Recent and relevant papers– July 23, 2014

Niche-specific cognitive strategies: object memory interferes with spatial memory in the predatory bat, Myotis nattereri (Journal of Experimental Biology)– Fruit and flower bats tend to use spatial memory over shape because those foods don’t move. But insect-eating bats tend to do the opposite, perhaps because insects have distinct shapes and don’t stay still.

Maternal lineages best explain the associations of a semisocial marsupial (Behavioral Ecology)–kin selection in brushtail possums

Frugivorous bats evaluate the quality of social information when choosing novel foods (Behavioral Ecology)– Tent-making bats copy the foods found on other bats’ breath rather than others’ fur

Tent-making bats (Uroderma bilobatum)

Roosting behavior and group decision making in 2 syntopic bat species with fission–fusion societies (Behavioral Ecology) — “In a field experiment where we created a conflict of interests among colony members where to roost, brown long-eared bats always achieved a colony-wide consensus about communal roosts. On the contrary, in Bechstein’s bats, individuals with conflicting interests often formed subgroups in different roosts according to their individual interests instead of reaching a consensus on a single communal roost. “

The dynamics of sperm cooperation in a competitive environment (Proceedings B)– sperm cooperation differs depending on sperm competition

Friendship and natural selection (PNAS) genetic similarity between unrelated friends versus unrelated strangers in large human samples

A functional role of the sky’s polarization pattern for orientation in the greater mouse-eared bat (Nature Communications)– bats use polarized light to set their compass

Partner switching can favour cooperation in a biological market (Journal of Evolutionary Biology)– partner switching in house sparrows and effects on fitness

Group augmentation and the evolution of cooperation (TREE) Do cooperative breeders try to increase the size of their own groups?

In August, I will be speaking at APA Convention in DC and the Animal Behavior Meetings in Princeton, NJ. Then off to Panama.

A vampire bat echolocates into my ear

A vampire bat echolocates into my ear

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A few recent updates

Some recent papers:

Latest on social bonds in baboons from Seyfarth and Cheney lab

Risky Ripples Allow Bats and Frogs to Eavesdrop on a Multisensory Sexual Display

A biological market theory approach to plant-fungi mutualism.

The past and future of Behavioral Ecology mentions vampire bat food sharing

Three-dimensional space: locomotory style explains memory differences in rats and hummingbirds … 3d spatial learning needs to be tested in bats

Food sharing is linked to urinary oxytocin levels and bonding in related and unrelated wild chimpanzees

Care for kin: within-group relatedness and allomaternal care are positively correlated and conserved throughout the mammalian phylogeny Confirmation of past findings

Assortative mating based on cooperativeness and generosity (in humans)

Underground signals carried through common mycelial networks warn neighbouring plants of aphid attack. I love plant communication studies.

also, Congratulations to Daniel Streicker, who received the prestigious SciLifeLab Prize for his work on disease transmission. Streicker is the foremost expect on rabies in vampire bats.



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Great talk on food sharing in primates (including humans)

presentation by Adrian Jaeggi at the UCLA Center for Behavior, Evolution, and Culture

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Foraging big brown bats use social calls to ward off competitors

Genni Wright has been studying social calls by flying big brown bats. She found that males produce distinct calls when foraging for food, and that they use these social calls to ward off competitors and claim aerial insects. Prey defense was one of the first functions of social calls suggested by field evidence in 1997 by Kate Barlow and Gareth Jones, but Genni’s study really demonstrates how the calls work by studying the vocal behavior of the bats in a flight room with arrays of synchronized high-speed stereo video and ultrasonic microphones.

The paper is here

Commentary here

Big brown bat catching a mealworm in the Moss Lab:

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More on evolutionary psychology and morality

I have been reading work by the evolutionary psychologists Peter Descioli and Robert Kurzban. Kurzban gave a great talk I saw last week at a conference proposing that the reason people have Kantian rule-based systems of morals is because morality serves as a way for bystanders to collectively coordinate which side to join in a conflict. As an illustration, imagine that you and I live in a communal house with ten people. Our housemates Adam and Bob get in a dispute. Adam is hungry, so he takes and eats Bob’s lunch. A fight breaks out. Because we tend to look to form alliances when in disputes, both Adam and Bob look to the other 8 members of the household for support. This dispute can potentially threaten us all. It could lead to a larger conflict or a war among all ten of us. Kurzban argues that morality evolves as a way for all 8 bystanders to pick the same side. The best way to do this is to use some clear rule that everyone can see. It can’t be a rule that is based on the participant’s identity or their relationship with bystanders. It must be something everyone can see objectively. Did Adam steal? Then Adam is wrong. Because stealing is wrong. This places the entire group on the side of Adam and the dispute is settled quickly and efficiently. People who fail to conform to this moral rule will be on the wrong side of the argument with less support, so it behooves everyone to be on the majority side.

This kind of “collective decision-making” is common in nature. For instance, it’s the way bees in a colony and brains make decisions. In social evolution, you can model the effects of these kinds of coordinated actions by considering how individual decisions feedback on individual inclusive fitness, or by partitioning the effects into individual and group fitness (multi-level selection). This sheds light on topics such as the evolution of society and multicellularity. The basic point here is that sometimes interests are aligned and it benefits everyone to do the same thing.

The more I think of it, the more I feel like a lot of what we know about how humans condemn others is consistent with this model of morality. It also explains some oddities in moral reasoning.

In another study, Kurzban posed the old classic Trolley moral dilemma to a sample of people. You probably know this already:



Version 1: There’s a trolley out of control. It’s going to kill 5 people. If you throw a switch it will change tracks and only kill one person. Do you throw the switch? Most people say yes.

Version 2: There’s a trolley out of control. It’s going to kill 5 people. But you can push a large fat man in front of it to stop it (your own body is too small). It will kill him but save 5. Do you push the person? Most people say no.

There’s a lot people have said about this finding. One basic point is that most people are Kantian in their moral reasoning. They follow moral rules like “Do not kill others” which is why the decision flips based on the action (flipping switch/pushing person) rather than the outcome. To a utilitarian, all moral actions should be based on outcome only.

Some people even find the utilitarian moral decision (killing 1 to save 5) offensive. It can seem cold and calculating rather than "human-hearted".

Some people even find utilitarian moral reasoning offensive. “Killing one to save the many” can seem cold and calculating rather than “human-hearted” approach of  following moral norms  like the Golden Rule or “Never kill anyone”

Kurzban gave both versions a novel twist. He posed the same problem but in one version he said the 5 saved and 1 person killed were all siblings. In another version he said they were friends and in another they were strangers. So what effect did this have?

People were significantly more willing to sacrifice 1 friend to save 5 other friends or to sacrifice 1 sibling to save 5 siblings. They were much less willing to sacrifice a stranger.

When people are dealing with kin and friends, they think more about welfare maximization (How many lives can I save?). But when dealing with strangers they worry more about following moral rules (Do not kill people.) This makes sense, if we think that the driving force for moral decisions dealing with strangers has more to do with how other people might judge us. By contrast, decisions to help or harm friends and relatives are treated differently in our brains. There is a different kind of moral calculation that goes on. Specifically, we have adaptations for true biological altruism with relatives (just like a mother would give up her life to save her children). And because of the importance of reciprocal cooperation to human social life, we also care directly about the welfare of friends, because they are valuable to us and their wellbeing feeds back on ours . With strangers, our moral calculation has more to with what decision is most consistent the moral rules, i.e. what is socially acceptable. It is not socially acceptable to kill a person by pushing them in front of a trolley.

In Kurzban’s view, the trolley problem pits altruism systems (maximize welfare) against moral systems (Kantian rule-based ethics). Surprisingly, he found that almost half of subjects
reported that they would not kill 1 stranger to save 5 siblings. This shows that moral systems might be able to over-ride evolved altruistic tendencies, which is a hallmark human pecularity. I would bet however that in an actual real situation most people would kill 1 stranger to save their close family. They just don’t think they would when answering a survey.

The main point here is that Kurzban’s ideas are not a mere just-so story. They lead to a novel unique prediction: that people will be more likely to switch from utilitarian to Kantian moral reasoning when switching from kin/friends to strangers. It’s hard to explain this using past explanations of moral behavior.

A lot of people I know don’t like evolutionary psychology. Many folks associate evolutionary psychology with bad scientific justifications for conservative political worldviews or simplistic posthoc just-so story explanations for gender stereotypes: “girls like pink because ancestral females used to gather fruits and flowers, and boys like math because men were hunters had to count mastodons”. This is an unfair characterization to be sure. I’ve heard evolutionary biologists sometimes say that evolutionary psychologists get evolution wrong. And I’ve heard clinical psychologists say that evolutionary psychology researchers doesn’t have a real purpose: how does this work help anyone?

In my view, the basic theoretical approach taken by evolutionary psychology is exactly how we study animal behavior (that is adaptationism– testing the extent to which biological traits have a functional design). This has been one of the most successful paradigms in biology. People study function of a trait and this helps us to understand when it evolved, how it develops during the lifetime, and how it works.

It’s often harder to study the evolution of human social behavior because it’s so easy to bring our own intuitive baggage to bear on the problem, including our own introspections and political world views. It’s also easy to slip between talking about the design on behavior (e.g. “evolutionary altruism”) and the actual thoughts and behaviors that people have (e.g., “psychological altruism). This happens often when we talk about things like “strategies”. It’s clear what we mean when we say that root allocation in a plant is a strategy for competing less with kin. But this becomes a bit more ambiguous when we talk about a strategy in a human or vampire bat. People mistakenly think you mean conscious planning.

Basically, “anthropomorphism” is possible even for humans. We falsely believe that other humans think the way that we think we think (which is often wrong).

Ultimately, psychology has to be based firmly in biology (and that means evolution), just like biology has to be based in chemistry and physics. Of course physics doesn’t explain everything about how cells divide, what causes species to go extinct, or why mammals but not reptiles have milk. But everything in biology can be understood as going back to physical and mathematical laws. The greatest leaps forward in biology occurred when abstract concepts (such as disease, genes, mind)  were routed in real physical things made of atoms and molecules (viruses, DNA, and neural circuits).

So to with psychology as it develops into a mature science with links to neuroscience and evolutionary theory. Many of evolutionary psychology’s controversial ideas are completely accepted in animal behavior—  that minds are composed of modular functional adaptive specializations, that learning is not a general associative process but based upon instinctual rules about what to learn and when,  and that all the complex traits of human nature at some point increased inclusive fitness in the environments in which they evolved. These ideas will soon be completely uncontroversial among all disciplines within my lifetime (I hope).

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Live Vampire Bat webcam at Organization for Bat Conservation website

Image Click on image to view

Live at Organization for Bat Conservation

Live at Dropcam

Past clips

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Conference on Evolution of Morality: why do people condemn others?

Last month, I moved my vampire bats to the Organization for Bat Conservation in Bloomfield Hills, Michigan. I’m now working on a group of more than 30 bats.

I recently attended a small conference on The Evolution of Morality at Oakland University.

My favorite talk was by Robert Kurzban on the evolution of third-party punishment (in humans). Kurzban started his talk with the crucial point that morality and altruism are not the same thing. Altruism is about mostly helping other people. Morality is largely about judging people’s actions. There is an obvious adaptive reason to judge our own actions (mostly because other people will also judge our actions and reward and punish us accordingly). But here’s the real mystery: why do we morally condemn other people’s actions? Even people who have no effect on us? And why do we do evolutionarily-nonsensical things like condemn the actions of our friends and family, even when those actions do not hurt us? Imagine a scenario between a bully and a victim. The aspects of human nature that can drive bullying make evolutionary sense. The aspects of human nature underlying the actions of the victim typically make evolutionary sense too. But now consider a third-party observer that is unaffected by the dispute. Most third-party observers don’t involve themselves in a typical dispute (for better or worse), but interestingly, almost everyone passes judgment. That is, almost everyone mentally chooses a side. Why do people always perform moral condemnation (even though most people will never take a moral action)?

How do you feel about this picture? We condemn other people in a dispute, even when we do not plan to take any action ourselves, and even when the dispute will not affect our own lives in any way (and even when the characters are fictional).


There are many ideas about this, but most of them don’t predict the weird ways people make moral decisions to condemn or not condemn others. And they don’t answer why we should even take the time to pass judgment at all. Kurzban makes a very compelling argument that the adaptive function of moral condemnation is for each third party bystander to choose the larger side in a dispute. All bystanders want a consensus to be reached on who is right in a dispute so that there won’t be a long drawn out conflict. And they also want to be allied with the larger, winning side. But how do we know which will be the largest side? Well, let’s examine some choices of strategy.

One strategy would be to always side with your friends and family. Here the problem is that many other people will be against you. If your friend murders someone and you take his side, now you have to defend yourself against the victim’s family and friends. The result is a lot of fighting. Not good. Another option: you could always side with the most powerful people. The disadvantage here is that it will quickly lead to a situation where certain people will dominate and repress everyone, including you. Not the best outcome long-term. Kurzban argues that people have evolved to conform to an implicit set of rules within each group for coordinating whose side to take. Conforming to these rules itself requires cooperation, but it’s easy to see how it would benefit everyone to have this set of rules. Crucially, the rule has to depend on people’s actions, not their identities. For instance, the rule might be something like: “If person A tries to kill person B for personal gain, then person A is wrong and take the side of person B” or “If person A steals from person B, then take the side of person B”, and so on.

Obviously, the actual moral rules we follow are more complicated and also not always so explicit or conscious. We often don’t know what they are, except through gut feeling. We can’t articulate why certain things just “feel wrong.” Compare moral rules with language. In language acquisition, we each adopt words and rules from a local language, but we all have an instinct to learn a language. A spot in our mind that says “language goes here”. Likewise, humans have an instinct to adopt a local set of moral norms and to want other people to agree with them. Those moral rules might differ a bit place to place, but they will serve the same functions and so have many similarities. That is how you get the evolution of morality. And this view explains why people make moral judgements in some very strange ways, based on rules rather than always on actual welfare. Now to be honest, I don’t know how much of what I just wrote is Kurzban’s ideas versus my ideas, extrapolating from what Kurzban and others have said. But I think it’s a very interesting view and I will be interested to read more of his papers.

I also enjoyed talks by Sarah Brosnan (moral emotions in primates) and David Buss (human sexuality), and I thought Randy Thornhill’s talk on his theory that pathogens have largely shaped human social behavior was really interesting. I enjoyed talking to Peggy Mason about her prosocial rats, Brock Brothers, Chinmay Aradhye, Mark McCoy about what personality traits predict religiousity, and why the incentive structure in academia are often bad for science. I also had interesting discussions with Michael Pham and Sylis Nicolas (who also study human sexuality) about all kinds of things I won’t discuss here, Alexis Garland (about counting in animals), and about all kinds of stuff with Bailey House who has studied the development of reciprocity in children. I had some other discussions with many other people that I can’t recall right now. It was a fun conference.

The most memorable talk was by a philosopher named David Benatar who made the most cringing (but intellectually brave) philosophical argument I’ve ever heard in my life. I don’t have time to go into it here, but you can read about it in this review which summarizes the argument (and by coincidence, my response to it was fairly close to what the reviewer said).

I was particularly impressed by the way that Todd Shackleford and Jennifer Vonk were very supportive of their graduate students. Young faculty tend to promote their graduate students a lot, and this is always heart-warming to see.

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