The not-so-WEIRD world of human behavioural wiring
Science is expanding its knowledge of behaviour to look at differences due to culture and biology
Some years back, an article in Nature caught my eye. Its title, "Most people are not WEIRD", makes good sense when it is clear that WEIRD stands for Western, educated, industrialised, rich, and democratic.
The authors report that the bulk of knowledge that researchers have accumulated on human behaviour has been drawn from studies done on university students in North America and Europe. This is of course a minuscule and highly biased sample; it cannot represent all of humanity.
Our ancestors migrated out of Africa only some 100,000 years ago, settling in the vastly different environments of the virgin planet, from steaming jungles to the white Arctic. Despite these recent origins, the experience has sculpted us into a highly heterogeneous species. In turn, these differences, both biological and cultural, give us the raw materials that feed into evolutionary processes.
Scientists have recently begun to investigate these differences in terms of geography. A behavioural difference that has been noted is that between the "holistic" approach of East Asia and the "analytic" process of the West. While the analytic mind reasons according to Aristotelian logic - such as "if A is true then not-A is false" - the holistic mind is more intuitive as well as more tolerant of differences. This cultural attitude is exemplified by late leader Deng Xiaoping's saying that it does not matter whether the cat is black or white as long as it catches mice.
A study published several months ago in Science goes a little deeper into these differences by comparing the behavioural effects of two forms of agriculture in China. It turns out that people from regions that have traditionally practised rice farming are more holistic and interdependent in their thinking, presumably because rice growing requires a more group coordination than wheat production. The 1,162 subjects of the study were university students of Han ethnicity who come from all over China. Since these students are all removed from actual farming themselves, the effect of rice culture on their mind may persist over many generations.
But our biology is even more critical than our culture. Especially sensitive is the issue of sex, the differences between men and women. When the president of Harvard University publicly mused on these differences in 2005, and how they might account for the scarcity of women in the sciences, it created a furore, both in academia and in the media. But "different" is not necessarily better or worse. With modern technology being used to examine the connections of the living brain, such differences are undeniable. In fact, as early as 1973, an autopsy study by a Canadian group reported a significant size difference in a language area in the brains of infants.
The latest report on sex differences, published in the Proceedings of the National Academy of Sciences of the USA, came from a group of researchers based in Philadelphia. Using the powerful methods of diffusion tensor imaging, which can show how various regions of the brain connect to each other, they studied the brains of 428 males and 521 females, between the ages of eight and 22. Findings extracted from such a large sample of brains are correspondingly significant statistically.
Previous data from structural imaging suggest that male brains are optimised for communication within the hemispheres, whereas female brains are optimised for communication across them. The Philadelphia study "overwhelmingly supported this hypothesis at every level [global, lobar, and regional]," the authors said. Furthermore, the neural basis for this sex difference can be seen even in their youngest group of subjects, aged between eight and 13 years.
This pool of subjects was also tested for various behavioural tasks. These tests also showed a clear sex difference: females doing better on attention, word and face memory, and social cognition, while males doing better on spatial processing, and motor and sensorimotor speed. Now we can better understand the brain basis for the complementary specialisations between the sexes, which may be seen as an advantage for our species as a whole.
Now that our horizons have been extended in this direction of human differences, we can see two major avenues for future research.
One has to do with achieving a better balance of knowledge based on all major populations around the world. Of the 949 subjects in the Philadelphia study, only 10 were Asian. It is also of great interest to see if the rest of the world shows similar differences between the sexes. Which behavioural differences have a brain basis?
The second avenue of research has to do with the later stages of our life.
While a great deal has been learned in recent decades about how we develop from infancy, through childhood and adolescence to adulthood, much less is known about the brain processes from adulthood to senescence, or deterioration with age.
The entire world is ageing rapidly, and people differ dramatically by culture and by geography in how well they cope with this process. It is also of great interest to see how the sexes differ in this part of life's journey, from brain to behaviour, in various regions of the world.
William S-Y. Wang, is Director of the Centre for Language and Human Complexity at the Chinese University of Hong Kong