Man Is But A Worm proclaimed a famous Punch cartoon lampooning Charles Darwin’s On the Origin of Species. While humans are of course more complex than worms, a recent find has underscored the fact that hominins have been molded by the same evolutionary forces that shaped what the Victorians would’ve called lower species into Alice-in-Wonderland morphs.
A couple of weeks ago, researchers announced a long-awaited new discovery on the Indonesian island of Flores. If you’re a paleontology nerd like me, I had you at Flores.
Yes, that’s right, this post is about the hobbits. Or, more precisely, about what Homo floresiensis reveals about hominin evolution.
If you are such an evolution geek, you couldn’t get enough of the news of the hobbits’ discovery in 2003. And if you also happen to be a science fiction/fantasy nerd, you had to love the species’ Tolkienian nickname.
Of course, you have to guard against wishful thinking in science. I prepared myself to be disappointed. At first, it looked like the arguments that the hobbits were merely deformed modern humans were gaining the upper hand. They had Down Syndrome or were microcephalic, for instance. But both theories have since been meticulously countered by careful analysis, including as recently as June 8 (see above links).
The recent Flores finds, however fragmentary, seem to have put a nail in the coffin of the deformity hypothesis. Can a fragment of a jaw and some teeth really justify such a claim? They can when the represent three individuals who lived 700,000 years ago…and were even smaller than the hobbits discovered in Liang Bua cave.
The original hobbit finds were about 50-60,000 years old. The oldest tools found on Flores are a million years old, meaning that it took a mere (in evolutionary terms) 300,000 years for the hobbits’ Homo erectus ancestors (or quite possibly an unknown pre-erectus species) to dwindle, Shrinky-Dink-like, to a child-sized 3 ½ feet.
Foster’s rule, or the island effect, states that species tend to either get smaller or larger on islands. It’s what made Darwin’s Galapagos tortoise grow so gigantic and the pygmy mammoths on the Channel Islands shrink to the point where an average-size man could see over its shoulders.
While I’m far from an average-size woman, it certainly didn’t take an island to make me five feet tall. And, no, it wasn’t because I didn’t eat my vegetables. But barely getting enough to eat over millennia on islands can make species shrink to allow them to make due with the relatively meager resources their isolated home provides. Small fries like me would have had a major survival advantage in such conditions. And, it seems, natural selection was able to work its wonders in a remarkably short period of time on Flores.
See also: Message from a Time Before Creation.
The hobbits were far from the only dwarfed species on Flores. Indeed, they hunted the island’s own pygmy pachyderm, the dwarf stegodon. The island also sported examples of the other form of Foster’s rule–gigantism. It has been speculated (without evidence) that the nearly 6-foot-tall storks of Flores might have feasted on juvenile hobbits. (Thank goodness Big Bird isn’t a carnivore!)
Homo floresiensis also shared the island with komodo dragons and rodents of unusual size (namely, giant rats). What, I’m not going to make that joke? My geek credentials would’ve been revoked!
It annoys me to no end when I read references to continuing evolution in modern humans. They always bring up a few examples dating to the Neolithic Revolution, no later than 5000 years ago. No, I’m not bitter that lactose tolerance didn’t make it to my ancestors. The fact is, except around the margins (immunity, genetic drift, etc.) Homo sapiens circumvent environmental pressures instead of adapting to them. My lactose intolerance is a case in point. I take lactase supplements and drink lactose-free milk.
We didn’t grow faster legs to chase down game; we made atlatls to throw our spears harder and straighter. During the last ice age, we didn’t evolve thick coats of fur; we developed tailored clothing. Instead of combatting Global Warming, we put our heads in the oil sands. Oops, bad example.
But when the earth’s climate continues to heat up because we didn’t act fast enough, is there any doubt that we will adapt our technology and not our bodies? Still, the latest hobbit finds on Flores give us a peek at a time when our genus was shaped by the forces of nature, instead of the other way around.