Tuesday, September 12, 2006

Where does culture come from?

The fact that we humans are not a bunch of robots that simply enact predetermined programs has a series of spectacular consequences such as the development of large societies and the high speed of cultural advances. While most animals have almost identical, unchanged lives for even millions of years, our lives are radically different from the lives of our ancestors who lived even 10,000 years ago (or should I say 50 years ago?). So, what is at the core of this difference between us and the other animals?

It is worth noting that this huge difference in result is not a consequence of a huge difference at the core. There is only a minor genetic difference between us and the rest of the animal kingdom – we share more than 99% of our genes with the chimpanzees and the genetic resemblance between us and the Neanderthals was even higher. In other words, the biological recipe for constructing a human is almost identical with the recipe for constructing a chimpanzee or a Neanderthal. Nonetheless, this minute difference in this recipe has produced somehow an avalanche effect; this difference has opened the door for something new. This "something new" is culture and the transmission of acquired knowledge over generations. Thus, the question is what is the ingredient that has made culture possible?

When Homo sapiens first entered Eurasia on their way out of Africa they only managed to spread toward Asia. Europe was occupied by another of Homo erectus' descendents – Homo neanderthalis. But after colonizing Asia, Homo sapiens returned for Europe, more than 50,000 years after its presumed first attempt, and wiped out the Neanderthals. In these 50,000 years or so, modern humans managed to develop their stone technology quite extensively, unlike the Neanderthals who, comparatively, continued to use a virtually unchanged technology.

One might assume that, at the core, this reveals a difference in inventiveness. However, this is probably not true. Instead, it was probably due to a difference in the ability of preserving and transmitting the discoveries rather than of making discoveries. (Maybe Neanderthals lacked advanced language - as Jared Diamond suggested.)

The same seems to be true of chimpanzees: they are also rather cunning creatures unable to mount an effective avalanche effect of piling up new inventions on top of each other, unable to make inventions that use and improve old ones. This happens because each chimp has difficulties transmitting its personal experience to others.

Thus, it seems we have to focus our attention on the transmission of information rather than on individual creativity. Creativity seems to be the easy part. So, what is the thing that makes cultural inheritance possible?

Where does empathy happen in the brain?

In order for the transmission of information to occur from A to B, B has to have the ability to put himself in the A's shoes, B has to observe something at A and to make that something his own. The neurologist V.S. Ramachandran has suggested that the key part in this story is played by the mirror neurons. Scientists have discovered that these neurons get activated in the brain both when we're doing something and when we are watching somebody else doing that same thing. In other words, these neurons really place us in somebody else's shoes – or, actually, mind. Professor Ramachandran has predicted that the importance of these neurons to psychology will prove similar to that of DNA to biology. (Read his essey.)

"The hominid brain grew at an accelerating pace until it reached its present size of 1500cc about 200,000 years ago. Yet uniquely human abilities such the invention of highly sophisticated 'standardized' multi- part tools, tailored clothes, art, religious belief and perhaps even language are thought to have emerged quite rapidly around 40,000 years ago — a sudden explosion of human mental abilities and culture that is sometimes called the 'big bang'. If the brain reached its full human potential — or at least size — 200,000 years ago why did it remain idle for 150,000 years? Most scholars are convinced that the big bang occurred because of some unknown genetic change in brain structure," Ramachandran wrote six years ago.
Scientists have recently discovered a gene involved in the development of the brain that might be responsible for our large brains. But no culture gene is known to exist, one that could have triggered that 'big bang'.

Instead, the idea of a cultural 'big bang' has suffered a serious blow recently, when D'Errico and Marian Vanhaeren of University College London have discovered that 100,000-year-old perforated shells found in Israel and Algeria and similar 75,000 year-old shells found in the Blombos cave in South Africa were in fact decorative beads. (Read article.)
"Our paper supports the scenario that modern humans in Africa developed behaviors that are considered modern quite early in time, so that in fact these people were probably not just biologically modern but also culturally and cognitively modern, at least to some degree," said d'Errico.
Thus, the cultural evolution of humanity was less abrupt than it was previously thought.
"I [...] offer a very different solution to the problem," Ramachandran said. "I suggest that the so-called big bang occurred because certain critical environmental triggers acted on a brain that had already become big for some other reason and was therefore 'pre-adapted' for those cultural innovations that make us uniquely human. (One of the key pre-adaptations being mirror neurons.)

Inventions like tool use, art, math and even aspects of language may have been invented 'accidentally' in one place and then spread very quickly given the human brain's amazing capacity for imitation learning and mind reading using mirror neurons. Perhaps ANY major 'innovation' happens because of a fortuitous coincidence of environmental circumstances — usually at a single place and time. But given our species' remarkable propensity for miming, such an invention would tend to spread very quickly through the population — once it emerged."
Many studies have supported this view. It appears that all important inventions, such as agriculture or writing or gunpowder, have happened only in very few places on Earth and then have spread from there to everywhere. Moreover, small, isolated communities always lag behind the larger ones and even lose some of their knowledge, unable to preserve useful know-hows. (Such issues are described at length by Jared Diamond in his book Guns, Germs and Steel: the different fates of human societies.)
"There may indeed have been a genetic change, but it may not have been an increase in the ability to innovate," Ramachandran wrote, "but an increase in the sophistication of the mirror neuron system and therefore in 'learnability'."
So, what exactly is learned?

The question is what exactly are we capable of imitating? In what way exactly is our understanding of other people superior to a monkey's understanding of other monkeys?
"Mirror neurons obviously cannot be the only answer to all these riddles of evolution," Ramachandran wrote. "After all rhesus monkeys and apes have them, yet they lack the cultural sophistication of humans (although it has recently been shown that chimps at least DO have the rudiments of culture, even in the wild). I would argue, though, that mirror neurons are necessary but not sufficient: their emergence and further development in hominids was a decisive step. The reason is that once you have a certain minimum amount of 'imitation learning' and 'culture' in place, this culture can, in turn, exert the selection pressure for developing those additional mental traits that make us human. And once this starts happening you have set in motion the auto-catalytic process that culminated in modern human consciousness."
At least for the time being, Ramachandran hands on the torch to other scientists who conduct behavioral studies of the conditions necessary for the development of culture. (Read about more recent discoveries about mirror neurons.) Michael Tomasello and his colleagues have studied the learning strategies used by humans and apes and have discovered very significant and interesting differences.

They have discovered that while humans imitate the actual behavior of other humans and copy their methods of doing things (imitative learning), chimpanzees learn from other chimpanzees mostly descriptive things about the world (called emulation learning because they "emulate" the external world inside their heads). For example a chimpanzee that sees his mother rolling a log and finding ants under the log learns that there are ants under the log (he would have learned the same thing if the wind had pushed the log) but does not learn how to roll the log (he has to learn that for himself). A human baby would rather remember that when you are hungry you roll logs and be less able at remembering what is under the logs.
"The interesting point is that many children insisted on this reproduction of adult behavior even in the case of the less efficient method — leading to less successful performance than the chimpanzees in this condition. Imitative learning is thus not a 'higher' or 'more intelligent' learning strategy than emulation learning; it is simply a more social strategy—which, in some circumstances and for some behaviors, has some advantages," Tomasello wrote in his book The cultural origins of human cognition.
The same thing was discovered by professor Andrew Whiten of the University of St Andrews with the help of an ingenious lab experiment. He and his colleagues designed "artificial fruits", a kind of devices that had to be opened for getting the edible core, which could be opened in two different ways. They then taught chimps and young children how to open the "artificial fruits" using one of the methods.

Image: chimpanzee with "artificial fruit". Credit: Andrew Whiten.

They discovered that "the apes are more ready to use their own approach where they can see it is more efficient; children are more likely to copy so faithfully that they are slower to succeed than the apes, but overall this is presumably a strategy that pays off for the supreme cultural species!" It seems that unlike the chimps, "children may copy certain behavior just because 'that is what is done'."

These differences between humans and the rest of the apes have subtle consequences for the understanding of tools. For a chimp, a tool is mainly an object designed to do something and they are good at understanding the changes in the environment caused by others' tool use. On the other hand, to a human, a tool is mainly an object designed to be used in a certain way. There is an important cause behind this difference: when watching the behavior of somebody else, the chimps have difficulties discerning the goal from the method used to achieve the goal and thus focus on the external impact of that behavior.
"For humans, the goal or intention of the demonstrator is a central part of what they perceive, and indeed the goal is understood as something separate from the various behavioral means that may be used to accomplish the goal, "Tomasello wrote. "Observers’ ability to separate goal and means serves to highlight for them the demonstrator’s method or strategy of tool use as an independent entity — the behavior she is using in an attempt to accomplish the goal, given the possibility of other means of accomplishing it."

"In the absence of this ability to understand goal and behavioral means as separable in the actions of others, chimpanzee observers focus on the changes of state (including changes of spatial position) of the objects involved during the demonstration, with the actions of the demonstrator being, in effect, just other physical motions. The intentional states of the demonstrator, and thus her behavioral methods as distinct behavioral entities, are simply not part of their experience."
Actually they are, as Tomasello himself has eventually proven, but not as prominently as in case of humans. Whiten has also observed the same kind of limited but nonetheless present capacity for understanding. The chimps are not just blindly and mechanically imitating something, "they have some understanding of when they are copying what the other does; to this extent their acquisitions can become self-conscious, as they do in the course of human childhood," Whiten wrote.

Their understanding however is not as such as to allow them to develop progressively and to accumulate inventions.
"Several aspects of the overall African distribution of chimpanzee behaviours are consistent with some form of cultural evolution, in which communities display what appear to be differentiated forms of certain behaviours found in their neighbours," Whiten wrote. "An example is that ecto-parasites removed in grooming by Taï chimpanzees are squashed on the forearm using a finger, whereas in east Africa they are either squashed on a leaf (Gombe) or placed on a leaf for inspection before being eaten or discarded (Kibale); the leaf use in these two communities may have differentiated from a universal habit amongst east African chimpanzees in which occasional 'leaf-grooming' is incorporated into social grooming episodes. However, such differentiation embodies little if any rise in complexity.

"Accordingly, a capacity for substantial cumulative cultural evolution may be the feature that most fundamentally distinguishes humans from the species that in other respects shows significant cultural richness," he added.
The bottom line of all this is that, in order for culture to develop, the individuals have to be capable of placing themselves in the shoes of each other. But one of the most important features of each individual is their intentionality, the fact that their behavior is oriented towards goals and guided by the search of methods for achieving their goals. Thus, in order to really be able to see the world from somebody else's eyes you have to be able not only to feel what they feel when they're doing something (the job of the mirror neurons) but also to discern the goals that drive their behavior.
"In general, then, human cultural traditions may be most readily distinguished from chimpanzee cultural traditions — as well as the few other instances of culture observed in other primate species — precisely by the fact that they accumulate modifications over time, that is to say, they have cultural 'histories'," Tomasello wrote. "They accumulate modifications and have histories because the cultural learning processes that support them are especially powerful. These cultural learning processes are especially powerful because they are supported by the uniquely human cognitive adaptation for understanding others as intentional beings like the self — which creates forms of social learning that act as a ratchet by faithfully preserving newly innovated strategies in the social group until there is another innovation to replace them."
So, it seems that what makes us human is, as I argued elsewhere as well, our ability to understand others as intentional beings and to guess what their goals might be. The consequence of this ability is the development of culture which subsequently has furthermore shaped our beings.

1 comment:

Anonymous said...

read the Meme Machine by Susan Blackmore. it's about culture-gene co evolution.

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