Lucy’s Great Mystery: How Could Australopithecus Survive and Evolve Into Us?

Part One:

She Should Have Been Caught and E A T E N !

Lucy evolved into us. Really, really (to quote “Shrek.”)

Her species, Australopithecus afarensis, or something extremely close, changed over three million years to become Homo sapiens – the species that includes you and me.

So we should treat Lucy with respect…….

….but wait.  There’s a problem. It shouldn’t have happened. Lucy and her whole species should have been gobbled up by a legion of voracious, bloodthirsty carnivores! She shouldn’t have had any time to evolve at all.

Darwin Makes Sense (usually)

Evolution should be logical – when we have enough data. Textbooks used to say that Lucy evolved from an ancestor who was built like a chimp. But Lucy’s knee and ankle and hip bones were NOT chimp-shaped. The design of Lucy’s joints is very close to what we have – so we know that Lucy walked upright, on just her hind legs, with left and right knees close together.

s-Parade-Blog-ColorFine.  Did leg evolution make Lucy better?  Faster? That’s what we’d expect. But it looks like evolution made Lucy  s l o w e r !  Chimps run very fast and can change direction in an instant. These apes zip around on all fours, running on their knuckles. A modern human has great difficulty catching a running chimp – I know, I used to be a zoo-keeper in charge of three boisterous chimps.

Lucy couldn’t match chimps in speed and maneuverability. Since she walked just on her hind legs, her arms were useless dead weight in running. Plus – she was very short in the legs. Her shins and thighs were far shorter than in modern humans. She was not nearly as fast as we are today.

Why would evolution make Lucy slower?

Lucy – Evolved for Holding Babies on the Open Plains?

The standard theory said that Lucy’s upright posture was fit for moving across savannah, open grassland with scattered trees. She could walk for hours and use her hands to hold her babies or an armful of fruit or a big Pliocene salad or whatever.  Meanwhile, her chimp ancestors stayed in the forest. Sounds good……except we have a huge problem. The savannahs were occupied by a whole host of predators  who would love to eat Lucy and her kind.

In fact, Lucy was evolving during the worst possible time. The australopithecine clan evolved between 5.8 to 1.8 million years ago. This interval produced the scariest variety of big feline meat-eaters the world has ever seen.  Here’s what was out there, ready to catch Lucy and her kin.

Leopards
s-Kitties-Blog-ColorLLeopards are stealth felines who lived with Lucy. They had short, wide paws, flexible legs and body. That’s a build excellent for climbing rocks, hiding in burrows, ascending trees – and sudden ambush! Body weights went from 50 lbs to 200 lbs.

Lions & Tigers
Lucy’s neighbors included lion-like cats, huge predators up to 500 lbs, with massive paws that could swat down a water buffalo. Legs were longer, straighter than a leopard’s and speed over level ground was higher. Because of the great weight, climbing was less agile than a leopard’s.

Dagger-Tooth Saber Cats – Homotheres
Lucy’s world was jam packed with saber-toothed cats. The biggest were the Dagger-Tooths, who were built like a cross between a cheetah and a leopard, with long legs, excellent for fast running with some climbing. Sizes ranged from up to 500 lbs. The jaws were like a rattlesnake’s. They opened so wide that the upper fangs were exposed and ready for action. The upper fangs were long, wide blades with very sharp, saw-toothed edges. Homotheres slashed and stabbed so deeply they could kill an elephant.

Long, muscular necks let saber-cats swing their head down like a battle-ax.

How could Lucy avoid these deadly cats?

Imagine that you are Lucy. You’re waking along the savannah, carrying a load of  melons. Then, without warning…..WHAM!  A leopard leaps on you, bites your neck, and you are leopard-kibbles. Or….you’re resting on a rock when…..WHAM!  A pride of lions jump you and tears you apart. Or….you’re plucking figs from a fig tree when…a Dagger-Tooth jumps up from the tall grass. You try to run as fast as you can….but in ten seconds…WHAM! Zip-Zap!  The cat slices you into bite-sized pieces.

Lucy Defended Herself With Spears?

An old theory says that Lucy’s kind used spears and rocks for defense. But that notion doesn’t work. We find no stone tools at all with Lucy’s bones, not a spear point or a stone knife.  How about a wooden spear? Chimps today make mini-spears from twigs and impale bugs and little furballs. Sure, Lucy might have picked up a branch and chewed the end to make a point.

But if Lucy poked a  Dagger-Tooth in the butt with her spear, she’d only make him mad.

No, wooden spears aren’t enough to drive away lions and leopard and saber-toothed cats.

Conclusion: Lucy and All Her Kind Should Have Been Massacred by The Big Cats.

We’re left with a big problem. How did Lucy get away?

Please! Help our Lucy!!!!!

Send in your suggestions about how to avoid predators!

Interested in learning more about Lucy? Check out my previous blog posts on Australopithecus afarensis migration.

The Truth is in the Tooth

When you take a bite into a juicy hamburger or dive into a pile of asparagus, do you ever wonder how you’re able to eat the way you do? Humans, by nature, are omnivores; this means that we eat fruits, veggies, and various meats. If you NEVER saw a person eat, though, you could still tell what his diet was! The truth is in the tooth, my friend.

something will jump in my mouth, if i just wait long enough
Creative Commons License photo credit: PhyrePh0X

Canine teeth (you could call them your vampire teeth) are found in carnivores, or animals that eat meat.  For instance, you wouldn’t find any blunted teeth in the mouth of a Velociraptor! Molars, on the other hand, are used by herbivores (animals that eat plants) for grinding hard to digest foods. Try looking into the mouth of camel sometime and see what you find – watch out though, they spit.

Diphyodont animals, like mammals, have two sets of teeth in their lifetime.
Polyphyodont animals like sharks have teeth that are constantly being lost and replaced; they grow a new set every few weeks. Can you imagine losing every tooth in your mouth twice a month? Sounds pretty terrible, but at least you’d collect a lot of quarters under your pillow! Incidentally, the Shark Tooth Fairy is also the Queen of England.

Elephant Tongue
Creative Commons License photo credit: greggoconnell

Another useful tool for eating is the ever-important tongue. Some tongues are attached and cannot be stuck out, like the elephant (no raspberries there,) and some are used for more than just eating. Cats’ tongues are rough to aid in grooming, for instance. A frog’s tongue is sticky to trap their food and bring it to their mouths. Did you know a frog uses its eyes to swallow? If they used their tongues, they’d choke.

If you find yourself without the opportunity to observe the mouths and eating habits of wild and extinct animals, come on down to the Museum! It’s the only place in town where you can see a poison dart frog in action and view a T. rex locked in battle with a duck-billed dinosaur.

Draw Dinos Right!

Someone asked me: What are you?  Science Guy or Artist?

Both.

Leonardo da Vinci said: “I don’t understand a thing ‘till I draw it.” When you draw, your finger tips teach your brain what’s important.

Cleaning Bones & Feeling Dinosaur Muscles

Most fossil-cleaners are good artists.  As they chip away the rock, their finger tips record each bump and hole, every place that’s smooth, every place that’s rough. Expert fossil-cleaners dream about the fossil – they see it rotating, turning every which way.

Let’s say we have an ankylosaur skeleton, fresh from the field. We clean off the rock slowly. Every time we have a square inch clean, we paint thin glue on it (so it doesn’t crack and fall apart). As we do, we make sketches of the bone. That helps plan the complete cleaning. It’s X-ray vision, sort of.  As we sketch the bone we can draw in the parts of the specimen that are still buried in the rock.

For instance: let’s say we have the upper left arm (humerus). And we have the elbow end cleaned, but the shoulder end is still in the rock. A sketch will help us imagine where the bone is and how to chip the rock off so we don’t break anything accidentally.

Putting Muscles and Ligaments Back On

Fossils from a Dimetrodon hip bone.

Texture of fossil bone is important:

Rough spots full of squiggly ridges are where tough ligaments and tendons attached to the bone.

Smooth spots are where soft muscle attached.

Bones with big pits are armor plate – in life the pits were filled with a thick layer of finger-nail like skin.

At the Zoo with Brachylophosaurus

Now let’s shift to Leonardo, the Brachylophosaurus,  the dino-mummy now visiting the Houston Museum of Natural Science. I wanted some drawings of the critter, and to prepare I spent a lot of time watching live animals.

I sketch live critters in the zoo all the time.  And I make diagrams of the heads, bodies and legs of skeletons from species that are still alive today. I can’t imagine a live Brachylophosaurus  or any other dinosaur without studying rhinos and elephants,  ostriches and cassowaries, giant tortoises and water buffalo.

Tweensy Gator Hands

Most plant-eating dinos have hands like the one in the little vegetarian dinosaur Hypsilophodon.  There were five fingers in this animal and most other herbivores. Carnivores sometimes have  three, as in Velociraptor,  or two as in T. rex  and all members of the rex family.  In all dinos, meat-eater and plant-eater,  only the inner three fingers had claws. In herbivores the claws are blunt and hoof-like. Carnivores tend to have sharp-tipped claws. In all dinos, the outer two fingers had no claws at all.

The five fingers/three claws is standard equipment for most ancestors of dinos too.

Gator
Creative Commons License photo credit: James Jordan

Who has this  five/three  hand in a zoo today?  Only in one clan – gators and crocs. Lizards and turtles have claws on all five fingers.  Crocs & gators have three claws, five fingers, no claw on outer two. Watch out when you draw dino hands – a lot of books make the mistake of giving a dino  four or five claws. Even the movie “Jurassic Park” makes that error with the Triceratops. Don’t YOU do it! Remember: five fingers but only three claws in most plant-eating dinosaurs.




No Bowling for Duck-Bills

Duck-bill dinos have a puzzling variation on the basic veggie-saur hand. The outer two fingers are fine – no claw or hoof. But there are only four fingers in total. Which is missing? The thumb. Duck-bills are the only dinos without any thumb. That’s strange because the thumb is usually one of the strongest fingers in all other dinosaurs. Even T. rex  has a thumb. There’s a predatory dino with just one finger – Mononychus – and that single finger is, you guessed it, the thumb.

One result of being thumb-less is that when you’re choosing a bowling team, you don’t want a duck-bill. They can’t hold the ball. Continue reading