Stories tagged evolution

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How does food matter to human evolution? We could ask this guy?
How does food matter to human evolution? We could ask this guy?Courtesy Lord Jim
What makes human beings so special? How did we evolve into an agriculture-developing, city-building, history-making, world-changing species that can live on every continent and even in outer space?

Scientists have been asking questions about our evolutionary trajectory and human "uniqueness" for as long as there's been science - and guess what? We still don't know the answer! Some of our best theories are explored by anthropologists in the PBS television series The Human Spark, airing throughout the month and also online at the PBS website. If you're curious, you might want to watch, but don't do it on an empty stomach! Many of the theories that anthropologists have developed to explain how we became human involve food.

That food and evolution would go hand in hand is not really surprising, since food is necessary to survival and an important and dynamic part of our environment. Did a search for nutritious plants and animals lead our ancestors to new environments, causing our species to adapt and change? Did hunting and eating meat mean the evolution of new physical characteristics? How has agriculture changed our environment and species over time? How will present and future foods change what it means to be human in the future?

Some evolutionary theories involving food look not just at what we ate, but how we ate it - namely the invention of fire and the use of heat to cook food. Think about it: our Hominid ancestors needed calories in order to develop into the big-brained humans we all know and love. How did they do it? And what did this mean for human evolution?

Sure, eating meat was an important dietary step, but cooking root vegetables can transform hard-to-chew or even poisonous plant parts into nutritious food that can be consumed out of season. With cooking, environments that would otherwise provide few nutritious options suddenly become bountiful. This change in diet may also have led to changes in body size and shape - even social structures! Large teeth and jaws were less desirable once food could be more easily chewed, and delaying the gratification of food until it could be cooked may also have meant that our species had to develop new social skills.

Those social skills - the same ones that mean you and I can now share a burger or beer without fighting each other for scraps - may be one of many "sparks" that makes us human.

If you live in the Twin Cities, you can meet an anthropologist and here how he thinks food impacted human evolution by attending tonight's Cafe Scientifique program in Minneapolis.


Better safe than sorry, eh?: Modified from the original for decency's sake.
Better safe than sorry, eh?: Modified from the original for decency's sake.Courtesy BaylorBear78
My psychological jargon might be a little mixed up, but Freud was the one who would deteriorate into fits of frightened giggling at any mention of sex organs, right? If so, this research is totally Freudian.

(I’m pretty sure Freud died of an aneurysm while watching a butcher make sausage links. So yeah, kids, I think you’re safe using this as a resource for your 10th grade psych class.)

Here’s the rub, as it were: duck penises are off the hook! And not just duck penises, duck vaginas too! Despite the questionable wardrobe choices of certain popular cartoon characters, I’ve never seen a duck’s penis. But I suppose that the hunters and duck enthusiasts among you might already know that ducks, unlike most birds, have penises, and that said penises are about 8 inches long and remarkably flexible. The reason we aren’t constantly being assaulted by the sight of duck genitals is that they usually keep the organs tucked inside their bodies. When the need arises, the appendages can be extended, or "everted," in less than a second, an act described (not by me) as “explosive.”

Here’s some footage of it happening. Be warned, though—it’s not for the more sensitive among you.

But, okay, so duck penises are crazy. What about the rest?

Well, ducks have crazy penises because it gives them an advantage in “forced mating.” But if male ducks could evolve a feature that increases their chances of a successful forced mating, mused some researchers at Yale, couldn’t female ducks evolve penis-confounding features that would protect them from unwanted attempts at mating?

Duck penises, it turns out, are somewhat corkscrew-shaped. The researchers tested their ability to evert into a set of glass tubes of varying shapes. They found that eversion was quickly and easily done in straight tubes, and tubes that spiraled counter-clockwise. A tube spiraled clockwise, however, or one with a sharp bend in it, could stop eversion altogether. It turns out that duck vaginas have evolved structures like the second set of glass tubes, with the purpose of thwarting wandering duck penises.

How strange. Apparently it’s one of the rare occasions when the evolutionary consequences of the battle of the sexes are so “dramatic.” Dramatic and bizarre.

Now pick yourself up and continue on with your day. That wasn’t so bad, was it? And now you have something to talk about at your family holiday party!


Richard Lenski (top) and Jeffrey Barrick view bacteria cultures in Lenski's lab.: They have watched the bacteria's DNA evolve over 40,000 generations.
Richard Lenski (top) and Jeffrey Barrick view bacteria cultures in Lenski's lab.: They have watched the bacteria's DNA evolve over 40,000 generations.Courtesy Michigan State University / photo by G.L. Kohuth

Sometimes you’ll hear people cast doubts on evolution because no one has ever seen it happen. As if that’s some sort of great insight. No one has eve “seen” atomic fusion, either, but the fact that the Sun was shining this morning is pretty strong evidence that, yep, it happens. No one has ever “seen” gravity. Seen gravity’s effects, sure. But seen gravity itself? Like Ms. Ono once asked, Who Has Seen The Wind?

Evolution used to be in the same boat. The effects of evolution are visible everywhere, in every cell of every living thing on the planet. But seeing the actual process of evolution? That was another matter.

Until now. Scientists at Michigan State University (go Spartans!) have been growing bacteria in bottles for the past 21 years. Every so often, they would freeze a sample for later study. Well, “later” is now. DNA sequencing and computer analysis have advanced to the state where they can readily map the genome of each sample. And guess what? The bugs evolved exactly as evolution says they should. Mutations in the genome pop up at random intervals. Mutations that help the bug survive—like make more efficient use of food, or fend off disease—get passed on to future generations, and eventually spread through the entire colony.

Twenty-one years may not seem like enough time for a species to change. But, as Mia Sorvino said in the truly awful 1997 movie Mimic, think generations, not time. In the two decades of study, the little bacteria went through 40 thousand generations—the equivalent of roughly 800,000 years in human terms. Plenty of opportunity for evolution to do it’s thang.

And the experiment continues. Understanding mutations in bacteria might help us understand the mutations that lead to some forms of cancer. In recent generations, the rate of mutation has increased; the scientists would like to know why.

Richard Lenski, the scientist heading up the research, has put together a video explaining his work.


Appendix removal
Appendix removalCourtesy Drvgaikwad

Why we need an appendix

Darwin thought that our appendix was vestigial, a left over organ that no longer served any purpose. Now we know that the appendix can serve as a hiding place for good gut bacteria so they can replenish the colon after unpleasant circumstances like diarrhea or colon cleansing.

"Two years ago, Duke University Medical Center researchers said that the supposedly useless appendix is actually where good gut bacteria safely hide out during some unpleasant intestinal conditions." Scientific American


The titans close on each other: Look at how much bigger they are than that house! But how do we know that's a werewolf and not just a normal giant wolf?
The titans close on each other: Look at how much bigger they are than that house! But how do we know that's a werewolf and not just a normal giant wolf?Courtesy JGordon
JK. The war has already been fought, Bigfoot totally won, you missed it, and remarkably little blood was spilled. Go figure.

A professor of the history of science at Kean University in New Jersey is arguing that Bigfoot, in fact, killed the werewolf. Not for really real, but in the collective mind of our society. However, Bigfoot had a secret weapon: Charles Darwin. (I’m assuming it was a silver-tipped Charles Darwin, at least.)

See, everybody has to be afraid of something, pretty much. And for a long time we were all, “I have to be afraid of something, huh? Well… I’m already sort of afraid of wolves, so why don’t we throw in this unnatural wolf/man mix thingy. I’ll be afraid of that.” And because we were too dumb to know about stuff like flesh eating disease and giant crocodiles and cancer, we were pretty satisfied being afraid of werewolves.

But then, says New Jersey science historian Brian Regal, then along comes ol’ Charles Darwin (and his silver tongue?), and begins to popularize evolution with On the Origin of Species. People start thinking, “Hey… wolf-man? Why did I ever think that was scary? That’s old, magicky nonsense. No, what makes sense is an ape-man. I’ll be afraid of that now.”

Science gave the supernatural a little boost of legitimacy, in a roundabout way. And at the cost of poor, dear wolf-man.

Or so says Brian Regal. Take it for what it’s worth; he’s an assistant professor, after all. I don’t trust assistant anythings. Especially not dental assistants. Regal will be presenting his theory to the British Society for the History of Science in Leicester, UK in July. He’s going to show how period artwork also reflects this werewolf to Bigfoot transition, which sounds pretty neat. So if you can make it to Leicester and into the British Society for the History of Science sometime in the next month, maybe you should check it out.

A brutal win!: Look—the wolf has pants. Case closed. Oh, right... this drawing isn't appropriate for more delicate viewers.
A brutal win!: Look—the wolf has pants. Case closed. Oh, right... this drawing isn't appropriate for more delicate viewers.Courtesy JGordon
I’m more than a little disappointed in the lack of an epic, bloody monster-on-monster battle here, though. So I’ll be drawing one for y’all just now, on the back of some paper I pulled out of my trash.


It will be a brutal fight: No one should expect to emerge unchaffed.
It will be a brutal fight: No one should expect to emerge unchaffed.Courtesy Joe Shlabotnik
For years now, members of the robust camp of biologists—paleontologists in particular—arguing that birds evolved directly from dinosaurs have kneeled on the thighs and arms of paleontologists who believe that birds did not evolve from dinosaurs, slapped their scrawny bellies pink, and rubbed dirt and grass in their bifocaled faces. And it was only right—the birds from dino people are bigger, and their veiny biceps ripple with the science of a substantial fossil record, while the clammy palms and toast-rack ribcages of the alternate theory paleontologists positively reek of onions and contrary opinions for the sake of argument. It’s only natural.

I mean, we have fossil impressions of feathers on dinosaurs, analogous bones and body-structures in birds and theropod dinosaurs (theropods, again, are two-legged meat-eaters, like T-Rex, velociraptor, etc.), similar bird-dinosaur proteins (take a look at that last link—Liza listed a bunch of other stories in that post)… the list goes on. Some paleontologists pretty much consider birds to be dinosaurs themselves (little dinos that never went extinct). The book is closed. It’s not even fun beating up on those other paleontologists anymore, because… what’s the point? You wouldn’t beat up on a worm, would you?

Ah, but these worms may have gotten their hands on something soft in this fight, and they’re about to give it a twist…

Check it out—like a hammer from nowhere, or sudden and blatant disregard for the no-scratching rule, the birds-didn’t-evolve-from-dinosaurs people have a new weapon, and they’re back on their feet.

Before we go on, I’m just going to emphasize something real quick here: nobody is saying that birds didn’t evolve, or that they didn’t evolve from something very different from birds as we know them. The question is, from what did birds first evolve, and when?

See, the winning theory is that some theropod dinosaurs began getting smaller and more birdlike in the Jurassic period (with a couple interesting exceptions eventually getting bigger and more birdlike later on, but that’s a different story.) These dinosaurs got little, and feathery, and probably started living in trees, and adapted to leaping, gliding, and eventually flying. By the late Jurassic, we have the archaeopteryx, a feathered, toothed, clawed, and bony-tailed flying machine. By the Cretaceous, there are plenty of pretty normal-looking birds around. Easy-peasy, and there are all those fossils I mentioned before.

“Oh yeah?” say the other paleontologists, “Well what about… this?!” And with that, they flick the back of their hand into the crotch of the unsuspecting bird-dino scientists.

“What are you… aaaaaaahh….” They ask.

Birds, say the alternate theory dudes, don’t have the right legs to be descended from dinosaurs. It’s so obvious, even jerks like you should have seen it.

See, birds need to breath lots of air to be able to fly (it’s hard, I’ve tried). To breath more efficiently, birds have air-sacs in addition lungs. Running all over their bodies (even in their bones) the air-sacs help pump lots of air through the birds' respiratory systems. Fossilized bones appear to show the presence of air sacs in some dinosaur species, too, and this has been seen as further evidence for the bird dinosaur link.

The new argument doesn’t dispute that everybody loves air-sacs. It points out that birds can only move their legs in a very limited way, to keep from collapsing some of their air-sacs when they breath. Birds’ femurs (their thigh bones) are largely fixed—when they walk or run, most of the movement comes from their lower legs. All other walking and running animals—including dinosaurs—have moveable thighs.

This difference, some scientists believe, is great enough that fixed-legged birds couldn’t have evolved from moving-legged dinosaurs. They might have evolved alongside dinosaurs, sharing a common ancestor, possibly one of the thecodonts. Thecodonts were dinosaur-like (but definitely not dinosaurs) and they lived during the Triassic period. Some thecodonts evolved into dinosaurs, and the group died off by the end of the Triassic.

“That’s… all?” says mainstream paleontology, straightening up and cracking its knuckles. “Someone is about to get slapped.”

“…Hiss!” say the other guys, squaring their Gollum-like shoulders.

Until I know a little more about the research, I think I have to side with the traditional birds evolved from dinosaurs argument. The alternative theory folks point out that birds are found much earlier in the fossil record than the dinosaurs they are supposed to have evolved from, but it seems to me that that’s more of a problem of overlap than of a gap—couldn’t later bird-like dinosaurs just be the descendants of the dinosaur-to-bird transitional species? It’s not as if anyone thinks that we look at individuals in the fossil record and say, “ok, you evolved from this one, which evolved from this one” etc. If birds didn’t evolved from dinosaurs like the ones we find from the Cretaceous, then we’re left with a huge gap between thecodonts and archaeopteryx and his pals. And it would have to be some pre-dinosaur thecodont, because I feel like the independent evolution of air-sacs, feathers, and everything else in both lines would be a little too much convergent evolution otherwise.

Plus… I’m not clear on why dinosaurs couldn’t have just evolved to have a fixed leg later on, when they needed more efficient respiratory systems for flying. Their mode of locomotion would have necessarily been changing anyway…


Interesting, though, right?

What do y’all think? Is this ridiculous? Or are we too attached to the mainstream model of bird evolution that we’re unable to keep an open mind to new ideas?

What makes humans unique? Do we have characteristics that make us different from other animals? PBS will be broadcasting a three-part series on the topic this fall. In advance of the series premiere, the producers want you to tell them why humans are special. You can submit a photo, a video, or text. Some entries will appear on screen, so make a grab for your 15 seconds of fame, and send in your ideas.


Darwinius  masillae
Darwinius masillaeCourtesy PLoS
There you were, thinking that lemurs were barely your relatives. It’s okay, I understand. I mean, Prosimians? Really? Sure, we’re all members of the primate family, but, like, two steps removed, like those cousins in Kentucky your mom pretends don’t exist. Or something. Prosimians are the non-human evolutionary line, how primitive. Prosimians are like NASCAR, and Anthropoids, like apes and humans, are like the DAR.

But, just like every president has an embarrassing brother, so too are we related to those furry simple primates. Now, we have proof! Scientists have found a 47 million years old human ancestor, the link between these early primates and human evolutionary lineage.

“Ida,” or Darwinius masillae, was actually discovered in 1983 by a private collector, although the fossil now belongs to the Natural History Museum of Oslo. An international team of scientists has been secretly conducting an in-depth study of Ida for the past two years. Now her skeleton is 95 percent complete.The fossil is significantly older than most fossils that explain human evolution, and, unlike Lucy and other famous primate fossils, this fossil was not found in Africa’s Cradle of Mankind; Ida is a European fossil (someone call Guinness, I just set a world record for using the word “fossil” the most times in a sentence).

Arms and hands of Darwinius  masillae
Arms and hands of Darwinius masillaeCourtesy PLoS
Ida was preserved with a full stomach, so we know that she was an herbivore. I hope that in 47 million years, scientists discover me and determine that humans subsisted mainly on a diet of Cheetos and grape soda. That would be pretty awesome. Her skeleton is pretty similar to that of modern-day lemurs, but she lacks a grooming claw and a row of teeth fused together called a “toothcomb.” She also has nails instead of claws, and teeth similar to small monkeys. She had forward facing eyes, like ours, and opposable thumbs.

Foot structure of Darwinius masillae
Foot structure of Darwinius masillaeCourtesy PLoS
What really links Ida to humans is a bone in her foot, called the talus. Her talus is nearly identical to your talus, only a lot smaller. Ida serves as a sort of “missing link,” a key part of the story of human evolution. So, you know, no big.


Dinos of a feather: New fossil discoveries throw the origin of feathers into confusion.  Or possibly Confucian.
Dinos of a feather: New fossil discoveries throw the origin of feathers into confusion. Or possibly Confucian.Courtesy treehouse1977

Science has known for a while that birds evolved from dinosaurs. We’ve discussed this before on Science Buzz, particularly here and here.

Now a new fossil has emerged from China that is complicating the picture. Tianyulong confuciusi was a small, two-legged plant-eater that lived in northeastern China about 130 million years ago. Its recently-discovered fossil included clear signs of feathers. This is nothing unusual—lots of dino fossils, especially from this part of China, have feathers.

What is unusual is that Tianyulong is not related to any previously known feather-bearing dinosaur. Not even remotely. All previously know dino feathers come from theropods, the two-legged meat-eaters like T. rex. Tianyulong was a type of hadrosaur—sometimes known as a “duck-billed dinosaur.” And the last time hadrosaurs and theropods shared a common ancestor was 230 million years ago!

This discovery raises several intriguing possibilities:

1. Perhaps feathers evolved very early in dinosaur history, far earlier than we now suspect. If the very first dinosaurs had feathers, then all other dinosaurs could inherit them, even after the various branches of the dino family tree split up and went their separate ways. But if that’s true, then why have we not found feathers on more dino skeletons?

2. Perhaps feathers evolved twice—once in the theropods, and once in the hadrosaurs. That would be pretty unusual. Right now, there seems to be no information on whether these new feathers are very similar to previously-known feathers, or completely different.

3. One thing has always bugged me about the whole bird-dino link. All dinosaurs fall into two major groups: those with hips shaped like those found in modern lizards, and those with hips shaped like those found in modern birds. But all the previous bird-like features, including feathers, come from the lizard-hipped group. Seems odd to me that nature would evolve bird-like hips twice. Maybe—just maybe—birds evolved from the bird-hipped dinosaurs.

Now, there’s tons of other evidence besides just hips to link birds to theropods, so nobody is going to be re-writing the bird family tree any time soon. All we can do is keep our eyes peeled for more interesting discoveries.