The Winding Path

Previously I wrote a brief overview of Merlin Donald’s paper which paints a picture of how our culture and our brain co-evolved. I also raised a question of what it might mean for the future. Now I’m going to give you an overview of Donald’s theory which actually details how that co-evolution may have happened. To try to give you a clearer picture I’m drawing on some of what Donald wrote in his book, Origins of the Modern Mind, in which he fully defined his theory.

It’s a theory which drew on the work of people from many fields including neuropsychology, cognitive neuroscience, anthropology, and comparative biology. The crux of the theory is that our cognitive-cultural evolution went through three transitions; each new stage involving a new way of mentally representing reality. It’s important to note that each stage builds on top of the previous, retaining all the advantages so that the last stage also includes all the previous ones.

Episodic Culture

This stage involved the ability to mentally represent complex events, including social ones, but with a very limited capacity to voluntarily express those representations. And while complex events could be understood, they could only be understood in a very situation-specific way. Modern apes are at this stage¹. An example of the limitations of this stage can be found in apes’ use of sign language. Apes can be taught how to sign, but they seem to only be able to use signs in the contexts in which they’re taught. However, humans can learn to apply the same sign in any context in which it could conceivably be relevant (and even when not relevant. Just think of how we’re coming up with new uses for old words all the time).

Mimetic Culture

The first transition brings us to a mimetic form of culture. It happened about 2 million years ago with the emergence of Homo erectus, who were the first of our ancestors to show clear evidence of an advanced, tool-using society. While some who came before do show evidence of tool-use, it wasn’t as systematic and widespread as it was with Homo erectus. Donald argues that our ancestors must have undergone a significant evolutionary adaptation at around that time, citing various sources as evidence including fossil records, cultural relics such as tools, and comparative anatomical evidence. The result of the adaptation was a form of representation which included the ability to model actions. This form of culture gets it name from that modeling ability; mimetic skill, or mimesis, which is the ability to consciously act in a way which conveys a message. Donald suggests that our ancestors still weren’t able to communicate verbally, but they now possessed enough nonverbal ability to allow individuals to share their knowledge of skills, such as tool-making, through various forms of behaviour including gestures, whole-body movement, facial expressions, eye movements, etc.

Mythic Culture

The second adaptation happened less than 400,000 years ago with the emergence of Homo sapiens, our closest ancestors. The adaptation was the ability to speak (and of course understand speech). This stage involved many cultural achievements including clothing, building shelter, transporting heaving objects, a huge variety of tools and weapons, social and religious activities involving elaborate rituals including dancing, masks and costumes. It was the latter achievement from which this form of culture gets its name; our ancestors could now form an understanding of the world which integrated everything that they experienced into a narrative form. They could construct and communicate those stories far more effectively than they could before, not just because of the advantages speech provide, but also because of the improvements to memory and thinking that came along with speech.

Theoretic Culture

The third, and to this point the last (though not necessarily the final) transition was not a biological one. It involved the use of tools to get our representations out of our heads, allowing us to manipulate them in more ways than ever possible before. By moving our ideas outside our heads those concrete representations became part of our cognitive processes. Our “thoughts” now also exist in various forms of written language, but also as every other kind of representation that technology allows, from graphs to photos to video, as well as music and other forms accessible to our other senses. Most importantly, along with this new form or representation came a new form of thinking; theoretical thought. This form of thought allows a much greater scrutiny of reality, and much more accurate representations than were possible at previous stages.

So there you have a brief outline of Donald’s proposed theory. It’s important because it provides a framework for understanding and further examining our current culture and cognition, the various ways in which we view the world, how that differs from culture to culture, and what might change in the future as our culture continues to develop. If you’d like to learn more I highly recommend picking up Origins of the Modern Mind.

Related entries:

• How did our mind and brain evolve?
• How do we process complex social interactions?

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Through this perspective we look at the how social influences and emotions shape our development, with a focus on the way we behave. From very soon after we’re born it becomes clear that we have an identifiable temperament. Most first-time parents probably think their constantly crying baby is going to grow up to be a disagreeable little… Well, thankfully they’re usually wrong.

Temperament has many definitions, though it can be summarised as stable, individual differences in the quality and intensity of emotional reactions. Your temperament forms the base of your personality and is one set of traits which is much more influenced by your genes than by the environment.

Temperament

Temperament is described by (and often measured according to) terms such as sociability, adaptability, persistence, activity level, and reactivity. Many studies have been done on temperament but I have to mention one particular Australian study, funnily enough called the Australian Temperament Project. It’s a long term and on-going study which began in 1982, and is continuing to follow around 2000 people born around that time, aiming to investigate “the influence of an individual’s temperament on his/her emotional and behavioural adjustment.”

That and other studies have produced some significant findings, not the least of which is to highlight just how important it is that parents interact with children in a way which is appropriate to the various aspects of the child’s temperament. There is no “one size fits all” method of raising children. For example, a highly reactive (very sensitive to all kinds of stimulation) and easily distracted child would require a different approach to a highly reactive but persistent child. This seems like common sense, but shows like Super Nanny show us that if it is common sense, some parents don’t have any.

The ATP study showed that highly reactive adolescents who had a low level of supervision had the highest number of incidents of fighting, stealing, disobedience, and other similar unwanted behaviours. And yet adolescents who weren’t reactive who also had little supervision showed very few of those unwanted behaviours.

Ironically it is the ideal balance of interaction between parent (or other carer) and child which allows the child to develop self-regulation, letting them then manage their own responses, stopping them from heading down a path towards poor psychological development and all associated problems such as getting into fights, caving in to peer pressure, or thinking Paris Hilton is a good role model. (Is Paris Hilton a good role model? A clue: no).

Attachment

Attachment, important to parenting and development, can be defined as a close emotional relationship between two people, in which each displays affection towards the other as well as a desire to maintain closeness.

John Bowlby developed a theory of attachment based on observations of children’s reactions to separation from their primary carer (usually a parent, most often their mother). The theory was also inspired by studies of imprinting in baby geese. While not quite the same as imprinting, Bowlby did propose that both adults and babies have complimentary innate behaviours which keep them close to each other, and which help create a stronger, long-lasting attachment. Just like super-glue and fingers.

That attachment lets the child see the parent as a safe haven to return to when something in the world seems threatening. You see this fairly often when a child runs to cling to his mother’s legs. But the parent also acts as secure base, somewhere from which the child can safely explore the world, confident that, if necessary, they can return to their safe haven. So according to Bowlby’s theory, security and comfort are at the core of attachment. Not so much so for super-glue and fingers.

One challenge to Bowlby’s theory was that feeding was the main reason that children formed attachments, and that security and comfort were not as important. This challenge was dismissed by some experiments Harry Harlow performed with rhesus monkeys. He started by building a pair of surrogate mothers for the monkeys; one feeder which was just a wire frame with a milk bottle poking out of it, and one comforter which was a wire frame wrapped in terry cloth. The monkeys all showed a clear preference for the comforter, spending most of their time with it, and always returning to it whenever they felt threatened, or once they had finished exploring or playing.

Mary Ainsworth and her colleagues applied the study of attachment to humans by developing what is called The Strange Situation. It involves a series of observations of a child reactions to the absence or presence of their primary parent, or a stranger. By watching how different children reacted to the same series of situations (carer in the room, carer leaving, carer returning, stranger arriving, etc), Ainsworth came up with three ways of grouping behaviour which highlighted the different degrees of security a child feels, and how that affects their behaviour.

Unfortunately a lack of long term studies doesn’t allow us to come to any strong conclusions of just how childhood attachment influences later life, though studies of orphans have shown that a lack of security during early years leads to psychological problems in later years of childhood, but that when placed in a caring environment, over time those problems mostly disappear.

Onwards

Temperament forms the basis of our reactions to the world during childhood, which influences the styles of attachment we form. Our temperament also demands that others adjust their interaction with us in a way that best teaches us to react in ways which are beneficial. With the right kind of interaction and teaching we’ll be able to develop in a way that sets the stage for positive development in later years, and a psychological make up that will allow us to enjoy our lives.

If you’re interested in finding out more about attachment theory, have a look at this review paper. But bear in mind it is an academic paper.

As you’ve noticed this is just part one of the social-emotional perspective, and I’ve barely touched on behaviour and emotion. Stay tuned.

Related entries:

• Introduction to Human Development
• Introduction to Human Development: Psychoanalytic/Psychosocial Perspective
• Introduction to Human Development: Biological Perspective
• Introduction to Human Development: Social-Emotional Perspective - Part 2
• Introduction to Human Development: Cognitive Perspective
• Introduction to Human Development: Socio-cultural Perspective

The biological perspective looks at how our genes influence our development. However, since the issue of how much influence genes have is rarely discussed without also considering how much influence the environment has, it makes little sense to try to look at either side in isolation. So what we’ll look at here is the age old argument of nature versus nurture.

How do genes and the environment affect development?

One way of looking at how genes and the environment affect development is through these three patterns of interaction:

• Active
  The active pattern is one in which you choose to do things which compliment your genetic disposition. So if you’re really tall, you might choose to play basketball.
• Passive
  This pattern is followed if your environment is set up for you in a way which compliments your genetic make up. In this case your highly intelligent parents may surround you with books and other educational material, including educational toys.
• Reactive
  In this pattern you’ll behave in a way that compliments your genetic endowment, and this will lead people to react to you in a way which reinforces that behaviour. So your Aunt sees you running around the backyard and says, “Oh look at little Timmy, running around just like his Dad. He’s going to grow up to be a sprinter too isn’t he?” Hearing this you gleefully run a little faster.

Another approach is to look at how genes result in the development of specific traits, where a trait could be eye colour, type of personality, level of intelligence, genetic disease, etc. It used to be thought that specific genes meant specific traits, and indeed many people still think that’s how genes work.

A more recent theory is that genes only indicate a likelihood of developing a specific trait, and that environmental factors play a significant part in determining whether or not that trait is expressed. The more complex the trait, the more factors involved, the harder it is to figure out the likelihood that having specific genes will mean having a specific trait. So for example, if you have genes which make it easy for you to put on weight, it’s no guarantee that you will put on weight, unless your environment allows it. Yes, put down that donut, pick up that carrot. Better yet, give me the donut!

How much of an effect do genes and the environment have?

One way of measuring the effect of genes on a particular trait is to look at it’s heritability. Heritability is a measure of how much variation there is between people. For example there is not much variation in the number of fingers people are born with, so we can say that the heritability of number of fingers is low. If you have fewer fingers it’s probably because a drinking game involving power tools went horribly wrong.

Compare this to the heritability of height. Height varies a lot, and as with the number of fingers, it’s mostly due to genetic factors. Some variation in height can be accounted for by environmental factors, though arguably if you ask someone who hunches over a computer all day to stand up straight so they can be measured, they probably won’t standing as straight as most people would. So it’s unlikely that being short is due to anything but genes. After all, if a drinking game goes horribly wrong and it affects your height, well, at best you won’t be a foot model any more. At worst… Well, let’s not go there.

But one thing to keep in mind when thinking about heritability is that it’s really just an estimate of variation across people in general. It doesn’t actually say much about genetic contribution to a specific trait in an individual. For that we need to look at the research.

How do we know how genes and the environment affect development?

Much of the most conclusive research on the influence of genes versus the environment has been done by studying twins, both identical and fraternal twins.

Various studies on IQ have produced some interesting results. Some early studies showed that identical twins were clearly more similar in intelligence than were fraternal twins. Yet these studies didn’t account for how identical twins may be treated almost identically, as opposed to more varied treatment of fraternal twins, though the effect of the differences in treatment was probably small.

Even more interesting are studies which looked at the difference in intelligence of identical twins who shared a placenta compared to identical twins who had separate placentas. Sharing a placenta resulted in more similar levels of intelligence, showing that even the pre-natal environment has at least some influence on development in contrast to the influence of genes.

Finally, a study of adopted children looked at the differences in their IQ, paying particular attention to the socio-economic status (SES) of both biological and adoptive parents. It turns out that genetic and environmental influences were about equal. Children of biological and adoptive parents of low SES had the lowest IQs, while children of low SES adoptive parents and high SES biological parents were similar to children of low SES biological parents and high SES adoptive parents, with children of both adoptive and biological parents of high SES having the highest IQs. So if you can follow that (sorry, the graph is under copyright), while you might not think the SES of biological parents would matter to a child’s IQ, it does, but as far as IQ of adopted children is concerned, both genes and the environment have comparable effects.

Onwards

The debate has gone back and forth for a long time, but for now it seems clear both genes and the environment have an influence on our development, with neither one nor the other necessarily having the greater influence in general. More research will let us figure out just how much each has an influence over specific traits, but for now we can rest assured that for many of the issues which may bother us, regardless of our genetic make up we can alter our environment to give us a good chance of expressing the kind of traits we’d prefer, rather than the ones we might think we’re stuck with.

Most of the info I’ve presented has come from books or papers which require a subscription for access, but a quick search for “nurture vs nature” will give you plenty of info, such as the wikipedia page or the about.com page. The BBC also have a good article on the topic, though being short it doesn’t say much more than you’ve just read.

Next up is the socio-emotional perspective which looks more closely at how behaviour develops in response to social and local environmental interaction, as well as emotion, temperament and attachment.

Related entries:

• Introduction to Human Development
• Introduction to Human Development: Psychoanalytic/Psychosocial Perspective
• Introduction to Human Development: Social-Emotional Perspective - Part 1
• Introduction to Human Development: Social-Emotional Perspective - Part 2
• Introduction to Human Development: Cognitive Perspective
• Introduction to Human Development: Socio-cultural Perspective