Photo credit: The Meta
The first person to describe red blood cells was the young Dutch biologist Jan Swammerdam, who had used an early microscope in 1658 to study the blood of a frog. Unaware of this work, Anton van Leeuwenhoek provided another microscopic description in 1674, this time providing a more precise description of red blood cells, even approximating their size, "25,000 times smaller than a fine grain of sand". Here's what a single red blood cell looks like balanced on the head of a pin. Click here to view the first image in this week's WINS gallery. Continue reading for a viral video of a man who wrestles a grizzly bear in his own garden.