Tag Archive: Evolution

No, they’re not dinosaurs. These critters are much more recent than the 60 million years since dinosaurs walked the Earth. In fact, our own species may be in part responsible for their demise. They were the top predators of Ice Age North America, and while the cause of their extinction is still subject to debate, they died out, along with their prey, shortly after humans first migrated into the Americas.

The DVD has National Geographic programs on three animals: the saber-toothed cat, the dire wolf, and the short-faced bear. Fossils of all three are found in the La Brea tar pits, and the excavations at La Brea are repeatedly discussed on the DVD. It is subject to the usual bias of this series: good interviews with scientists; poor quality animation clips which are repeated over and over. Another problem is that the science is posed on a “proof” basis when in fact science works by disproof. In general the narrator speaks of “proof” when the scientist involved has shown that his or her hypothesis as not been disproved. This is a very common problem with National Geographic science DVDs.

All three animals hunted the same mega-herbivores: bison, horse, and mammoth. In the same habitat they selected somewhat different prey. Camel and (for the short-faced bear) ground sloth may also have been on the menu, but all three predators were specialized to go after very large prey.

The saber-toothed cat was no more a tiger than it was a house cat. Its weight was in the same range as the modern lion, but it was far stockier and more muscular, with a short tail which reduced its agility at a run. It probably was much more of a wrestler than the modern large cats, and a fair part of the program is devoted to the question of how it used its saber-like but brittle canines for killing. It’s not as obvious as it seems; those oversized canines would have slid off the rounded belly of a prey animal. Nor was its skull constructed for a hard bite. But I have a feeling that it may have used its momentum more than the video clips suggest in pulling down a large animal. (I suspect also that any mammoths it killed were young, very old, or injured. I have a highly unsuccessful saber-tooth attack on a mammoth calf with its mother close by in Tourist Trap.)

The dire wolf closely resembled the modern gray wolf, but was considerably larger and sturdier, with greater bite strength. It probably ran in larger packs than modern wolves, but is thought to have had a very similar hunting style. I suspect the video clips show a far more immediate pulldown of prey than actually occurred. With very large herbivores thick on the ground, the dire wolf would have been an advantage over the gray wolf. When only smaller game became available, the faster, lighter, more behaviorally flexible gray wolf survived and the dire wolf did not.

The third of the predators, the short-faced bear, may not have been a predator so much as a scavenger, stealing kills from the other large predators. It was a very large bear, larger than the largest of the modern grizzlies, such as Kodiak bears. Its legs, however, were relatively long and slender, and it seems to have built for efficiency of gait rather than speed. It probably had an exceptional sense of smell (modern grizzlies have a better sense of smell than bloodhounds) so it was actually well adapted for stealing the kills of other predators. Certainly grizzlies today steal wolf kills if an opportunity occurs. But as I said, possibility or even probability is not scientific proof.

As an introduction to these three Pleistocene predators, this DVD is definitely worth watching. But don’t take everything it says too literally.

This is an entry from the (fictional) Journal of Jarn, an alien stranded on Earth some 125,000 years ago, during the interglacial preceding the one we are in. His stranding ultimately led to the Jarnian Confederation, the setting for my science fiction novels Homecoming and Tourist Trap. The setting is Africa, in the southern hemisphere. The Journal to date is also posted on my author website.

Day 625

I think I am beginning to have some handle on the seasons of this planet, and how they affect the nomads. The rains come a little before the southern solstice. It takes a few days for the flush of new growth, which is followed by the herd animals and the nomads and other predators who hunt them. Not that there aren’t some predators, and animals they prey on, year round, but the migratory herds are far more numerous.

I teleported to the nomads’ camp today. The shaman asked me about the fish trap Songbird had made after seeing a picture on my computer, and after I answered I asked the shaman why the nomads did not stay in one place as some of the lions and wild dogs do.

“We follow the food,” she said, and I was reminded of my own early struggles to find things I could eat. I could teleport to where food was abundant, once I found where that was. These people could not. But the shaman continued. “Also, we go to meet with other clans. The young people find mates at the Gather, and it is a good place to trade ideas. But if we stayed there, as you stay at your shelter, there would not be enough food.”

I was reminded of what Songbird had said, when I first asked her why her parents had left her, and the questions I had then about the role of the shamans. “If mates come from different clans, what determines which clan they stay with?”

“That depends on what they want, on the sizes of the two clans, and on the food supply. Sometimes there is a question, and then the shamans of the two tribes decide together. If a clan is too large there is a problem finding food; if it is too small it cannot fight off predators. Our clan could be a little larger, especially with the fish traps you have shown us. That is an idea we will share.

All I had done was observe that the trap in the picture worked because fish could not swim backwards. Songbird worked out how to make the trap and set it where it looked like the natural vegetation of the stream. “Give Songbird the credit,” I urged.

She giggled. “You make us think, and from that comes new things.”

Do not interfere. How can I stop interfering?

This is the first of a number of reviews of National Geographic’s DVDs on prehistoric animals, so I will start out by saying something that applies to all. They are very good in interviews with actual paleontologists. The computer graphics of the extinct animals are of moderate quality, and there are only a few clips repeated over and over again. These videos are excellent for budding paleontologists or those actually interested in the science of how we know about extinct animals, and are better than series like “Walking With Dinosaurs” in that they allow scientific arguments to be heard. They are not in the same league when it comes to the re-creation of the extinct animals.

This DVD contains two programs originally shown on the National Geographic channel: Dino Autopsy and Dino Death Trap. The first is about a rare fossilized mummy of a hadrosaur, nicknamed “Dakota,” found in the badlands of North Dakota. The fossil was found in 1999 by a teenaged paleontologist, and has supplied information on skin texture and musculature of hadrosaurs. The science is fascinating. The quality of the animation is somewhat less so.

The second program involves the excavation of a site in China. This site produced a number of near-complete skeletons from a period, the Late Jurassic, very poorly represented until now. Most of the attention is given to Guanlong, a very early form of tyrannosaurid. The skeletons are in three dimensions rather than flattened, which has been interpreted as evidence that they were trapped in soft sediments, and lie above each other in a vertical column.

There is speculation about how they died included in the video. Was a volcanic eruption to blame? Was the mud in which they were trapped due to volcanic ash falling into a marsh? Also, while these animals are the early forms of species known from the Cretaceous, the Cretaceous forms were giants, and these animals are relatively small. Guanlong’s back would about reach the waist on a standing human, yet it is an early relative of Tyrannosaurus Rex. What caused the increase in size? Did guanlong really have feathers as part of its crest? They are in the computer animation, and a relative, Dilong, is known to have had primitive feathers. The crest does appear to be a display organ (relatively thin and brittle) and feathers would have made it more conspicuous.

Overall the DVD is worth watching if you are really interested in dinosaurs. If you are looking primarily for entertainment, others are better.

Day 615, Morning

I dreamed last night.

I don’t dream very often, but the bodies leaping in the firelight, the flash of feathers and body paint, and the singing and drumming that accompanied them followed me into sleep. This morning I looked again at the things they had given me, and again I was impressed by the fact that everything these people make is ornamented in some way.

My people love beauty. Perhaps once more than a very few of us could create it, for what we brought with us from R’il’n is more than we can create in these times.

Could it be genetic? I know the stories of lost R’il’n, that there were two suns in the sky, and astronomers warned that the smaller would eventually collide with the larger. It was already disrupting our orbit. We had star flight, and it was agreed that we should split up and search for another place where we could live. Art and culture – the creation of beauty – received very little attention, I suspect, in those years when we were building the great ships that might save our people.

And the fleet that found my world, Kentra, for some reason had mostly engineers and technicians, with very few who could create beauty.

Oh, we brought with us recordings of the great art and music of our past. With time these have become ever more precious, for all too few of us can create such things.

When we returned to where R’il’n’s sun had been, to bring anyone left to Kentra, our home planet was no longer there.

Could these humans still have the spark the R’il’nai have lost?

Day 614

They seem to have decided I am a benign god, at least. The fear that I felt yesterday gradually subsided today, though the awe remained.

I teleported to the spot I’d been teleporting Songbird from. She was watching for me, though she’d been gathering foodstuffs while she waited, and proudly escorted me to the camp. This time I was shielded against emotions – not entirely, for safety’s sake, but enough I could function.

They were preparing a feast. Every person in the group filed before me while I was enthroned on a large rock,, and each bore a gift. Some were very welcome indeed, like the clothing – far finer than what Songbird had made me, and beautifully decorated with bits of fur, feather and shell. Some were containers, or items of food. Some were decorations, for the head, throat, arms and legs. Others …. Well, I am still not sure what they are, but I smiled and accepted them as the honors they were intended to be.

The food was primitive relative to some I have eaten, but by far the best I since I was stranded here. Songbird is a better cook than I am, but for the first time I realized that her mother had only started to teach her how to prepare food. Not that I found everything they ate to my taste, but I did manage to eat at least a little of everything they offered.

By that time it was growing dark away from the fire, which seemed to grow brighter as the stars appeared. I was wondering how to excuse myself when several of the men of the group came into the firelight, so ornamented with feathers, animal skins tanned with the hair on, and beads that I could not recognize any of those I had met. They moved in patterns – dancing, the shaman called it – while others made sounds by pounding on shoulder blades, blowing on reeds, and doing other things I could not quite see, as well as singing.

Makers of beauty, I thought. Such are rare among my people. What have I found here?

Back in 1981 a book came out – After Man, by Dugal Dixon – that I loved to read in the Geophysical Institute Library. It took as a premise that human beings were extinct, and asked what animals might have evolved to fifty million years in the future. The Discovery Channel, with Dougal Dixon, updated the idea and produced a TV series, now available as a set of 3 DVDs, called The Future is Wild. (It’s also available as a paperback book, but this review is of the DVD set.)

Most of the computer-aided nature videos I’ve reviewed to this point have involved re-creations of extinct animals, from early arthropods to mammoths. With these, we generally have enough fossil evidence to have a pretty good idea of how the animal (or plant) was built. Colors, scales, feather or fur are to some extent guesswork – but increasingly evidence is being found even for these. The movement of these extinct animals is increasingly well understood, in part from animators and paleontologists working together.

What will happen in the future takes a lot more guesswork.

These videos cover three time periods: 5 million years in the future, 100 million years from now, and 200 million years ahead, the last assumed to be 100 million years after a catastrophe has produced a major extinction event.

Some things we can do a reasonable job of predicting. We have a pretty good feel for how the tectonic plates move, and just as we can take that back in time to know what the overall distribution of continents and oceans was in the distant past, we can carry it forward to tell where land, water and mountains will be in the future.

Climate is to some extent determined by the distribution of land and water, so future climates can also be very roughly estimated. One factor not so easy to predict, the amount of greenhouse gasses in the air, is uncertain and remains so.

Further, we have a pretty good idea of how evolution works. The best part of the DVD is the tracing back of the evolution of assumed future creatures using our knowledge of how creatures alive today have evolved.

The actual predicted animals are flights of fancy, constrained by known facts about the adaptations of modern plants and animals. The 5 million year scenario assumes an ice age. The shagrats, for instance, correctly show the reduction of appendages, thick coats and increased size typical of cold-evolved animals. But animals that migrate seasonally must have efficient locomotion, as well. Modern animals able to tolerate and thrive in cold climates include some long-legged types such as caribou and moose, for long-distance travel (caribou) and travel through deep snow (moose) as well as compact creatures such as musk oxen. Granted some of the rather poor locomotion of the shagrats may be attributed to the animation (the original program was produced in 2002) but it still seems to me that features leading to poor locomotion would be selected against.

The other two time periods addressed are 100 thousand and 200 thousand years in the future. In the first, carbon dioxide and oxygen levels are assumed to be very high, leading to a hothouse world with insects much larger than today’s. In the second, after a major extinction event, the continents have all come together to create a supercontinent and a global ocean. Fish are assumed to have evolved into a flying creature, though they are spoken of as extinct even though sharks have survived. Inconsistent. The environments are reasonable; I’m not so sure about the inhabitants.

I also have some doubts about the assumed extinctions. It is certainly true that bears, big cats and wolves are under threat today – but the threat is primarily from human activities. The starting point for this assumed evolution, especially in the 5 million year scenario, is critically dependent on how and when humans become extinct, but this is never addressed. Still less is the extinction of entire large clades, such as the mammals. This has rarely happened in the past. Even the dinosaurs are still with us, as birds. Mammals may well evolve into something quite different, but it seems unlikely to me that the strategy of high investment in young and feeding them through special glands will become extinct.

The DVD is worth watching for its insights on how evolution works and some of the more interesting and bizarre relationships it has produced today, as well as the geography and weather patterns of the future. But don’t take the future life-forms too seriously.

I ran across an article recently claiming that modern humans have a better sense of smell than Neanderthals.

Well, some modern humans.

I happen to be practically devoid of a sense of smell. Maybe it’s years of allergies. Maybe it’s diabetic neuropathy. Maybe it’s living in a cold, dry climate. Neanderthals do appear to have been better cold-adapted than modern humans who, after all, evolved in Africa. But the fact remains that my eyes start burning from charring food on the stove before I smell it. And I can’t even smell the odors from some of my plants, including mint, unless I rub or crush the leaves. I have to put my nose right into fragrant roses, jasmine or citrus blossoms before I smell them.

It hasn’t always been that way. I can remember smelling the differences between herb plants at a nursery, for instance, and sniffing appreciatively at pineapple sage and lemon verbena. I’m sure lilacs once spread their scent, while I now have to bury my nose in a panicle to get anything.

It’s not all a loss, of course. I remember also the stench of my grandparents’ outhouse, especially in summer, and deep-cleaning a dirt-floored stall in spring. Considering what sanitation was like a couple of centuries ago, I suspect that modern humans must have learned to turn off or ignore their sense of smell pretty often, just as a matter of survival.

Strangely I am still sensitive to some odors, especially cigarette smoke and some artificial perfumes. But they make my eyes water as well as being distinctly unpleasant odors, and I suspect my reaction may be linked to the fact that “perfumed” detergents make my skin itch.

But now and then I notice a pleasant odor. Right now, it is narcissus.

They started blooming this week, next to the kitchen table. I saw them first, but the last couple of days my meals have had a distinct, intensely floral narcissus flavor. I remember how my mother used to force narcissus bulbs. I am still sensitive to the link between odor and memory, it seems.

In fact, writing about odors often brings things to mind I have almost forgotten. The smell of cut green grass, for instance, brings back the years one of my chores was cutting the Bermuda grass with our old push mower. Not too surprising in terms of brain wiring – the sense of smell is the only one that goes straight from the environment into the brain, but it’s interesting that simply remembering a smell from when I could detect it has the same effect.

I can’t help but wonder how much variability there might be, both in modern humans and in Neanderthals, in the capacity to detect and distinguish odors.

Jarn’s Journal is the fictional journal of an alien stranded on Earth roughly 125,000 years ago, just when our species was beginning. His story is the backstory of the Jarnian Confederation, the science fiction universe in which Homecoming and Tourist Trap are set.

Day 610

Do not interfere.

I ignored that wisdom, and now it seems I am hopelessly entangled.

Songbird is back, and not alone. She has brought her whole clan with her. At least, I suppose it is a clan – they all seem to be related in one way or another. And while I never bothered to count them when they were in their own encampment, her words suggest they are all here.

I am rattled. No, incoherent. Not with rage, but with sheer bewilderment at what to do or say.

When I awoke this morning Songbird was perched cross-legged on the floor where her bed used to be, with Patches on her lap.

My mouth dropped open, and a little of the happiness faded from her face. “You are not glad to see me?”

“Of course I’m glad you are safe. But how did you get here?”

“We walked, of course.”

Matter-of fact. Puzzled at my not seeing the obvious. But I have never walked directly to their camp. Pieces, of course. I explore by walking to a point I can memorize as a teleport destination, and then teleporting back to the shelter. The next day I teleport to that spot and start walking again. If there is a distinctive enough landmark, I may be able to teleport to that landmark. But direct walking? The encampment must have been several fivedays of walking from my shelter! And Songbird had never even seen the landmarks along the way!

Then my mind suddenly caught up with her first word. “We?”

“Of course. It is not safe to travel that far alone. They all wanted to meet you, and my family wishes to give their thanks.” As a god, her mind said.

“Songbird, I am not a god. I am a lost traveler.” I do not know how many times I have tried to tell her that.

This time was no more successful than usual. “We did not wish to interfere with your hunting or your calendar, so we set up camp an hour’s walk downstream. We hope you will visit, but we did not wish to intrude.”

That, I suspected, was a memorized speech. Her mind said that many of her people were frankly afraid of me and what I might do, and wished to propitiate me. That I did not want! Frightened animals are dangerous, and I suspected the same was true of Songbird’s people.

Maybe ….

“I would like you to carry a message for me. I wish to see the shaman. Here.” I suspected an hour’s walk for Songbird would take me several hours, and I have some thinking to do before I meet these people. And some things to check on the computer.

At least I will have a chance to meet that shaman!

Jarn’s Journal, or at least what I have written to date, is on my author website.

(“Blue Babe” is a steppe bison that was killed by a lion, frozen and buried by silt some 36,000 years ago. He was found by a placer miner near Fairbanks, and rests today in the museum at the University of Alaska Fairbanks.)

The bison sniffed the frosty air, his head swinging back and forth as he scanned the snow-covered steppe. Vigilance was part of life, but within the herd it was a shared duty. Here, alone, he felt exposed and vulnerable. He lowered his head and pawed at the wind-crusted snow, uncovering a batch of browned grass, but he took only one bite before jerking his head up to look around.

The dead grass was harsh on his tongue, but it would be the only food available for months. And how could he feed, without others to keep watch? In the herd, at least one or two individuals at a time were always looking around, ready to sound a warning if danger approached. He swallowed the first bite, and lowered his head briefly to snatch more of the poor feed.

The wind tugged at his thick coat, but could not penetrate to his skin. He spread his nostrils and swiveled his ears, seeking warning of any predator, but the hiss of the blowing snow covered other sounds. Again he turned. Where was the rest of the herd? Sheltering from the wind? Perhaps in the valley to his left?

The narrow stream valley provided little shelter from the biting wind, and no other bison. Instinctively he knew the danger of being alone, but until he found the rest of the herd, he had little choice. Again he paced in a tight circle, seeking the source of every imagined sound.

What was that? One eye caught a blur of motion, and he bolted farther into the little valley. But the snow had drifted deeper here, and as he started to turn back, a sudden weight almost collapsed his hindquarters. Bellowing wildly he bucked and spun, the musk of lion rank in his nostrils. For an instant he was free, plunging though the snow for the mouth of the valley, but out of the thickening storm came another lion, leaping for his head.

His nose was pulled down, and again weight came on his hindquarters. He hardly felt the pain of claws and teeth. All his attention focused on the demands of his lungs for air. He tried to shake his head, to throw off the weight clamped to his muzzle, but his legs would no longer support even his own weight, and buckled under him. Redness fading to black washed across his world. He never knew when the lions began to feed.

The OLLI classes are on again, and my favorite teachers are back – this time, with a course on the Alaskan Mesozoic.

What’s that? Well, the Mesozoic is the “Middle period” of multicellular life on earth, lasting roughly from 250 million years ago to 65 million years ago. It is probably better known as the age of dinosaurs, although many of the animals of the time often looked on as dinosaurs – weren’t. And the fossils of many of these animals are indeed found in Alaska – which has led to a new look at dinosaurs.

I missed the first class of the series, on the paleogeography of Alaska, but a good deal of it was put together at the Geophysical Institute, where I used to work. I already knew that the mountain ranges that make up most of Alaska were originally island chains, carried into the state on the moving Pacific and Arctic plates and crushed against it. The north slope was actually at a higher latitude than today during the Mesozoic, and while the world (and Alaska) were a good deal warmer then, the sun was still below the horizon 24 hours a day in midwinter. Plants cannot grow without sunlight, herbivores would have a lean time of it in winter, and carnivores need herbivores to survive. It is difficult to imagine cold-blooded reptiles managing this (there are no crocodiles or snakes in mainland Alaska today) so the discovery of dinosaurs, but not fossil crocodiles, at these high latitudes has forced some reconsideration of their cold-bloodedness.

So what are dinosaurs? That was the Saturday lecture.

First, they are diapsids. That means they have two holes (other than those for eyes, nostrils and ears) in their skulls. In contrast we mammals have one on each side and are called synapsids, and turtles have none and are called anapsids. Don’t think you have one? It’s behind your cheekbone, and your jaw muscle passes through it. Feel above your cheekbone and clench your jaw, and you can feel the muscle. Well, dinosaurs, crocodiles, lizards and birds have two such holes.

In order to be a dinosaur, however, something else is required. Diapsids (think reptiles) started out sprawling. At some point some brought their hind legs under themselves – somewhat earlier than we mammals learned the trick – and began to use their forelegs as grasping hands. The first dinosaur probably looked like a large (but not too large) featherless (we think) bird.

And dinosaurs, as defined by being diapsids with upright rear legs and three-toed grasping forelegs, include birds. Furthermore, discoveries over the last ten to fifteen years have made it clear that many perfectly good, classic dinosaurs had feathers. After all, feathers make excellent insulation, as demonstrated by the down parka I wear.

So far, we’ve learned also that some creatures often lumped with dinosaurs are in fact not dinosaurs. The sail-backs often included with dinosaurs, for instance, are in fact synapsids and are our own distant relatives. Pterosaurs and marine reptiles, though flourishing at the same time as dinosaurs, were not dinosaurs, though they were diapsids.

I know there were marine reptiles in Alaska, but I’ll be fascinated to hear about pterosaurs in our long, dark winters. Did they live here, even in the summer? Did their wings allow them to migrate?

Next week we’ll focus on plants, but the final week is scheduled to cover the marine reptiles and pterosaurs. If you can’t wait, there is some information on a PBS NOVA program.

(P.S. That’s a Pterosaur skull that Pat Druckenmiller is holding.)


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