facial recognition paper wasps

When I was younger, a lot younger, one of my favorite lines for approaching the opposite sex was “haven’t we met before? you look so familiar” Sometimes it worked even if I had never seen the girl before. Unbeknownst to me at the time, in addition to the ruse of getting a conversation going, I was telegraphing a freighted psychological message: we belong in the same social circle; even if we haven’t met, we should have.

Facial recognition is not just an excuse for boys to meet girls; it has a profound role in our species sociability. Think about it: if we didn’t have this capacity, how could we form bands? Band formation is not only the basis for cooperative behavior, it is the very reason for our evolutionary success. In fact, recent research showed that facial patterns such as skin and hair color may have evolved to help primates to recognize and communicate with others of their species. Sharlene Santana and her colleagues at UCLA analyzed skin and hair color patterns

Sharlene Santana and her colleagues at UCLA analyzed skin and hair color patterns in the faces of adult males of 129 species of primates from the Americas. They found that species that live in smaller groups have more complex facial features. One possible explanation is that such animals interact with other members of the species less frequently than members of a species that live in larger groups, and therefore are more dependent on facial pattern recognition. Maybe.

But we don’t have to resort to such speculation to realize that facial recognition is important to our survival. We have a special area in the brain, a module dedicated to facial recognition. In fact, there is a theory that large brains developed because living in groups required tasks such as facial recognition that involved a large number of neurons and a high degree of neuronal interactions. Sounds plausible enough, but no real data to support it.

When in doubt, look at the insects

Insects are fascinating animals not only because they are a success story in biological adaptation (cockroaches shall inherit the earth after we kill each other with nuclear bombs), but also because several species evolved highly structured societies. And because of their relative simplicity, they can serve as ideal models for studying traits that they share with us.

Sheehan and Tibbetts ( Science, Dec. 2, 2011) present fascinating evidence that the paper wasp Polistes fuscatus not only recognize the faces of individuals of the same species, they are also experts in facial discrimination, in other words, they can recognize differences in relationships between facial features, like the distance between the eyes.

 

How on earth did the researchers study it?

They trained the insects to choose one of two arms of a maze, each marked by an image. If the wasps turned to the wrong image it experienced an electric shock (any PETA readers here?) whereas choosing the correct arm provided safety. The image pairs consisted of normal wasp faces, manipulated wasp faces, simple geometric patterns or caterpillars -their normal prey. The wasps of this species learned to recognize wasp faces more quickly and more accurately than they did other image types.

Why should they be proficient in face recognition? Every spring several queens join forces to build, defend and provide for a new nest. cooperation boosts the chance for success, but it poses a dilemma: who is going to be the queen of the new nest? This is decided by a series of one-on-one fights. The strongest queen dominates egg-laying and the other are relegated to more menial tasks. After a duel, individuals recognize their opponents by their distinct facial markings, which helps to avoid the repetition of potentially costly battles. Quite similar to the establishment of social hierarchy in primates.

The finding that not only primates, including humans, can recognize faces – insects do it too- puts a question mark on the “social brain” hypothesis, which posits that group-living and complex social interactions require large brains. A complex function such as face recognition does not necessarily involve a large number of neurons. Just look at these small-brained insects.

King Solomon admonished us to ”

go to the ant, O sluggard; consider her ways, and be wise” (Proverbs, 6;6).

Not much has changed since.


This post was reviewed and updated on 5/5/17

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.

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