Personality traits: evolutionary perspectives

I have been reading and enjoying The Handbook of  Personality Psychology by Hogan et al, and found the chapter written by David Buss particularly useful.

Here I would like to expand on the idea and while buss explicitly does not want to indulge in a discussion of a few psychological tendencies and associated behavioral class acts; I would like to walk exactly that particular path.

First to recap,

Humans, like other organisms, can be viewed as organized structures that exist in their present form because of a long history of natural selection, operating over millions of years. Each one of us owes our existence to a long and unbroken line of ancestors who successfully solved problems posed by survival and reproduction in our evolutionary past. Therefore, human structures, as well as human psychological mechanisms, at some fundamental level of description, can be analyzed in terms of the problems they solve.

But "survival" and "reproduction" are broad categories, each subsuming a large and complex array of subproblems. To the extent that the evolutionary psychologist can identify the nature of the specific problems that humans have evolved to solve, she or he has some advantage over the nonevolutionary psychologist in discovering the nature of human nature.

Buss then goes on and breaks the survival and reproduction into many component and also adds genetic investment to the mix. I parse the same data in my own way and generate the hypothesis that the most important concern of any living organism, and especially humans are survival, genetic investment and reproduction.

Survival behavioral tendency can be further split in three parts: one pure survival as in escape from predators or death; I'll refer to this as Foes! the second concerns growth or acquiring resources necessary for thriving and I;ll call this Food. The third maintaining one'd edge in avoiding foes and finding Food by building alliances with con specifics. I'll call this Friends. Thus survival is characterized by the three F's of Foes, Food and Friends!

Genetic investment can be split into two K's that of Kids and Kins. The first tendency that of Kids is concerned with issues of parental investment and care of offsprings.the second that of Kin is concerned with how to help other genetic related individuals at minimal cost to self such that maximum fitness ensues.

Reproduction can be split into three parts that of mate selection, that of mate attraction and that of mate retention. I'll call these the three S's of reproduction(Sex is *NOT* one of them!). The first task is to Select the right mate; the second task is , that once you have zeroed in on a suitable mating partner, you have to court and attract the partner, I call this function Seduce; the final task, especially in long-term pair bonded species like Humans is to guard or retain the mate, I call this Securing the mate.

What I propose is that given these Eight tasks ( 3 survival, 2 investment and 3 reproductive tasks ) that each species has to solve, each specie would evolve some mechanism to solve these problems that are species-typical; however there would be individual variation to the extent that the extent to which an individual organism is driven by that particular conscious motivation/ behavioral tendency and gets into environments and situations that trigger that particular task would determine the psychological mechanism that drives that individual.

To make things more clear , what I am proposing is that there are bound to be individual differences in the relative importance of these psychological mechanisms for an individual- thus a human may be primarily driven by mate selection concerns at a particular age- while another may be forever primarily concerned with safety, security etc- and this would be the first factor that would lead to individual variation in personality. Moreover, I am proposing something radical, that depending on the environment, there may be two extreme types of responding to each of these tasks- and the second most important variation that we get from person to person - is in whether one habitually and instinctively (genetically determined) responds in one way or the other as one faces the task and whether or not one factors the environment and context in which the task demand is made or whether ones behavioural tendency is fixed and inflexible.

To take by way of an example, lets us focus on the Kids part of genetic investment. It has been well documented that their are two types of parental strategies r-type and K-type; now a species may have predominantly K-type investment strategy, but within the species individual organisms would differ in their reproductive strategy around the mean in K-type and r-type directions. thus, Humans exhibit predominantly K-strategy, but Africans show more r-type and Asians more K-type. It is equally well documented that these r-type and K-type strategies are actually responses to the external environment (food abundant, predictable , stable environment etc) and thus, though a species has a set point, there is enough individual variation such that in changing environemnetal conditions at least one sub type is able to thrive and survive and reproduce and invest!


To take another example from Buss, Absence of father leads to short term mating strategy in daughters (amongst other things like premature puberty etc) and this environmental facyor may be the most important environment variable as related to Securing task of retaining the mate; if one sees the father as absent from home, one may think its wise to go for a short term mating strategy as the culture is one that encourages low stability of pair bonds; this might be a justifiably welcome strategy; on the other hand it might be genetically the case that someones set point is set towards short-term relationships.

I will now claim that the eight personality traits I had outlined earlier are directly related to these eight evolutionary task (see here for another slightly different list of the eight tasks ) that one faces- and more so are mapped one-on-one with the same ordered mapping!

Thus,

1. Foes (survival 1) : A behavioral tendency to be on the lookout for foes / troubles leading to Neuroticism trait. The extremes of courage/calmness and fear/anxiety  are driven by what type of environment one lives in - whether it is full of dangerous objects or not so! One prediction is that those high in N should have more Phobias and vice versa. 
2. Food (survival 2):A behavioral tendency to acquire resources leading to Conscentiousness. The extremes of ambition/ covetousness and laziness/ easy-going are driven by whether the environment is abundant in resources or lacking thereof! One prediction is that those high in C should be more readily diagnosed with OCD and vice versa.
3. Friends (survival 3):A behavioral tendency to form alliances leading to Extraversion. The extremes of sociability and seclusion dependent on some environmental factor (like how important is community interference in day to day activity) . Might be related to mean group size (150 in humans)
4. Kids (investment 1)   A behavioral tendency to invest in ones offsprings leading to Agreeablness. the extremes of care/ empathy vis-a-vis apathy/ psychopathy may be driven by the same concerns that decides whether to go for r-strategy or K-strategy.
5. Kins (investment 2) : A behavioral tendency to help one kins leading to Conformity / Rebelliousness: Here it is instructive to note that older siblings are generally conformists while younger siblings are rebellious - thus age-order and environmental variable may decide whether one would be conformist or rebellious and this somehow affects your behavior towards sibling and his/her reproductive fitness. Also, irrespective of your birth order in the family (kin) , due to variation, some may be genetically predisposed to be conformists and other rebellious!
6. Selecting (reproduction 1) : A behavioral tendency to judge others intentions etc accurately and thus determine who is a suitable candidate for mating/trusting  leading to Trust/Defensiveness. The extremes of trust and suspicion may be adaptive in environments differing with respect to levels of promiscuity; in a highly promiscuous and cheating/ cuckolding environment it may pay to be suspicious.     
7.   Seducing (reproduction 2): This behavioral tendency of intra sexual competition can be broken into three components: i) Testing against own sex con specifics(building better muscles for men) ii) Embodying preferences of opposite sex (Chauvinism in case of Males) and the third I havent been able to figure yet!! The extremes of too much effort/activity  in seducing as against the extreme of being dull/boring and uninterested in other sex leads to the dimension of Activity. 
8. Securing (reproduction 3) : A behavioral tendency towards sociosexuality;At one end of this dimension are individuals who are "restricted" in sociosexuality—they require more time, attachment, and commitment prior to entering a sexual relationship. At the other end are those who are "unrestricted" in sociosexuality—they require less time, attachment, and commitment prior to sexual intercourse. These extremes may lead to the trait of Masculinity- Feminity in how one guards and forms a pair bond.

I would thus end my argument; to me the eight stage process is compelling- I am sure with each passing day there are more converts to that developmental and evolutionary eight stage theory.

References: Buss, D. M. (1997). Evolutionary foundations of personality. In R. Hogan, J. A. Johnson, & S. R. Briggs (Eds.), Handbook of Personality Psychology (pp. 317-344). New York: Academic Press..

Sphere: Related Content

101 Fascinating Brain blogs

OEDB has put together a list of 101 fascinating Brain blogs and it is an excellent list with most of the usual suspects and some new ones too. The descriptions of the blogs are good and informative. The Mouse trap has been featured under Multidisciplinary blogs and I cannot agree more. The focus of this blog has been multi-disciplinary and I am by nature drawn to anything and everything that is remotely tied to brain, no matter what the discipline or the methods.

On a related note, I had thought that the mouse trap being featured in WIKIO Science top 100 was a one-off affair, but it seems that the ranking has only improved this month (the mouse trap is up at #78 this month); so thanks again to all the readers of this blog for continuing to read and link. BTW, I saw a significant drop (about 10%) in the number of RSS feed subscribers after my 26/11 and 'Beyond revenge' post; maybe the subscribers thought that I had decided to leave science blogging for good and thus unsubscribed; political blogging for me may lie in the future, but not for now; for now I intend to continue blogging about brains only. The Mouse Trap blog, at the least, will always remain focussed on psychology and neuroscience only. If  I do decide to blog about political matters I'll maybe start a new blog, just like The Fool's Quest blog which I use for poetry and literature.

Sphere: Related Content

Novelty Seeking and Reward Dependence: the dopamine white matter connection.

I had earlier wrote extensively on Cloninger's personality temperaments and proposed that dopamine lies behind the trait Novelty Seeking; while norepiniphrine lies behind Reward Dependence trait. New research , as reported in Nature Neuroscience makes me rethink some of that simplistic schema.

As per Cohen et al, they have found a double dissociation between white matter connectivity between dopamine and sub-cortical and cortical regions and found that these white matter connectivities differentially predict and correlate with traits novelty seeking and reward dependence. Let me quote from the article:

Myriad cognitive, emotional and motor functions of the brain rely on the integrity of the striatum and on interactions between the striatum and other cortical and subcortical networks1, 2, 3. Lesion work in animals supports the idea that fronto-striatal connectivity is crucial for aspects of behavioral adaptation and learning. In these cases, it is clear that anatomy constrains function. Here, we investigated whether anatomical connectivity underlies more global aspects of behavioral and cognitive organization: human personality. We found that the strength of connectivity between two different striatum-related networks predicted individual differences in self-reported personality traits in humans.

Then they go on to show which two networks they studied and found the dissociation in.

In humans, novelty seeking is characterized by impulsivity, exploratory drive and excitability, and has been proposed to be driven by individual differences in dopamine system sensitivity. In rats, both striatal dopamine and hippocampus inputs modulate novelty seeking, linking these structures into a network for novelty detection. The hippocampus may support novelty seeking in part by signaling when sensory input differs from memory-driven expectations (that is, a sensory prediction error), whereas the amygdala may support novelty seeking by modulating hippocampal and striatal activity in novel environments or during emotional memory encoding. Our findings provide additional support for this novelty-loop theory by demonstrating that the hippocampus– and amygdala–ventral striatal pathways are related to stable individual differences in novelty seeking personality.

High reward dependence is characterized by several cognitive, emotional and social facets, including enhanced learning from reward signals, persistence in repeating actions associated with rewards, high sociability and reliance on social approval. These functions recruit the striatum, including dorsal regions. Indeed, the tracts predicting reward dependence were not confined to one particular subregion of the striatum, but were instead observed in striatal areas in which there were strong inputs from these seed regions . This suggests that the white-matter circuits subserving reward dependence are distributed throughout multiple cortico-striatal loops. These loops have been linked to processes ranging from reward learning to cognitive control to action selection.

From the above it is clear that the striatal dopamine system is implicated in both Novelty seeking and Reward dependence. While the implicit, first-line, sub-cortical 'emotional' and unconscious processes sub served by hippocampus and amygdala may be the white tract inputs to the striatum that result in Novelty seeking behavior; the explicit, second-order, cortical, 'cognitive' and conscious processes sub served by frontal cortex may be the white matter inputs to the striatum that result in reward dependence behavior.

This indicates that the stage theories are true!! If one considers the sub-cortical responses to be immature and the cortical responses to be more mature than moving from novelty seeking focus to reward dependence focus is a move up the stages. What I propose is that each stage marks a movement from sub-cortical input reliance to cortical input reliance and also involves novel mechanisms and systems.

Thus, as per my theory, in the first stage of personality development, or for the trait Harm Avoidance, the white matter connections implicated should be between sub-cortical regions and raphe nucleus ( the serotonin system).

In stage 2, or for trait Novelty seeking, the white matter tracts involved should be between cortical regions and Raphe nucleus (serotonin system). Also as the earlier serotonin system comes moer and more unedr cortical control, the second system based on dopamine becomes active but is under sub-cortical control. Thus, white matter tracts involving sub-cortical regions and striatum/ VTA should also be involved.

In stage 3, or for trait Reward Dependence, the white matter tracts should be between cortical regions and striatum/ VTA as the earlier dopamine system predominance us reigned in and a new system based on nor-epinepherine replaces it. This nor-epinepherine will be under sub-cortical control and white matter tracts from sub-coritcal regions to locus ceruleus should also be involved.

And this same scheme should go on for fourth (epinepherine), fifth (histamine/ melatonin), sixth, seventh and eighth stages/ personality traits.

All these are testable hypothesis and can be easily verifed. If verified, they can shed immense light on how perosnality develops and what do temperaments/ character strengths really mean.

Hat tip: Neurological correlates


Michael X Cohen, Jan-Christoph Schoene-Bake, Christian E Elger, Bernd Weber (2008). Connectivity-based segregation of the human striatum predicts personality characteristics Nature Neuroscience DOI: 10.1038/nn.2228

Sphere: Related Content

26/11 and 'Beyond revenge'

26/11 has happened and I still write about  Science and Psychology.

It has been a week of introspection in which I have been questioning myself and whether by doing science blogging I am doing my bit as a responsible human being. Perhaps I will move on. But while I'm at science blogging let me discuss the topic about which the science blogosphere has been relatively silent.

Today, I have started reading Michal McCullough's "Beyond Revenge" and I want to discuss ideas from it. The decision to read the book at this juncture stems from the immense feelings of outrage that have been seething within and paradoxically without any overt war-mongering desires or ill-will towards the state that continue to let its soil be used for terrorist activities. Of course forgiving the citizens of that state was never an issue for the ordinary citizens do not foment violence and wars- it is the state or the alleged 'non-state' actors that are the real culprits; but I strangely feel a desire to forgive even them and give them a  second chance. But I cannot just forgive and forget. at least not this time. This time the world has to change to create the conditions whereby forgiveness is the norm and revenge an exception.

But let me not digress. Let me go straight to reviewing "Byond Revenge" . I have just read the introduction and the first chapter so let me share with you Mculloughs main thesis.

As per him there are three angle or truths to the revenge story:

• Truth #1: The Desire for Revenge Is a Built-In Feature of Human Nature
  
• Truth #2: The Capacity for Forgiveness Is a Built-In Feature of Human Nature
  
• Truth #3: To Make the World a More Forgiving, Less Vengeful Place, Don’t Try to Change Human Nature: Change the World!
  

I've decided to the last, viz change the world, but perhaps not in exactly the same way that Michale may have intended. Let me elaborate what Michael means by the three truths:

The desire for revenge isn ’ t a disease to which certain unfortunate people fall prey. Instead, it’s a universal trait of human nature, crafted by natural selection, that exists today because it was adaptive in the ancestral environment in which the human species evolved .

I believe it is important to pause here and think over whether the perpetrators of 26/11 were themselves pathological or just normal ordinary people subjected to un-normal propaganda and state help to turn into monsters.

Its also important to acknowledge our own feelings of anger and outrage as vengeful feelings towards those who indulge in such heinous crimes; but it is heartening to note that Indians have largely turned their anger into constructive channels - towards lapses in security and towards insensitivity and callousness of politicians. It is heartening to note that the anger and revenge has not been mistakenly directed towards the citizens of a state or towards a community. I salute my fellow Indians for what they have done with their feeilngs of outrage and revenge.

Next truth Micahel elaborates as follows:

The capacity for forgiveness, like the desire for revenge, is also an intrinsic feature of human nature — crafted by natural selection — that exists today because it was adaptive in the ancestral environment in which the human species developed .

Forgiveness as per him is normally activated with friends and family; but India has always thought 'vasyudhev kutumbkam' or the 'whole world is my family'. India perhaps has been an epitome of forgiveness and perhaps will rightly remain so. I'm not just talking about India as a nation-state, I am talking about India as a civilization which has a unique honor of never committing aggression or getting involved in a war unprovoked. India has absorbed all erstwhile aggressors in its fold and today everyone lives as one community- one nation- one family. No heinous acts of aggression and terror make Indians turn towards each other. The need for that forgiveness instinct to continue is perhaps the greatest today. And believe me when I say that the common Indian citizen, still has no hard feelings towards the state who's soil is being used to foment terror on its territory.

The next truth he talks about is:

To forgive a stranger or a sworn enemy, we have to activate the same mental mechanisms that natural selection developed within the human mind to help us forgive our loved ones, friends, and close associates. To encourage more forgiveness in our communities, and on the world stage, we must create the social conditions that will activate those mechanisms .

This is what he means by changing the world. Creating conditions such that even enemies/ strangers seem like friends. Its heartening to note that partly as a result of state initiative, but largely due to initiative of non-state actors in India, like the media, we have been successful in creating a 'world' in which the ordinary citizen of Pakistan is not seen as an enemy. TV programs like 'the great Indian laughter challenge' on Star One have been able to make the ordinary Indian realize that there is much more in common that he shares with the Pakistan citizen than just a sub-continent. These non-state actors of my country, be it the film and music industry or NGOs have been working to foster stronger ties and the results are for all to see. For the first time, I do not hear war cries towards Pakistan , just a desire to eliminate the terror camps operating on foreign soil perhaps by very targeted and specific strikes. Is that asking too much? Is ensuring one's safety and taking preventive measure condemnable and will still be viewed as punitive and vindictive action by western and Pakistani media. Only time will tell whether the non-state actors in west and Pakistan have been creating their 'world' as per what template.

Sphere: Related Content

Primate Evoloution: stage I: prosimians and predation

In my last post  I hinted at how primate evolution may be an example of eight stage evolutionary process in action and today I'll try to support my first prediction that the prosimian stage evolution was dominated by predatory concerns.

Prosimian evolution and branching within the primate order took place 55 million years ago or a bit earlier, near the beginning of the Eocene Epoch. These first primates , it is safe to assume were nocturnal just like today's prosimians like lemurs, bushbabies, tarsiers etc are. Why they were nocturnal remains a question to be answered. Species turn nocturnal usually to avoid predation by day predators. Crypsis  is the mechanism that even today is used by prosimians to avoid predation.

It is instructive to note here that though predation in primates has not been considered a big force, in pro-simians it is important. A whole book Primate anti-predator strategies  has been written which focuses more on pro-simian anti-predator strategies than on other primates. It is testament to the fact that predation was/ remains important for prosimian evolution. Here I quote from the preface of the book:

The impact of predation on the morphology, behavior, and ecology of animals has long been recognized by the primatologist community (Altmann, 1956; Burtt, 1981; Curio, 1976; Hamilton, 1971; Kruuk, 1972). Recent thorough reviews of adaptations of birds and mammals to predation have emphasized the complex role that predation threat has played in modifying proximate behaviors such as habitat choice to avoid predator detection, degree and type of vigilance, and group size and defense, as well as ultimate factors including the evolution of warning systems, coloration, and locomotor patterns (Thompson et al., 1980; Sih, 1987; Lima & Dill, 1990; Curio, 1993; Caro, 2005).

We have conducted research on nocturnal primates for more than ten years. Immersed as we have been in the literature of nocturnal primatology we recognize a spectrum of diversity amongst the nocturnal primates in their social organization, cognitive behavior, and ecology (Charles-Dominique, 1978; Bearder, 1999; M¨uller and Thalmann, 2000). Our studies on tarsiers and lorises showed that these species were highly social and that resource distribution was not sufficient to explain why they defied the supposed “stricture” of being solitary (Gursky, 2005a; Nekaris, 2006). Furthermore, our animals defied another supposed “rule” — namely, that all nocturnal primates should avoid predators by crypsis (Charles-Dominique, 1977). Even recent reviews of primate social organization and predation theory included one-sentence write-offs, excluding nocturnal primates from discussions of primate social evolution on the basis that crypsis is their only mechanism of predator avoidance (Kappeler, 1997; Stanford, 2002).

An analysis of the mammalian literature shows this type of generalization to be crude at best. Small mammals are known to have extraordinarily high rates of predation, and a plethora of studies of rodents, insectivores, and lagomorphs, among others, have shown that predation is a viable and powerful ecological force (Lima & Dill, 1990; Caro, 2005). Furthermore, although researchers have long considered it critical to include prosimian studies in a general theoretical framework concerning the evolution of the order Primates (Charles-Dominique & Martin, 1970; Cartmill, 1972; Oxnard et al., 1990), a pervading view contends that prosimians are too far removed from humans for the former’s behavior to shed any light on the patterns of behavior seen in anthropoids (Kappeler & van Schaik, 2002; Stanford, 2002).

However, an excellent review by Goodman et al. demonstrates the dramatic effect predation can have on lemurs, and it remains the most highly quoted resource on lemur predation, despite that it was published in 1993. Studies of referential signaling aid in dispelling the view that prosimians are primitive and not worthy of comparison with monkeys and apes (Oda, 1998; Fichtel & Kappeler, 2002). A handful of studies further reveal that prosimians are not always cryptic and may engage in social displays toward predators (Sauther, 1989; Sch¨ulke, 2001; Bearder et al., 2002; Gursky, 2005b).

Leaving for the time-being the fact that prosimains too engage in social behavior as a defense against predation, and sticking to the traditional view that crypsis best defines their defense mechanism, the thing to be noted is the relative abundance of predatory strategies on prosimian evolution. A whole book has been written keeping that in mind!!

So my thesis is that for the very first stage of evolution when a leap was made, prosimains got left behind, still struggling with predation; while the common ancestor of new world and old world primates somehow solved/ reduced the problem of predation and became diurnal and maybe started living in large social groups and thus exhibiting social defenses against predators. This evolutionary successful completion of the first developmental/ evolutionary task of avoiding predators, then enabled these ancient primates to focus their energies on finding food and thus from insectivores become fruit-eating and move towards a rich diet and focus on acquisition of resources. but that takes us to stage II marked by focus on food and the new world monkeys. More on that later!

Sphere: Related Content

Guest Post: Matters of the Monkey Mind

I was recently contacted by a reader of this blog, who wanted to do a guest post on The Mouse Trap, and I thought why not! Guest posts allow those who might not have their own blog to start getting familiar with the Media and for those who already have their blogs, an exposure to a new audience. As long as science blogging wins I don't mind publishing posts on my blog, which are not authored by me, though I'll typically like to restrict the Mouse Trap to my own musings. So if you want to do a guest post on the Mouse Trap, you are welcome, but the theme has to fit in with the overall theme of the mouse trap.

Without much ado, I'll now publish the first guest post on Mouse Trap. Do send me in your feedback, as to whether it is worth doing guest posts here , and whether you liked this one.

What follows is a guest post by Sarah Scrafford.

The human mind is extremely complicated – we can never say for certain why people act the way they do. Some of us are even confused about our own actions, and there are times when we don’t know why we did certain things and other times when we regret the things we do the moment they’re done. And there are times when the mind is like a monkey, jumping randomly from one thought to another till you don’t know where one begins and the other ends. While some people emphasize the importance of a steady mind that’s able to focus, there are times when monkey minds are ok and even desirable, and that’s when:

• Emotions rule: When you’re upset and tend to think with your heart rather than your head, you’re bound to do something stupid if you’re not careful. But when your mind jumps from one thought to another with not much time to dwell on one emotion alone, it’s kind of therapeutic and prevents you from acting blindly upon your emotions.
• You need to forget: In my book, the greatest ability of the human mind is the one to forget – hurts, disappointments and failures. Without this ability, we would all be nervous wrecks without an ounce of positivity in our blood. Love affairs gone sour, the death of a loved one, or a humiliation that we’d rather not think about – these are all things that we want to leave behind in our past as we move into the future. When the mind is capable of moving rapidly from one emotion to another, one thought to another, it’s easy enough to forget these negative things.
• You’re bored and need mental stimulation: An active mind allows you to live out fantasies, in your imagination, of course. So if you’re bored and need to entertain yourself but are stuck without a laptop, phone or even a book, daydreaming is the next best thing to do. Thinking of positive make-believe scenarios has an uplifting effect on your mood, and you feel good about yourself.
• You need to multitask: Not many people are able to multitask efficiently without any major mistakes being made. And the ones that do are the ones who are able to change thought processes very quickly or even run thought processes that are parallel. Being able to control your thoughts, even though there are a large number jostling for attention in your mind, is a good thing when you’re trying to handle more than one job at the same time. Of course, efficiency increases with the mundane nature of the jobs, but some people are able to process both simple and complicated tasks simultaneously.

This article is contributed by Sarah Scrafford, who regularly writes on the topic of Radiology Technician Training. She invites your questions, comments and freelancing job inquiries at her email address: sarah.scrafford25@gmail.com.

Sphere: Related Content

Get Enchanted with the Enecpehalon # 59

Ionian Enchantment has published the 59th edition  of the brain carnival Encephalon and it contains some of the best blogging from the usual suspects.

I found the new technique of cooling a brain region to slow the neural activity (spike rate I believe) and thus to deduce as to which particular brain region in songbirds is associated with Rhythm very fascinating. Girrlscientists at Living the Scientific Life does a great job of describing the study.  Greg at Neuroanthropology discuses the work of Andy Clark with reference to massive modularity and innate/learned controversy and concludes that a middle-of-the-road neuroconstructivist approach is the best.

Other cool stuff includes new findings that some cognitive auditory abilities may be enhanced in late Huntington disorder and a writeup of the hallucinatory states induced by Ganzfiled procedure.  There is more cool stuff, so go and have a look!

Sphere: Related Content

Primate evolutionary tree: a case of eight stage evolution leading to humans?

I have been looking at primate evolution and taxonomic tress for quite some time and am aware that different scholars parse the same tree in different ways, specifically people try to avoid being anthropocentric. I , on the other hand , will focus exclusively on the primate tree as it relates to humans and try to to show that it might be a living proof of the eight stage theory of evolution/ development.

First let me show you a popular way of portraying the primate tree from Philadelphia Inquirer's Going Ape website.

Now, let me show you an alternative classification (just slightly different from this, but based on cladistics) . It is hard to see the figure (I've lost the original full -kleght versions), but the idea is that the first level branching happens at the level of suborder, then infraorder, then family etc within the order of primates.

Here is a similar diagram from the The Third Chimpanzee by Jared Diamond.

It is instructive to note that here barnching within primate tree is as follows:

1. Suborder branching: Prosimians: I hypothesize that prosimian evolution be driven by first adaptive problem that of hiding from / avoiding predators. (lemurs etc)
   
2. Infraorder branching: Platyrrhine (flatnosed) or New World Monkeys: I hypothesize that these would be most adventurous of all and would be focussed on finding food and resources, having mastered the predation problem. Maybe the main factor here would be their range size etc. This family is as opposed to Catarrhine (down-nosed) or Old World primate to which humans belong.
3. Superfamily branching: Cercopithecoidea: Old World Monkeys. Lets say we focus on old world monkeys here. The hypothesis is that they would be specialized for forming alliances and territorial hierarchical behaviors. This superfmaily is as opposed to hominoidea superfamily.
4. Family branching: Hylobatidae or Gibbons: the hypothesis is that Gibbon evolution may be driven by parental investment conflicts. this family is as opposed to Hominidae to which humans belong.
5.  Subfamily branching: Ponginae or Orangutans :  Orangutan evolution may be driven by kin selection concerns.
6. Tribe branching: Panini or gorillas: Gorilla evolution may be driven by theory of mind considerations. Maybe the driving force behind gorilla evolution is reading others mind and we would find good evidence for the same in gorillas. 
7. Species branching: pan of chimpanzees and bonobos and humans: may be driven by communication or language concerns. Of course language or communication in Humans is phenomenal; but may be of equal importance for the other two also.
8.   This species may be a branching of humans later on along sexual selection lines or assortative mating considerations along the lines of Elois and Morlocks.

I am not a primatologists and the above appears too simplistic and fishy to me; but is there evidence for any of the  hypothesis presented above; if so do let me know! Meanwhile I will be on the lookout for any confirmatory evidence!!

Sphere: Related Content