We may grow tall, ever wondered if our body will diminish in size. The only time this is possible is when we get old. However, scientists say this is not the only reason why we could shrink.
Global warming could be a big contributor to it. Known as hyperthermal, it can cause mammals to shrink in size.
A new study unveils the underlying effects of current human-caused climate change. More than 50 million years ago, when the Earth experienced a series of extreme global warming events, early mammals responded by shrinking in size, researchers said.
‘We know that during the largest of these hyperthermal, known as the Paleocene-Eocene Thermal Maximum (PETM) temperatures rose and some mammals shrank by 30 per cent over time, so we wanted to see if this pattern repeated during other warming events,’ said Abigail D’Ambrosia, a doctoral student at University of New Hampshire in the US.
‘The hope is that it would help us learn more about the possible effects of today’s global warming,’ said D’Ambrosia. Researchers collected teeth and jaw fragments in the fossil-rich Bighorn Basin region of Wyoming.
Their focus was on several early mammals including Arenahippus, an early horse the size of a small dog, and Diacodexis, a rabbit-sized predecessor to hoofed mammals. Using the size of the molar teeth as a proxy for body size, the researchers found a statistically significant decrease in the body size of these mammals’ during a second, smaller, hyperthermal, called the ETM2.
Arenahippus decreased by about 14 percent in size, and the Diacodexis by about 15 per cent. ‘We found evidence of mammalian dwarfism during this second hyperthermal, however it was less extreme than during the PETM,’ said D’Ambrosia.
‘During ETM2 temperatures only rose an estimated five degrees and it was shorter only lasting 80,000 to 100,000 years, about half as long as the larger PETM,’ she said.
Researchers propose that the body change could have been an evolutionary response to create a more efficient way to reduce body heat. A smaller body size would allow the animals to cool down faster. Nutrient availability and quality in plants may have also played a role.