A simple question deserves a simple answer. How many cells are in your body?

Unfortunately, your cells can’t fill out census forms, so they can’t tell you themselves. And while it’s easy enough to look through a microscope and count off certain types of cells, this method isn’t practical either. Some types of cells are easy to spot, while others–such as tangled neurons–weave themselves up into obscurity. Even if you could count ten cells each second, it would take you tens of thousands of years to finish counting. Plus, there would be certain logistical problems you’d encounter along the way to counting all the cells in your body–for example, chopping your own body up into tiny patches for microscopic viewing.

For now, the best we can hope for is a study published recenty in Annals of Human Biology, entitled, with admirable clarity, “An Estimation of the Number of Cells in the Human Body.”

Continue reading “How Many Cells Are In Your Body?” →

Mimicry is one of the eeriest feats of evolution. An insect doesn’t know what a leaf looks like, and yet some species have evolved to resemble leaves down to the finest details. Their mimicry emerges from the ruthless cycle of evolution. The ancestors of leaf insects produced lots of genetic variation, thanks to mutations and mating. Some of that variation affected how they looked. Birds have been feasting on the insects for millions of years, and their victims have tended to be the easiest ones for them to see against their leafy background. The insects that were harder tended to survive and reproduce. Over time, evolution acted like a sculptor, turning an ordinary insect body into a shape that blended in with the surrounding leaves.

But the mimicry of leaf insects, as cool as it may be, is simple stuff compared to what’s evolved in other species. Continue reading “Nature’s Double Con” →