Like most of you, I'm sure, I worry about why my toes are as long as they are. Oh sure, you can pretend you don't know what I'm talking about, but every time you take your socks off I'll bet you wistfully gaze at your stubby metatarsals and and wonder how they came to be.
Answer (maybe): we're built to run. And run. And run.
But a handful of scientists think that these ultra-marathoners are using their bodies just as our hominid forbears once did, a theory known as the endurance running hypothesis (ER). ER proponents believe that being able to run for extended lengths of time is an adapted trait, most likely for obtaining food, and was the catalyst that forced Homo erectus to evolve from its apelike ancestors. Over time, the survival of the swift-footed shaped the anatomy of modern humans, giving us a body that is difficult to explain absent a marathoning past.
We know that roughly 2 million years ago, Australopithecus, with its tiny brain, hefty jaw and diet of rough, fibrous plants, evolved into Homo erectus, our slim, long-legged ancestor with a big brain and small teeth suited for tearing into animal and fruit flesh. Such a transformation almost certainly involved a reliable supply of calorie-laden meat, yet according to the fossil record, spear points have been in use for 200,000 years at most, and the bow and arrow for only 50,000 years, leaving an enormous stretch of time when early humans were consuming meat without the use of tools. Lieberman believes they ran their prey to death, often called “persistence hunting.” [More]
If this approach is anywhere near correct, shouldn't our sedentary lifestyle be selecting for long-toed humans? In fact, could the popularity of sandals be an early indicator?