Social cognition in reptiles

A MindBlog reader referred me to this interesting post by a blog, "The Thoughtful Animal," that I had been unaware of, and have now added to the BlogRoll in the right column of MindBlog.

If several others are all directing their attention at a specific point in space, there might be something important there. We're naturally aware of where others are looking. And so are lots of other animals.

Gaze-following is the ability of an animal to orient its gaze to match that of another animal, and though this ability has been observed in mammals and birds, the phylogeny of gaze-following is still uncertain...gaze-sensitivity - the ability of an animal to avoid the gaze of another animal - seems to be somewhat more common in the animal kingdom, having been observed in mammals and birds, and some reptiles and fish. Gaze-sensitivity may have evolved as an anti-predator defense; a theory known as the "evil eye hypothesis" suggests that the awareness of the gaze direction of a predator would help an animal know when it was safe to move about or come out of a hiding spot. Gaze-following requires gaze-sensitivity; indeed, gaze-following develops in human children after gaze-sensitivity. It therefore follows that gaze-following is cognitively more complex than gaze-sensitivity.

Are these abilities also present in reptiles? If so, it could suggest that all amniotic species (birds, mammals, and reptiles) share them, and that it emerged quite a long time ago, in evolutionary terms...Eight captive-bred red-footed tortoises were socially housed for six months prior to this experiment. One tortoise, the demonstrator (the same individual was always used as demonstrator), was placed on one side of a tank, and a second tortoise, the observer, was placed on the opposite side of the tank. They were separated by transparent screens. Above, a small opaque partition separated the two sides of the tank. The investigators directed a small laser beam towards the opaque partition on the side of the demonstrator. Once the demonstrator noticed the light, she invariably looked up at it. The experimenters varied the color of the light to maintain her interest, such that she would not habituate to it. When the demonstrator looked up, would the observer direct his or her gaze up as well? If so, it would suggest that red-footed tortoises, despite their solitary existence, are sensitive to the gaze direction of their conspecifics.

There was a clear difference between the conditions, with the observer tortoises looking up in the experimental condition significantly more than in either of the control conditions. This was the first study to demonstrate that reptiles are able to follow the gaze of conspecifics, suggesting that gaze following may occur more often in the animal kingdom than previously thought...It is possible that the common ancestor of the three amniotic classes - birds, mammals, and reptiles - possessed the ability to co-orient and follow the gaze of others, rather than gaze-following having evolved two or three separate times. There was theoretically little selective pressure for such an ability to have emerged in this particular species, given their solitary lifestyle. Another possibility, however, is that gaze-sensitivity may be innate, and that gaze-following builds on this innate mechanism through associative learning. This could also explain the results of this experiment, as the tortoises had six months of social experiences prior to the beginning of the study.