Body Diversity Threatens to Undermine Paleoanthropology
People don’t all look the same today; body types vary tremendously. Why should we assume differently about the past?
You give it a name, say, Homo erectus, and the mind pigeonholes it into a category. All H. erectus are supposed to fit. But then reality hits; the boundaries between the pigeonholes are fuzzy, and may overlap. It becomes harder to pigeonhole each new fossil. Are the boundaries real? Are we deceiving ourselves with our own classification scheme?
This report should reverberate like thunder to paleoanthropologists: “Earliest humans had diverse range of body types, just as we do today.” That’s a press release from the University of Cambridge talking. The increasing realization that ancient humans don’t look like clones of each other threatens to unravel many assumptions about human ancestry.
It should be obvious. Look at people today. Some are tall, some are short. Some are fat, some are skinny. Some are big-boned, others are scrawny. Yet we are all Homo sapiens – all one big happy family. If our bones were fossils to future paleoanthropologists, what’s the chance they would classify us into a number of different species? There are traits in common, to be sure; jaw shapes, tooth types, wrist bones, ratios of legs to arms, etc. But who decides what traits are significant for classification? Are today’s paleoanthropologists really carving nature at its joints, or fooling themselves with their own made-up schemes?
Let’s have the Cambridge guys weigh in:
One of the dominant theories of our evolution is that our genus, Homo, evolved from small-bodied early humans to become the taller, heavier and longer legged Homo erectus that was able to migrate beyond Africa and colonise Eurasia. While we know that small-bodied Homo erectus – averaging less than five foot (152cm) and under 50kg – were living in Georgia in southern Europe by 1.77 million years ago, the timing and geographic origin of the larger body size that we associate with modern humans has, until now, remained unresolved.
But a joint study by researchers at the Universities of Cambridge and Tübingen (Germany), published today in the Journal of Human Evolution, has now shown that the main increase in body size occurred tens of thousands of years after Homo erectus left Africa, and primarily in the Koobi Fora region of Kenya. According to Manuel Will, a co-author of the study from the Department of Early Prehistory and Quaternary Ecology at Tübingen, “the evolution of larger bodies and longer legs can thus no longer be assumed to be the main driving factor behind the earliest excursions of our genus to Eurasia”.
Researchers say the results from a new research method, using tiny fragments of fossil to estimate our earliest ancestors’ height and body mass, also point to the huge diversity in body size we see in humans today emerging much earlier than previously thought.
They are not questioning the classifications. But their warnings have deep implications. Right off the bat, we see that they have subdivided Homo erectus into “small bodied” and “large bodied” groups, but then, those groups have misled them. They can’t assume that longer legs were a “driving factor” in their migration. More importantly, they failed to recognize the “huge diversity in body size” that existed “much earlier than previously thought.” What else have they missed? The light has come on for Cambridge prof Jay Stock:
“It’s possible to interpret our findings as showing that there were either multiple species of early human, such as Homo habilis, Homo ergaster and Homo rudolfensis, or one highly diverse species. This fits well with recent cranial evidence for tremendous diversity among early members of the genus Homo.”
“If someone asked you ‘are modern humans 6 foot tall and 70kg?’ you’d say ‘well some are, but many people aren’t,’ and what we’re starting to show is that this diversification happened really early in human evolution,” said Stock.
Here we are, in 2015, decades after these classifications were standardized and printed in textbooks, and now all those pigeonholes have possibly collapsed into one (see 10/18/13). If it took that long to recognize morphological diversity in Homo, why not recognize it in Australopithecus? After all, look at the diversity in Canis, the domestic dog. Imagine the fun a future paleontologist could have classifying the bones in a pet cemetery.
Stock delivers a coup-de-grace without realizing it:
“Basically every textbook on human evolution gives the perspective that one lineage of humans evolved larger bodies before spreading beyond Africa. But the evidence for this story about our origins and the dispersal out of Africa just no longer really fits,” said Stock. “The first clues came from the site of Dmanisi in Georgia where fossils of really small-bodied people date to 1.77 million years ago. This has been known for several years, but we now know that consistently larger body size evolved in Eastern Africa after 1.7 million years ago, in the Koobi Fora region of Kenya.”
“We tend to simplify our interpretations because the fossil record is patchy and we have to explain it in some way. But revealing the diversity that exists is just as important as those broad, sweeping explanations.”
The rest of the article, though, shows that he still believes in human evolution. He should know better than to ever say, “we now know”.
Being the case that all Homo are one, it’s silly for reporters and explorers to keep using “Neanderthal” as if it represents a distinction with a difference. Some recent examples of theory inertia:
- Did dog-human alliance drive out the Neanderthals? (Nat Geo)
- Did a volcanic cataclysm 40,000 years ago trigger the final demise of the Neanderthals? (Geological Society of America)
- Neandertals modified white-tailed eagle claws 130,000 years ago (PhysOrg, Live Science, Nature)
Substitute “human being” for Neanderthal and the silliness becomes apparent immediately. Groups of people have flourished, perished, and made artistic trinkets throughout history. What does that imply about human evolution? Absolutely nothing.
With the collapse of evolutionary paleoanthropology in progress, it would be superfluous to point out other kinds of silliness. But we will:
- Men’s preference for certain body types has evolutionary roots: “Prehistoric and evolutionary influences appear to shape men’s expressed preference for women with a curvy backside” (Science Daily)
- Beards as badges of honor? “In a paper published online in Evolution and Human Behavior, Dr Grueter and his colleagues investigate the hypothesis that in big, multilevel societies, male primates have developed more ostentatious ‘ornaments’ or ‘badges’ (PhysOrg)
They might as well say that “prehistoric and evolutionary influences appear to shape paleoanthropologists preference for pigeonholing other humans into imaginary categories.”
What a sorry lot these paleoanthropologists are. They’re the latest instantiation of the old fable, The Blind Men and the Elephant. To see the elephant as it is, read Genesis. It stands like an unshakeable sundial, strong and steadfast amidst a sea of collapsing evolutionary quicksand.