We’ll, I’ll be a Monkey’s Uncle. Or an Orangutan’s.

Our Guest blogger today is Dr. Todd Disotell, a professor of anthropology and a molecular primatologist at New York University’s Center for the Study of Human Origins. He will be speaking at HMNS on Feb. 9 at 6:30 p.m. about new molecular analytical techniques and how mapping whole genome sequences has affected what we know about the past. In his blog below, Dr. Disotell debates a recently proposed theory that humans are more closely related to orangutans than chimpanzees – a theory he disagrees with.

Posing for the Camera
Creative Commons License photo credit: jimbowen0306

This past summer upon the publication of a paper by a colleague, I found myself at the intersection of a 25 year old hypothesis, the latest research in genomics and bioinformatics, and popular culture.  Jeffrey Schwartz of the University of Pittsburgh and his coauthor, John Grehan of the Buffalo Museum of Science published an updated version of their hypothesis that orangutans are more closely related to humans than are chimpanzees in the Journal of Biogeography.  This intrigued me because in my final year of graduate school, my advisors and I published one of the earliest papers utilizing DNA sequence data supporting the growing consensus that chimpanzees were our closest relative, followed by gorillas, and much more distantly orangutans.

Perhaps due to my working in New York City, a producer from the Daily Show with Jon Stewart called me at my office and wanted to know if I was willing to be interviewed about Schwartz’s hypothesis.  As a fan I readily agreed and correspondent John Oliver was dispatched to my laboratory to interview me.  During the course of the interview in which I stated that the hypothesis flew in the face of all known genetic evidence, I opined that I would at least get to write a counter paper and perhaps a counter-counter paper if Schwartz responded.  That got me thinking about newly available genomic data that was now available in various databases which had not been fully analyzed.

Confused chimp
Creative Commons License photo credit:
Tambako the Jaguar

I then downloaded the complete genome alignments that included human, chimpanzee, gorilla, orangutan, macaque, marmoset, lemur, and galago.  After writing a series of Python scripts (an open source computer programming language) to parse and reformat the masses of sequence data, I chose the first 1 million bases of each chromosome for which all of the above species were represented.  I then used well characterized statistical and analytical techniques to infer the evolutionary history of each DNA region.  Not surprising to me, the analysis of each region convincingly rejects the hypothesis that orangutans are more closely related to humans than are chimpanzees.  Furthermore, when these 30 million DNA bases are used to estimate the time of divergence between humans, chimpanzees, and orangutans using molecular clock techniques, the orangutan appears to have diverged at over twice the age chimpanzees have from humans.

These results are not at all surprising to the absolute majority of paleoanthropologists and evolutionary primatologists.  However, it is still worthwhile to occasionally revisit theories and hypotheses that we now take for granted when new data are generated and new analytical techniques are developed.  In this genomic age, as the genomes of more and more species and even individuals within species are being sequenced, a whole new class and scale of analyses can be carried out from the keyboard.

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Check out Dr. Disotell’s lecture, “Times Are a-Changin': New Methods Tell A New Tale of Primate Evolution” at HMNS on Feb. 9 – get tickets here!

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.


Explore Evolution with Lucy’s Legacy

lucy-model-face

Lucy’s Legacy, an exhibition featuring the world’s most famous fossil, recently opened at Discovery Times Square Exposition in Times Square, New York. The exhibit will remain on display until October 25, 2009.

The Lucy exhibit has been an exciting catalyst for discovery, discussion, and debate within the scientific community. In this series of blogs, Dirk presents all sides of the controversy surrounding Lucy’s existence and significance while skillfully separating fact from fiction with supporting evidence and research.
  
Do you enjoy debate about scientific theories or issues? If so, prepare yourself for a great read while perusing the following blogs by Dirk. In addition to his perspective and logic, Dirk also provides links to research and evidence that will leave you on the edge of your seat…and excited about evolution!

-In fide constans… Always loyal [Lucy's Legacy]     
-Neanderthal Controversy
-A Letter From Lucy: Making no bones about it. (Pun intended)
-Lucy loves Houston – and she’s not leaving. Yet.
-If Humans came from monkeys, than why are monkeys still around?
-Evolution
 
 Neanderthals—most people know what they were, but do we know who they were or how they lived? Join Dirk as he discusses these unique people and their lifestyle.

-Neanderthal Controversy 
-Neanderthals on the move
-Neanderthals Speak Out

Why are genetics important in the development of humans? More than just appearance, genetics play a role in where we live and even how we survive. In the following blogs, Dirk explores where genetics has contributed to history and evolution. 

-Neanderthals on the move
-We are all mutants
-10,000 BC: The story behind the date
-A major step forward – 40,000 years ago

s-legacy-exhibitSure, they’re adorable and entertaining to observe but chimps and monkeys offer far more than that! They provide valuable information about human behavior and progress. Follow-up with these blogs and read Dirk’s presentation of our connection to these magnificent animals.

-Chimps using tools: Archaeology’s most fascinating discovery of 2007
-The Apple Doesn’t Fall Too Far from the Tree
-Monkey business
-If Humans came from monkeys, than why are monkeys still around?
  
The study of fossilized remains (like Lucy and other hominids) offers an exciting opportunity to draw parallels on our own existence and physicality. What did they look like and how did they live? Dirk has explored these questions in the following blogs:

-Discovering behavior: a step-by-step process
-Reconstructing ancient hominid behavior
-Lucy’s kitties
-Paleoanthropology: making the past come alive.
-Extinction doesn’t mean failure

If you ask a fossil to share the secrets it holds, it will provide invaluable information and insight into the past. But how can we piece the puzzle together? Dirk explains the wisdom of what happens when fossils meet modern technology…and dating begins (pun intended).

-How do we know: dating techniques
-Meet Lucy, Australopithecus afarensis. (What’s in a name?)
-Teeth Tell Tales
 
Want to find out more about Lucy’s home, Ethiopia? Click below and discover a wealth of history, culture and tradition.

-Timkat, an Ethiopian Epiphany celebration
-The Ark of the Covenant and Aksum