The Hillocks of Hiss might sound like a location from Lord of the Rings, but in fact they are a feature of the human embryo.
Six swellings of tissue begin to appear around week five and eventually coalesce to become our outer ear.
The human embryo is not a thing of beauty but it contains many clues to our evolutionary history. We will return to evidence from embryology a few more times later in this series.
In approximately 10% of the population a defect occurs at the junction of the fourth and fifth hillock. This results in a node of cartilage on the helix of the ear. Charles Darwin noted this vestigial feature in his "origin of Species" and so it has come to be known as Darwin's Point or Tubercle.
Combined with our three auricularis muscles that allow 10-20% of people to wiggle their ears, Darwin's Tubercle is another example of a vestigial feature that shows our relationship to our primate cousins.
Evolution is a Fact - Index #1-20
Evolution is a Fact #21 - Footprints in the Sand
Footprints at Laetoli show our Australopithecus afarensis ancestors were bipedal 3.6 million years ago.
