Climate Change Caused Mammal Dwarfing: Would Humans Shrink As Well?


Global warming has been a cause for concern for quite a while and everyone, from governments to citizens of a country, is concerned about the implications of climate change. Apparently, global warming along with climate change can affect the size of an animal considerably.

According to a new study, nearly 50 million years ago, when the Earth suddenly heated up, three species of mammals shrank considerably. This phenomenon can occur once again according to the researchers and this time, it can affect humans as well.

The Study

Based on the analysis of fossil teeth dated 54 million years old, due to the sudden heating of the planet, an early compact horse reportedly decreased in size by 14 percent, from 17 pounds to 14.6 pounds.

The study suggests that with the increase in global warming, mammals are expected to shrink more rapidly. Two of the group of species discovered during the study showed prominent shrinkage.

Professor Philip Gingerich, the co-author of the study, claimed that if Earth continues to experience the same temperature change, the day is not far when even humans may decrease in size.

However, since humans are placed high on the food chain, the result will be comparatively less severe as compared with those of animals. Dwarfing affects herbivorous animals more when compared with carnivorous mammals.

Abigaill Carroll, the lead author of the study, however, believes that global warming effects won't actually have any impact on the size of humans.

'We, as humans, are very good at controlling the environment around us. We're good at finding ways or seeking shelter to cool off, whether using air conditioning when it's hot, or simply packing up and moving to a cooler place," said Carroll to MailOnline.

According to Carroll, since humans are really good in finding places or shelters to cool themselves, as well as stay under air conditioners during the summers, the dwarfism terror may have lesser effect on them when compared to animals. Why? As animals have supposedly lesser control over their surrounding environments.

Factors That May Have Caused Animal Dwarfism

Climatic changes are known to affect both plants and animals in a way which are rather impossible to fathom.

Both the authors listed some possible reasons behind the triggering of dwarfism in animals. They state that lack in availability of food, due to the changing climate of the region, may have forced animals to evolve into smaller sizes. This change would have enabled them to consume less food.


During the Paleocene-Eocene Thermal Maximum (PETM), which took place about 55 million years ago, mammals like primates, as well as other groups which include horses, were said to have decreased in size during the bout of sudden heat on Earth.

The second wave of global warming took place 53.7 million years ago and is known as the Eocene Thermal Maximum 2 (ETM2). To get a clear idea about the maximum impact of global warming on the size of mammals, the researchers analyzed various animal fossils from the time period to make a comparative study regarding body sizes.

Fossils of Arenahippus pernix, an ancestor of horse, teeth from Diacodexis metsiacus — an ancient rabbit — among many others were taken for examination and analysis.

It was then found that A. pernix and D. metsiacus displayed a significant change in size during those two global warming waves. During ETM2, the body size of A. pernix shrank about 14 percent in comparison to a drastic change in the body size of Sifrhippus, another ancient horse relative, by 30 percent during PETM.

Photo: NASA Goddard Space Flight Center | Flickr

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