Monthly Archives: February 2015

What is the motive?

It is clear from bacteria to ourselves that cooperation has evolved many times in all sorts of organisms and so it clearly has an advantage that can be realized. However, it is also obvious that simple unquestioned cooperation works if everyone cooperates but would be a great disadvantage once cheaters became numerous. This looks like a paradox – it evolves but why. Cooperation is especially important to humans. You cannot develop our sort of civilization – do neurosurgery or send rockets to the moon or use language – as lone uncooperative individuals.

Two types of cooperation do seem to fit in an evolutionary picture – cooperation between related animals (kin), and reciprocity/trading favours. It is easy to see how these would arise in evolution and be stable. Also (if you accept group selection) groups that were predominately cooperators could out perform groups that were mostly cheaters. Group selection may only work well if the groups are on the small side and then it would be hard to separate this from helping kin and reciprocal relationships. But how does cooperation survive in the large society starting with both cooperators and cheaters?

The Prisoner’s Dilemma game has been used for many years with various modifications (both played by people and by programs) to find the conditions that are needed for cooperation to lose its disadvantages. One of the first fairly successful modifications was ‘tit-for-tat’ in various forms. If someone does not cooperate with you on some occasion then you do not cooperate with them in future. In a population that starts with lots of cooperators and few cheaters, the cheaters will be frozen out of any cooperation and the cooperators will flourish. The models were improved with more ingredients. By itself it is not quite good enough. Another ingredient is punishment of cheaters over and above tit-for-tat. For example cheaters can lose their reputation or in some other way carry a sign that says, “I’m a cheater.” Or a cheater could be directly punished by the individual that was hurt, or by the whole society, or by 3rd party punishers. They can be banished from the group or from participating in particular activities. We humans seem to have a built in joy in cooperating, but also a pleasure in gossip about people who are not worthy, and a need for justice and/or revenge for those that take advantage of our trust.

A recent paper (citation below) by Hoffman and others, examines the idea of examining a person’s motives in deciding whether they are trust worthy. “Why do we trust people more when they do good without considering in detail the cost to themselves? People who avoid “looking” at the costs of good acts can be trusted to cooperate in important situations, whereas those who look cannot. We find that evolutionary dynamics can lead to cooperation without looking at costs. Our results illuminate why we attend closely to people’s motivations for doing good, as prescribed by deontological ethicists such as Kant, and, also, why we admire principled people, adhere to taboos, and fall in love.

Here is the abstract: “Evolutionary game theory typically focuses on actions but ignores motives. Here, we introduce a model that takes into account the motive behind the action. A crucial question is why do we trust people more who cooperate without calculating the costs? We propose a game theory model to explain this phenomenon. One player has the option to “look” at the costs of cooperation, and the other player chooses whether to continue the interaction. If it is occasionally very costly for player 1 to cooperate, but defection is harmful for player 2, then cooperation without looking is a subgame perfect equilibrium. This behavior also emerges in population-based processes of learning or evolution. Our theory illuminates a number of key phenomena of human interactions: authentic altruism, why people cooperate intuitively, one-shot cooperation, why friends do not keep track of favors, why we admire principled people, Kant’s second formulation of the Categorical Imperative, taboos, and love.”

Hoffman, M., Yoeli, E., & Nowak, M. (2015). Cooperate without looking: Why we care what people think and not just what they do Proceedings of the National Academy of Sciences, 112 (6), 1727-1732 DOI: 10.1073/pnas.1417904112

Another brick gone in the wall

The idea that there is an unbridgeable gap between human language and animal communication has taken another hit. For many years it has been maintained that chimpanzees cannot change their vocal signals, so although the grunts vary in different populations, in any particular group they are fixed. Therefore their vocalizations were not at all like a proto-language. A new paper by Watson and others (citation below) documents change in the vocalization in chimpanzees.

Goodall has said, “the production of sound in the absence of an appropriate emotional state seems to be an almost impossible task for a chimpanzee”. The general consensus was that variation of vocalization depends on emotional not informational factors, and that manual gestures were relatively flexible and intentional, whereas vocal signals were fixed.

The new study shows that chimpanzees can change the grunt for a particular food in order to better communicate with another group that they have joined. They can learn vocal symbols in a social context.

This make a big difference to our understanding of our own language ability. The proposition that our close relatives lack some important ingredient in the make-up of their brains and that is why they did not evolve a proper language has become extremely weak. It cannot be assumed that language is such an obvious advantage that any animal that has not evolved language obviously is unable to. The other idea therefore becomes stronger – we have language because we are more cooperative and trusting than our cousins. Language use is risky. Once individuals can risk open communication within a society, language takes off in both cultural and biological evolution (fast, although it probably took a few hundred thousand years). It is likely that all the ingredients were there (in our common ancestor with chimpanzees) for a proto-language and all that was needed was the safety to talk.

Here is the abstract: “One standout feature of human language is our ability to reference external objects and events with socially learned symbols, or words. Exploring the phylogenetic origins of this capacity is therefore key to a comprehensive understanding of the evolution of language. While non-human primates can produce vocalizations that refer to external objects in the environment, it is generally accepted that their acoustic structure is fixed and a product of arousal states. Indeed, it has been argued that the apparent lack of flexible control over the structure of referential vocalizations represents a key discontinuity with language. Here, we demonstrate vocal learning in the acoustic structure of referential food grunts in captive chimpanzees. We found that, following the integration of two groups of adult chimpanzees, the acoustic structure of referential food grunts produced for a specific food converged over 3 years. Acoustic convergence arose independently of preference for the food, and social network analyses indicated this only occurred after strong affiliative relationships were established between the original subgroups. We argue that these data represent the first evidence of non-human animals actively modifying and socially learning the structure of a meaningful referential vocalization from conspecifics. Our findings indicate that primate referential call structure is not simply determined by arousal and that the socially learned nature of referential words in humans likely has ancient evolutionary origins.

Watson, S., Townsend, S., Schel, A., Wilke, C., Wallace, E., Cheng, L., West, V., & Slocombe, K. (2015). Vocal Learning in the Functionally Referential Food Grunts of Chimpanzees Current Biology DOI: 10.1016/j.cub.2014.12.032


Why do coaches keep reminding golf and tennis athletes to concentrate on a good follow-through? It really should not matter that is done after the moment of contact with the ball. But it does. Howard and others show how, in a paper (citation below) on the effect of follow-through on learning and execution.

The details of motor control of an action (the details and timing of muscle commands) are held in memory as motor programs or motor memories. The appropriate motor memory must be learned and it must be retrieved from memory to be used. If we think of what happens just before and just after the important moment in an action, we have three things that can vary (lead-in - main-action - follow-through). Each different lead-in and each different follow-through would produce a different motor memory. So if there is only one lead-in and one follow-through there needs to be only one motor memory. All the practice in learning the skill can be concentrated in one motor memory. This results in faster, more accurate execution. If there are different actions near the main-action in time, those differences will give separate motor memories; and, if there are unrelated actions by in other parts of the body during the main-action, those too will give separate motor memories. The fewer similar motor memories the better.

Although we have shown that consistent follow-through leads to faster learning through selection of a single memory, this does not preclude other potential advantages of the follow-through, such as injury reduction or other biomechanical advantages … Our findings suggest that distinct follow-throughs associated with different motor skills, such as different tennis strokes, will help maintain these skills in separate motor memories, thereby protecting them from interference when learning other skills. Moreover, even for a single skill, maintaining a consistent follow-through will speed up learning. An intriguing question is why a particular follow-through might be preferred when learning a skill. Our results suggest that variability in the follow-through, which might arise from planning variability, motor noise, or other sources of variability, would lead to a reduction in the speed of skill acquisition. Therefore, it may be optimal to choose the follow-through for a skill that can be executed with the minimum variability.”

Here is the paper’s abstract: “In ball sports, we are taught to follow through, despite the inability of events after contact or release to influence the outcome. Here we show that the specific motor memory active at any given moment critically depends on the movement that will be made in the near future. We demonstrate that associating a different follow-through movement with two motor skills that normally interfere allows them to be learned simultaneously, suggesting that distinct future actions activate separate motor memories. This implies that when learning a skill, a variable follow-through would activate multiple motor memories across practice, whereas a consistent follow-through would activate a single motor memory, resulting in faster learning. We confirm this prediction and show that such follow-through effects influence adaptation over time periods associated with real-world skill learning. Overall, our results indicate that movements made in the immediate future influence the current active motor memory. This suggests that there is a critical time period both before and after the current movement that determines motor memory activation and controls learning.

Howard, I., Wolpert, D., & Franklin, D. (2015). The Value of the Follow-Through Derives from Motor Learning Depending on Future Actions Current Biology, 25 (3), 397-401 DOI: 10.1016/j.cub.2014.12.037

A mapped tiny bit of brain

Kristin Harris has spent years mapping all the cells and connections between them, in a very small volume of brain. She introduces and shows how it is mapped and put together in a video (here). It is very interesting to see just how complex and crowded the brain is. We have been spoiled on the microscope slides with individual neurons pick out amongst the multitude, as in a Golgi stained preparation.