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Archive for the ‘comparative studies’ Category

sad-dog_resized.jpgIt should come as no surprise to you that after a prolonged hibernation, the BrainEthics team is heading back to the web-surface to present the novelties and oddities of cognitive neuroscience. And let’s start again with some fresh news from Nature, which besides featuring a nice focus section on the Drosophila, also has a nice article on (non-human) animal personality. Max Wolf et al. writes that personality has been shown in a number of other animal species. For pet owners such as myself, this is hardly any surprise (I can read that the cotons we have here are” playful, affectionate, intelligent breed. It loves people and as a result can have separation anxiety”. Indeed! But with the two we have, there are differences that are not only slight, but what I would say differences in temperament, or maybe even personality.

So what is new with the Nature article? Three things:

  1. it is a scientific acknowledgement of animal minds and personality
  2. it holds promise of the operationalization of personality
  3. it provides a model to explain the existence of human personality

As a matter of fact, I can see a whole new research field coming to existence through this very article (although the earliest findings already came in the 60’s). Through the study of animal personality, it may be possible to break down the good ol’ paradigms that have solely focused on humans.

The central theme in the Wolf paper is why personalities did evolve in the first place. The researchers ask the question:

First, why do different personality types stably coexist? Second, why is behaviour not more flexible but correlated across contexts and through time? And third, why are the same types of traits correlated in very different taxa?

Basically, the authors’ model starts by assuming that an individual can either reproduce now, but having acquired low-quality resources, or delay reproduction by one year, having acquired high-quality resources. For example, an individual that becomes sexually mature at a young age will have to balance the benefit of early reproduction against the cost of reproducing at a smaller size. Individuals that postpone reproduction must be able to survive to realize their reproductive expectations, and should therefore be generally risk-averse, whereas the opposite is true for those planning to reproduce early. So stable individual differences in risk-taking behaviours can evolve and be maintained when there is a trade-off between early versus late reproduction.

I won’t go more into details now, except point you to the ongoing discussion in Nature about this article (here and here). It’s certainly also going to get non-biologically personality theorists out of their armchairs, too. I look forward to keep an eye on this debate as it rolls out.

– Thomas

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llchckrs.jpgRecently, the newspaper Guardian provided a news story that many people probably thought of as a prank. The chimpanzee Hiasl (pronounced Hee-sel) was suggested to be given human rights, i.e., to be recognized as a person. But it was not a prank. Indeed, activists and well-renowned scientists such as Jane Goodall have fought for the recognition of Hiasl as a person. However, the court ruled down the suggestion.

You can read more about the story from Nature, Guardian, and other googled resources. But what if the ruling have ended otherwise? What if Hiasl had been accepted personal rights? An article in Nature Neuroscience discusses some of the impacts of this ruling. For example, Hiasl could bring a lawsuit against the pharmaceutical company that was involved in his kidnapping and illegal import to Austria some 20 years ago. But should one chimp get granted some — even not all — human rights, then chimps as a group should have many lawsuits going their way. Chimp group representatives could accuse companies for deforestation. And if chimps why not other non-human primates or even mammals?

What I find particularly interesting is that whether or not we have a reason to reserve basic rights to humans, an increasingly stronger scientific literature demonstrates a huge similarity in mental functions between humans and non-human primates as well as mammals. Self-recognition, emotions and personality are just well-known phenomena that are not just anecdotally evident, but even scientifically sound. So the question is (perhaps to me) not necessarily so much if we should grant animal X specific rights. The question is: given that we know that animals are experiencing, emotional and personal beings, albeit not necessarily in a fully human sense, how does this imply that animals should be treated?

Just peeking back into the history of mankind, it is not that many centuries ago that children were thought of as “small adults”, and that donkeys and even axes could be put on trial (and “executed”) for, e.g., the murder of a person. Since then, the pendulum has shifted from such a panpsychism and anthropomorphism towards a human-only rights view. But to some extent, the baby could have been thrown out with the bathwater here. Maybe we should not necessarily grant non-human primates legal rights per se. Or maybe we should.

At the least, we should raise a fundamental neuroethic question: does our increased knowledge about the animal mind (and mental properties such as consciousness, self, emotions and suffering) urge us to treat these animals in a different way? In a century from now, will we see that these are the first feeble steps of acknowledging animals a significant increase in legal rights?

-Thomas

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kristan.jpgWilliam B. Kristan at UCSD gave a very interesting talk today about decision making in the leech (!), but instead of providing you with a review of this talk, which is a little bit outside my own domain (put mildly), I’ll quote Kristan in a way that kind of captures his presentation style: present and witty.

In a novel situation an organism has to choose what to do. Here, we can typically speak of the possible options as the four F’s; flight, fight, feed or mate.

-Thomas

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Here is a great story: human imitation has been known to be present in newborns, supporting a notion of the human race being predisposed to social interaction. However, an obvious question of whether this is also the case in non-human primates below our closest evolutionary relatives has not been asked. Until now. In an excellent study by Pier Ferrari and colleagues in PLoS Biology, imitation of facial expression is demonstrated in neonatal monkeys (that disappeared after approx. 7 days).

From ScienceDaily we can read:

Ferrari et al. tested 21 baby rhesus monkeys’ response to various experimental conditions at different ages (one, three, seven, and 14 days old). Infants were held in front of a researcher who began with a passive expression (the baseline condition) and then made one of several gestures, including tongue protrusion, mouth opening, lip smacking, and hand opening.

Day-old infants rarely displayed mouth opening behavior, but smacked their lips frequently. When experimenters performed the mouth opening gesture, infants responded with increased lip smacking but did not increase any other behavior. None of the other stimuli produced significant responses. But by day 3, matched behaviors emerged: infants stuck out their tongues far more often in response to researchers’ tongue protrusions compared with control conditions, and smacked their lips far more often while watching researchers smacking theirs. By day 7, the monkeys tended to decrease lip smacking when humans performed the gesture, and by two weeks, all imitative behavior stopped.

Here is an example from the article:

And from the abstract:

Our findings provide a quantitative description of neonatal imitation in a nonhuman primate species and suggest that these imitative capacities, contrary to what was previously thought, are not unique to the ape and human lineage. We suggest that their evolutionary origins may be traced to affiliative gestures with communicative functions.

UPDATE: Jown Hawkes has an in-depth presentation and discussion of this study.

-Thomas

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drosophila.jpgWhat is the nature of instincts and inborn behaviour? The cover article of this week’s issue of Current Biology is an article by Kim et al. on how the central nervous system produces inborn behaviour. The researchers found that the innate behavior is initiated by a “command” hormone that orchestrates activities in discrete groups of peptide neurons in the brain (peptide neurons are brain cells that release small proteins to communicate with other brain cells and the body). The action of the hormonal influence, however, was not an all-at-once phenomenon. The ecdysis-triggering hormone or ETH, activated discrete groups of brain peptide neurons in a stepwise manner, making the fruit fly perform a well-defined sequence of behaviors.

Says Michael Adams, the research team leader:

Our results apply not only to insects; they also may provide insights into how, in general, the mammalian brain programs behavior, and how it and the body schedule events. By understanding how innate behavior is wired in the brain, it becomes possible to manipulate behavior — change its order, delay it or even eliminate it altogether — all of which opens up ethical questions as to whether scientists should, or would want to, engineer behavior in this way in the future”

An instinct is an inborn disposition for a specific kind of behaviour. Although we often regard instinctual behaviours to be in the domain of non-human animals, humans also have well-known instincts, the most known are found in infants. However, many researchers suggest that other behaviours — such as altruism, disgust, face perception, and language acquisitions are also instinctual, at least in part so.

Would the present result mean that behaviour — let’s start with instinctual behaviours — could be edited? Adams seems to think so, and in the Drosophila it certainly seems to be the case. Since the steps leading to the well-orchestrated instinctual behaviour were identified, and the neurochemical properties of these circuits are — or are soon — known, it should be a trivial thing to alter the behaviour at any stage during the process. What about human behaviour, then? In principle, the same idea should apply.

Complaints will certainly arise that “human behaviour is so much more complex than instincts”. Indeed it is. But recall studies of voluntary action, of subliminal perception and of automaticity (e.g. riding a bike). These behaviours resemble instinctual behaviour a lot. They are not under conscious control, or are at least not initiated by such. In this sense, it might be that even human behaviour can be edited in much the same way as the Drosophila.

Admitted, this study only focuses on the ecdysis sequence behaviour in an insect. So we need more advanced (still instinctual) behaviours to believe the story. Replications & variations as always… But hey, maybe this will end up as the next cure for odontophobia…?

-Thomas

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In a thorough and very good review in PLoS Genetics, James Sikela writes about the comparative genetics between the chimp and the human genome. From the article:

It has been pointed out that the primary molecular mechanisms underlying genome evolution are 1) single nucleotide polymorphisms, 2) gene/segmental duplications, and 3) genome rearrangement. In addition, a “less-is-more” hypothesis has been proposed that argues loss of genetic material may also be a source of evolutionary change. Given these factors, what are we learning about their respective roles now that we can compare multiple primate genome sequences?

As we have pointed out repeatedly in this blog, the study of genetic influence on the brain is going to change our understanding of what a human is, how and why our thoughts are formed (and restricted) the way they are. This review surely puts the finger on the pulse and notes:

One of the most important findings to emerge from the latest human and primate genome-wide studies is that a fundamental assumption underlying this model has changed: the interspecies genomic changes are numerous and diverse, and, as a result, there appear to be many additional types of genomic mechanisms and features that could also be important to the evolution of lineage-specific traits. Given this new perspective, we now know that the degree of difference between our genome and that of the chimp depends on where, and how comprehensively, we look. The multitude of genomic differences that we now know exists should provide an abundance of fertile genomic ground from which important lineage-specific phenotypes, such as enhanced cognition, could have emerged. 

Here is the abstract:

The jewels of our genome: the search for the genomic changes underlying the evolutionary unique capacities of the human brain

James M. Sikela

The recent publication of the initial sequence and analysis of the chimp genome allows us, for the first time, to compare our genome with that of our closest living evolutionary relative. With more primate genome sequences being pursued, and with other genome-wide, cross-species comparative techniques emerging, we are entering an era in which we will be able to carry out genomic comparisons of unprecedented scope and detail. These studies should yield a bounty of new insights about the genes and genomic features that are unique to our species as well as those that are unique to other primate lineages, and may begin to causally link some of these to lineage-specific phenotypic characteristics. The most intriguing potential of these new approaches will be in the area of evolutionary neurogenomics and in the possibility that the key human lineage–specific (HLS) genomic changes that underlie the evolution of the human brain will be identified. Such new knowledge should provide fresh insights into neuronal development and higher cognitive function and dysfunction, and may possibly uncover biological mechanisms for information storage, analysis, and retrieval never previously seen.

-Thomas 

______________________________

John Hawks has a very good discussion about this article. 

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“The time in which the chimpanzee lives is limited in past and future” Wolfgang Köhler once wrote. One of the things we see as a typical human trait is the ability to plan our next move, or just anticipate that we have a future. In a report in this week's Science, this view gets a blow from the study of some of our closest evolutionary relatives, bonobos and orangutans. Here, Mulcahy and Call demonstrate that great apes such as bonobos and orangutans save tools for later use. In other words, our closest relatives seem to be able to anticipate the future in a much more specific way than has been originally thought.

-Thomas

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In this week’s Nature a report from Kate Arnold and Klaus Zuberbühler from the Scottish Primate Research Group demonstrates that the putty-nosed guenon can combine vocalizations in order to convey different meaning. The meaning is is found between alarm calls for different situations and contexts.

From the article:

Like most forest guenons, male putty-nosed monkeys (Cercopithecus nictitans) produce two acoustically distinct loud calls (‘pyows’ and ‘hacks’) in response to a range of disturbances. Males also call spontaneously, especially during morning foraging and evening travel to sleeping sites. In addition, these calls can function as alarm calls to warn the group of an approaching predator and to discourage attack: pyows are used primarily when a leopard (Panthera pardus) is in the vicinity, and hacks are produced mainly in response to crowned eagles.

In addition to these calls, the researchers found that males often combine the same two calls into a third structure, a ‘pyow–hack’ (or P–H) sequence. The P-H sequence was emitted either to threats of leopards or eagles. In response to these calls the group of guenons respond by beginning to move. So, calls for either P or H did not significantly get the group moving. But P-H calls did.
Arnold and Zuberbühler went further on by playing different sounds to the groups (there were 17 guenon groups studied in all). Each group consisted of several adult females and one male (…hmm…).First, leopard growls were played to the group. In over half of the groups the male responded with P-H calls. In the other groups the males did call, though not with the P-H sequence.

Now wait a minute! Is this really something worth reporting in Nature? Evoking specific alarm calls in only half of the groups is not normally seen as powerful statistics. But hold on; here’s the neat part of this study. The researchers used a GPS to locate where the groups were as they moved (they are easy to locate by the calls, then move to that location and look up the GPS location). Here it was found that the groups in which males expressed the P-H combination moved for significatly longer distances. Furthermore, the groups “response to P–H sequences was not confined to the predator context, but was generally related to whether the group moved”.

In other words, this study demonstrates that not only do these putty-nosed guenons display differential vocal expressions (in males) to threats. The expressions are interpreted differently according to the context (movement). Altough it is known that syntax sets human language apart from other natural communication systems, it is also agreed that the evolutionary origins of human language are obscure. The study by Arnold and Zuberbühler sheds light on the evolutionary building blocks of language.

If you have access to Nature, you can also listen to the calls (single or combined form) through the supplementary material.

-Thomas

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Let me point you to a nice article, by Simon Fisher and Gary Marcus, in the January issue of Nature Reviews Genetics. Fisher was one of the co-discovers of the link between a verbal dyspraxia disorder in an English family and a point mutation on the FOXP2 gene. Marcus, a former student of Steven Pinker, is well-known for his critique of connectionist models of language-aquisition. Although I personally think it overstates the case for innate modules, I wholeheartedly recommend Marcus' book The Birth of the Mind which is, as far as I know, the first, and still only, popular account of what is known today about the genetic basis of brain development. Together, they have earlier written a review of the FOXP2 story in Trends in Cognitive Science. The present paper aims to show how genetical studies can aid our understading of the evolution of language.

In recent years interest in this topic has been booming. A large number of possible adaptative causes have been proposed by a range of researchers. [Language Evolution, edited by Morten Christiansen and Simon Kirby, will give you a short overview of most of these hypotheses.] There is a problem with this approach, though, in that it tends to focus on just one magical change in hominid behaviour, with the accompaying change to the brain being passed on to following generations. To take one prominent example, Robin Dunbar, for instance, sees the decisive moment in the evolution of language to be the expansion of hominid social groups, some time around the appearance of homo erectus, making it advantageous to be able to keep account of the larger number of conspecifics through communication. Dunbar speculates that a change in our ability to mentalize – sometimes also referred to as Theory of Mind – could be the new cognitive function to have facilitated this improved capacity for social communication. Another, more simpleminded hypothesis, is the still widespread idea that neuronal changes to Broca's area brought about a novel ability to string together words into syntactical phrases.

But, as more and more becomes known about the brain processes underlying language, it appears increasingly unrealistic that any such single-stroke wave of the magic wand will suffice to explain the emergence of language. The neural language system is enormously complex and encompasses, to just name a few things, auditory analysis, conceptual knowledge and memory, semantic selection processes, motor control, and a great number of other functions. It stands to reason that all these processes must have evolved on an individual basis. It is therefore much more probable that the evolution of language has gone through several different adaptive events since the last common forefather of homo and pan.

This is exactly the approach taken by Fisher and Marcus. They call it "descent with modification", and write that "[in this paper] we argue that language should be viewed not as a wholesale innovation, but as a complex reconfiguration of ancestral system that have been adapted in evolutionarily novel ways". The offshot of this approach is that the evolution of language can be studied by comparing human genetics and neurobiology to other species. Write Fisher and Marcus:

(…) although non-human primate communication shows qualitative differences from human language, studies have established that most components of language how some degree of continuity with other species. For example, the human vocal tract supports a wider epertoire of speech sounds than could be produced by other primates, but the capacity to create richly modulated formants is not unique to humans. Likewise, many animals and birds can distinguish different human speech sounds, and adult tamarin monkeys can discriminate between the distinctive rhythmic properties of different languages. Debate continues about exactly how much of the machinery of language is species – or language – specific; for example, opinion is divided over whether recursion represents the only component that is genuinely new to the human species. Nevertheless, views that consider language to be fully independent of ancestral systems are no longer tenable, and there is a growing recognition that cognitive, physiological, neuroanatomical and genetic data from non-speaking species can greatly inform our understanding of the nature and evolution of language.

The bulk of Fisher and Marcus' paper is dedicated to a review of methods for such genetical comparisons of humans to other species. But its true importance lies in the way it dismantles the adaptionist programme in evolutionary psychology. Like language, social cognition, reasoning, and other forms of cognition, are in most cases complex amalgams of a range of neurobiological processes, and therefore very unlikely the product of "wholesale innovation". A more precise picture of the evolution of human cognition is to be found through an detailed understanding of how the human brain differs from other species, and through a comparison of the genes and gene-expression systems characterising these species.
Reference

Fiser, S. & Marcus, G. (2006): The eloquent ape: genes, brains and the evolution of language. Nature Reviews Genetics 7: 9-20. [The paper can be downloaded from Marcus's homepage.]

-Martin

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Today’s NY Times Magazine has a rather fascinating story about research on animal personality. Although eradicated by behaviourism, the notion that others animals than ourselves display various personality types – timid, bold, aggresive, etc. – is becoming increasingly accepted in the worlds of biology and psychology. Researchers such as Sam Gosling – visit his site for in-depth research papers on the topic – are pondering why personalities exist at all; why aren’t the behavioural profile of the members of an species just uniform and similar? The answer may be that it is advantageous to have a repertoire of behavioral traits around if the milieu of a species should change. In some niches bold members will have a survival edge, in others cautious members will be better of.

Unfortunately, the article doesn’t go into the issue of what brain processes underlie personality traits. This kind of research is also booming, though. So, perhaps we may hope to see a follow-up article on this topic as well.

Reference

Siebert, C. (2006): The Animal Self. New York Times Magazine, January 22 issue.

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