If any of you read National Geographic News or follow them on Facebook you might have recently seen something about the California Dwarf Fox coming back from the brink of extinction. The drastic increase in numbers over the last nine years has been staggering. While this is all well and good what really caught my attention was the idea of island dwarfism, something I have been fascinated with since I was a little girl.
Yeah, I was a weird child. I wanted toy dinosaurs instead of barbies. I loved dinosaurs. I will admit that my fascination with dinosaurs has faded, but I still love a good Discovery dinosaur movie as much as I did when I was seven. One that really sticks out in my memory is one about these tiny dinosaurs that were almost miniature versions of larger ones that lived on the mainland.
See, these little dinosaurs had floated over on a log or bunch of brush during a storm or earth quake. But they weren’t little dinos when they arrived. Over the generations they became smaller and smaller to fit their new found island home. There is a rule known as Foster’s rule which states that members of a species get smaller or larger depending on the resources available in the environment. Species that have shrunk once being stuck on island include mammoths, deer, snakes and even humans!
The pygmy mammoth was descended from the Columbian mammoth and inhabited several of the northern Channel Islands of California. These mammoths measured at about 5 and a half feet (1.72 meters) tall and are thought to weigh an average of 1,700 pounds (760 kilograms). This may not sound ‘dwarf’ to many people, but they were quite tiny compared to their mainland cousins who stood 14 feet (4.3 meters) tall and weighed over 20,000 pounds (9,100 kilograms). It is thought that the mammoths ended up on the island by swimming the 4 miles to the islands from the mainland, and over the generations evolved to be increasingly smaller.
Homo floresienses lived roughly 13,000 years ago on an Indonesian island called Flores. These tiny humans lived with the island dwarfism affected pygmy elephants of Indonesia and stood no taller than the average three year old human. There is some speculation as to whether or not the female skeleton found had a disease that caused her to be so little, as she is the only specimen that has been found. However she seems to have been relatively healthy at the time of her death. Not to mention that she stood 3.3 feet (1 meter) tall and weighed 55 pounds (25 kilograms) with a skull the size of a grapefruit.
She is not only an exciting specimen, but it means that she was walking around, bipedal, and using tools at the same time as modern humans. That is insane. The Flores people lived on the island from roughly 95,000 years ago until the time they died out about 13,000 years ago. Talk about convergent evolution! Wow this stuff excites me.