Washington State University

Ask Dr. Universe

We eat well because bees have hairs!

January 6th, 2012

Dear Dr. Universe,
Why do bees have stuff that looks like hair? The hair on their legs looks like a real hassle, what with all the crud that sticks to it.

Dozy autumn bee. By John Spooner/Flickr

Dozy autumn bee. By John Spooner/Flickr

That crud is their food, Elliott. That’s what I learned from Steve Sheppard. He studies bees here at WSU.

In fact, these hairs (which are branched, kind of like feathers) are one of the main characteristics of bees. They use the hairs to gather plant pollen. As they crawl in and out of flowers to gather the sweet nectar that flowers produce, the flower pollen gets caught on the hairs. The bees use their legs to comb the pollen down and pack it in little pollen baskets on their legs so they can carry more.

Bees are vegetarians. Of course, they make that nectar they gather from flowers into honey, which is their food supply for the winter. But even vegetarians need protein, and that’s what the pollen provides. They use the protein they get from eating pollen to produce “brood food” in special glands in their heads. You can think of flowers as a bee supermarket—a place where they can get all their groceries!

And this brings us to another question I got, from someone who didn’t include her name: “…I would like to know why bees are important to apples.”

Great question, says Professor Sheppard. Bees love apple blossoms. And that’s lucky for the apple trees—and lucky for us. This pollen that bees collect is the “sperm” of plant reproduction. Some plants can reproduce without outside help. (We’ll get to this in the next column.) But apples produce best if they get pollen from other apple trees.

Well, someone needs to move the pollen from a blossom on one tree to a blossom on another tree so the blossom can turn into an apple. That someone, more often than not, is the honey bee!

A single full-grown apple tree can have as many as 100,000 blossoms on it. Only a fraction of those will actually develop into apples. But still, it’s fortunate for the apple tree that they have the busy little bee.

One bee will visit 10 to 15 blossoms a minute and up to 5,000 a day! In order to produce one pound of honey, says Professor Sheppard, bees have to fly about 75,000 miles, about three times around the Earth!

But here’s the key point of all this. When the bee crawls in and out of the blossom, pollen from that blossom collects on the bee’s hairs—and one bee can carry around as many as 100,000 grains of pollen. And some of the pollen already on the bee from other blossoms gets rubbed off, so the blossom gets pollinated. The bee collects nectar and pollen, the blossom gets pollinated, we get apples and honey, and everybody wins!

And it’s not just apples. Professor Sheppard says that as far as what bees do, the pollination is actually more important to us than the honey–if you can imagine. About 15 percent of what we eat—both fruits and vegetables—depends completely on insect, mostly bee, pollination. Also, a lot of things we eat depend PARTLY on bee pollination. For example, the alfalfa that cows and other animals eat is pollinated by bees.

As important as honey bees are, they are not native to North America. They were actually brought here by European settlers. Even “wild” honey bees are bees that decided to go out on their own.

So before honey bees got here, who pollinated everything? Professor Sheppard says that before the settlers and their bees got here, all sorts of pollinating insects were doing the job, including thousands of species of “solitary bees,” bees that do not gather in hives.

But at least a couple of things have changed. Much of our farming today is in “monoculture,” huge fields in one crop. This does not provide a very good place for all these other pollinators to live. Also, even if they did hang around, huge areas of one tree or crop are just too much for these insects to handle by themselves. So be kind to those honey bees!

One more thing. Professor Sheppard is very interested in how honey bees evolved and where they came from originally. In a couple of weeks, he is going to Kazakstan. He believes there might be an undiscovered species of bee that lives there that would help answer some of these questions. I’ll keep you posted.

Not everything has a reason

January 6th, 2012

Dear Dr. Universe,
Why do spiders have eight legs?
Kingston, Ontario

Tup Wanders/Flickr

Tup Wanders/Flickr

Phylogenetic inertia, that’s why.

Though I guess that’s not really WHY. So another way of answering your question is “because their ancestors had eight legs.” That’s about all I could squeeze out of Pat Carter, who studies evolutionary physiology here at Washington State University. That means he studies how animals came to work the ways they do.

Spiders belong to a large group of animals called the Chelicerata (kuh-LIH-suh-RAH-da), says Professor Carter. They are named for the snappers on their heads, their jaws, their chelicera. Some chelicera snap up and down, and some snap sideways.

The other thing that animals in the Chelicerata group have in common is four pairs of legs.

Though that doesn’t explain WHY they have four pairs of legs, does it?

Well, let’s think about horseshoe crabs, which also belong to the Chelicerata group and are actually more closely related to spiders than crabs. They also have four pairs of legs. But they also have other leg-like appendages on their abdomens. (Appendages are things that stick out from the body.) Horseshoe crabs, which haven’t changed much for hundreds of millions of years, and spiders probably developed from the same ancient relatives.

But spiders lost those extra appendages. Spiders DO, however, have a pair of appendages surrounding their chelicera. These PEDIPALPS help the spider grab food and shove it in her mouth. PEDI means foot, by the way. Get my drift?

Clearly, says Professor Carter, the Arachnids (spiders, scorpions, mites and ticks, all of which are Chelicerates) are pretty successful. They’ve been around for millions of years and show no sign of disappearing. But the same could be said for insects. In other words, six legs seem to work pretty well for insects, and eight legs seem to work pretty for spiders and their relatives.

No, I’m NOT dodging your question, though it must seem like it. It’s just, says Professor Carter, that maybe there really isn’t any REASON that spiders have eight legs. They just do. And maybe different appendages that different relatives developed came to be used differently. Just as a reminder, this process took place over millions and millions of years.

SO—for some random genetic reason, some ancient relative of the spider developed eight legs. Or maybe he developed ten legs, two of which eventually developed in a later relative into pedipalps.

People tend to think about evolution in terms of adaptation, says Professor Carter. Adaptations are features that organisms develop through genetic mutations that happen to help them adapt to their environment.

It’s NOT that these adaptations develop in ORDER to help these guys survive. Rather, these chance mutations help them survive better than similar organisms that didn’t develop the adaptations. This is part of what is called NATURAL SELECTION. Those best adapted for survival survive. Got it?

But lots of traits are NOT adaptive, says Professor Carter. They just happen. Neither are they NON-adaptive, which means the trait would make the organism LESS able to survive and reproduce.

The reason we don’t know more about spider evolution in general is that fossils of spiders are relatively rare. The first spider probably appeared around 400 million years ago. But finding a fossil that old is rare.

Scientists HAVE found many less ancient spider fossils, many of them preserved in amber, which is hardened tree sap. More than 300 species of spiders have been described from about 40 million years ago.

However, these so closely resemble modern spiders that they really don’t tell us much about spider evolution.

But back to your question. We don’t know WHY spiders have eight legs, says Professor Carter. They just do. There is no WHY. That’s part of what “phylogenetic inertia” is all about. And a big part of how evolution works.

Listening for worms

January 6th, 2012

Dear Dr. Universe,
We have a lot of robins that come in our yard to look for worms, which made me wonder: how do birds find worms underground?

Peter Cruickshank/Flickr

Peter Cruickshank/Flickr

Thank you, Charleen, for asking one of THE big questions that everyone wonders about. Of course, in spite of everyone’s wondering, this is another one of those questions whose answer no one is absolutely sure about.

I called ornithologist Richard Johnson here at WSU. He didn’t know the answer, but he dug out an article from 1965 in which a scientist from California named Frank Heppner reported the results of his worm-finding experiments with robins. After a series of experiments, Professor Heppner decided that robins find earthworms by sight.

That makes sense. Have you noticed how robins cock their heads from side to side? Their eyes are on the sides of their heads, so they have to turn their heads to see straight ahead.

However, says Professor Johnson, their EARS are also on the sides of their heads. You can’t see them, but they’re there, covered up by feathers.

So for 30 years, scientists tended to believe that robins find their food by sight.

Then we found an article that came out just last year, in a magazine called “Animal Behaviour.” Two Canadian scientists, Robert Montgomerie and Patrick Weatherhead, came up with a different conclusion.

They’d watched robins catch worms in fairly long grass, and it seemed to them that maybe they used another sense to find them. So they decided to do their own experiments.

For each experiment, they buried a bunch of mealworms in a tray of soil and let the robins go at it—but under different conditions. First, they buried two live mealworms and two that were frozen to death. The robins found the live ones, but not the dead ones. Since all the worms seemed to smell the same, the scientists concluded the robins probably don’t use their sense of smell to find them.

Another possibility was that robins sense worm vibrations in the soil. So the scientists rigged up the tray so the robins could not feel the vibrations through their feet. The robins had no problem finding worms. So vibrations are at least NOT NECESSARY for finding worms.

Next, the scientists buried the mealworms not quite an inch deep, laid a sheet of thin cardboard over the tray and put more soil on top of it. This would eliminate any visual cues, such as particles of soil moving around above the mealworm.

The result? No problem. They pecked right through the cardboard!

So where does this leave us? Besides taste, the only sense left is hearing. Do they HEAR the worms?

Professors Montgomerie and Weatherhead buried a little speaker in the soil with the worms and played “white noise” through it to block out any possible worm noise. White noise sounds like static on your radio.

Although the results were not completely clear-cut, the noise did cut down on the robins’ success rate. In fact, they didn’t even strike the ground as many times as they did in the other experiments.

So it seems that they DO hear the worms. Professors Montgomerie and Weatherhead figure the robins could hear some worms even through the white noise. Robins must have pretty sharp hearing!

By the way, what do worms moving in soil sound like? The scientists say that, when amplified, they sound like a person walking on gravel.

The Whole World Is Breathing!

January 6th, 2012

Dear Dr. Universe,
Plants give off oxygen and take in carbon dioxide. Do they do the reverse at night?

Alexis Bellido/Flickr

Alexis Bellido/Flickr

That’s right. At night, they breathe in oxygen and breathe out carbon dioxide, a process called respiration. Basically, at night they act like animals, says Gerry Edwards, a botanist here at Washington State University.

But wait a minute! Don’t plants provide us with oxygen and take in carbon dioxide?

Yes, of course. That’s photosynthesis.

So what’s going on here? Well, let’s think this through. Photosynthesis, as you probably know, is the process by which plants absorb light energy from the Sun through their leaves to make food from carbon dioxide that they absorb from the atmosphere.

Act like animals at night? Well, not quite, says Professor Edwards. Of course, plants don’t have the lungs that enable animals to breathe in oxygen and then transport it throughout their bodies via hemoglobin in their blood. Plants just suck it in as best they can.

Actually, oxygen diffuses into the plant tissue through membranes and air spaces around their cells. Plants also exchange, or “inhale” and “exhale,” carbon dioxide, oxygen and water through STOMATA, openings on the “skin” of their leaves that they can close to prevent water loss.

Lungs or not, the process of respiration is basically the same in plants and animals. Sugars break down through a process called GLYCOLYSIS and carbon enters the very tiny mitochondria within the cells, which help convert food to energy.

But photosynthesis MAKES the food in the first place. And how do plants get food to parts other than their leaves? They transport sugar through their veins to parts of the plant that do not photosynthesize, such as roots and seeds, which need energy to grow. Also, if you think about it long enough, you realize that this transfer of energy itself requires energy.

And back to your question, the whole plant also needs energy at night so it can keep on growing. Without sunlight, it has no energy source—except what it has stored during the day in the form of carbohydrates, which can be converted to sugar.

Respiration also does a lot more than just provide energy. Respiration involves at least 50 different steps. Each step in the break-up of sugars results in different compounds. Some of these compounds lead to other compounds used by the plant. Fats, oils and hormones are produced indirectly by respiration. So are compounds such as caffeine and nicotine. And rubber. And amino acids, which are needed for proteins, and nucleotides, which are building blocks for making DNA and RNA.

In spite of the surprising fact that plants produce carbon dioxide by respiration—and in spite of us animals pumping it out constantly—the proportion of carbon dioxide in the atmosphere is actually very small. Seventy-eight percent of the air is nitrogen. Twenty-one percent is oxygen. Carbon dioxide makes up only a fraction of the atmosphere, about .035 percent!

However, even a slight change in that proportion not only can lead to global climate change, but it can affect photosynthesis. More carbon dioxide doesn’t necessarily mean more photosynthesis. Some plants will sense the increase in carbon dioxide and figure they’ve had enough and, through a process called “negative feedback,” slow down their photosynthesis.

Professor Edwards is very interested in how the increase of carbon dioxide in the atmosphere will affect plant growth. Many scientists are worried that some plants may not be able to adjust on their own to the different makeup of the warmer atmosphere caused by increased carbon dioxide and other “greenhouse gases,” at least quickly enough to keep us in food.

So Professor Edwards and others are particularly interested in helping plants, through genetic modifications, adjust. The breakfast cereal you eat 50 years from now could very well be the result of work they are doing right now. But that’s another story. So stay tuned.

Not (quite) by air alone

January 6th, 2012

Dear Dr. Universe,
How do plants get their food?
San Diego, California

Sorghum, a C4 plant. Robert Hubner

Sorghum, a C4 plant that's very good at photosynthesis under adverse conditions. Robert Hubner (Read more about C4 plants in in Washington State Magazine)

How do plants get their food? Out of thin air, says Ernest Uribe, a plant physiologist here at Washington State University. A plant physiologist studies how plants work.

All living things, you realize, need energy. Animals get their energy and the materials they need to grow their bodies through the food they eat, which generally includes plants. Since plants have no mouths or digestive systems, how do they get their energy and nutrition?

Plants make themselves out of carbon dioxide from the air and water and a few minerals from the soil. They do this with the aid of sunlight, in a process called PHOTOSYNTHESIS, which means “putting together with light.”

This process was not always obvious to people. In fact, up until about 350 years ago, everybody basically agreed with Aristotle’s idea that plants just sucked their food up out of the soil as a pure “nutrient fluid.”

That’s really not a bad guess. After all, most plants do grow out of the ground. But think about it. Think about the trees in your yard. Every year the leaves fall, and you and your parents rake them up and haul them away. If that tree got its food from the soil, eventually it would suck itself a big hole, right?

This was what Jan Baptista van Helmont finally realized in the 17th century. In one of the first recorded experiments, he weighed a young willow tree, then grew it in a pot for five years. When he weighed it again, he found that it had gained 165 pounds. However, the soil in the pot had lost only a few ounces.

Van Helmont decided that it must be water that led to the tree’s weight gain and growth. Although he was wrong about the water, he was right about the tree’s food not coming from the soil—and he managed to completely change the way we think about plant nutrition.

What other scientists after van Helmont discovered is that plants use the energy of the sun to capture carbon dioxide from the air. Plants use carbon dioxide as a building block to make sugars and other carbohydrates.

How do they do this? Well, here’s where things start getting complicated, says Professor Uribe. And pretty neat.

Pigments in the leaves of plants absorb sunlight. The most important pigment is chlorophyll. Sunlight, as you might know, is actually different “wavelengths” of different colors of light. Chlorophyll absorbs blue and red light. The wavelengths of light that not absorbed are reflected—as green.

The energy absorbed from the sunlight dislodges electrons from the pigment molecules. The electrons then organize within the leaf cells into tiny electric currents. THIS is the energy that powers a series of very complicated chemical reactions. The first thing that happens is the plant splits water molecules into hydrogen and oxygen. Then it transfers hydrogen and electrons to carbon dioxide molecules.

This results in two things that are very important to us. First is the release of oxygen into the atmosphere. Second, sugar (glucose) forms from the combination of carbon dioxide, hydrogen and electrons. Here’s how chemists describe this sugar: C6H12O6. In other words, the glucose molecule is made up of 6 atoms of carbon, 12 atoms of hydrogen and 6 atoms of oxygen.

The glucose that the plant does not use immediately for food is used to make other kinds of storage carbohydrates and CELLULOSE fibers for plant structure.

However, even plants can’t live on air alone. Even though they do not suck nutrient fluid out of the soil, they do need some nutrients contained in soil. The main one is nitrogen. Nitrogen is necessary for making protein and nucleic acids. Nucleic acids are the main ingredient of DNA, the material that holds genetic information in every cell.

Plants also need phosphorus, potassium, sulfur, calcium, iron and magnesium, and a list of “micronutrients”: molybdenum, copper, zinc, manganese, boron, chlorine and nickel. And probably others in amounts too small for use to detect.

But mainly, plants get their food from the air, which is a lot more than the nothing it seems!

Trouble in Bear Land

January 6th, 2012

Dear Dr. Universe,
How many grizzly bears are left in the world?
Anthony Alvarez
New York

Winnie the grizzly bear at WSU.

Winnie the grizzly bear at WSU.

As you can imagine, counting grizzly bears is pretty hard, and estimates vary a lot. Grizzlies might be big, but they don’t care to be seen. So I checked with Rob Wielgus, a wildlife biologist here at Washington State University who studies large predators.

He estimates that in the lower United States, there are probably fewer than 700-900 grizzlies. That, he says, is probably less than 1 percent of their population before the U.S. was settled by non-natives. There were about 100,000 bears in the lower U.S. in the 1850s, but they have disappeared from 99% of their former range. Professor Wielgus adds that there are probably 700-800 grizzlies in Alberta. British Columbia might have as many as 10,000-13,000, though he says that is a government figure and could be way too high.

There MIGHT be 35,000 grizzlies in Alaska and 6,500 in the Yukon, but Professor Wielgus says these guesstimates could be way off.

But you asked about the world population. Grizzlies, also called “brown bears,” live in Asia and Europe. In fact, most of the world’s brown bears live in the conifer forests of the former Soviet Union. The total worldwide population? Perhaps 125,000-150,000, but no one really knows. Most biologists believe that grizzlies are declining worldwide.

So even 150,000 isn’t very many if present trends continue.

In spite of grizzlies being “threatened” in the lower U.S. and “vulnerable” in Canada, they are still hunted, which causes some unexpected problems, says Professor Wielgus.

One common justification for hunting grizzlies is that killing large males makes more room and more food for more cubs. According to this argument, “removing” adult males increases the number of cubs produced by females and cub survival rate. More available food means more cubs.

Professor Wielgus believes the opposite happens.

Grizzly cubs stay with their mother for as many as three to four years. The number of female grizzlies in an area depends on how much food there is. The number of male grizzlies depends on how many female grizzlies there are. If the food is plentiful, a grizzly male’s home range will be about a thousand square kilometers.

A male grizzly does not appreciate male company. He wants these females for himself, to raise HIS cubs. So if another male tries to invade his turf, he’ll kill him or chase him off.

But let’s say some trophy hunter wants a bear rug for his den, so he shoots Mr. Griz. What happens next, says Professor Wielgus, is that all these younger male grizzlies come to the funeral and start fighting for the territory.

Even if one of them chases off his competitors, that’s not good enough. HE wants the females to himself, to start producing HIS offspring. But if females are nursing cubs, they cannot get pregnant.

This is a major problem to a young male who wants his own cubs. So he starts killing the cubs to make room for his own and to get the female to breed. Grizzlies can be pretty intense.

Of course the female grizzly is not going to hang around and have her cubs killed. She might take them out of the area, maybe to where there’s less bear food and solitude, where males are unlikely to go. Maybe, in other words, to real crummy areas where food is scarce. Or she moves into human territory and starts digging through garbage cans.

So let’s sum up. What happens when somebody shoots a large male? The grizzly world gets very upset. Lots of young males, who are often troublemakers, move into the territory. Mrs. Griz might go to town to escape the new guys.

Also, more males means more demand for food. Of course, humans get all upset when the young males start showing up in their back yards and eating their sheep. So somebody decides, hey, we’ll solve this problem. We’ll shoot that male and everything will be fine.

WRONG, says Professor Wielgus. It just starts the problem all over again! The griz population gets bigger because of more young males! And more ornery.

But what happens eventually, says Professor Wielgus, is the population just can’t stand the upset. Because of the influx of males, the population goes up, up, up. Then all of a sudden, all of the offspring have been killed, there are no more females, and without females, it’s good-bye grizzlies.

So many beetles, so much time!

January 6th, 2012

Dear Dr. Universe,
How is it that every animal is different?
Valley Village, California

Entomologist Rich Zack with some of the insects in WSU's collection. Photo Robert Hubner

Entomologist Rich Zack with some of the insects in WSU's collection. Photo Robert Hubner

The fill-in-the-blank answer is “evolution.”

But if you were the type to be satisfied with fill-in-the-blank answers, you wouldn’t have asked this kind of question. So I went to talk again with Rich Zack, who runs the entomology museum here at Washington State University.

In this museum are approximately 1,250,000 dead insects representing about 50,000 species. (A species is a group of organisms with many things in common, including the ability to interbreed.) Most of these species live in the Pacific Northwest and are a fraction of the species that exist worldwide.

Biologist E.O. Wilson of Harvard has estimated that scientists have named 6,300 species of reptiles, 9,040 species of birds and 4,000 species of mammals. The total number of vertebrates (animals with backbones) they have described is around 42,580. In contrast, about one million species of insects have been identified, and some scientists think that there may be anywhere from 8 million to 30 million species of insects out there waiting to be named!

How can this be? How can there possibly be so many kinds of insects? And WHY?

Niches are one reason, says Professor Zack. A niche is an insect’s role in its community. The way an insect finds its niche is through adaptation and natural selection. As their surroundings change, insects best suited to this change survive. They are “naturally selected” to pass on that species’ genes.

A related reason there are so many insect species is they adapt by specializing. Let’s take beetles, for example.

Professor Zack says that over a third of all insect species are beetles, around 400,000 of them. And remember, that’s just the ones that have been identified. Groups, or “populations,” of species can become different for various reasons. Maybe they get separated from the others. Maybe their environment or food supply changes.

Let’s imagine, way back, that one species of beetle liked brontosaurus dung. They were perfectly happy to eat brontosaurus dung for the rest of time. Brontosaurus dung was their world!

But then, brontosauri started disappearing. Maybe a few of these beetles got hungry enough to start sampling a little dung from another plant-eating dinosaur. And maybe some of these beetles were actually able to digest this new dung without getting fatal heartburn.

One thing that makes natural selection work is that EVERY INDIVIDUAL is different. With that in mind, maybe some of the individuals able to digest the new dung were able to pass this ability to their children. And maybe some of their buddies across the swamp developed a taste for yet another variety of dinosaur dung. Not only were they able to get by on it, they even liked it!

As time passed, whatever made these different beetles able to digest different kinds of dungs got passed along to their offspring, so that they all became a new species—once they got so different they could no longer interbreed.

Now let your imagination run for a while. Think of variations on this situation over and over through time, as different populations adapted to different conditions as the environment changed.

Admittedly, insects are small, and we are big. Insects and larger mammals live and evolve at much different scales, of both time and space. Insects can pass through their whole life cycles in weeks, rather than decades, as we do. That means, says Professor Zack, that insects tend to take advantage of dividing up their habitat and becoming specialized, both because they’re smaller and because they can evolve more quickly.

But what about us? Why are humans different from monkeys and elephants and cats? Even though it takes longer for us to change, it’s basically the same idea. Over time we have adapted to the environment we live in. In the process, a BUNCH of different versions of us have come to share this world.

Chimps Just Don’t Want to Be Human!

January 6th, 2012

Dear Dr. Universe,
Is it possible to cross a chimpanzee with a human?
Dave W.

Chimpanzee mom and baby. Wikipedia

Chimpanzee mom and baby. Wikipedia

Excuse me? I suppose I’ve got the question straight, but I’m having a hard time trying to imagine my chimpanzee buddies having any desire to join the human family. No offense, but from what I’m told chimps are pretty content with how they look.

We could think about this question several different ways. The one I just referred to we could call “aesthetic.” Another is what we call “ethical.” Ethics has to do with whether something is right. And both aesthetics and ethics have something to do with the queasy feeling in your stomach about the question.

Then there’s your question: can it can be done?

So I went to ask Professor Michael Skinner. He said, “NO.”

Professor Skinner is the director of the Center for Reproductive Biology at WSU. He studies how animals reproduce, so he’s got a pretty good handle on your question. I also got the feeling he felt pretty strongly about this. So I’ll repeat his answer: “NO.”

Well, that kind of takes care of the other angles, doesn’t it?

But why not? After all, you’ve probably read that, when it comes to their genes, chimpanzees and humans are 98 or 99 percent alike.

Although humans and chimpanzees share a common ancestor, their evolution split apart millions of years ago. So the “99 percent similar” genetic makeup of humans and chimps doesn’t mean all that much.

Professor Skinner told me that the 99 percent refers only to a fairly basic comparison of proteins and not the actual “DNA sequence,” which is what really makes us what we are. In fact, scientists are busy right now trying to unravel the human DNA sequence as part of the Human Genome project.

Professor Skinner also told me that the sperm and egg from a chimp and human just wouldn’t recognize each other. Since reproduction is all about the sperm and egg getting together, this is a pretty major problem.

Within the past few years, scientists have been able to inject, with a very tiny needle, uncooperative human sperm directly into a human egg. This is called “in vitro fertilization.” But even if you tried to do this between humans and chimps, their bundles of genes, called chromosomes, wouldn’t match up.

One definition of “species,” such as humans, is that it cannot breed with another “species,” such as chimpanzees. Now, this definition doesn’t always hold up. For example, horses and donkeys can breed to make mules. But horses and donkeys are much, much closer in their ancestry than are humans and chimps. And even so, mules cannot reproduce, which means not everything between the donkey and horse matched up correctly. As Professor Skinner says, “If species COULD cross breed easily, we’d have many fewer species.”

Genetic engineers can put genes from one species into another species, but this does not make the second species part of the first. It just means the second species has some different genes.

Maybe your question comes from knowing about Oliver, the chimpanzee who lives at a place in Texas called Primarily Primates. Oliver walks upright and likes to sip beer and watch television. For these and other reasons, some people thought for a while that Oliver might be a human-chimp combination.

But recently, scientists tested Oliver’s chromosomes and found that he was indeed just a chimp. An unusual one perhaps, but a chimp. So even if chimps and humans cannot breed, Oliver has proved that chimps can develop just as bad habits as humans!

More than just a pretty bug!

January 6th, 2012

Dear Dr. Universe,
What are butterflies good for?
David Steury
Potlatch, Idaho

Fender’s blue butterflies

Fender’s blue butterflies. Read more in Washington State Magazine.

It just so happens that Robert Michael Pyle was here at Washington State University the other week to talk about butterflies. Mr. Pyle is a lepidopterist, which means he studies butterflies. He is the author of many books about nature and butterflies, including The Audubon Society Field Guide to North American Butterflies. He recently wrote a book called Chasing Monarchs, about following Monarch butterflies on their migration from British Columbia to the Mexican border!

So what are butterflies GOOD for? Humans tend to think of things as either good or bad (for humans!), and the same goes for insects. Insects are either pests or “beneficial,” which basically means “good to humans.” Well, that’s only part of the story, says Mr. Pyle.

Most insects are neither “good” nor “bad.” They’ve probably never seen a human and could care less about people. But they all perform some role in nature.

And this certainly includes butterflies.

A big job that butterflies do is pollinate plants so that plants can produce seeds and fruit. Many plants need help getting pollen from the flower’s male stamen to the ovules, either from their own flowers or from other plants of the same species. Ovules are like plant eggs, from which the seeds grow.

Many insects—including wasps, beetles, bees and flies—pollinate plants when they search for flower nectar for food. The pollen from one flower sticks to the head or legs of the insect and then falls off in another flower.

Butterflies are great pollinators, says Mr. Pyle. Their proboscis, a long feeding tube, reaches way down into the flower to suck nectar, and their heads get pollen all over them.

Butterflies are also food to many birds. They are particularly tasty when they are still caterpillars. Moth and butterfly larvae are a major food group for warblers and many other songbirds.

Butterflies, like other insects, can change plants through adaptation or evolution. Butterflies, particularly their larvae (the caterpillars), and other insects eat plants. These plants don’t always just stand there and take it. They develop defenses. One way is to produce substances that are either poisonous or taste bad to the insect.

However, many of these substances actually taste good to humans! Plants that have developed defenses against insects (and resulting good tastes to humans) include onions, cilantro, basil, cabbage and peppers.

Butterflies also let us know how the rest of nature is doing where they live. If their home is healthy, then they are usually healthy also. If their home is not healthy, then neither are they. Other animals besides butterflies are also thought of as “indicator species.” But the nice thing about butterflies, says Mr. Pyle, is that they are so visible.

If a place has a lot of butterflies, which then become fewer or disappear altogether, then that’s a pretty good sign that place has problems. Maybe too many chemicals are being used to kill other insects. Or maybe too many humans have moved in and destroyed the butterfly’s habitat. If that’s the case, the habitat has also disappeared for a lot of other animals and plants.

And when this happens, we have lost something very special. Mr. Pyle says butterflies are especially GOOD for their beauty. Imagine, he says, a world without butterflies. “I think the world would be a much poorer and sadder place without the brilliance and excitement and sheer pleasure that the sight of a butterfly brings.” I agree.

Thanks for a great question!

Why don’t you ever see dead birds in the forest?

September 22nd, 2011

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