Opinion | The impact of income inequality on the evolving brain

Income inequality is an undeniable reality in India and in most other parts of the world. The effects of poverty on health, education and other dimensions have been well documented. Recent research studies seek to understand how income levels may be correlated with differences in the structure of the human brain.

The brain’s primary function is to enable cognition—the action or process of acquiring knowledge and understanding through thought, experience and the senses. Unlike all other organs, which look and behave more or less the same from birth to death, the brain evolves constantly over a person’s lifespan. This happens as a response to the brain’s external environment—which is the totality of all stimuli which have historically been transmitted to the brain via all of the human senses.

In other words, everything you ever saw, heard, smelt, tasted or touched has shaped your brain.

Unlike in a computer, where hardware and software are two disparate aspects, in the brain, form and function are deeply interwoven. Learning results in a change in the connectivity and structure of the brain, and therefore the type of activity it is able to produce, and the subsequent nature of learning it is capable of. It is an intricate feedback loop. The physical structure of the brain and its processing capacity are two sides of the same coin. To use an economics analogy, one cannot describe the gross domestic product (GDP) potential of a country independent of the infrastructure it has created. It is only once the requisite infrastructure is built that achieving a higher level of economic output becomes possible. And the output, in turn, may be re-invested to modify the infrastructure in big and small ways to enable even greater GDP.

Science has shown us that the structure of the brain is shaped by the complexity of the stimulus environment one encounters. Studies done on rodents, for example, show that placing the animal in a more complex or enriched environment with greater stimuli has far reaching impact on gene expression in the brain, the growth of new neurons and the number of connections between them, and how synapses “learn”. This translates to changes in terms of brain volume and surface area. The more things you see, hear, touch, taste or smell, the bigger (and more complex) your brain is.

Now if this is true, it is also true that modern life presents a far more complex environment than ever before. Scientific progress over the past century has been accompanied by dramatic expansions in the rate and scope of the landscape of human stimulus experience. For example, motorized transport profoundly altered the scope of exploration of your environment and the speed of changes in your visual experience.

In urban environments, the complexity of visual and physical encounters is further amplified by the greater variability of stimulus. Similarly, cell phones and the internet profoundly change the rate of access to information and formal education, which expands the scope of knowledge.

Therefore, one might expect that modern brains must be evolving and altering their capability and potential at a much faster rate.

Indeed, our research has found that the electrical activity of brains living in “pre-modern” environments produce substantially less complex patterns compared to brains living in “modern” circumstances, in addition to a whole range of other differences. Yet, in India, more than almost any country on earth, vast populations with little or no access to these elements of modernization sit alongside fast paced digitally connected urban ones.

Access to modern complexity is largely determined by a person’s income. By spending on things like technology, transport and education, one essentially buys a more complex and faster pace of stimulus to the brain. In the US, studies have shown that income, particularly childhood poverty, has a dramatic negative effect on brain volume and surface area, as well as the complexity of patterns of electrical activity produced by the brain. Conversely, years of education have been shown to bear a positive correlation with these aspects. In India too, our own research has shown a dramatic relationship between the complexity of brain activity and income.

When we draw poverty lines, we typically go by what funds are sufficient to fuel the human body and thereby keep away hunger, but not what the mind needs. The cost of fuelling the mind is far higher.

In our research work, we found that there was little change in brain activity for those under ₹20,000 per month of income, after which there was a sharp increase as income increased to ₹60,000 per month. It is in this range that a person begins to go beyond the basics of food, clothing and shelter to afford fuel for the mind—better education, internet access and transport. Beyond ₹60,000 per month, your cars and phones may get more stylish, but the quality of the stimulus you can access does not change much.

We have a long way to go to realize the cognitive potential of the country. Yet, there are more serious consequences. When the very physiological structure and activity of the brain diverges with a divergence in income, what does it mean for what we are becoming as a society?

Kapil Viswanathan & Tara Thiagarajan are, respectively, vice-chairman of Krea University and chief scientist at Sapien Labs