Cm by cm

I was going to title my column “inching up” as this is about heights. But in the Philippine context, progress has been so slow; heights move up by fractions of a centimeter—to be exact 8.3 cm (3.3 inches) over the last 100 years for Filipino men and, get hold of yourselves, 1.8 cm during that same period for our women; that’s less than 1 inch in a hundred years!

I found these figures after reading a scientific journal article, “A century of trends in adult human height,” which was just published last July 26 in the journal eLife.  It is an amazing study that reviewed height measurements in surveys from 200 countries. Some 800 researchers were involved in the study, so the journal article simply reads, “NCD Risk Factor Collaboration” to refer to the group in Imperial College London that coordinated the research.

Mass media pounced on the survey results, mainly about Dutch men being the tallest people in the planet, with an average height of 183 cm or 6 feet; and Guatemalan women being the shortest with an average height 149.4 cm or 5 feet and 8 inches. (Among women, the Dutch ranked second, trailing behind the Latvians.)

I was curious what the figures were for the Philippines, so I looked up more information on the research at the NCD Risk Factor Collaboration website, which provides not just scientific articles but supplementary information on their studies around height—as well as diabetes and adiposity. (Don’t you love the latter word? Next time, you can tell people, “I’m not fat; I’m adipose.”)

What was more important than the current heights was the way heights were tracked over the last century—by cohorts, meaning, looking at average heights of people according to the year they were born. This was why the century covered went from 1896 to 1996 because they needed to get statistics on height for people who were at least 18 years of age. For the 1996 cohort, this would have been around the year 2014.

Through this century-long review, the researchers could analyze trends across time; and they found the most impressive gains in adult height over the past century occurred among South Korean women, who gained 16.5 cm (6.4 inches) and Iranian men, who gained 20.2 cm (7.9 inches).

Genes and environment

The statistics from the study give us valuable insights into the interactions between nature (genes, natural environment, even climate) and nurture (social and economic development) in shaping heights.  Heights have a high genetic component, but this varies from one country to another.  In more developed countries, the genetic potential is more easily reached; in poorer countries, environmental conditions can dramatically block individuals from reaching their potential.

Good nutrition—quality and not just quantity—is essential, extending from the time the fetus is still developing, through the crucial periods of childhood and adolescence. There are also vicious cycles operating to cause stunting: shorter women have greater difficulty at childbirth, with higher rates of miscarriages and the mothers themselves at higher risk of dying during childbirth. Being malnourished themselves, the mothers have low birth-weight babies, who are disadvantaged from the start of life and through their development, until they become parents themselves.

The impact of social development is shown clearly in the ways our neighboring countries have gained in height. South Korean men born in 1896 had average heights that ranked them 151st among 200 countries. The rank increased to 51st for those born in 1996.  Even more dramatically, the height of South Korean women born in 1896 ranked 196th among the 200 countries, practically at the bottom.  With the 1996 cohort of these women, the rank was 55th.  Similar rapid improvements in height are found for our developed neighbors, including Japan, China, Singapore and Thailand.

Looking at the rankings based on height, you find many parallels with human development indices, with richer countries ranking higher, some to the point where they no longer add centimeters or inches to their average height, the plateau in numbers suggesting they’ve reached their genetic potential.

In contrast, poorer countries seem to plateau at much lower heights, not necessarily because their genetic potential is lower but because their social conditions are so dismal the children are barely able to develop. This seems to be the case in sub-Saharan Africa, where earlier surveys showed they had greater heights than Asians, but these decreased in recent years to the point that they are now shorter.

The authors of the height study speculate that in earlier years Africans had a more diverse diet, and lower population density, which favored economic development and taller people. This changed over the last two or three decades when their economies were adversely affected by global changes, ultimately affecting their heights.

Short, short Filipinos

Now to the figures for Filipinos, about which I’m afraid I have bad news that isn’t reported in the journal article itself but in the additional data from the NCD Risk Factor Collaboration site.

For the 1896 cohort of Filipino males, the average height was 154.7 cm or 60.9 inches, nearly 5 feet 1 inch.  Among 200 countries, our average height ranked us 195th. I thought immediately of Jose Rizal, who was said to be barely 5 feet, but remember he was born much earlier, in 1861. So he wasn’t really short for his time, maybe even slightly taller than the average.

Fast forward to the 1996 male cohort and the average height is 163.2 cm or 5 feet 3 inches. (Do I hear cheering?) It may seem like an impressive gain compared to the 1896 cohort, but other countries also gained, some of them literally reaching for the sky. So our 1996 male cohort improved only to 192nd in rank.

As for the women in the Philippines, for those born in 1896 the average height was a tiny 147.9 cm or 4 feet 8.2 inches.  That ranked our women 164th in the world, which meant there were many countries that had even tinier women.

Sadly, after a hundred years, the average height for our women born in 1996 still didn’t make it to 5 feet, with the average height only 149.6 cm or 4 feet 9 inches. Moreover, our rank had plummeted—to 199th. Only Guatemalan women are shorter than our women.

There are many reasons to be alarmed with the statistics, and I’m going to ask some of our scientists in nutrition and pediatrics to look at the alarming trends: Our heights are not only marked by slow progress; for women, some 20 years of cohorts, the average height actually decreased year to year.

Given current figures from Unicef (UN Children’s Fund) that show 30 percent of our children are stunted, the height studies only underscore the need to probe more deeply into a serious public health problem and how it mirrors our socioeconomic development.

Next Friday, I’ll share more figures on heights, particularly the trends over one century, and my take on what’s going on.

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mtan@inquirer.com.ph