attacks. These non-human microbes are what actually produces a person's smell.

There are hundreds of different alleles, or versions, of these genes. Scientific Match only matches people who have completely different versions of these three genes. Their clients take a swab of their cheek, send it to the company in a pre-paid envelope, and the company runs their DNA and matches them .

Scientific Match operates in the Northeast and began in December of 2007. So far they can't point to a successful couple matched on their site, however.

"It's really difficult to keep track of people after they leave the Web site and meet in person," said Eric Holzle of Scientific Match. "But we are building up our database of clients, and hope to have some soon."

The advantage that Scientific Match and Basisnote have over dating Web sites, says Martie Haselton, a professor at UCLA who does her own smell and attraction studies, is more than 40 peer-reviewed and published studies documenting the positive effect of different MHC's in couples.

"The science is real; different MHC's are good for the sexual aspects of a relationship," said Haselton. "But to commercialize it there are a number of challenges."

For Basisnote and Scientific Match the biggest challenge is getting enough people to sign up for their services to create a large enough pool of people to draw from. To do that, Holzle is considering licensing his technology to other dating Web sites.

"You can't have hundreds or even thousands," said Haselton. "You need hundreds of thousands in an area because in addition to the MHC, you have to screen for demographics, political preferences, etc., and these things can be real deal-breakers."

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NHNE Male/Female/Relationship Research