Modern Humans, Not Neanderthals, May Be Evolution's 'Odd Man Out'

Contact: Neil Schoenherr
nschoenherr@wustl.edu
314-935-5235
Washington University in St. Louis

Could it be that in the great evolutionary "family tree," it is we Modern Humans, not the brow-ridged, large-nosed Neandertals, who are the odd uncle out?

New research published in the August, 2006 journal Current Anthropology by Neandertal and early modern human expert, Erik Trinkaus, professor of anthropology at Washington University in St. Louis, suggests that rather than the standard straight line from chimps to early humans to us with Neandertals off on a side graph, it's equally valid, perhaps more valid based on what the fossils tell us, that the straight line should be from the common ancestor to the Neandertals, and the Modern Humans should be the branch off that.

Trinkaus has spent years examining the fossil record and began to realize that maybe researchers have been looking at our ancient ancestors the wrong way.

Trinkaus combed through the fossil record, identifying traits which seemed to be genetic markers – those not greatly influenced by environment, life ways and wear and tear. He was careful to examine traits that appear to be largely independent of each other to avoid redundancy.

"I wanted to see to what extent Neandertals are derived, that is distinct, from the ancestral form. I also wanted to see the extent to which modern humans are derived relative to the ancestral form," Trinkaus says. "What I came up with is that modern humans have about twice as many uniquely derived traits than do the Neandertals."

"In the broader sweep of human evolution," says Trinkaus, "the more unusual group is not Neandertals, whom we tend to look at as strange, weird and unusual, but it's us - Modern Humans. The more academic implication of this research is that we should not be trying to explain the Neandertals, which is what most people have tried to do, including myself, in the past. We wonder why Neandertals look unusual and we want to explain that. What I'm saying is that we've been asking the wrong questions."

The most unusual characteristics throughout human anatomy occur in Modern Humans, argues Trinkaus. "If we want to better understand human evolution, we should be asking why Modern Humans are so unusual, not why the Neandertals are divergent. Modern Humans, for example, are the only people who lack brow ridges. We are the only ones who have seriously shortened faces. We are the only ones with very reduced internal nasal cavities. We also have a number of detailed features of the limb skeleton that are unique.

"Every paleontologist will define the traits a little differently," Trinkaus admits. "If you really wanted to, you could make the case that Neandertals look stranger than we do. But if you are reasonably honest about it, I think it would be extraordinarily difficult to make Neandertals more derived than Modern Humans."

Good article and good post.

I saw this earlier and have been thinking about it much of the day.

This seems to be one of those areas where scientists are challenging their own previous assumptions to see if there might be better interpretations.

The jury is still out and the fossils will remain the same no matter what. These folks are arguing about the best way to interpret the data.

Don't know how this debate will turn out, and don't have a strong opinion either way.

It does coincide with some of the ideas I was exposed to in grad school some (unspecified) years/decades ago. That idea suggested progress from early to late erectus in four areas of the world, with Neanderthal being late European erectus. If that is the case, then modern humans could indeed be a side branch.

Well sure!

Neanderthals look a lot more like apes than men do.

We're clearly the odd ones here.

The most interesting article I ever read on this suggested that what the article called "neotony" is the key. (Forgive me, but I read the article at least 15 years ago, can't remember the source, and probably don't even have the term "neotony" exactly right. So, this is from memory and probably filled with error.)

Adult human beings show the facial and physical traits of being essentially large babies. We are not so strong, we are "softer" and "bigger eyed", etc. What is characteristics of babies is that they are extremely malleable, and all of their neural pathways are open. They play a lot and learn a lot. With most animals, the onset of adulthood changes that, and hardens the playful cub into an instinctive killing machine. The childhood learning window is closed. New learning is largely foreclosed, at least at the rate of the young.

With humans, something went haywire in the genetic makeup, and the thing that makes babies minds so absortive remained partially open for human adults. You can't teach an old dog new tricks, but you CAN teach a middle-aged man new things. Adult humans don't have the strength of any of the other apes, proportionally. We're weak and soft and babylike. But we're infinitely more trainable and capable of learning. Now, to be precise, the article suggested that our physical features are not the CAUSE of our difference, but rather the sort of "birth defect" from the genetic accident. The apes grow up, but we don't fully. Our genes don't let us go to full homo erectus ape-like adulthood. We stay juvenile, adolescent...soft, and weak, and not anywhere close to reaching the full strength and power and coordination that our ape-like bodies ought to be able to attain. Given our size and muscles, we really SHOULD be much stronger than chimps...practically as strong as gorillas. But we're really weaklings, runts, physically stunted and retarded - our genetic flaw. But what a flaw! Because the same defect that didn't let the body grow to full ape-like prowess ALSO didn't let the mind close and the neural pathways hardwire into instinct. Our brains remained more babylike, more juvenile, and capable of massive absorption of information, like all young animals.
That brainpower of course proved more than a tradeoff for the physical weakness. Not one chimp yet has ever thought to pick up a rock and bash the attacking lion on the head, and even if one did, none of the other chimps watching him actually beat a lion would learn one damned thing from it.
There is a snow monkey in Japan that rolls snowballs and stands on them, but in all the hundreds of years men have been living with and around these monkeys, and studying them, nobody has ever seen even one of them get the idea to pick up the snowball and have a snowball fight. You can't teach and old dog new tricks.

Well, actually you CAN. One of the points in the article was that domestic dogs ALSO show the neotony effect as compared to wolves. Wolves look a lot like dogs, especially in their adolescence, but then they grow up. Dogs are weaker, and have those big eyes and soft faces, and inveterate playfulness. They are smarter than wolves too: you can domesticate them easily and naturally. Take a wolf cub, and it will be domesticated...until it hits adolescence...then those neural pathways go hardwired and you'll be living with a wild animal anyway. It might tolerate you as its friend, but it ain't going to fetch or be generically playful with other humans. You'll have a wolf that is selectively tame, to you, but never domesticated. Dogs can be trained to be mean, but it takes training. They aren't INFINITELY trainable...it really is hard to teach an old dog new tricks, but even an old dog can be taught some things. Because dogs have that same neotony fault. Dogs are wolves who had a genetic defect that didn't let them grow up all the way, but left them capable of absorbing more, left them soft, malleable, and able to be friendly. Humans are apes with a similar genetic defect. The symbiosis between these two species is due to that glimmer of openness and capability to learn that comes from being genetically condemned to never quite grow up.

It's a nice story.
And it has a plausible ring to it.

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