A new study reveals that the body size of mammals has shrunk dramatically during at least 2 past global warming periods. Scientists from the University of Michigan suggest that a similar occurrence will take place due to man-made global warming as well. According to data, global warming has "shrunk" mammals twice already.
The fact, that during the period of warming 55 million years ago (the Paleocene–Eocene Thermal Maximum) primates and groups of animals, such as horses and deer became much smaller, has been known for years.
The paleontologist Philip Gingerich and his colleagues have discovered evidence for the same phenomenon in a much more short-lived warming, which occurred 2 million years later.
The scientists are convinced in their discovery, since this has already happened not once, but twice. They clearly see a cause-and-effect and that one fascinating result of past global warming has been the significant reduction in the body size in mammals.
The Paleocene–Eocene Thermal Maximum lasted 160 000 years. Global temperatures during this time increased from between 41 and 46.5 °F (5 and 8 °C). The second warming, registered by scientists, was shorter - between 80 000 and 100 000 years. Then, temperatures rose by approximately 37.5 °F (3 °C).
Teeth and jaw fossils of primates and ungulate mammals, living during that period, have been found in the Bighorn Basin plateau. They have been used to estimate the body size of the specimens.
Results showed that the mammals became smaller in the studied period, but not as much as during the Paleocene–Eocene Thermal Maximum.
It has been learned that a species of horse ancestor has had a 19% body size reduction, for example. During the last big global warming, this indicator was 30%.
The scientists believe that their research will be of great import, considering current global warming. The discovered interrelationship between mammals' body size and global warming in the geological past will help us predict ecological changes, resulting from the current climate change on Earth.
