Lucy’s Great Mystery: Part 3

In Part One we learned the frightening facts: Lucy was surrounded by formidable felines. She was too slow to run away and she didn’t have weapons to repel 150 pound leopards or 500 pound  homothere saber-tooths.

In Part Two we discussed even more of the fearsome predators surrounding Lucy, and began to discuss how futile fighting back would be.

How Could Our Lucy Survive a Legion of Cats and Hyenas?

How did she defend herself?

Here are some suggestions:

She made sharp-edged knives out of broken antelope bones and buffalo horns
Lucy model - faceThis was a popular theory in the 1950’s.  In South African caves, Lucy’s relatives are found with hundreds of broken antelope bones, horse bones, and broken horns form all sorts of hoofed creatures. Conclusion: Australopithecus didn’t make stone tools – they made bone-tools.

Supposedly Lucy and her clan smashed antelope legs and used the sharp-edged ends the way a hockey fan would use a broken beer bottle in a bar-fight. “Poke, whack, stab!”

Broken bones can be nasty weapons, it’s true, but….

Hyenas broke the bones
Careful analysis of the way the bones were broken proved that Australopithecus didn’t do the breaking. Teeth marks on the bones and the style of breakage matched what we see today around a hyena lair. All of those cave bones had been smashed by the big teeth of hyenas and maybe big lion-sized cats. The predators smashed Australopithecus bones too.

Maybe – Lucy Smelled Bad – Or Tasted Bad

Striped Skunk
Creative Commons License photo credit: Charles & Clint

Seriously – this is a theory we must consider. A few animals stink so thoroughly that predators won’t attack. Skunks are a good example. Even mountain lions are repelled by one spray from the stink glands of a Texas skunk.

And meat can stink or be poisonous. Toxins in the Fugu fish are deadly – if you go to a restaurant and gulp down the wrong part of your Fugu, you’ll die. So…..maybe Darwinian processes gave Lucy toxic flesh.

But primates don’t evolve super-stink
Today we just don’t find any lemurs, bushbabies, monkeys or apes with toxic meat or stinky glands.  In fact, most stinky mammals are predators – skunks, ferrets, and stink-badgers. So, although it’s theoretically possible, we should not be too enthusiastic about Lucy evolving chemical defenses.


Let’s Review Lucy’s Potential


ChimpUs-frontSkeletonLabelLet’s review what Lucy could do – we have nearly all the bones from the skeleton if we supplement Lucy and other Ethiopian finds with close relatives dug from South Africa. Follow along by scrutinizing our Lucy-chimp-us body diagram.


No Grabber Toe
Lucy’s big toe was like ours – it didn’t face away from the other toes the way a chimp big toe does. So Lucy couldn’t grab a branch and climb like a chimp.

Knees Together
Chimps can’t stand perfectly upright, because their knees slant down and out. But Lucy could stand in a modern posture – her joints were shaped so the right and left thighs came down and towards each other. She’d walk and run like us modern humans too – knees close together.

Strong Shins & Thighs
Lucy did have muscular, short shins and thighs. No, she couldn’t sprint as fast as a modern human but she could accelerate fast and turn quickly. And short legs actually are good for climbing.

Modern Hips
Lucy had wide upper hips, like ours, not narrow hips like a chimp’s. Wide hips are good for supporting guts when standing and running upright. And….wide hips could be good for climbing straight up a tree, if arms and legs work together. We see modern people shimmying up coconut palms this way.

Lucy – NOT America’s Next Top Model – Compact Torso
Today’s humans have long waists – especially in the Hollywood starlets and runway models. Not our Lucy. As the song goes, Lucy had “..strong thighs and shins… and her torso…even more so.” Lucy had no waist. Her barrel chest was set on top of her wide hips.

That gave her a low center of gravity, a design useful for three-dimensional movement. Lucy was a natural gymnast! She could jump and twist and do somersaults.

Shoulder-Socket Half Chimp
Lucy’s shoulder socket was half-chimp, half human. The joint let her raise her arms further up, above her head, than we can – but not as far as a chimp. Raising your arms high is useful for climbing vertically; hand over hand (the way we were taught in gym class in seventh grade).

Long Arms
Lucy is half-chimp in arm proportions too – her whole arm is longer and stronger compared to her legs than what we see among modern people. And strong arms certainly would assist in climbing.

Curved Fingers
So far, our review of Lucy’s anatomical equipment is a surprise – she’d walk like a modern human on the ground, but she might be able to climb vertically much better than we can. However – if she really was supposed to climb, she’d need long, curved fingers to wrap around branches.

Did she? Were Lucy’s fingers more curved than ours?

YES!!!!!!

Australopithecus did have more curve in the digits. Not as much as in a chimps but still more than in modern humans.

So, after reviewing all of Lucy’s potential, we now can give her advice:

LUCY!  To avoid being eaten…..STAY NEAR A TREE!

She wouldn’t have to climb like a chimp, but she would have to be near enough to a tree so she could shimmy up when the cheetah charged or the hyena pack came galumphing over a hill. She wouldn’t have to scoot over a branch, holding on with her big toe, chimp-style. But she could avoid most meat-eaters by going vertical.


The Old Theory Is WRONG! Lucy Did Not Evolve on the Open Plains.

Back to our original problem: the old theory said Lucy and her kind evolved to move over open, tree-less terrain. We now have new evidence – from fossil herbivores – that the theory is incorrect. If Lucy lived in treeless areas, her bones should be found only with hoofed animals adapted to plains– the wildebeests and gnu, for example. And zebras. We shouldn’t find woodland herbivores like black rhinos and mastodons.

In fact, the antelope and rhinos and hippos and mastodons we dig with Lucy are mostly woodland critters, adapted to move over grassy areas with many bushes and clumps of trees nearby.

Mystery Solved! Lucy Evolved to Stay Near an Escape Tree.

Her family could forage on the ground. And climb up and away. And maybe they did use pointed sticks to jab down at any leopard who tried to follow.

Our ancestor, Lucy, was a success because she made her world three-dimensional.


Lucy’s Great Mystery: Part 2

Big Cats Everywhere:
Fast Cats,  Semi-Saber Cats, Super-Fast Cats. Not to Mention the Super-Hyenas!

In Part One we learned the frightening facts: Lucy was surrounded by formidable felines. She was too slow to run away and she didn’t have weapons to repel 150 pound leopards or 500 pound  homothere saber-tooths.

Actually – we left some facts out. The predator situation was even worse then what we discussed in the last article.  Lucy’s world had even more kinds of meat-eaters to fear:

Cheetahs
These speedsters have greyhound-like limbs, very long and tipped with nails, not claws. Cheetahs sacrifice climbing ability for acceleration and velocity on the ground. Living cheetahs are leopard size – 120 lbs average. But in Lucy’s time cheetahs were as big as modern lions.

Semi-Saber Tooths – Dinofelis
These felids had the slinky bodies of leopards with an enlarged upper fang. Their saber teeth weren’t as long or as sharp as a Sword Tooth cat but were far larger than in any modern cat.

Sword-Tooth Saber Cats – Smilodonts
These are the chunkiest, most heavily muscled saber-tooths.  In Lucy’s time, smilodonts grew to jaguar size, were heavier than a leopard, but had even more massive forearms and paws. Climbing would be excellent but speed on the ground was slower than a lion’s.  The upper fangs were much longer than those in a Dagger-Tooth homothere.

Lucy would have had to deal with Hyenas too……

The feline situation looked bad enough. The hyenas made it much, much worse.

s-cats-hyenColorRSmallLucy’s time saw the maximum diversity among the African  Hyena clan. Today, the most advanced pack hunter is none other than the Spotted Hyena, Crocuta crocuta. This is a matriarchal hunter. The biggest males don’t rule. Mom does. The alpha female is bigger, smarter and scarier than the males and she makes most of the decisions. Her sisters are next in charge. The Spotted Hyena has a close-knit social structure, and the dominant females are needed to keep order. It works to the kids’ advantage. If  Mom-Hyenas dies, her sisters will help raise the orphans. Hyena clans fan out and go after zebra and antelope, even water-buffalo and young rhinos. The Hyenas run and run and run. They’ve got great stamina.

Super-Crusher Hyena
Lucy had to watch out for Pachycrocuta, what I like to call the Super-Crusher-Hyena. This monster was a close kin of today’s Spotted Hyena but weighed almost as much as a lion – 300 pounds. And the Super-Crusher had jaws with even greater bone-smashing power than in the Spotted Hyena.

A clan of Super-Crusher-Hyenas would have instilled fear even in the biggest Saber-Tooth Cat.

Wolf-Hyena
In Lucy’s time there was a Hyena menace we don’t have today. It was Chasmaporthetes, the Wolf-Hyena. A Wolf-Hyena, seen from a hundred yards away, would look like big-headed Timber Wolf – long-legged, fast, and graceful. Up close, you’d see the Hyena family design. The paws were more compact than a wolf’s and the jaws had meat-cutting teeth were longer and sharper. And there weren’t any big molars in the rear of the mouth. Wolves and coyotes use those rear molars to crunch berries and fruit and other vegetable food. The Wolf-Hyena was more of a pure carnivore.

The Wolf-Hyenas must have been the nightmare of mid-sized hoofed stock, and primates of all sizes, including our Lucy.

Can’t Bite Back.   What defenses Did Lucy Have?

IMG_0876.JPG
Creative Commons License photo credit: rdicker

Chimps and baboons can bite back. They have big canine teeth, especially large in the males. A 90 pound baboon or ape is a nasty close-in fighter. Leopards and hyenas can get terrible wounds from ape and monkey teeth.

But not Lucy.  When australopithecines evolved from apes, the canine teeth got small. Lucy had much poorer dental weapons than what her ape ancestors had.

Final Conclusion:

Let’s roll-play again…..,you’re Lucy or her mate. You weigh 60 to 90 pounds. What do you do when a pack of Wolf Hyenas come over the hill? You can’t out-run them. You might be able to fight off just one Wolf-Hyena, but not a pack of a dozen.

Let’s say by some miracle you get away from the Wolf Hyena clan – then a Giant Cheetah comes at you at 55 mph.

Or you’re resting and a Semi-Saber Tooth Cat attacks. Or a smilodont?

You haven’t a chance….

Old Theories Are Missing Something.

BUT….Lucy and her family did get away, again and again and again. They lived long enough to mate and raise kids and evolve.

How did they do it?

What do you think?

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.

Lucy, meet Ardi

More than 4 million years since she last walked the Earth and more than 15 years since her discovery was first announced, a distant human ancestor dubbed “Ardi” was introduced to the general public on Oct 1, 2009.  Nicknames abound in this field where long scientific nomenclature is common. So, meet “Ardi”, a member of the genus Ardipithecus.

Who was Ardipithecus? When and where did they live? What can we say about their diet and behavior? How do they relate to later fossils, such as Lucy, as well as to us? Where do they fit in with regards to our closest living primate relatives, the chimps? This is an extensive array of questions, not unusual to find when fossils are discovered. Scientists rely on an equally extensive array of approaches to find answers.

Lets start with the first question: who was Ardipithecus?

The genus Ardipithecus derives its name from an Afar language word, “ardi“, which means “ground” or “floor.” By choosing this term, the scientists involved in the discovery clearly wanted to reflect the place Ardipithecus occupied in human evolution: as close to the very beginning of hominids as possible. Defining “hominid” as any fossil species closer to modern humans than to chimps and bonobos, which are our closest living relatives, Dr. Tim White stated: “This is the oldest hominid skeleton on Earth.”

After their discovery of the first Ardipithecus remains in 1992, scientists had identified the bones of 17 hominid fossils by the end of 1993. These specimens were retrieved from a cluster of localities West of the Awash River, within the Afar Depression, Aramis, Ethiopia. Hominid and associated fossil faunas, including wood, seed and vertebrate specimens, were dated to about 4.3 million years ago.

Over a period of several years, the team followed up with more excavations at the location of the original discovery. They collected 125 fragments of skulls, teeth, arms, hands, the pelvis, legs and feet. In addition to this skeleton, the area yielded a total of 110 other catalogued specimens representing body parts of at least 36 other Ardipithecus individuals.

Ardi is the most complete individual among those found, with about 45% of the skeleton intact. Ardi, an adult female, probably stood four feet tall and weighed about 120 pounds, almost a foot taller and twice the weight of Lucy

Ardi
Ardi, as shown in the Oct. 2 issue of Science.
Image (c) Tim White, 2008

When did they live?

There is more than one species within the genus Ardipithecus. Scientists distinguish between Ardipithecus kadabba (5.8 – 5.2 million years ago) and Ardipithecus ramidus (4.4 million years ago). Both discovered in the Awash valley in Ethiopia, these two species lived after the split between the human and chimpanzee lineages. They represent the earliest known hominids from Ethiopia.

Where did they live?

The remains of Ardipithecus kadabba and Ardipithecus ramidus have been found in Eastern Ethiopia. When they roamed that area, the Great Rift was a well-established geologic feature. The environment 4-to-5 million years ago was very different from that of today. The climate was cool and wet. Ardipithecus kadabba and Ardipithecus ramidus lived in an area of swamps, streams and dense tree cover, rather than in a mosaic of forest and grassland, as originally thought. This evidence has caused a re-examination of the hypothesis on the origin of upright walking.

What can we say about their behavior?

It seems that Ardi was equally at home on the ground as she was in the trees. Her feet, pelvis, legs, and hands suggest she walked upright on the ground but moved around on all fours when in the trees. The large, flaring bones of the upper pelvis were positioned so that Ardi could walk on two legs without lurching from side to side like a chimp. Ardipithecus gives us a close look at an upright walking being and a chance to evaluate the mechanisms that may have caused this behavior to evolve and remain until today.

Traditionally, scientists suggested that the evolution of upright walking was closely related to the disappearance of the forest cover and its replacement by grasslands. Creatures adapted to living in trees were now forced to cross grasslands in order to go from one island of trees to another, the thinking went. However, crossing through the grass would make them very vulnerable to predator attacks. Walking upright allowed one to see predators sooner, thus representing a beneficial adaption to a changing environment.  We now know that the origins of upright walking pre-dates the widespread disappearance of the forests and their replacement by grasslands. Bipedalism did not evolve as an adaptation to receding forest cover and expanding grasslands. Back to the drawing board, in other words.
Bipedalism is now thought to have evolved in a tree environment.

Questions remain: how and why? Among living non-human primates, researchers have observed bipedal stances in creatures such as orangutans as they move around in the trees, while chimpanzees most often stand upright when they feed on small objects in the trees. Early human ancestors, such as Ardipithecus, who lived in a tree environment, may have had similar adaptations.

The discovery of the genus Ardipithecus and the study of the environment in which they once lived have caused us to revisit and refine the thinking on the origins of upright walking. However, we can’t be sure that bipedalism first emerged in the Awash Valley. Its origins may lie even further back in time.

Upright walking may also relate to another aspect of Ardipithecus’ behavior: monogamy. Here is where a hypothesis originally dating back to the 1980s has found new traction. Dr. Owen Lovejoy suggests that instead of fighting for access to females, a male Ardipithecus would supply a “targeted female” and her offspring with gathered foods and gain her sexual loyalty in return. Walking upright freed his hands to carry the food, thus helping him to achieve this goal.

Lucy fossil
The fossil Lucy.

How does Ardi relate to Lucy?

Ardi pre-dates Lucy by more than a million years. She was larger and heavier than Lucy. Lucy was a more adept upright walker than Ardi. Both Ardi and Lucy lived well before stone tools were in use. Their brain size was similar to that of a chimp. Both were found in the same region of Ethiopia, with Ardi’s site just 46 miles (74 kilometers) away from where Lucy’s species, Australopithecus afarensis, was found in 1974.

What traits does Ardi share with us, Australopithecines and chimps?

Like chimps, Ardi had an opposable big toe. However, she was probably not as agile in the trees as a chimp. Unlike chimps, however, she could have carried things while walking upright on the ground, and would have been able to manipulate objects better than a chimp. And, contrary to what many scientists have thought, Ardi did not walk on her knuckles, White said.

Ardi was not a chimpanzee, but she wasn’t human,” stressed White, who directs UC Berkeley’s Human Evolution Research Center. “When climbing on all fours, she did not walk on her knuckles, like a chimp or gorilla, but on her palms. No ape today walks on its palms.”

Moreover, Ardi’s small, blunt, upper canine teeth, very likely reflect amicable relationships, leaving open the possibility of pair-bonded couples living together in social units. Ardi’s dentition contrasts sharply (no pun intended) with the much larger canine teeth found in chimpanzees and gorillas, animals known for their teeth-baring threat behavior. The latter statement is a good example of how paleoanthropologists rely on various sources of information in their attempt to reconstruct past behavior, including comparative primatology. In this case, similarities in dentition between fossil and living primates form the basis for suggested similarities in behavior both past and present. While Ardi’s canines were smaller than those of chimpanzees and gorillas, Lucy’s canines were even smaller in comparison.

Ardi’s teeth also revealed her and her ilk to be omnivores, eating a wide range of foods rather than specializing in a more restrictive diet of fruit or leaves. Being an omnivore is another trait that sets Ardi apart from chimps, animals that eat primarily fruits, and and gorillas, which eat primarily leaves, stems and bark. The research team surmised that Ardipithecus spent a lot of time on the ground looking for nutritious plants, mushrooms, invertebrates and perhaps small vertebrates.

The shape of Ardi’s upper pelvis and aspects of muscle attachment in that part of the hip resemble much more an upright walking human than a knuckle walking chimp. However, the lower pelvis is much more primitive than anything found in other hominids.

Why the buzz?

When the news about Ardi was released, it generated quite a buzz, underscoring the great interest in the study of human origins. Hundreds of media outlets covered the story. Predictably, creationist outlets use the sentiment that Ardi has overturned our understanding of human evolution to make their point that scientists “do not agree” when it comes to human evolution.  In making this statement, they display a fundamental misunderstanding of how the scientific process works. Fortunately, there are a number of excellent sites that make the process of understanding the latest news both easier and much more palatable.

Quite often, scientists were quoted stating that this find was “far more important than Lucy.” It also showed that “the last common ancestor with chimps didn’t look like a chimp, or a human, or some funny thing in between.”  Questions also abound about what this will do to Lucy’s preeminent status in the world of paleoanthropology. Now that we have an older creature also capable of walking upright, so the thinking goes, will “Ardi” now become the buzzword du jour, instead of Lucy?

In my opinion this is not the right question to ask. We are not dealing with a beauty contest among fossils. Each of these finds has substantially increased our understanding of human evolution. Lucy taught us that bipedalism pre-dates the expansion of the human brain as well as tool making. With Ardi, the most important contribution seems to be that we now need to look beyond chimps (the 98% genetic overlap between humans and chimps notwithstanding) as a model for a common ancestor. What this common ancestor may have looked like and when and where it lived, remains, as of now, a great unknown.