Tag Archives: height

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Humans got taller, then bulkier in ‘bursts’ during our evolution

Hominins have seen “pulses” of growth during their evolutionary history, followed by periods of “stagnation,” a new paper reports. This was the widest-scale study on the evolution of human stature and weight to date. Data was drawn from hominid fossils spanning the entire known evolutionary path of the genus. It reveals that over the last four million years, hominid stature and body mass have increased independently and at different speeds. Some extinct lineages even went through phases of shrinking.

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Image credits Igor Ovsyannykov.

The paper drew on 311 specimens dating from roughly 4.4 million years ago (the time of the earliest known upright hominid species) through to the modern humans that followed the last ice age. It’s the largest study of hominid body size evolution to date, and the authors conclude that although this was a “long and winding road with many branches and dead ends,” the overarching pattern they’ve observed is one of bursts of growth followed by millennia of ‘stagnation’.

Taller, bigger, better

Earlier hominin evolution saw a wide range of body sizes, mostly owed to the number of different species and their particular evolutionary roots. Some were broad, ‘gorilla’-like, such as Paranthropus, or slimmer and agiler, as was Australopithecus afarensis. On average, hominins from four million years ago weighed a roughly 25kg and stood at 125-130cm tall. Observing how physicality evolved over time, however, the team reports at least three major “pulses” of significant changes.

The first one occurred as our own genus, Homo, made an appearance around 2.2-1.9 million years ago. This period saw an increase in both height (of about 20 cm) and weight (of between 15-20 kg).

Stature and height further separated about 1.4 to 1.6 million years ago, following the emergence of Homo erectus. Fossil evidence shows that hominid species living around this time grew taller by roughly 10 centimeters (3.93 inches) but wouldn’t significantly gain in body mass for another million years. This is the point where a familiar stature was reached. Body mass still remained lower on average than today.

It would take roughly one million years (around 0.5 to 0.4 million years ago) before heavier hominids made a consistent appearance in the fossil record. On average, hominid species saw a body mass increase of 10-15 kgs (22-33 pounds) about 500,000 years ago. This increase in body mass likely points to an adaptation to environments north of the Mediterranean.

Height and stature chart.

A and b show weight (kg, blue) and stature (cm, green) evolution over time, by geologic period and taxa, respectively. C and d show variations (in %) for weight and stature, by geologic period and taxa, respectively.
Image credits Manuel Will, Adrián Pablos, Jay T. Stock, 2017, RSOS.

“From then onwards, average body height and weight stays more or less the same in the hominin lineage, leading ultimately to ourselves,” says lead author Dr Manuel Will from Cambridge’s Department of Archaeology, and a Research Fellow at Gonville and Caius College.

There are a couple of exceptions, as is the case for Homo naledi and Homo floresiensis, which have in fact decreased in size over time, the team reports. However, this was likely due to their evolutionary roots in smaller-bodied ancestors, or the effect of evolutionary pressures acting on isolated and small populations. Floresiensis, for example, was discovered on an Indonesian island.

“Our study shows that, other than these two species, hominins that appear after 1.4m years ago are all larger than 140cm and 40kg. This doesn’t change until human bodies diversify again in just the last few thousand years.”

“These findings suggest extremely strong selective pressures against small body sizes which shifted the evolutionary spectrum towards the larger bodies we have today.”

Sizing up to the requirements

This tall to ride.

Image via NewStorkCity.

The findings could help us better understand what early hominids were up to. Initially, hominid height and weight largely evolved “in concert,” the team adds. The latter decoupling between height and bulk were likely caused by early humans’ migration out of the forest and as an adaptation to hunting in the savannah.

“An increase solely in stature would have created a leaner physique, with long legs and narrow hips and shoulders. This may have been an adaptation to new environments and endurance hunting, as early Homo species left the forests and moved on to more arid African savannahs.” Dr Will adds.

“The higher surface-to-volume ratio of a tall, slender body would be an advantage when stalking animals for hours in the dry heat, as a larger skin area increases the capacity for the evaporation of sweat.”

Later, as these populations moved further north and ran into colder climates, the increase in bulk would make them better at fighting the cold.

“The later addition of body mass coincides with ever-increasing migrations into higher latitudes, where a bulkier body would be better suited for thermoregulation in colder Eurasian climates.”

The results also suggest cladogenesis (lineage-splitting) may have played a part in increasing the average human’s height and mass. It’s possible that inter-species competition later drove the smaller-bodied lineage extinct. Sexual dimorphism — the physical distinction between genders, with mammalian females typically smaller than males — was also more prevalent in early hominid history, the authors added, and seems have become less emphasized.

However, Will says the theory should be taken with a grain of salt. It suits the available data very well, but there are vast gaps in the fossil record that the team has had to work around, ones that may have obscured the truth. He notes that at times, the team had to work on body size estimates starting from very fragmented remains, in some cases from as little as a single toe bone.

Overall, we know certain groups of humans have continued getting taller over the last century, most likely due to improvements in nutrition and healthcare. As these keep increasing, it’s likely that the average human stature is going to keep increasing.

“However, there is certainly a ceiling set by our genes, which define our maximum potential for growth,” said co-author Dr Jay Stock, also from Cambridge’s Department of Archaeology.

The paper “Long-term patterns of body mass and stature evolution within the hominin lineage” has been published in the journal Royal Society Open Science.

What country has the tallest men

Dutch men are often regarded as the world’s tallest — at an average 183.8 cm (just over 6 feet tall), that’s no surprise. But a new study indicates that Bosnian should be even taller… except they’re not.

The variability of male height in Bosnia and Herzegovina. Image credits: Pavel Grasgruber / Royal Society.

The new study mapped geographical differences in male stature and some other anthropometric characteristics (such as sitting height and arm span) in the Balkans, finding that people from Bosnia and Herzegovina (BiH) display a large variation in average height. This variability is influenced by a number of factors including genetics and nutrition, but also race and culture.

Bosnia is a multiethnic country, and religion often influences a person’s dietary choices (such as most Muslims not eating pork and Christians fasting a few times a year). When you consider that over half the population of BiH is Muslim, and the country is one of the poorest in Europe, the variation becomes easier to understand. But the study also identified a less obvious factor which plays a role here.

Firstly, a particular genetic profile in men (called Y haplotype I-M170) is correlated with height. In the Netherlands, some 35% of all people have this gene, which is impressive, but in Herzegovina (the southern part of the country), 70% of men have the gene. This is likely a legacy of the Upper Paleolithic Gravettian culture — a culture of mammoth hunters. Yes, Bosnians and Herzegovinians are descended from ancient mammoth hunters!

“The Gravettian is the most important prehistoric culture of the Upper Paleolithic Europe and is sometimes called ‘the culture of mammoth hunters,’” lead author Pavel Grasgruber of Masaryk University told Seeker. “I suspect that this big game specialization associated with a surplus of high-quality proteins and low population density created environmental conditions leading to the selection of exceptionally tall males.”

By extrapolating existing data, the average height in that part of the country should be 1.90 cm for men — and yet the average Herzegovinian just isn’t that tall. This is where the second factor comes in: nutrition. Protein quality has a lot to do with average height, and people from BiH just don’t eat as much protein as they did during their mammoth hunting days. People from nations who eat more pork, dairy, eggs, and fish tend to be taller, while those who eat more cereal tend to be shorter. Poverty also plays a role, as people from poorer areas of the same country are also generally shorter. Another factor affecting the Bosnia and Herzegovina men could be higher calcium intake. The mountains from BiH contain limestone rocks with high mineral content, including calcium.

Together, all these point a pretty complicated picture, but the bottom line is that people in Bosnia and Herzegovina have the genes to be the tallest people in the world, but they’re just not eating enough protein to grow. So, can they ever become the tallest? Yes, just “give it 20-30 years,” Grasgruber says.

Journal ReferencePavel Grasgruber, Stevo Popović, Dominik Bokuvka, Ivan Davidović, Sylva Hřebíčková, Pavlína Ingrová, Predrag Potpara, Stipan Prce, Nikola Stračárová — The mountains of giants: an anthropometric survey of male youths in Bosnia and Herzegovina. DOI: 10.1098/rsos.161054

 

height_gene

Genes that Define How Tall You Grow Identified

It’s common knowledge that babies born out of tall parents will most likely grow to be just as tall, but it’s only recently that scientists report finding most of the genes responsible for height. Information like this could prove to be useful in diagnosing genetic growth deficiencies or, in the not so distant future, genetic manipulation to enhance growth in height.

Short and tall genes

height_gene

Researchers at the GIANT (Genetic Investigation of Anthropometric Traits) project studied the DNA of about 250,000 Europeans and more than 2 million genetic factors. Mining the data helped reveal that height is determined by the different variations in DNA sequences. From this, they identified 697 genetic variants located in 424 genetic regions that were linked to height. A while ago, ZME Science reported how men’s average height has risen by 11 centimeters since the industrial revolution. This astonishing growth was made possible through better nutrition, yet diet only accounts for a fifth of the growth spurt, the researchers report.

Surprisingly, the team also found some genes that they never would have thought would be involved in height. One of which is a gene that has always been known to be related to cell growth, but not skeletal functions.

“It’s a mix ranging from completely known things, to those that make sense to things that are completely surprising and things we don’t even know what to think about them,” said Dr. Joel Hirschhorn, the leader of the GIANT consortium at Boston Children’s Hospital, Broad Institute of MIT.

Now it is possible to make reliable genetic tests that screen for diseases that have to do with height, including osteoporosis, at a very early age. In the meantime, treatments may dampen the disease’s advance.

“It’s also a step forward towards a test that may reassure parents worried that their child is not growing as well as they’d hoped – most of these children have probably simply inherited a big batch of ‘short genes,” Hirschhorn said.

This isn’t a full, comprehensive list, though. By enhancing their database, more genes that influence height will be discovered. Even so, the GIANT team made an impressive leap forward in this field of research.

“In 2007 we published the first paper that identified the first common height gene, and we have now identified nearly 700 genetic variants that are involved in determining height,” says co-senior investigator Timothy Frayling, PhD, of the University of Exeter in the UK. “We believe that large genetic studies could yield similarly rich lists in a variety of other traits.”

Findings were reported in Nature Genetics.

men's height

Men’s height up 11 cm on average since the industrial age

men's height

A new study that surveyed through records of hundreds of thousands of men from 15 European countries found that the average height has risen by 11 centimeters since then 1870s. This remarkable surge in men’s height over the span of just four generations has been attributed to the advances in health care since, most notably antibiotics and a massive drop in infant mortality. Improved nutrition is factor that also played a determining role, according to the researchers involved in the study.

“Increases in human stature are a key indicator of improvements in the average health of populations,” said Timothy Hatton, a professor economics at Britain’s University of Essex who led the study.

Only men were surveyed since data on women were more limited. In the XIXth century and early XXth century, public records of men’s health and physical characteristics were far more abundant than those of women because of military service.

On average, men’s height had grown by 11 centimetres (cm) – from 167 cm to 178 cm –  in just over a century, the researchers found, but there were differences from country to country. Most surprising was that during the two great wars, as well as the following Great Depression, there was a significant surge in average height for a select couple of countries like  including Britain and Ireland, the Scandinavian countries, Netherlands, Austria, Belgium and Germany – times of notoriously great turmoil.

This was most surprising to learn because major advances in both medical science and medical reforms came after this period.  Long-term improvements in sanitation, hygiene and nutrition were being seen at the time and this most likely is the cause of the upsurge, the researchers report. Reduced infant mortality, which is linked with basic child health in general, also means that children were healthier at the time, than they were before. The most important period that goes on to determine much of a human’s health later on in life are the first 2.5 years according to health experts. A downward trend in fertility during this period also played an important role, as fewer children per family meant there were more resources to spare, and thus an improved nutrition.

Dr John Middleton of the UK’s Faculty of Public Health said: “Does how tall we are really tell us how healthy we are? This interesting research suggests that it’s certainly a factor.

“Increasing height is a reflection of how the availability of food and nutrition had broadly improved until the recent excesses of fat and sugar.

“However, we can’t conclude that shorter men are somehow unhealthier. Like a lot of research, this paper prompts more questions than it set out to answer.

“While our average height is a useful barometer to bear in mind, what we really need is to tackle the many reasons for poor health that we can address.

“Employment is one of the best ways to do that, which is why we need to focus on more than just diet and exercise when it comes to improving the nation’s health.”

The findings were reported in the journal  Oxford Economics Papers.