Maria Konnikova looked at the research done by anthropologists on the sizes of social groupings. The research initially studied why non-human primates spent so much time on grooming one another but then got extended to humans.

[I]n the nineteen-eighties, the Machiavellian Intelligence Hypothesis (now known as the Social Brain Hypothesis) had just been introduced into anthropological and primatology discourse. It held that primates have large brains because they live in socially complex societies: the larger the group, the larger the brain. Thus, from the size of an animal’s neocortex, the frontal lobe in particular, you could theoretically predict the group size for that animal.

Looking at his grooming data, [anthropologist and psychologist Robin] Dunbar made the mental leap to humans. “We also had humans in our data set so it occurred to me to look to see what size group that relationship might predict for humans,” he told me recently. Dunbar did the math, using a ratio of neocortical volume to total brain volume and mean group size, and came up with a number. Judging from the size of an average human brain, the number of people the average person could have in her social group was a hundred and fifty. Anything beyond that would be too complicated to handle at optimal processing levels.

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Environmental writer Elizabeth Kolbert had an interesting article in the New Yorker about the little-known world of caterpillars and other insects. I have to admit, caterpillars had not figured much in my consciousness but was impressed to learn that they undergo a dizzying array of transformations in their very short lives.

From a caterpillar’s perspective, humans are boring. The young they squeeze out of their bodies are just miniature versions of themselves, with all the limbs and appendages they’ll ever have. As they mature, babies get bigger and stronger and hairier, but that’s about it.

Caterpillars, for their part, are continually reinventing themselves. They emerge from tiny, jewel-like eggs and for their first meal often eat their own egg cases. Once they reach a certain size, they sprout a second head, just behind the first. They then wriggle free of their old skin, the way a diver might wriggle out of a wetsuit. (In the process, the old head drops off.) In the course of their development, they will complete this exercise three, four, in some species sixteen times, often trying out a new look along the way. The spicebush swallowtail, for example, which is found throughout the eastern U.S., emerges from its egg mottled in black and white. This color scheme allows it to pass itself off as a bird dropping. After its third molt, as a so-called fourth instar, it turns green (or brown), with two yellow-and-black spots on its head. The spots, which look uncannily like a pair of eyes, enable the swallowtail to pretend it’s a snake.
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I was talking with someone recently and during the conversation, she started telling me about the psychic she visits who had been very helpful in enabling her to communicate with her dead husband who had given her various kinds of advice. She said that the psychic has also told her many things that were accurate. She also said that on one occasion, she had seen her dead husband in the corner of the room and had made eye contact with him. She said that another person who was with her had also seen her husband.

I got to know this person just within the last couple of years, and while we are not close friends, she is very nice and I like her. While she was telling me this, I simply kept silent, even though I am dyed-in-the-wool materialist who does not believe in the existence of the afterlife and the spirit world. I am also aware that psychics and mediums use cold reading and other methods to give the impression of channeling the voices of dead people. And yet, my friend was so obviously happy with her experience that I did not have the heart to try and disabuse her of her belief.
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