Stories tagged human evolution

Jan
19
2010

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.

Homo erectus skull
Homo erectus skullCourtesy Thomas Roche
Just a reminder, the Twin Cities Public Television presentation of “Our Origins: The Human Spark” will be airing Sunday, January 24th at 4 PM on tpt2 and statewide on tptMN at 8 PM. It will re-air on tptLIFE on Sunday the 31st at Noon. This excellent program was produced in collaboration with the Science Museum of Minnesota and features interdisciplinary research from University of Minnesota faculty in several departments including the Department of Anthropology's Evolutionary Anthropology Lab and researchers with the Jane Goodall Institute’s Primate Center (The U of MN Evolutionary Lab is currently updating their website to incorporate 3-D interactive videos of evolutionary teaching casts so check back in the future for more interactive learning). Internationally significant work on early human evolution is being done at the University of Minnesota and there were several faculty members interviewed for the production including: Professors Michael Wilson, Gillian Monnier, Kieran McNulty, and one of my mentors Professor Martha Tappen. Don’t miss it! Check out more details at Science Buzz.

Jan
05
2010

After some three and a half billion years of life’s evolution on this planet – and after almost two million years since people recognizable as human first walked its surface – a new human burst upon the scene, apparently unannounced.

It was us.

Until then our ancestors had shared the planet with other human species. But soon there was only us, possessors of something that gave us unprecedented power over our environment and everything else alive. That something was – is – the Human Spark.

What is the nature of human uniqueness? Where did the Human Spark ignite, and when? And perhaps most tantalizingly, why?

In a three-part series to be broadcast on PBS in 2010, Alan Alda takes these questions personally, visiting with dozens of scientists on three continents, and participating directly in many experiments – including the detailed examination of his own brain.

"The Human Spark"

Twin Cities area show dates and times:

  • Wednesday, January 6, 7:00 pm, on 2
  • Thursday, January 7, 1:00 am, on 2
  • Thursday, January 7, 3:00 pm, on LIFE
  • Wednesday, January 13, 7:00 pm, on 2
  • Thursday, January 14, 1:00 am, on 2
  • Thursday, January 14, 3:00 pm, on LIFE
  • Wednesday, January 20, 7:00 pm, on 2
  • Thursday, January 21, 1:00 am, on 2
  • Thursday, January 21, 3:00 pm, on LIFE
  • Sunday, January 24, 1:00 pm, on 2
  • Sunday, January 24, 2:00 pm, on 2
  • Sunday, January 24, 3:00 pm, on 2

"Our Origins: Exploring the Human Spark"

Twin Cities area show dates and times:

  • Sunday, January 24, 4:00 pm, on 2
  • Sunday, January 24, 8:00 pm, on MN
  • Sunday, January 31, 12:00 pm, on LIFE
Dec
17
2009

Ardipithecus ramidus skull recreation: a composite image of Ardi's skull recreated with imaging technology
Ardipithecus ramidus skull recreation: a composite image of Ardi's skull recreated with imaging technologyCourtesy Tmkeesey
Move over Lucy, there is a new hominid in town. Her name is Ardi. One could say Ardipithecus ramidus to be formal. She is a 4.4 million year old ancestor of ours and nearly a million years older than Lucy (Australopithecus afarensis). She is by far the most complete of all the older hominids. Researchers have recovered feet, a leg and pelvis, hands and lower arm, along with the majority of a skull and its teeth. As an added bonus, parts of nearly three dozen more specimens were recovered during the work in the Western Afar Rift of northeastern Ethiopia. This is the same region that gave us Lucy and some early Homo species.
map of Ethiopia: the Middle Awash rift area runs northeast from Addis Ababa
map of Ethiopia: the Middle Awash rift area runs northeast from Addis AbabaCourtesy Yodod

Ardi and her kin walked upright, although their gait was debatably awkward. She retained an opposable toe which could still be used to grasp tree branches, but the remainder of the foot was built for the ground. Like later hominids, the teeth reveal a modern structure and lack enlarged canines. Her pelvis is a mosaic between chimps and Lucy. The Ilium developed short and broad more like a human, while the lower pelvis remains similar to a chimp. Ardi’s skull shows that her brain was still the size of a chimp, being smaller than Lucy’s. Its shape, however was more hominid and had begun evolve more advanced functions.

Unlike Lucy in her savannah habitat, Ardi roamed lush but temperate woodlands. More than 150,000 plant and animal fossils were recovered from the sites. Included are 20 new species of small mammals along with monkeys, antelope, elephants, and multitudes of birds. This was a much different environment than that of the savannah. Theories of the development of bipedalism on the open grasslands will be challenged now because of Ardi and her habitat.

This isn’t a recent find. The original excavations of the search teams started in 1992. But years of field work followed by more than a decade of lab time have really unearthed a mass of data about this time and place in history. 47 diverse researchers from all over the world have included excerpts of their findings about Ardi and her environment. The October 2009 special issue of the publication Science details the discovery and ongoing analysis of this latest find in the continuing quest to uncover the origins of man. With debate well underway, I’m positive we’ll all continue to learn more about our past.

more on Hominid evolution

Full story

Podcast with author Ann Gibbons

Oct
27
2009

Help this little boy find his parents: Sorry. I couldn't find any pictures from Encino Man.
Help this little boy find his parents: Sorry. I couldn't find any pictures from Encino Man.Courtesy cote
It’s a weird suggestion, I know, because you probably give a lot of thought to whom the various cavemen had sex with anyway, regardless of the weather. But give it a little extra thought today. Because it’s nice out, and the dark corners of your brain could use the sunlight.

So, you guys all know that we aren’t the only human species ever to exist, right? The human family tree had other branches before it got to us (take a look at our Human Spark feature for more on that), and there were times when more than one species lived in the same area, and—in all probability—had interactions with each other. Neanderthals, for instance, lived alongside modern humans for many thousands of years in ice age Europe. Keep in mind, “Neanderthal” isn’t just a synonym for “cave-man.” Neanderthals were a distinct species—they had heavier, longer skulls, and thick, strong bodies. The modern humans of ice age Europe would have looked, more or less, like us. And because the two species were living in the same area for so long, it seems pretty likely that they interacted. But did those interactions include, you know, dinner, dancing, and romantic music?

Svante Paabo of the Max Planck Institute for Evolutionary Anthropology in Germany says yes, for sure they were having sex.

On one hand, these are sort of fightin’ words. People have suggested that Neanderthals faded into extinction as they interbred with modern humans, but when human DNA was compared with a sequence of Neanderthal DNA, it didn’t look like there was any overlap. That is, if there was any interbreeding, the Neanderthal contributions to our genes have been so diluted with human genes that it doesn’t appear that we have any Neanderthals in our family at all.

On the other hand… Well… I mean… People do all sorts of stuff… We all just want someone to love, right? Or, you know, just think of what a puppy will do to a piece of furniture. And humans and Neanderthals are a lot more similar to each other than puppies and ottomans. Too much? I don’t think so. Look at ligers. Or tigons. Or mules. Similar animals interbreed all the time, but very often they have infertile offspring. And that would explain why we don’t see any Neanderthal genes around today—everybody could have been doing it like it was 2012, but if the offspring couldn’t reproduce it wouldn’t matter to future generations.

Another factor that could explain the lack of genetic overlap (despite Paabo’s certainty of caveman/Neanderthal sexiness) is that our Neanderthal DNA sample just isn’t good enough. Mitochondrial DNA from Neanderthals doesn’t show up in modern humans, and while that’s an incredibly valuable genetic marker, it only makes up a tiny fraction of an organism’s total DNA. The Neanderthal genome hasn’t been completely sequenced yet, and that’s what Paabo means to do. Once we can fully compare the genomes, we can see if the two species became at all mixed.

Because they were definitely doing it.

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.

May
15
2009

The best questions we bury for later: We also bury the worst questions.
The best questions we bury for later: We also bury the worst questions.Courtesy Ed Fitzgerald
Ahoy, Buzzketeers! Captain JGordon here, waltzing on the poop deck of the HMS Puddleduck, pride of the Science Museum’s little navy, and harvester of the juiciest, richest random questions.

Usually.

See, when I answer random questions, it generally goes something like this: I grab the stack of question cards and shuffle through them, “Good, good, garbage, good, garbage, garbage, garbage, good, delightful, garbage.” It’s not that I think any of your questions are garbage, of course, it’s just that many of the cards consist of vulgar personal attacks against celebrities, some are illegible, and a few are just too greasy for me to touch. And sometimes there are simply too many of them for me to address, so I select the choicest questions, to construct an enjoyable and inclusive didactic experience.

But it’s springtime, and the Puddleduck is currently taking a leisurely cruise up the coast of Knowledgarnia. (Knowledgarnia is the union of the formerly independent states of The Republic of Knowledge and Narnia. Think about Czechoslovakia, only in reverse.) The water here in the warm seas off Knowledgarnia is so shallow and clear that you can see the facts swimming lazily just beneath the surface. It is… glorious. And it suits a much more lackadaisical attitude toward question selection.

Last night, in the grips of a wild upswing of Springmania (the union of the two formerly independent psychiatric disorders spring fever and bipolar disorder) I was firing my captain’s revolver randomly into the ocean. When I woke up on the deck the next morning and crawled over to the rail, I saw that a good handful of truly random questions had been shot and killed by my… enthusiasm. Perhaps an angel guided those bullets, or perhaps it was pure chance. Either way, here they are, just as I found them:

Q: Would you eat the moon if it were made of ribs?

A: Yes, but I would eat only some of it. This is partly because I would want to leave some of the moon for people to look at, but also because the moon is too big for me to eat by myself. The mass of the moon is 7.3477 x 10^22 kg. That’s… let’s see… 73,477,000,000,000,000,000,000 kg, or 161,649,400,000,000,000,000,000 pounds. Now, if a rack of ribs weighs about 2 pounds, that means that the moon should be made of about 80,824,700,000,000,000,000,000 racks of ribs. Now, if I were to live another 60 years, and eat 2 racks of ribs a day, every day, I’d be able to eat only 43,830 racks of ribs. This would not make any appreciable dent in the mass of ribs that is the moon. Plus, I think most of them would go bad before I even got there.

Q: Why are flamingos pink?

A: Ooh! Okay! Flamingos are actually born (hatched?) gray. Don’t believe me? Take a look at this ridiculous little creature. It’s the flamingos’ food that eventually turns them pink. Flamingos eat by getting beaks full of water, and then straining out all the liquid until just little shrimp and algae are left. The shrimp and algae (which are eaten) have lots of the vitamin beta carotene in them. Beta carotene is a colorful vitamin (eating too much of it can turn your skin a little bit orange), and it makes the flamingos’ feathers pink. Viola! (In zoos, though, where flamingos might not get all the beta carotene they would in the wild, the birds are sometimes fed the pigment additive canthaxanthin, which has the same effect.)

Q: The “swine flu” was named H1N1. Why did they decide to call it H1N1?

A: Another good one! We’re all about the swine flu here at the museum (It’s interesting! Really! Look here!) so I was ready for this one. See, the “swine flu” is a form of the disease influenza, which is caused by viruses. There are a bunch of different viruses that cause influenza. They’re all related, but each variety, or strain, of virus has some subtle differences in the molecules that they’re made of. Scientists use two molecules in particular to identify different strains: hemaggluten (that’s where the “H” comes from), the molecule that allows the virus to stick to our cells and infect us, and neuraminidase (that’s the “N”), the molecule that allows viruses to exit a cell to spread the infection throughout more of the body. The numbers after H and N correspond to different variation of the two molecules. So this year’s swine flu is H1N1. The bird flu, or avian flu, in Asia that people have been concerned about for the last few years is H5N1. Does that make sense?

Q: How long can you tread water before drowning?

A: Hmm. Well, if you’re asking me, the answer is about 30 seconds. I have a narrow, dense body, and I’m not very strong, so I sink like a glass rod. I suppose it sort of depends on the person, and on the water. See, salt water is more dense than fresh water, so objects in it are more buoyant—they float better. So treading water in the ocean is easier than treading water in a lake. Also, if the water is cold, your body is going to use up more energy to keep you warm, and you’ll have less energy for treading water. A powerful swimmer can tread water for hours on end, and even after your energy is gone, you could always float on your back, keeping your face above water. I suppose, at that point, it’s just a matter of staying awake and fending off the sharks.

Q: Why is it 3 levels? I spend 11 dollars for this bull ****.

A: Sir! Well I never! Perhaps you should have saved those eleven dollars to spend on soap for your filthy mouth! Seriously, though, those three levels are jam-packed. You explored the mysteries of the human body. You floated a ball on a jet of air, and watched a tornado form from steam. I mean, did you not see the dinosaurs? Realtalk, bro: what more could you ask for?

Q: Do you know anything about Area 51, or its space objects?

A: Well… is the government watching? No? OK. Let’s do this.

“Area 51” is a nickname for a military base in Nevada. It’s part of the huge piece of land that is the Air Force’s “Nevada Test and Training Range.” Civilians generally aren’t allowed on it, and the airspace around it is restricted. There are a lot of conspiracy theories surrounding Area 51 involving time travel technology, New World Order junk, energy weapons development, etc, etc, etc. The most popular theory, of course, involves “space objects,” as you put it. Or, more specifically, space aliens. Some folks are convinced that Area 51 is used to study the remains of an alien spacecraft that crashed in Roswell, NM in 1947. Unfortunately, the argument that this is Area 51’s real purpose, or if there ever actually was alien material at Roswell, is pretty much based on conjecture, some creative interpretation of government documents, and a few personal accounts of people that claimed to have worked there. It’s not a lot to go on, and an Internet search for “Area 51” will tell you as more than I can here. I just wouldn’t write any school papers on it.

But “space objects” or no, Area 51 is a pretty interesting, sneaky sort of place. And there’s probably plenty of science (of a sort) happening there, because area is used for development and testing of new weapons and aircraft. Several stealth fighter and bomber planes got their start there, and those are pretty neat, even if aliens didn’t invent them.

Q: What do you foresee in the future for humanity in regards to our evolution, and what role might technology play in that?

A: Huh. Well, how a species evolves depends on the natural pressures that are placed on it. And evolution takes place on a huge timescale—it can be millions of years before enough changes accumulate in a species for another species to emerge from it.

But what natural pressures will humans face over the next million years? Modern humans haven’t even been around that long so far (we’re a pretty young species, at about 200,000-years-old), so saying where we’re going to end up in millions of years is awfully tricky. As the evolutionary biologist Richard Dawkins puts it in this MSNBC article on the future of human evolution, “it’s a question that any prudent evolutionist will avoid.”

But that’s a boring answer. It’s not an answer at all, I suppose. If you want to predict how we’ll evolve, I’d learn about the principles of evolution (time, natural selection, adaptation, etc), then imagine what the world of the future will be like, and then try to think how we’d need to be different to fit into that world. Will the climate be dramatically different? If we haven’t got technology to protect us from the elements, maybe our skin will change to better protect us from solar radiation, or we’ll be harrier to deal with the cold. Maybe, on average, human body types will be taller and more slender to get rid of the heat, or shorter and thicker, to reduce mass to surface area and conserve heat. Maybe we’ll have to adapt internally to deal with more or less oxygen in the air, or our digestive systems will change to eat different kinds of foods (try eating everything a goat eats—you couldn’t, because you don’t have a four-chambered stomach). Or maybe the Earth will change faster than we can, and we’ll die out altogether. It’s a creepy thought, but mass extinction events have happened over and over again in Earth’s history, eliminating thousands of species before they even got the chance to evolve.

But your mention of technology is a good point. It seems likely at this point that people might influence their own evolution through technological means. This concept is sometimes referred to as “participant evolution.” The rate at which we’re figuring out how to integrate technological components into our bodies seems to be moving a lot faster than any natural adaptations we might be undergoing. Prosthetics are getting awfully sophisticated, as are the ways we’re able to interface them (and other technology) with our brains. I mean, we’ve got monkey brains controlling robot legs and people posting to twitter using just their brains (and some fancy equipment). It seems pretty reasonable to assume that this stuff is only going to get more advanced and more common.

But participant evolution wouldn’t be restricted to just computer chips and electric motors. There’s also biotechnology; we’ve mapped the human genome, and we’re constantly advancing our genetic engineering abilities. So augmenting human evolution with technology might not necessarily lead to dudes with robot eyes and laser fingers so much as populations that have genes that protect them from cancer, allow them to live far beyond our current lifespan, and fart clouds of lavender. (I’m hoping for the lavender thing most of all.)

It’s all sort of sci-fi stuff, but when you’re dealing with what’s going to happen thousands or millions of years in the future… why not?

Q: What shampoo do you use? Why?

A: I, um, don’t really use a lot of shampoo. Why? I ran out a couple months ago, and decided it wasn’t a huge priority.

Q: How much wood can woodchucks chuck?

A: Very little, possibly none. I guess it sort of depends on what you mean by “chuck.” If “chuck” means to, like, stand next to, then I guess a woodchuck could potentially chuck lots and lots of wood. But if “chuck” means to eat, or chew, or throw, or whatever, then I’d have to stick with “very little” as my answer.

See, the name “woodchuck” probably comes from the Algonquian (a Native American language) word for this big North American rodent, “wuchak.” It sounds a little like “woodchuck,” doesn’t it? But it’s got nothing to do with wood or chucking.

One of the animal’s other names, groundhog, is maybe a little more fitting. If you were to have asked, “how much ground can a groundhog hog if a groundhog could hog ground?” I’d have said, “A groundhog actually can hog ground, and when digging a burrow (they live underground, not in trees), groundhogs have are estimated to move about 700 pounds of dirt. So 700 pounds is your answer!”

But that’s not what you asked.

Gosh. All things considered, I think that random question session went pretty well. I’ll have to do it this way more often. Until then… avast. Or whatever. It’s lunchtime.

Sep
12
2008

Three black cats: So that's a triple negative... run! Run!
Three black cats: So that's a triple negative... run! Run!Courtesy heyjupiter
Evolutionary biologists and math wizards have put their minds together to summon a pulsating, glistening packet of truth from the void.

Biting into the fruit of this magnificent spell, the meta-scientists gained the following information: superstitions, it seems, are an evolutionary adaptation.

This isn’t an entirely new train of thought, even here on Science Buzz, but this research takes the notion a little further. It has already been proposed that superstitions—false connections between cause and effect—prepare us for “just in case” scenarios. That is to say, as Gene put it, it won’t actually rain on a particular day just because we forgot our umbrellas, but thinking that that’s true will encourage us to bring our umbrellas just in case. The scientists behind this new study are looking at that idea in a more mathematical way.

They started with a similar premise: that assuming a potentially false connection between cause and effect will sometimes be beneficial. For example, to a prehistoric man, rustling grass might sometimes mean that there’s a lion getting ready to pounce on you. Even though a lion isn’t the only thing that will make grass rustle, treating rustling grass as a sign of danger isn’t a bad idea in the long run; the caveman looses nothing by avoiding grass that is actually being disturbed by the wind, but gains everything by avoiding grass the few times that it actually hides a predator.

The scientists then decided that the theory could be tested mathematically. By weighing the losses of false associations (avoiding wind rustled grass) against the gains from when those associations turn out to be real (hungry lions hiding), we can see if that sort of behavior is beneficial to survival in the long run, and will therefore be selected for evolutionarily. The model gets more complicated when there are multiple potential causes to connect to an effect (is it the rustling grass, the full moon, or the random sneezing that means a lion is on its way?), but it seems that assuming false causes is, in general, a decent survival strategy. Fortune favors the timid, apparently.

In modern times, the scientists say, this behavior can manifest in things like attitudes toward alternative and homeopathic medicines; while most of them may be ineffective, the chance that some work is enough to get people to use them all.

Superstitions like avoiding black cats, paths under ladders, and opening umbrellas indoors, however, may have more to do with evolutionarily superstitious behavior getting mixed up with culture and “modern life.” These days, the researchers point out, superstitions are probably less beneficial than they used to be.

That’s a little bit of a copout, I’d say. Fortune, after all, favors the bold, so why not go out on a limb here?

You don’t want black cats crossing your path, obviously, because a much larger black cat could be chasing them—and you don’t want to mess around with huge black cats (especially if they’re being chased by an even larger cat).

Walking under ladders is an easy one. There’s always the chance that a bucket of paint could fall on your head, and once you’ve got a bucket stuck on your head any number of awful things can and will happen to you. Trust me.

Opening umbrellas indoors—if you’re in a very small house, you could seriously damage your umbrella.

Unlucky number thirteen? Thirteen of anything can’t be divided fairly between friends, leaving you with no other option than to kill one of your friends. That’s how blood feuds start.

I should be a scientist. Or a fortune teller.

A study in Britain finds that human skulls have grown significantly larger in the last 650 years.

Unfortunately, there is no direct correlation between brain size and intelligence.