Dear Ancestor

A recent paleontological discovery in China resulted in what is now determined to be the most ancient primate from which we humans descended. (Yes, Virginia, we evolved from monkeys.) This dear little ancestor, dubbed Archicebus achilles (it means “ancient monkey”), lived 55 million years ago, during a global warming period when Earth was far hotter and more humid than today. (Although we descendants currently seem bent on returning the climate to that hellish situation.) 

This little critter was tiny. It was about three inches long, weighed about an ounce, had a tail longer than its little body, long legs, a round face, and big eyes. It was about the size of a small songbird. This is our—yours and my—forebear: a wee runt of a thing that we could easily hold in the palm of our hand and allow it room to do somersaults, without it falling off. It ate insects, as the drawing shows.

 

Archicebus achilles (let me call it “primeval primate”) came into being just after the dinosaurs were wiped out by an asteroid, some 65 million years ago. Before this tiny mammal existed, tiny shrew-like creatures scampered around the underbrush, doing their best to avoid being squashed by a mighty dinosaur. When the dinos disappeared, mammals flourished. It was our turn to dominate the Earth.

From this small primeval primate, gorillas evolved, some eight million years ago. Chimpanzees and bonobos split off from gorillas a few million years later and the first human-like critters came into being about four million years ago.

What is fascinating is that this dear ancestor seems to have originated in China. Since our hominid ancestors came into being much later in Africa, this primeval primate had to have floated its way to Africa at some point (which was an island at the time, when sea levels were much higher). We humans evolved on that continent and later migrated back out of Africa (120-60 thousand years ago) to inhabit the entire globe. So our deepest primate ancestor originated in China, its descendants found their way into Africa, and their descendants (humans) migrated out of Africa and spread over the Earth.

We've been on the move ever since. Many people believe we will one day leave Earth for outer space habitats. Maybe so. Maybe we'll have to leave, since we're despoiling this lovely little planet at a record pace. Maybe we'll evolve back into little creatures like dear ancestor, who could thrive on a hot, humid planet. The evolutionary beat goes on.

Tomato Hornworm

Those spots on its side is how it breathes. The red protrusion on the right is its horn. Click to enlarge.

Flying Dinosaurs?

In the past decade or so several feathered dinosaur fossils have been found in China. (What? Feathers on dinosaurs!? Didn’t they have scales or leathery skin, like crocodiles?) Feathers rarely last long enough to be fossilized like bones, so these findings have been exceptionally rare; yet several recent discoveries have confirmed that some dinos indeed sported feathers. Until those discoveries, it was thought by paleontologists that only prehistoric birds grew feathers. 

A related finding by scientists in recent years is that birds evolved from dinosaurs. So let's put these two results together: Birds fly and have feathers. Dinosaurs also had feathers but did not fly (among other things, they were too heavy). So what's going on here? What use may feathers have had for dinosaurs? Aren't they supposed to be for flying?

Those who misunderstand the process of evolution are inclined to think that feathers were “designed” for flight. But this is not how evolution works. There is no “intent,” no design to the evolutionary process. Rather, feathers appeared at some point in the deep past (for no “reason” at all), well before birds did—in their ancestral dinos. Hair-like follicles literally began erupting as rudimentary feathers, that slowly evolved into real feathers. When birds later came on the scene, they arrived with these inherited feathers, and then later further evolved the kinds of feathers that enabled them to fly. (Note that not all birds fly; some feathered extant species such as the ostrich can't flap themselves off the ground.) 

So, of what use were feathers to some of the dinosaurs that sprouted plumes; creatures that could not use them to fly? Well, feathers have some advantages over scales and hair, as skin covering. Besides, even today, most types of feathers are not used for flight. (Think of soft down.) Here are some useful functions that feathers can provide, that the flightless dinosaurs may have enjoyed:

1. Insulation—they are excellent for preserving body heat.
2. Colorful and decorative—sexual selection today has resulted in many birds becoming almost psychedelic in appearance, as males seek to attract mates. Dinos may have preceded birds in this swaggering sexual game.
3. Molting—feathers shed and then regrow, allowing a critter to change seasonal color and appearance, or to replace damaged ones.
4. Transformation—feathers can be fanned out and then retracted, to change size and appearance; useful for both sexual selection and to intimidate foes.
5. Maneuvering—feathered appendages can be extended to aid in balancing when running or gliding (the precursor to flying).
6. Defense—horny, stiff feathers can defend a critter, similar to how porcupines and hedgehogs do. (On my 6/17/13 posting, “Whistling Wings,” I wrote about how mourning doves use their wings in battle.)

As an example of a couple of these uses, I once watched my cat round the corner of the house with a bird in its mouth. Lying down to dine on his prize, he momentarily relaxed his jaw and the bird flew away, leaving the stunned cat with a mouthful of dry feathers, which the bird could later regrow.

Science does not yet know what uses dinos may have found for their feathers, or even how feathers further evolved, to be employed for various purposes. So dinosaurs may well have taken advantage of some of the offerings on the list above. We just don't know. Maybe someday more revealing fossils will be found.

New ways of preserving and analyzing fossils are rapidly being developed by paleontologists. DNA analysis is an especially powerful technique. Whether fossils from dinos or mammals or hominids—scientists are rapidly filling the gaps in our understanding of evolution. What fascinating stories they are telling!

(P.S. My 'puter is alive and active again! May it stay so for awhile.)

Bumble Bee on Echinacea

Look at that stuffed pollen sack on her leg! Click to enlarge.

Dead Computer

I recently experienced a trauma that is all too common in our culture: my computer died. Ever since I acquired my first ‘puter, I’ve struggled with their lack of reliability. In contrast, the ancient tools forged by human hands were simple and reliable. Chip an arrowhead or primitive knife from a flint stone and it would serve its creator a lifetime. Fashion a bow and arrow and it’d be a trustworthy partner for years. I still use some of my grandfather’s hand tools—hammer, pliers, gouge, plane—that he utilized seven decades ago.

A computer, however, can do so many more things than a hammer or saw can manage. It has brought humankind an unimaginable and rich panoply of capabilities. It has become so much at the center of our lives that we cannot conceive of existing without it. Yet its reliability sucks. Computers have so many ways that they can malfunction, and they seem bent on demonstrating to us their whole spectrum of faults. They are so complicated and their workings so far beyond the comprehension of your average citizen, that we non-geeks are helpless when they fail. (Much in the same way when our computer-driven cars quit running.)

I remember watching a computer-savvy friend many years ago, as he attempted to fathom the reason why my primitive ‘puter was being recalcitrant and threatening to obliterate all the precious information I had entrusted to it. I sat there, on the verge of a mental meltdown, as he twiddled away at the infernal machine. While I was both terrified and feeling irate about its feeble dependability, he commented that, considering how complex a computer is, he was rather amazed at how often it succeeds in what it does. For me it was a taste of reality of the computer world—a taste I’m still struggling to swallow.

So, once again, my ‘puter has died. With virtually no warning, it refused to turn on when I pressed the “run” button. That’s an upsetting nonstarter to start with. What can you do when the damned machine won’t even light up? There are no diagnostics you can try; there are no internet searches you can initiate. You’re dead in the water. You’re prey to the local computer repair shop predators—and you pray that you won’t get too badly burned.

In the meantime my routine is disrupted. (And of course, the ‘puter repair guy seems to have all the time in the world to get to my problem.) I cannot open the crucial emails that have been sent me. I cannot surf to my favorite news sites to stay abreast of all the critical developments in the world that utterly depend on my monitoring presence. I cannot post to my blog or write my next penetrating essay on what ails the world. A few years ago I quit subscribing to the local newspaper and have distanced myself from the use of the intrusive phone. The snail mail brings me only junk. I can live without them, but without my “faithful” computer, what’ll I do with myself?

Several days have now passed and I’m managing to survive. It ain’t been easy. But in fact, I’m beginning to find benefit from backing off from my ‘puter dependency. I reminded myself that when I take a vacation I survive without the constant companionship of my computer. (I carry no mobile devices.) If I can make it computerless through a vacation, I can survive a little more time without that confounded machine. The difference, of course, is that on vacation I choose to disconnect. Now it’s being forced on me… by a damnable machine that doesn’t like me!

As I gain some distance from the ‘puter catastrophe, I find that I’m surviving rather well. In fact the (forced) opportunity to step back and assess my ‘puter addiction gives me the chance to survey my daily routine and ponder how much of it makes sense. About two decades ago a lightning bolt hit and destroyed our TV reception. The loss was a bit traumatic at first, but we came to regard the failure as a blessing and let TV viewing expire. That said, I don’t think I’m ready to exist without my computer… although it’s tempting to, like the TV.

Morning Dew on Kale Leaf

Click to enlarge

Whistling Wings

For the first couple of years of living out here in the woods, I thought that the sound a mourning dove makes when it takes to flight was a kind of excited song—sounding like a repeated “fwee-fwee-fwee.” After getting more acquainted with this member of the pigeon family (Columbidae), I realized that the sound was not coming from its beak, but was an airy whistle emanating from its wings, as it beats the air on takeoff.

Over the years I’ve gotten used to this sound. It’s an indication that doves are flying about, without my having to look up to verify their presence. They announce themselves very uniquely. The wing flaps of most songbirds, in contrast, are pretty quiet—you have to be within several yards of them to hear their wings beating. In fact, large predatory birds like owls have nearly silent wings—quiet enough to swoop down on prey without warning them. They are true stealth birds.

A question came to my mind recently: What evolutionary advantage might there be to the dove’s whistling wings? It’s obviously an evolutionary advantage to the owl to have silent wings—any ancient owls who experienced a genetic mutation for wings that made a noise would have immediately died out, while the quiet-winged owls survived. That’s how evolution works.

So why do doves have noisy wings? Well, to begin with, a dove’s diet consists solely of seeds and grain, so the bird doesn’t need to worry about warning a seed that it’s about to pounce on it. OK, no need to stay quiet for that reason, but I couldn’t imagine any advantage to whistling wings—or any reason why doves would evolve them because they were useful. So what’s going on?

It occurred to me that maybe there is no advantage. Could it be that their wings evolved as they have, for some other advantage—and those wings just happen to whistle? In a similar fashion, the peacock’s tail is this magnificent thing that certainly does not give it the most graceful flight skills. But the peacock puts up with the cumbersome tail because the peahen likes the look of it and he damned well better look fancy, if he wants to win her eye. That’s a case of sexual selection trumping flying skills.

A little research into dove characteristics, in an attempt to solve the whistling wing question, gave me two relevant facts. One, the dove’s bill is not hard, like a finch. It can’t bash or crunch the seeds it swallows with that soft bill, so it swallows the hard seeds, sending them down into its crop, where they get ground up by gravel, to reveal the seed’s nutritious interior. Second, when a dove gets into an altercation with another bird, it doesn’t attack with its beak like other birds do (remember that tender bill of theirs), but beats at its foe with its wings.

So maybe that’s my answer: a dove’s wings have evolved to be these tough devices that can be used to go into battle, as well as to fly. And it so happens that tough dove wings whistle. So the evolutionary advantage is not the whistle, it’s the strong wings to fight with. These wings just happen to whistle, which is no disadvantage for the dove, so the whistle endured. Sounds reasonable, although there may be more to the story than that. I’ll just keep on watching and researching and maybe I’ll eventually tease the whole story out.