Today’s guest blogger is Idan Frumin, a student in the group of 
Prof. Noam Sobel in the Neurobiology Department. Their research on the transmission of odor compounds while shaking hands appears today in eLife.
It all started one day after lunch, sometime back in 2011. We sat in the lab’s living room (Yeah, we have a living room. And a bedroom. And a blind pet cat. But that’s a different story), when Noam asked – ever wonder why people shake hands?
– To show you don’t have a saber up your sleeve – I immediately retorted.
– But that seems odd, doesn’t it? After all, we’re not in the Middle Ages anymore, he responded.
Noam had just gotten back from an international conference, one of many, and did there what all better scientists do in their leisure time: observed.
– and what if I tell you people sniff their own hands right after they shake someone’s hand?
–You’re kidding right? what are we, rodents?!
–Well, you should know by now we’re not that far from that…
So we devised a simple paradigm to test this. Do people really sniff their hands following a handshake? And is it directly related to the handshake? And more importantly – is it related to our sense of smell?.. Which is our lab’s frame of reference for, well, almost anything.
We already had most of what it takes – we have rooms where we can put human subjects and sit them relatively comfortably on a dentist-style chair (talk about comfortable…), we have CCTV cameras that only need to be set up, and plenty of subjects that come and go for the various experiments taking place in the lab. So off we went. We knew we needed a big sample of subjects to be able to say something meaningful, so we started with 60. The paradigm was pretty simple – A person was seated alone in the room, unaware at that point that they are being filmed. After three minutes of idle seating, one of my lab mates (or myself at times) would enter and either shake or not shake the subject’s hand, saying the same “greet” sentence. The subject thought they’re waiting for the “real” experiment to ensue, so we told them we are getting everything ready, and that the experiment will start momentarily. After an additional three-minute period, the experiment was essentially over.
Analysis of substances on the rubber glove after a handshake revealed that chemicals from human secretions were transmitted through handshake alone
Then the fun part started. Watching this quantity of videos could be “a bit” tedious, but it has its perks embedded – people do the most hilarious things when they are alone… the most interesting for us – they constantly touch their faces. Much as Noam and that late-90’s song both foresaw – “you and me baby ain’t nothing but mammals,” and may we add – indeed not very far from rodents so it seems. We constantly “groom.”
One of the more perplexing results was the “self-sampling” behavior after encountering another individual — as if to assess or validate one’s own place within some sort of hierarchy.
But the jackpot was the statistics of before and after handshake – there was a significant and substantial increase if a handshake was involved!
After a handshake (left), a volunteer sniffs her “shaking” hand more (right) (photo illustration)
Though we got nice results with 60 subjects, and presented those in two international conferences, we wanted something more comprehensive to tell. Is this effect happening only between males and females? Is it gender specific at all? So up went the count – to 160 subjects, 20 in each possible combination of subject, experimenter and shake/no shake. And this number continued to swell as we added more conditions and more controls. You can check the article to see what we did there. Calvin Klein was unwittingly involved as well…
Along the way the paper got some pretty and colorful additions. One day Ofer came and asked – did you check and see WHERE people touch their faces? I replied “Well it’s a very interesting question which I am not going to address, but feel free to check that”. So he did just that, and the answer became figure 2C – which I must say is one of my favorite pieces of art since. Another day Yaara wondered what actual chemicals are transferred when we shake hands, and that’s Figure 1.
Heat map: The likelihood of people touching their faces close to the nose was highest (red, yellow) after a handshake (left)
When people ask why study such stuff, and what scientific field or discipline do such studies fall under anyway – we have several answers. First – because it’s there – and it’s interesting. Everyone shakes hands and if the common explanation as to why is partial – we need to amend it. We do basic science – and the notion of applicability is important but not the main thing. Second, this really serves a broader argument – in which our stand is quite obvious – there is no advantage for man over beast, and we’re a part of the greater evolutionary tree.
So here you have it – a story that started off as a casual conversation in the living room of a lab, and 280 subjects / cups of coffee / new grey hair later became the paper you ought to read, if you haven’t done so already!
