Silly Stories About Early Man

The few fossils of alleged human ancestors leave a lot of room for imagination.

We lead off with Live Science‘s super-silly headline, “Nom Nom! Paleo Diet Helped Humans Evolve Speech.” To say this right, you need to use the caveman accent: Nom nom. Meat help man evolve speak. Harvard evolutionary anthropologists used a form of torture to get their story going:

Scientists who forced volunteers to chew raw goat flesh (yes, chew) have found that such meat-gnawing likely caused human teeth and jaws to shrink throughout our evolutionary history.

Slicing raw flesh into smaller pieces and then chewing would have helped ancient hominins spend less time and energy eating than their ancestors.  These changes, in turn, might have supported the evolution of speech and language by changing human facial anatomy, scientists added.

Oh. Well if scientists said it, then—wow. They must know. It’s not Lamarckian, is this? someone whispers. PhysOrg tries a more scholarly headline: “Processing food before eating likely played key role in human evolution, study finds.” Oh. Well if a study found it, then—wow. The BBC News showed no restraint, posting “Meat eating accelerated face evolution” in large font over artwork of naked apemen scavenging a carcass.

Big brains make big bodies. Mark Grabowski at the American Museum of Natural History has a new evolutionary twist: as early man’s brain grew, it “pulled along” a body size to match. Science Daily explains his idea. This new just-so story may get him in trouble with other Darwinians. “While selection no doubt played a role in refining the physical changes that came with larger body sizes, my findings suggest it was not the driving force behind body-size evolution in our lineage,” Grabowski said. “Therefore, evolutionary models for the origins of Homo based on an adaptive increase in body size need to be reconsidered.” Will this ever happen to Grabowski’s own story? Will it need to be reconsidered? Why not now? Maybe he could explain why bigger is better. Wouldn’t there be a “driving force” to miniaturize the brain for energy cost savings, and pull the body down to a smaller, more maneuverable size? Maybe he could also describe this pulling force. Could he measure it like a good physicist?

Genes determine your virginity. This idea is making the rounds: Cambridge researchers have identified 38 genes that influence when you will lose your virginity (see Live Science and New Scientist). But so what? New Scientist comments, providing an interview with the researchers. They admit that social influences (e.g., religion, social mores) have much more influence on the age of first sex. That being the case, how can anyone measure such a moral choice in material genes? By comparison, genes for tallness may influence a 7-foot man to bump his head on doorways, but that doesn’t mean he is going to walk around with bruises all his life. And that’s an obvious case. While genes undoubtedly affect our dispositions, genes for personality type and maturity are notoriously hard to measure. An impulsive, early-maturing teen still has the capacity (and responsibility) for self-control.

Everything you know is wrong (again). This is the lament uttered after almost every new find in paleoanthropology. New Scientist gives us the latest version: “Oldest ever human genome sequence may rewrite human history.” The latest puzzles, overturns of convention, and alterations of the timeline come from a new Neanderthal genome echoed by Science Daily and Nature News. The new anomalous dates require modern humans and Neanderthals to have diverged 430,000 years ago. Odd, isn’t it, that after being so long distinct, they could still have sex and produce fertile offspring just a few tens of thousands of years ago in the evolutionary scheme? Get the full theory rescue story in Nature. More about this in Science Magazine from the usual suspects. Another Nature paper’s authors look familiar.

Neanderthal matches. It’s also odd that it took the Neanderthals 390,000 of those years to figure out how to use manganese dioxide for fire making. That’s a long science experiment for such smart hominids. PhysOrg says,

The selection and use of manganese dioxide for fire making is unknown from the ethnographic record of recent hunter gatherers. This knowledge had been lost. This unusual behaviour holds potential significance for our understanding of Neanderthal cognitive capabilities through the extent of their knowledge and insights. The actions involved in the preferential selection of a specific, non-combustible material and its use to make fire are not obvious nor intuitive. The knowledge and insights suggested by Neanderthal selection of manganese dioxide and use in fire-making are surprising and qualitatively different from the expertise commonly associated with Neanderthals.

Interestingly, whilst Neanderthals may have sourced and used manganese dioxide in fire making 50,000 years ago, manganese dioxide has important uses today in energy storage (batteries) and potentially in future clean energy production systems.

Next just-so story. Whenever you see “likely” you know the storyteller is making things up. Here’s a headline from Live Science: “Why Neanderthals Likely Fathered Few Kids with Modern Humans.” The story hinges on analysis of Y chromosome differences between Neanderthals and modern humans. Supposedly, the differences led to more miscarriages. One wonders why the parents didn’t figure out that mixed marriages were not working well. One also wonders whether the scientists considered the possibility of genomic damage in the samples over time. Problem #3: this article pushes the Neanderthal-modern split back even further, to 590,000 years, and with it, the problems of genetic incompatibility and delayed technology.

Insert miracle here. In a letter to PNAS, Ajit Varki ponders “Why are there no persisting hybrids of humans with Denisovans, Neanderthals, or anyone else?” After all, if they got together and had grandkids, one might expect some enduring lineages today. Insert miracle here, as we observe Varki’s perhapsimaybecouldness index skyrocket:

Although genomic evidence indicates interbreeding, the number of functional genes incorporated is limited, resulting in a “leaky replacement”, without persistence of true hybrids. Thus, our single BMH [behaviorally modern human] (sub)species was the “winner” in every contact/replacement event, spanning tens of thousands of years. I cannot find any other example wherein a single (sub)species from one geographic origin completely replaced all extant cross-fertile (sub)species in every planetary location, with limited introgression of functional genetic material from replaced taxa, and leaving no hybrid species. Typically, one instead finds multiple cross-fertile (sub)species, with hybrid zones in between.

Although this apparent one-of-a-kind phenomenon could have occurred by chance, the singularity allows one to posit a uniquely complex genetic/biological/cultural transition of BMHs. As Pääbo suggested, adaptive accumulation of an “explosive constellation” of genetic variants (alleles) could have endowed BMHs with an unparalleled combination of cognitive features, guaranteeing success at every subsequent encounter with other hominins.

Unique happenstances are generally frowned on in scientific explanations. They lead to embarrassing admissions such as, “This explanation works, except when it doesn’t.” Varki’s particular miracle also runs afoul of political correctness:

Such “human exceptionalism” is currently frowned upon, as are extraordinary explanations of evolutionary events. However, unless there are other clear examples of such complete replacement of all related taxa by one single (sub)species, BMHs may indeed be a rare exception.

Varki is not done with miracle stories yet. He’s got a lottery encore. The scenario “suggests an improbable BMH transition through a long-standing “psychological evolutionary barrier”–– possibly involving initially maladaptive features such as reality denial and mortality salience, which conspired to generate the winning combination.” Ummm… “reality denial.” Interesting choice of words.

The Hobbit. Along with older dates for the extinction of so-called Homo floresiensis (see BBC News) come a flurry of new stories. The revised date (50,000 years instead of 12,000) is closer to the alleged arrival of modern humans in their Indonesian territory. Aha! This must mean that those mean modern humans are responsible! Altogether now: one, two, three, four,

• Did humans drive ‘hobbit’ species to extinction? (Ewen Callaway in Nature)
• Did Modern Humans Wipe Out the ‘Hobbits’? (Adam Hoffman in National Geographic)
• Did hobbits live alongside modern humans? (Charles Q. Choi in Live Science)
• Indonesian ‘Hobbits’ may have died out sooner than thought (Science Daily)

Below its artwork contrived to make the naked hobbits look as ape-like as possible, the BBC quotes an Australian anthropologist about the earlier “head-scratcher” situation, i.e., “how it was possible for floresiensis to survive for 30,000 to 40,000 years after modern humans are believed to have passed through Indonesia.” Turn on your Aussie dialogue: “Well, it now seems we weren’t living alongside this little species for very long, if at all [mate]. And once again it smells of modern humans having a role in the downfall of yet another species.” Here’s how it works. You get the blame even though you weren’t there. Why? You’re a member of a privileged class. Even though you love The Hobbit, your race caused their downfall along with many species, so you must bear the guilt. Pay up those reparations! “But to whom? They’re all gone,” you protest. That’s been pre-arranged. You must pay in the form of higher taxes to fund evolutionary anthropologists so that they can continue their storytelling.

Now that we’ve shown how to respond to silly stories, try your hand at these others:

• Australopithecus fossils found east of the Great Rift Valley: New remains demonstrate early hominid’s adaptability (Science Daily)
• A world map of Neanderthal and Denisovan ancestry in modern humans (Science Daily)
• Five matings for moderns, Neandertals (Ann Gibbons in Nature)
• How extinct humans left their mark on us (BBC News)
• Ancient DNA identifies ‘early Neanderthals’ (BBC News)
• Asian stone tools hint humans left Africa earlier than thought (New Scientist)
• When humans split from the apes (PhysOrg)