All posts by Inês Varela-Silva

About Inês Varela-Silva

Human Biologist. Interested in health and wellbeing. Zumba addicted. Theatre enthusiast. Arts' lover. Lover of life...

Notes on engaging Biosciences’ students during lectures

This is all Patrick Clarkin’s fault!

Last year, in one of his modules (in the US they’re called “courses”), Patrick organized his students in groups. He named each group after a Human Biologist or a Biological Anthropologist, and he challenged his students to learn as much as possible about the scientists that gave name to their groups.

His students also had to do class exercises that were formatively assessed, graded, and given a certain amount of points. By actively participating in the activities during lectures, students would aim to get the highest possible amount of points for their scientists. It was a system similar to the one used in Hogwarts – with no magic wands or invisibility cloaks, but equally cool.

I was one of the researchers included in Patrick’s list. When he told me about it I felt, of course, very honoured. I also thought this was a great idea for me to try with my Part A (first year) students.

We are on our first week of teaching and I have just launched the “My Scientist” scheme, among Loughborough University students attending the module “Data Analysis and Study Skills”. This module includes students from three programmes: Human Biology, Biological Sciences, and Biochemistry. It was challenging to organize class activities with the potential to equally motivate students in all programmes and that’s where the “My Scientist” scheme turned out to be very helpful. The choice of the scientists took a while to be fully done. Many amazing colleagues were not included because there were only 10 groups to be named after but, if this scheme proves successful, there will be another round next year and more awesome people will be included.

I aimed for a group of researchers that would be equally relevant for students in all programmes, and as diverse as possible. After careful consideration, this was the final list for this academic year:

Starting next week, students will work in groups and, in some occasions, will answer questions using the electronic voting system Meetoo. They will connect with the system using their scientist’s last name. Scores will be given by group, and individual anonymity will be preserved. Hopefully, this will promote group discussion and allow for greater participation in class. Furthermore, students will have to go through three stages during the “My Scientist” scheme, according to the following guidelines:

Stage 1 (weeks 1-7). Find the following:

  • Details of your scientist current academic/scientific post
  • Their main area(s) of research
  • A photo (to show on lecture 2)
  • Their career trajectory
  • One publication
  • One detail that is NOT on their institutional website
  • Their social media presence

Stage 2 (weeks 8-10). Aggregate this information in one or two sentences and be ready to read it in class. I’m hoping this will generate further discussion and more interaction among students.

Stage 3 (week 11). Summarize your scientist in a tweet. We hope it goes viral!

To be continued (hopefully)…

A stunted note on stunting


This is a stunted note on stunting. The photo above shows a group of bike riders going through a Maya village in Guatemala. On the left side of the photo is a Maya family. Note the differences in body size. The bikers are not giants. The Maya are not genetically short. Their very short stature reflects the poor living conditions, systemic hardship, and ingrained racism and segregation. For more on the Maya health and height see HERE. For more on the non-genetic basis of the height of the Maya see HERE.

Stunting is defined by the World Health Organization as a very short height-for-age. Stunting is an indicator of chronic malnutrition and if not curbed early in life will cause lifelong physical and cognitive impairments.

This photo will be included in the Maya Project eBook which will be released in April 2018. Stay tuned.



Inspiration of the Day

Thanks Patrick. We need more of this news. You have just made my day.

Patrick F. Clarkin, Ph.D.

Don’t let anyone tell you that there is nothing more to humanity than aggression and destruction.

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The health of the Maya people in Mesoamerica: what do we know?


“The Maya people descend from the indigenous inhabitants of southeastern Mexico, Guatemala, Belize, San Salvador, and Honduras. They are the largest Native American group (6-7 million people) and show the shortest average height of any non-pygmy human population” (1: 679).

The Maya carry a long legacy of political, educational, and socioeconomic deprivation that feeds racism and perpetuates a livelihood of poverty. These socio-political aspects negatively impact on the health of the Maya and bring about further cycles of adverse outcomes. I use a biocultural approach (2) on my research and include inputs from the Maya communities when defining research designs. This post summarises most of the research conducted by my research team. It is not a systematic review of the literature on the health of the Maya, but I hope it becomes a useful resource as a starting point for further research. This is a live post, I welcome comments and suggestions for improvement, and I will be adding information when relevant.

Physical growth

The measurement of physical growth and the accurate measurement of stature and other long bones – such as limb length – are powerful reflexions of the social, political, and moral conditions of a society. James Tanner (b1920-d2010) coined the expression “growth as a mirror of the human condition” and stated that:

“ the growth of children (…) is a wonderfully good gauge of living conditions and the relative prosperity of different groups in a population” (3:96)

Height has been used extensively as an economic variable that reflects health and human capital, especially when other economic indicators are not available.

I started this post with a quote from our most recent paper (1), stating that the Maya are, on average, the shortest non-pigmy people in the world. Being “non-pygmy”, in this context, is an important factor because it means that there are not any known genomic and/or hormonal factors that code for the Maya short stature. However, for a long time, they were considered the “pygmies” of Latin America” (4) . This was damaging because it assumed that being so short was “genetic” and “adaptive”, that everything was fine with this group of people, and nothing needed to change. However, our research showed that, when the Maya started migrating to the US, and benefited from clean drinking water, basic health care, much lower rates of infection load, extended education, enough food, and a peaceful environment, the average stature of the school children increased almost 11cm, in less than one decade. From these, 7cm were due to the increase in the relative length of the legs, in proportion to total stature (5). Genetic/genomic expressions do not change in such a brief period of time, therefore, all evidence suggest that the short stature of the Maya is due to a combination of environmental and epigenetic factors.


I must emphasize, here and now, that no human group “adapts” to poverty, segregation, racism, deprivation, infection, heavy workloads, and shortage of nutrients. They all suffer and many die. The ones who survive to adulthood, do so at the expense of their health and productivity, in some way or other. These are trade-offs that may maximize survival but come at a cost that, sooner or later, will be painfully paid with interest (6).

Very short stature-for-age, or stunting, is an indicator of chronic undernutrition and has long lasting health implications (7). Stunting is usually defined as the individual’s height-for-age being below the 5th percentile of the references, although slightly different cut-off points can be used (8). This makes stunting a sort of moving target. Depending what references and what cut-off points are used, a stunted child may or may not be classified as such. Stunting affects all body systems and, if not curbed early in life, will leave permanent and damaging physical, cognitive, and developmental traits.

In his paper “Nutritional status and physical work capacity”, Spurr (9) summarizes the effects of stunting on physical work capacity, maximal oxygen consumption, aerobic power, heart rate response to exercise, and endurance at submaximal work loads. Other studies have shown that no body system is spared of the nefarious consequences of stunting and that the longer it lingers, the worse the outcomes will be (10-12).

High levels of stunting have been consistently reported, for more than two decades, among the Maya in Belize (13-15), Guatemala (16-19), and Mexico (20-21). Fast and steep increases in height and leg-length, among the Maya migrants to the US, have been mentioned already in this post (5) but this positive outcome needs to be addressed in the context of the whole physical and health changes that characterize this group. Increments in height were accompanied by even steeper increments in weight, and body-mass-index (BMI) (22). The height of the Maya-American children averaged at the 25th percentile of the height of the US children, but their weight and BMI averaged at the 85th percentile. In summary, although the average height of these Maya-American children increased, and the percentage of stunted children decreased, they were still significantly shorter, but much heavier, than the references.

The nutritional dual-burden paradox

The nutritional dual-burden is defined as the coexistence of stunting and overweight/obesity in the same person (individual dual-burden), in the same household (stunted child, overweight/obese mother), or within the same population (8,23,24).

Nutritional dual-burden at the individual level is not common among Maya children, but is frequent among Maya adults, who tend to be very short and very fat. This means that they were stunted children who grew up to become stunted, overweight/obese adults, and accumulate in their bodies the negative effects of both of these conditions (25). Nutritional dual-burdened adult individuals, and specially women, are at higher risk of producing offspring who will also be stunted and, therefore, will perpetuate the short-and-fat legacy throughout generations. This is a non-genomic mechanism that may lead to low birth weight and elevated cardiovascular risk in the subsequent generations (26).

Intergenerational effects of stunting on health and disease

The intergenerational influences hypothesis (IIH) was proposed by Irving Emanuel (27:35) as, ‘‘… those factors, conditions, exposures and environments experienced by one generation that relate to the health, growth and development of the next generation.’’ The IIH has been further discussed elsewhere (26, 28–30), and put in perspective with related concepts such as “foetal programming”, “life history trade-offs”, and developmental origins of health and disease (DOHaD) (6,31–36). We have tested the IIH with the Maya communities and found out that Maya-Mexican children with a stunted mother were more likely to be stunted by 4-6 years of age (30). Also, in another Maya-Mexican three-generational sample, stunting in children was directly associated with the short stature of the mothers; and the children’s levels of fatness were also directly associated with the short stature of the mothers and the maternal grandmothers (20,37).

Stunting, muscle mass, and energy expenditure

Associations between stunting, body composition, and energy expenditure (or work capacity) have been studied for decades, showing that stunted individuals have less muscle, and much less energy for voluntary physical activity (9,11,12,38,39). In the last 10 years, this area of research has benefited considerably due to the commercialisation of accurate portable technology that allows free-living assessment of all components of energy expenditure, metabolism, and respiratory and cardiac function. Usually, the sample sizes are small and the studies tend to focus on only one or two parameters, making it difficult to establish more complex associations.

We conducted a study with a sample of 37 Maya-Mexican children and found that a lower height-for-age z-score, as a continuous variable (but not stunting as a categorical variable) significantly predicted lower activity energy expenditure (40). This study was innovative because the children wore a combined heart-rate and uni-axial accelerometer for 7 days (The Actiheart), but it was challenging because the device, when used in the field, performed differently than under laboratorial conditions (41), and required a much greater deal of maintenance than initially predicted. The continuous advance of portable, wearable technology, for the estimation of energy expenditure and other physiological parameters, is promising. This line of research must be pursued to further disentangle the associations between stunting, energy expenditure, body composition, and other health outcomes. The state of Yucatan has one of the highest rates of childhood stunting and, at the same time, the highest mortality rates for diabetes, cardiovascular diseases and stroke in Mexico as a whole. Among these, the Maya – being the poorest of the poor – tend to suffer more than the rest of the population (42).

Nutrition and globalization

The nutritional patterns of the Maya, in the last 20 years, have moved away from a diet high in fibre, vegetables, and pulses to a globalised diet with a very high content of salt, sugar, fat, processed foods, and carbonated beverages. In a study conducted in 2013 (43) the most common diet among the Maya in Mexico was characterized by a low consumption of fruits and vegetables, a medium consumption of pork, eggs, oil and lard, and a high consumption of soda and whole milk. The Maya health and culture has deteriorated as a result of this nutritional transition which is affecting the physical growth and health of the Maya families. The summary illustrates clearly the shifts in food consumption, and emphasises the role of globalization in the exacerbation of negative health outcomes among the Maya (44).

A photo that summarizes it all

The photo below was taken in 2010, in the Colonia San Jose Tecoh, Merida, Yucatan, Mexico. I am with a Maya grandmother and her 8 year old granddaughter. In this photo, I am the tallest person which is very unusual for me, because I am only 159cm (5ft 1inches). This photo illustrates the height gap of the Maya much better than any written description. Therefore, I will say no more!



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