Africans are getting shorter: This is why your children are most likely to be shorter than you

By Christine Mungai | 7yrs ago | 6 min read

Every year in their annual Gates letter, Bill and Melinda Gates outline some of the progress that their Foundation is making in human health, and the challenges that remain.

In this year's letter, Bill Gates gives a little anecdote that has huge, but often unnoticed, implications.

"When I first started traveling to Africa, I would meet kids in the villages I was visiting and try to guess their ages," writes Bill Gates. "I was amazed how often I was wrong. Kids I thought were 7 or 8 told me they were 12 or 13."

Most of those children were stunted, which means they were shorter than their healthy height, because they were missing key nutrients in their diets, or they had missed key nutrients in the womb because their mothers were malnourished.

Most of us believe that height is one of those things that are hard-wired in the genes and runs in families: one is either tall, or not, and there's nothing that can be done.

But that isn't the whole story. Although individual differences in height are indeed genetic, differences in height between groups of people (populations) is influenced much more by the quality of nutrition and health care during the first three years of a child's life.

The influence of nutrition on average height in a population is so powerful that scientists often use height-for-age in children as a proxy indicator for health and, by extension, a society's biological standard of living.

Height is a particularly accurate way to measure a society's well-being because unlike other indicators such as GDP, national income, or poverty data, it is straightforward to measure and difficult to fudge or fiddle with using complex formulas.

Final stature

Although it seems that height increases dramatically in the teenage years during puberty, the greatest impact a person's final stature is the quality of nutrition from birth to age 3.

A child who is stunted is actually chronically malnourished, reflecting a failure to receive adequate nutrition over a long period of time, and is worsened by recurrent and chronic illness.

This kind of malnutrition is not necessarily starvation, and is not affected by short-term changes in diet, such as the occasional hungry evening or the odd Christmas binge.

In a nutshell, during childhood the body has very high energy demands, and needs a large amount of protein to both grow in stature, and create antibodies to fight off disease.

If a child is not eating enough high quality food, the body actually makes a trade off – reducing its growth so that it can have enough reserves to create antibodies. The child ends up shorter that he or she would otherwise have been.

Looking at height-for-age data from the Kenya Demographic and Health Survey (DHS) suggests that chronic malnutrition is the daily reality for a huge number of Kenyan children, whose impact will be felt for the rest of their lives.

Nationally, 26 per cent of children in Kenya are stunted, while 8 per cent are severely stunted. Analysis of this indicator by age group shows that stunting is highest in children aged 1-and-a-half to two years (36 percent) and two to three years (34 percent).

As they get older, after age 3, children's energy and protein needs drop slightly, and so stunting levels begin to fall somewhat.

Stunting is higher among boys (30 per cent) than girls (22 per cent), partly because boys' immune systems are slightly less developed than girls at birth, so boys tend to fall sick more often.

It is also higher among rural children (29 per cent) than urban children (20 per cent). At the regional level, Coast (31 percent), Rift Valley and Eastern (each 30 percent) have the highest proportions of stunted children, while Nairobi (17 percent) and Central (18 percent) have the lowest.

Stunting in children generally decreases with education of the mother and wealth of the household. Children of mothers who did not complete primary school or who have no education are more likely to be stunted than children of mothers with a secondary or higher education.

Human potential

"Malnutrition destroys the most human potential on the planet. Kids who are stunted are not just below their global peers in height; they're behind their peers in cognitive development, and that will limit these children their whole lives," the Gates letter states.

"Nutrition is the biggest missed opportunity in global health. It could unleash waves of human potential—yet only 1 per cent of foreign aid goes to basic nutrition."

Even more sobering is the World Bank's Global Monitoring report 2012 that stated: "A malnourished child has on average a seven-month delay in starting school, a 0.7 grade loss in schooling, and potentially a 10-17 per cent reduction in life-time earnings – damaging future human capital and causing national GDP losses estimated at 2-3 per cent."

Still, that's not the whole story. If you look at historical data, even more intriguing trends emerge. A report by the OECD titled How Was Life: Global Well Being Since 1820 reveals the trends of human stature among different populations around the world since the 19th century – and suggests that life in Africa has not always been a hard-scrabble one.

The report assessed historical data from populations in Kenya, South Africa and Nigeria, and found that these Africans born in the 1870s all the way to the 1940s grew up to be 1-2 centimetres taller than the global average.

It suggests something radical – that even with high infant and child mortality, and a heavy disease burden before the introduction of Western medicine, life in Africa may not necessarily have been one of squalor.

At least by this indicator, African children had better diets and healthier lives than those in Europe and America, who at that time were often cramped in the miserable Dickensian conditions of industrialising cities.

But the trend began to reverse in Africa starting with children born in 1950s; those ones grew up to be just 0.2cm taller than the rest of the world.

From the 1960s, children born in the rest of the world had caught up with Africa, and in the subsequent decades the downward trend continued, such that today's 25-34 year olds – those born in the 1980s – are now 1.4cm shorter on average than their age-mates around the world.

The data also indicates that Africa is the only region in the world where average height has been declining since the 1960s. (The 1990s and beyond is not included in the data set because those born in these decades have not yet achieved their full adult stature).

It suggests that 'modern' Africa, from a nutritional standpoint, is doing much worse than a century ago.

This may be surprising, but many historians and scientists have actually suggested that the diet of pre-agrarian societies was much more varied and nutritionally dense than today's diet.

Control

In some ways, the agrarian revolution and industrialisation was a large leap forward for mankind, but it had a high cost. Once humans started large-scale agriculture and living settled lives, they began to eat one or two grains as their main food – maize, wheat or rice – the kind of food that was easy to dry and store, and thus easy for a central authority to control.

But it also meant a loss of many nutrients, as cereal grains are much less nutritionally dense than, say, a diet of roots, tubers, vegetables and insects. Living in close quarters in cities also meant wave after wave of deadly disease: cholera, typhoid, bubonic plague.

Throughout the world, the shift to agriculture resulted in more powerful societies because they now had secure food reserves and centralised authority.

But it also resulted a dramatic drop in the quality of most people's diets and overall health, writes historian Jared Diamond.

What can we do today? Breastfeeding in the first hour of a child's life, and exclusively for six months is the first and simplest intervention. There's also much research going into how we can fortify staple foods with micronutrients, such as Vitamin A and iron.

But it is also a political problem. Children stunted by chronic malnutrition is a reflection of broken and inefficient food systems, those that result in healthy food being expensive and out of reach of most people, and cheap food being nutritionally poor. It's a problem that will take more than food to solve.

- Christine Mungai is a writer, journalist and executive editor of Africa data explainer site Africapedia, and a 2018 Nieman fellow at Harvard University.