Why Mice Don’t Get Ulcers

In his 1994 book “Why Zebras Don’t Get Ulcers,” Robert Sapolsky described the difference between the types of stress that people often experience and the ones that other animal species do. In his titular example, if you were a zebra, you’d most likely face acute physical stress – the lion about to eat you – which requires immediate physiological adaptations (the fight-or-flight response). A second type of stress might be chronic and physical (drought, famine, parasites, etc.).

However, the third type of stress on Sapolsky’s list – the type most prominent in an industrialized human’s life – was social and psychological. While our species certainly benefited from expanding brain size over the last few million years, it too came with trade-offs, including the ability to overthink and worry about things to come down the road. This type of stress would not have featured too prominently into the mental lives of other species. As Sapolsky wrote:

“How many hippos worry about whether Social Security is going to last as long as they will, or what they are going to say on a first date? 

For the vast majority of beasts on this planet, stress is about a short-term crisis, after which it’s either over with or you’re over with. When we sit around and worry about stressful things, we turn on the same physiological responses – but they are potentially a disaster when provoked chronically. A large body of evidence suggests that stress-related disease emerges, predominantly, out of the fact that we so often activate a physiological system that has evolved for responding to acute physical emergencies, but we turn it on for months on end, worrying about mortgages, relationships and promotions” (p. 5 – 6).

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“I’ve never seen a Chinese monkey” (Essentialism & Human Variation)

I taught my first undergraduate anthropology class seventeen years ago, which is sometimes hard for me to believe. In that time, I’ve had over two thousand students enrolled in my courses, many of whom have left an impression on me. I hope I make a good impression on them too, though sometimes I have my doubts. A few years ago, a student asked me what my name was as they started to fill out the line after “Instructor” on the front page of their exam blue book. That was about halfway into the semester. You can’t reach them all, I suppose.

During my fourth year of teaching “Introduction to Biological Anthropology,” we got about two-thirds into the semester, and I paused to take the class’ pulse on how things were going. I asked them if they had any general thoughts about the class, such as what ideas they found interesting (or not), things they wished we could discussed more in depth, etc. I have since forgotten most of the students’ comments, except for one.

I remember that he wasn’t exactly the best student, and that he had struggled with most of the graded assignments. Nonetheless, I still learned something from him that day. He told the class that he thought evolution was an interesting idea, but he was skeptical about it applying to humans because, as he said, “Well, I’ve never seen a Chinese monkey.” This all occurred a long time ago, but I remember that at first I was puzzled by what he meant. And then it clicked.

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Primates and the Day of Atonement

“As far as possible without surrender/  be on good terms with all persons.”

– Max Ehrmann, Desiderata


Our kids were home on Wednesday last week, as our school district observed Yom Kippur, the Day of Atonement in Judaism. I’m not a theologian and can’t claim to have anything beyond a superficial understanding of Yom Kippur, but as we walked past the local synagogue in our neighborhood, surrounded by parked cars, I speculated about how and why such a tradition might have arisen.

From my understanding, Yom Kippur is primarily concerned with seeking forgiveness from God for any transgressions accrued in the last year. However, I was more curious about another related aspect of the holiday, which is that – prior to the day itself – people are also encouraged to seek forgiveness from others they have harmed.

I can see parallels here to my own Roman Catholic childhood and the sacrament of Penance. Of course, as a boy I was just doing what the adults told me to do, going through the motions – perfunctorily confessing to a priest about fighting with my siblings. But I never contemplated why something like Penance might exist, aside from the obvious one of avoiding Hell (that fear seems a lifetime ago).

Most religious traditions and societies probably have concepts like forgiveness, reconciliation, and atonement built into them to some degree. These likely have deep roots, and we can even find some of the basic building blocks of these among other species of primates. Most primate species are highly social, group-living animals, which has a list of pros and cons. The benefits of being social include having more eyes and ears to detect predators, the ‘selfish herd’ idea (less chance for me to be eaten), defense (against conspecifics for territory, against predators), more models of adult behavior (socialization), easier to find mates and food, and (in some species) reaping the benefits of specialized division of labor.  

However, all things in biology have tradeoffs. If you’re going to live in a group, chances are next to nil that there will not be at least some internal conflict. It’s certainly not all-conflict-all-the-time, but the degree of internal conflict depends on circumstances. Two individuals may want similar things most of the time, but they cannot maintain perfectly overlapping interests indefinitely.

Among baboons, social life is rife with conflict as individuals vie for status. In an interview with Robert Sapolsky, he described the impact social stress can have on baboon life, while drawing a comparison to humans:

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Time and Reconciliation: the Christmas Truce

The biologist Robert Sapolsky had a recent essay in The Wall Street Journal on the Christmas Truce of WWI, where he discusses how cooperation might develop under difficult circumstances. I wrote a blogpost on the same topic here a few years ago (in fact, it is still the most viewed thing on this site), and I think we cover much of the same ground. Sapolsky’s essay is better, which I’m fine with; it’s Robert Sapolsky after all.

At the end of the essay, he presents a thought experiment about trying to fast-forward mentally through the passage of time and seeing the present through the eyes of our older, wiser selves. 

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