Tuesday, December 4, 2018

The Beginnings of Jurassic Park: Dinosaur Blood Discovered? (A Guest Post)

A reposting of an original article by Samantha Vold

The classic tale of Jurassic Park, where dinosaurs once again walked the earth has tickled the fancy of many a reader. Dinosaur DNA preserved in a fossilized mosquito was used to bring these giants back to life. But in real life, it was previously thought that there was no possible way for organic materials to be preserved, that they often degraded within 1 million years if not rapidly attacked by bacteria and other organisms specialized in decomposition. Skin and other soft tissues, such as blood vessels, would never withstand the test of time. Or would they…?

T. rex skeleton at Palais de la découverte. Image by David Monniaux at Wikimedia

In 1992, Mary Schweitzer was staring through a microscope at a thin slice of fossilized bone, but this bone had something unusual. There were small red disks located in this tissue and each had a small dark circle in the middle resembling a cell nucleus, the command center of the cell. And these little disks very much resembled the red blood cells of reptiles, birds, and other modern-day vertebrates (excluding mammals). But it wasn’t possible, was it? These cells came from a 67 million-year old T. rex. And it was commonly accepted that organic material never lasted that long.

Comparison of red blood cells. Image by John Alan Elson at Wikimedia

This opened a huge controversy in the scientific community, but Schweitzer persisted. She consulted with her mentor, Jack Horner, a leading scientist in the paleontology field, and he told her to prove to him that they weren’t red blood cells. Schweitzer took the challenge and began to run some tests.

The first clue to these mysterious scarlet-colored cells potentially being red blood cells was the fact that they were located within blood vessel channels of the dense bone that were not filled with mineral deposits. And these microscopic structures only appeared inside the vessel channels, as would be true of blood cells.

Schweitzer then began to focus on the chemical composition of these puzzling structures. Tests showed that these “little red round things” were rich in iron, and that the iron was specific to them. Iron is important in red blood cells as it helps to transport oxygen throughout the body. And the elemental make-up of these little red round things differed greatly from the surrounding bone and sediment around them.

The next test was looking for heme, a small iron-containing molecule that gives blood its characteristic color and allows hemoglobin proteins to transport oxygen throughout the body. Schweitzer tested for this through spectroscopy tests, which measure the light that a given material emits, absorbs, and scatters. Her results from these tests were consistent with what one would find in heme, suggesting that this molecule existed in the dinosaur bone she was analyzing.

Schweitzer then conducted a few immunology tests to see if she indeed had found hemoglobin in these ancient bones. Antibodies are produced when the body detects a foreign substance that could potentially be harmful. Extracts from the dinosaur bone were injected into mice to see if antibodies were produced to ward against this new organic compound. When these antibodies were then exposed to hemoglobin from turkeys and rats, they bound to the hemoglobin. This suggested that the extracts that caused an antibody response in the mice included hemoglobin. This in turn suggested the T. rex bone contained hemoglobin, or something very similar.

Through years of research, Schweitzer has shown that what was once believed to be impossible is indeed true. Soft tissues, blood cells, and proteins can withstand the test of time. This process is possibly done through iron binding to amino acids (the molecules that make up proteins) and thereby preserve them. Research is advancing in this area, but as of yet, no DNA has been found to bring Jurassic Park to life. But for the avid believer, don’t get up hope yet. Perhaps one day we truly could walk amongst dinosaurs.


References:

Fields, Helen. (May 2006). Dinosaur Shocker. Smithsonian. Smithsonian Magazine.

Pappas, Stephanie. (13 Nov. 2013). Mysteriously Intact T. Rex Tissue Finally Explained : DNews. DNews. Live Science.

Schweitzer, M. (2010). Blood from Stone Scientific American, 303 (6), 62-69 DOI: 10.1038/scientificamerican1210-62

Tuesday, November 27, 2018

Birds, Vitamin E, and the Race Against Time: A Guest Post

A reposting of an original article by Alyssa DeRubeis

The long and tapered wings on this young
Peregrine Falcon means it was built for some
serious speed! Photo by Alyssa DeRubeis.
Maybe you’ve been put under the false assumption that humans are cool. Don’t get me wrong; our bodies can do some pretty neat physiological stuff. But I’m gonna burst your bubble: humans are lame. Just think of how fast we can run compared to a Peregrine Falcon in a full stoop: 27 MPH versus 242 MPH.

Keep thinking about all the cool things birds can do. It doesn’t take us long to realize that our feathered friends are vastly more fascinating compared to humans. Now that you’re finally admitting defeat, I ask that you read on.

The most amazing avian physiological feat is the ability to travel long distances seasonally (a.k.a migrate). Between poor weather conditions, preventing fat loss, and staying alert, migration is not easy by any means. However, birds can cope with all of these things by assimilating and using antioxidants like vitamin E.

Here’s a classic bird migration scene: thousands of Tundra Swans, geese, and ducks congregate on the Mississippi River in Minnesota. Here, they rest and refuel before continuing their journey south. Photo by Alyssa DeRubeis.

Let’s talk a little bit about bird migration. It’s a two-way street, where a migratory bird will (usually) fly north as soon as possible to rear its young, and then fly south where it can stay warm and eat all sorts of goodies. During these two bouts of intense exercise, the birds produce free radicals, which are types of atoms, molecules, and ions that can harm DNA and other important stuff inside the body. This is where vitamin E comes in to save the day, because this vitamin, along with vitamin A and carotenoids, are antioxidants. They drive away bad things like free radicals from birds’ bodies; some scientists suggest that they may even reduce risks of cancer! In the case of migrating birds, antioxidants can make this migration headache a lot more bearable.

Well, that’s great. But where do these antioxidants come from? The short answer is avian nom-noms, but it’s one thing to eat something with an antioxidant in it. It’s quite another to actually be able to assimilate and use this antioxidant. Okay…so where do the birds get this ability from? It’s parentals!

Anders Møller from the University of Paris-Sud, along with his international team including Clotilde Biard (France), Filiz Karadas (Turkey), Diego Rubolini (Italy), Nicola Saino (Italy), and Peter Surai (Scotland), pointed out that there is little research looking at maternal effects on our feathered friends. Møller hypothesized that maternal effects (the direct effects a mother has on her offspring) play a critical role in migration: If mothers put a lot of antioxidants in their eggs, the chicks will be able to absorb antioxidants better later in life. This would give these birds a competitive edge because they will migrate in a healthier condition and arrive to breeding grounds earlier.

This male Barn Swallow on the left must’ve gotten back pretty early for him to have landed himself such a beautiful female. Thank you, Vitamin E! Photo by Alyssa DeRubeis.

In the early 2000s, Møller and his five colleagues collected 93 bird species’ eggs. The crew was able to analyze how the natural differences in antioxidant concentrations (put in by the mother) related to the birds’ spring arrival dates in 14 of them. They found that vitamin E concentration, but not vitamin A concentration, was a reliable predictor of earlier arrival dates.

This European posse took it a step further by injecting over 700 barn swallow eggs with either a large dose of vitamin E or a dose of corn oil (which contains a small amount of vitamin E). It was soon evident that the chicks with more vitamin E were bigger than chicks that received less vitamin E, thus already giving the big chicks a competitive edge over their less vitamin E-affiliated brethren. The researchers kept track of the eggs that hatched out as males in the following spring via frequent mist-netting sessions (a bird-capturing technique). Guess what? The fellas with higher vitamin E concentrations arrived earlier on average by ten days than those with lower concentrations!

Sweet. But what does it all mean? First off, vitamin E is crucial for migratory birds because it allows them to process antioxidants more efficiently. In fact, another study done by Møller, Filiz Karadas, and Johannes Emitzoe out of University of Paris-Sud suggested that birds killed by feral cats had less vitamin E than birds that died of other reasons. Furthermore, the early birds get the worm. Events such as insect hatches—vital for baby birds—now occur earlier in the spring as temperatures rise (read: climate change). Plus, if you’re a male arriving at the breeding grounds early, you get to pick the best spots to raise your offspring.

Wood-warblers, such as this Palm Warbler, must get back to their northerly breeding grounds in a timely fashion in order to hit the insect hatch for da babies. Photo by Alyssa DeRubeis.

Obviously, there’s an advantage to up the vitamin E intake and get a head start as a developing embryo. In an egg, most nutrients come from the yolk…which comes from the mother. The healthier the mother, the more vitamin E she will put in her eggs. And vitamin E isn’t produced internally; birds must consume it. While Møller’s paper on maternal effects states that vitamin E can be found widely in nature, a separate study found no apparent association between vitamin E and avian diet. Hmm. So then where DO birds get vitamin E from? Is it a limiting resource? Is there competition for it?

Clearly, we’ve got some questions and answers. As the field of “birdology,” advances, we will learn more and keep humans jealous of birds for years to come.


REFERENCES

1. Møller, A., Biard, C., Karadas, F., Rubolini, D., Saino, N., & Surai, P. (2011). Maternal effects and changing phenology of bird migration Climate Research, 49 (3), 201-210 DOI: 10.3354/cr01030

2. Møller AP, Erritzøe J, & Karadas F (2010). Levels of antioxidants in rural and urban birds and their consequences. Oecologia, 163 (1), 35-45 PMID: 20012100

3. Cohen, A., McGraw, K., & Robinson, W. (2009). Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species Oecologia, 161 (4), 673-683 DOI: 10.1007/s00442-009-1423-9

Tuesday, November 20, 2018

Science Beat: Round 9

If you're stressing out over midterms and you learn science better with a beat, take an educational break:

Chemistry:




Cellular Biology:




Genetics:




Which was your favorite? If you liked these, check out other science songs worth learning at Science Beat, Science Beat: Round 2, Science Beat: Round 3, Science Beat: Round 4, Science Beat: Round 5, Science Beat: Round 6, Science Beat: Round 7, Science Beat: Round 8, and Science Song Playlist. Check out some song battles about the life of scientists at The Science Life, Scientist Swagger and Battle of The Grad Programs! And if you feel so inspired, make a video of your own, upload it on YouTube and send me a link to include in a future post!

Tuesday, November 13, 2018

Can Animals Sense Each Other’s Wants and Hopes?

A repost of an original article from November 13, 2013.

Is the ability to empathize uniquely human? This question has long been pondered by philosophers and animal behaviorists alike. Empathy depends in part on the ability to recognize the wants and hopes of others. A study by researchers at the University of Cambridge suggests that we may not be alone with this ability.

A male Eurasian jay feeds his female mate. Photo provided by Ljerka Ostojić.
Ljerka Ostojić, Rachael Shaw, Lucy Cheke, and Nicky Clayton conducted a series of studies on Eurasian jays to explore whether male jays could perceive changes in what their female partners desired. Eurasian jays are a good species with which to explore this phenomenon because males routinely provide food to their female mates as a part of their courtship. The researchers wanted to know if males would adjust what food items males offered their mates depending on what food type the females wanted more.

In order to make a female prefer one food type over another, the researchers fed each female one of two food types (wax moth larvae and mealworm larvae) until they were full. But being full of one type of food doesn’t mean you can’t find room for desert, right? So when the researchers then offered the females access to both wax moth larvae and mealworm larvae, those that had previously eaten wax moth larvae now preferred mealworm larvae and those that had previously eaten mealworm larvae now preferred wax moth larvae. But could their male partners tell what they preferred at that moment?

In order to test whether male jays were sensitive to their partners’ desires, the researchers fed the females either wax moth larvae or mealworm larvae until they were full. They did this while their male partners watched from behind a transparent screen. They then removed the screen and gave the males 20 opportunities to choose between a single wax moth larvae or mealworm larvae to feed their partner. In this context, males usually chose to share with their mates the food that their partners preferred rather than the food their partners had already been fed! But are the males responding to their mate’s behavior or are they responding to what they saw when the females were eating earlier?



This video (provided by Ljerka Ostojić) shows the experimental process
in which the male chooses a food type and then shares it with his mate.

The researchers repeated the study with an opaque screen so the males could not see their mates while the females gorged on one particular food type. Without the ability to see the mate eating beforehand, males chose both food types equally and did not attend to their mate’s preferences. Because the females still had a preference for the opposite food type but the males were not adjusting for that preference, this means that the males are not responding to their mate’s behavior in this experiment or the previous one. This suggests that if male Eurasian jays see what their mates are eating, then somehow they have the ability to know to give their mate the opposite food type!

Whether this process involves the males having an understanding of their mate’s desires or some other mechanism is not fully known. But male Eurasian jays are certainly adjusting what they give their mates according to what she wants. Now if we can only teach human males to do that!

Want to know more? Check this out:

Ostojić, L., Shaw, R.C., Cheke, L.G., & Clayton, N.S. (2013). Evidence suggesting that desire-state attribution may govern food sharing in Eurasian jays PNAS, 110 (10), 4123-4128 DOI: 10.1073/pnas.1209926110

Tuesday, November 6, 2018

Striving for a Honeybee Democracy

A revision of an article from August 14, 2017.

Democracy is hard. And slow. And complicated. But if it is done well, it can result consistently in the best decisions and courses of action for a group. Just ask honeybees.

When a honeybee hive becomes overcrowded, the colony (which can have membership in the tens of thousands) divides in what will be one of the riskiest and potentially deadliest decisions of their lives. About a third of the worker bees will stay home to rear a new queen while the old queen and the rest of the hive will leave to establish a new hive. The newly homeless colony will coalesce on a nearby branch while they search out and decide among new home options. This process can take anywhere from hours to days, during which the colony is vulnerable and exposed. But they can’t be too hasty: choosing a new home that is too small or too exposed could be equally deadly.

Our homeless honeybee swarm found an unconventional "branch". We'd better
decide on a new home soon! Photo by Nino Barbieri at Wikimedia.

Although each swarm has a queen, she plays no role in making this life-or-death decision. Rather, this decision is made by a consensus among 300-500 scout bees after an intense “dance-debate”. Then, as a single united swarm, they leave their branch and move into their new home. At this point, it’s critical that the swarm is unified in their choice of home site, because a split-decision runs the risk of creating a chaos in which the one and only queen can be lost and the entire hive will perish. This is a high-stakes decision that honeybees make democratically, efficiently, and amazingly, they almost always make the best possible choice! How do they do that? And how can we do that?

The honeybee house-hunting process has several features that allow them, as a group, to hone in on the best possible solution. The process begins when a scout discovers a site that has the potential to be a new home. She returns to her swarm and reports on this site, using a waggle dance that encodes the direction and distance to the site and her estimate of its quality. The longer she dances, the more suitable she perceived the site to be. Other scouts do the same, perhaps visiting the same site or maybe a new one, and they report their findings in dance when they return. (Importantly, scouts only dance for sites that they have seen themselves). As more scouts are recruited, the swarm breaks into a dancing frenzy with many scouts dancing for multiple possible sites. Over time, scouts that are less enthusiastic about their discovered site stop dancing, in part discouraged by dancers for other sites that head-bump them while beeping. Eventually, the remaining dancing scouts are unified in their dance for what is almost always the best site. The swarm warms up their flight muscles and off they go, in unison, to their new home.

Each dot represents where on the body this dancer was head-bumped by a dancer for a
competing site. Each time she's bumped, she's a little less enthusiastic about her own dance.
Figure from Seeley, et al. 2012 paper in Science.

What can we learn from these democratic experts? As much as I would love to see Congress in a vigorous dance-debate head-butting one another, I don't think that is the take-home message of choice. Tom Seeley at Cornell University has gained tremendous insight into effective group decision-making from his years observing honeybees, which he shares with us in his book, Honeybee Democracy. Tom has summarized his wisdom gained from observing honeybees in the following:

Members of Highly Effective Hives:

1. share a goal

2. search broadly to find possible solutions to the problem

3. contribute their information freely and honestly

4. evaluate the options independently and vote independently

5. aggregate their votes fairly

All of these critical guidelines can be encapsulated with a single objective: The decision-making body needs to objectively consider a range of information from individuals with diverse backgrounds, expertise, and knowledge. We can apply this to our own human decision-making: It means that we all need to vote objectively and honestly and independently. This means casting votes that are consistent with our own information and judgements, even when they are not consistent with the policical party we may align ourselves with. It also means that if you don't agree with the decisions of your School Board, Town Board, City Council, County Legislature, State Legislature, or National Legislature, then your background, expertise and knowledge are likely missing from the deciding body. Yes, you can write and call your representatives and provide them with part of your knowledge, or you can run for office yourself and make people with your background truly included in the decision-making process.

Many feel that our hive has been homelessly clinging to our exposed branch for too long. If we are going to make good, well-informed, effective, and efficient decisions, we need open and respectful communication across diverse backgrounds. Independent thinking and diversity improves the quality of the decisions that affect us all. If honeybees can do it, so can we.


Want to know more? Check these out:

1. Honeybee Democracy by Thomas Seeley

2. Seeley, T., Visscher, P., Schlegel, T., Hogan, P., Franks, N., & Marshall, J. (2011). Stop Signals Provide Cross Inhibition in Collective Decision-Making by Honeybee Swarms Science, 335 (6064), 108-111 DOI: 10.1126/science.1210361

3. List, C., Elsholtz, C., & Seeley, T. (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms Philosophical Transactions of the Royal Society B: Biological Sciences, 364 (1518), 755-762 DOI: 10.1098/rstb.2008.0277

Tuesday, October 30, 2018

Nature's Halloween Costumes

A repost of an original article from October 23, 2013.

Image by Steve at Wikimedia Commons.
It seems like everyone is racking their brains to come up with a great Halloween costume. But we’re not the only ones to disguise ourselves as something we’re not. Many animals put on costumes just like we do. Take this gharial crocodile for example (do you see him?), covering himself in parts of his environment to hide.

Other animals, like this tawny frogmouth below, develop physical appearances that help them blend in with their surroundings. When threatened, these birds shut their eyes, erect their feathers and point their beak in such a way to match the color and texture of the tree bark.

Image by C Coverdale at Wikimedia Commons.
Rather than hide, some animals have a physical appearance to disguise themselves as other species that are often fierce, toxic or venomous. This type of mimicry is called Batesian mimicry, named after Henry Walter Bates, the English naturalist who studied butterflies in the Amazon and gave the first scientific description of animal mimicry. This plate from Bates’ 1862 paper, Contributions to an Insect Fauna of the Amazon Valley: Heliconiidae, illustrates Batesian mimicry between various toxic butterfly species (in the second and bottom rows) and their harmless mimics (in the top and third rows).

This plate from Bates’ 1862 paper, Contributions to an Insect Fauna of
the Amazon Valley: Heliconiidae is available on Wikipedia Commons.
The bluestriped fangblenny takes its costume another step further, by changing its shape, colors, and behavior to match the company. This fish changes its colors to match other innocuous fish species that are around so it can sneak up and bite unsuspecting larger fish that would otherwise bite them back! Learn more about them here.

The fish on the far left is a juvenile cleaner wrasse in the act of cleaning another fish. The two fish in
the middle and on the right are both bluestriped fangblennies, one in its cleaner wrasse-mimicking
coloration (middle) and the other not (right). Figure from the Cheney, 2013 article in Behavioral Ecology.
But the Master of Disguise title has got to go to the mimic octopus. This animal can change its color, shape and behavior to look and behave like a wide range of creatures, including an innocuous flounder, a poisonous lionfish, or even a dangerous sea snake! Check it out in action:




Tuesday, October 23, 2018

Vampires!

Photo by Alejandro Lunadei at Wikimedia.
A reposting of an original article from October 19, 2015

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Tuesday, October 16, 2018

The Smell of Fear

A repost of an original article from October 24, 2012.

Several animals, many of them insects, crustaceans and fish, can smell when their fellow peers are scared. A kind of superpower for superwimps, this is an especially useful ability for prey species. An animal that can smell that its neighbor is scared is more likely to be able to avoid predators it hasn’t detected yet.

Who can smell when you're scared? Photo provided by Freedigitalphotos.net.

“What does fear smell like?” you ask. Pee, of course.

I mean, that has to be the answer, right? It only makes sense that the smell of someone who has had the piss scared out of them is, well… piss. But do animals use that as a cue that a predator may be lurking?

Canadian researchers Grant Brown, Christopher Jackson, Patrick Malka, Élisa Jaques, and Marc-Andre Couturier at Concordia University set out to test whether prey fish species use urea, a component of fish pee, as a warning signal.

A convict cichlid in wide-eyed
terror... Okay, fine. They're
always wide-eyed. Photo by
Dean Pemberton at Wikimedia.

First, the researchers tested the responses of convict cichlids and rainbow trout, two freshwater prey fish species, to water from tanks of fish that had been spooked by a fake predator model and to water from tanks of fish that were calm and relaxed. They found that when these fish were exposed to water from spooked fish, they behaved as if they were spooked too (they stopped feeding and moving). But when they were exposed to water from relaxed fish, they fed and moved around normally. Something in the water that the spooked fish were in was making the new fish act scared!

To find out if the fish may be responding to urea, they put one of three different concentrations of urea or just plain water into the tanks of cichlids and trout. The cichlids responded to all three doses of urea, but not the plain water, with a fear response (they stopped feeding and moving again). The trout acted fearfully when the two highest doses of urea, but not the lowest urea dose or plain water, were put in their tank. Urea seems to send a smelly signal to these prey fish to “Sit tight – Something scary this way comes”. And the more urea in the water, the scarier!

But wait a minute: Does this mean that every time a fish takes a wiz, all his buddies run and hide? That would be ridiculous. Not only do freshwater fish pee a LOT, many are also regularly releasing urea through their gills (I know, gross, right? But not nearly as gross as the fact that many cigarette companies add urea to cigarettes to add flavor).

The researchers figured that background levels of urea in the water are inevitable and should reduce fishes fear responses to urea. They put cichlids and trout in tanks with water that either had a low level of urea, a high level of urea, or no urea at all. Then they waited 30 minutes, which was enough time for the fish to calm down, move around and eat normally. Then they added an additional pulse of water, a medium dose of urea, or a high dose of urea. Generally, the more urea the fish were exposed to for the 30 minute period, the less responsive they were to the pulse of urea. Just like the scientists predicted.

A rainbow trout smells its surroundings.
Photo at Wikimedia taken by Ken Hammond at the USDA.

But we still don’t know exactly what this means. Maybe the initial dose of urea makes the fish hide at first, but later realize that there was no predator and decide to eat. Then the second pulse of urea may be seen by the fish as “crying wolf”. Alternatively, maybe the presence of urea already in the water masks the fishes’ ability to detect the second urea pulse. Or maybe both explanations are true.

Urea, which is only a small component of freshwater fish urine, is not the whole story. Urea and possibly stress hormones make up what scientists refer to as disturbance cues. Steroid hormones that are involved in stress and sexual behaviors play a role in sending smelly signals in a number of species, so it makes sense that stress hormones may be part of this fearful fish smell. But fish also rely on damage-released alarm cues and the odor of their predators to know that a predator may be near. Scientists are just starting to get a whiff of what makes up the smell of fear.

Want to know more? Check these out:

1. Brown, G.E., Jackson, C.D., Malka, P.H., Jacques, É., & Couturier, M-A. (2012). Disturbance cues in freshwater prey fishes: Does urea function as an ‘early warning cue’ in juvenile convict cichlids and rainbow trout? Current Zoology, 58 (2), 250-259

2. Chivers, D.P., Brown, G.E. & Ferrari, M.C.O. (2012). Evolution of fish alarm substances. In: Chemical Ecology in Aquatic Systems. C. Brömark and L.-A. Hansson (eds). pp 127-139. Oxford University Press, Oxford.

3. Brown, G.E., Ferrari, M.C.O. & Chivers, D.P. (2011). Learning about danger: chemical alarm cues and threat-sensitive assessment of predation risk by fishes. In: Fish Cognition and Behaviour, 2nd ed. C. Brown, K.N. Laland and J. Krause (eds). pp. 59-80, Blackwell, London.

Tuesday, October 9, 2018

Caught in My Web: Mind-Altering Substances

Image by Luc Viatour at Wikimedia Commons
Drunken birds have gone viral this week! For this edition of Caught in My Web, we wonder if animals alter their mental states like people do.

1. Drunk Minnesotan birds are flying into windows! At least that is what the viral story says. But the truth may be a bit more measured. As the Police Chief of Gilbert, Minnesota says, “It sounds like every bird in our town is hammered, and that’s not the case.” Read the real story here.

2. But do wild animals really drink alcohol? Not in the way that we do, maybe, but many consume overly fermented fruits. Some have developed a tolerance to the high alcohol content, others, not so much. Just ask this poor drunk moose that got herself stuck in a tree after eating too many fermented apples.

3. But it’s not just fermented fruits that get animals drunk. Some fish can make their own alcohol to help them survive a long winter under the ice.

4. What about the effects of other mind-altering substances on animals? Ever wonder what kind of web a spider would make on different drugs? In 1948, a zoologist at the University of Tubingen in Germany by the name of H.M. Peters did.



5. Octopuses are normally very solitary creatures… that is, unless they are given ecstasy. Apparently, even octopuses seek social interactions when they take the common party drug.

Tuesday, October 2, 2018

Friends Without Benefits: A Guest Post

A reposting of an original article by Joseph McDonald

Do you want to avoid the friend zone?
Photo by freedigitalphotos.net.
Guys DREAD the friend zone. That heart-aching moment when the girl you’ve been fawning over for years says you’re the best listener, the sister she never had, or so much better than a diary! You’ve been so nice to her and her friends, listening to all their drama. But that’s just the problem... you’re too nice to too many people.

Research performed by Aaron Lukaszewski and Jim Roney at the University of California – Santa Barbara (UCSB) tested whether preferences for personality traits were dependent on who the target was. In Experiment 1, they asked UCSB undergrads, on a scale from 1 to 7, the degree to which their ideal partner would display certain traits towards them and towards others. These traits included synonyms for kindness (e.g. affectionate, considerate, generous, etc.), trustworthiness (committed, dependable, devoted, etc.), and dominance (aggressive, brave, bold, etc.). Experiment 2 replicated the procedures of Experiment 1. The only difference was that the term “others” was divided into subsets including unspecified, family/friends, opposite sex non-family/friend, and same-sex non-family/friend.

Let’s go over the do’s and don’ts so that future “nice guys” aren’t friend zoned. According to the findings, as graphed below:

Figure from Aaron and Jim's 2010 Evolution and Human Behavior paper.
1. Women generally prefer men who are kind and trustworthy. So, to get that girl, don’t be mean; that’s not the point. This isn’t 3rd grade so don’t pull her hair and expect her to know that you LIKE-like her.

2. Women prefer men who are kinder and more trustworthy towards them than anyone else. So it’s not so much whether you are nice enough, its whether she knows you are nicer to her than anyone else.

3. Women prefer men who display similar amounts of dominance as they do kindness. Dominance isn’t a bad thing, as long as you can distinguish her friends from her foes; especially her male friends.

4. To make things more complicated, women also prefer men who are directly dominant toward other men but don’t display dominance toward them or their family/friends, whether male or female. Some guys may want to befriend these other men, but be weary. Women preferred dominance over kindness in this situation, so kindness may not be enough.

These preferences may have developed to avoid mating with someone willing to expend physical and material resources for extramarital relationships, and invest greater in her and the children. Moderate kindness and trustworthiness toward others will maintain social relationships and prevent detrimental relationships, which may be why women generally prefer kind and trustworthy guys. But in all fairness, women can be in the friend zone too; just look at Deenah and Vinny (excuse the shameful Jersey Shore reference).

There are some things that guys look for in a mate, so ladies, here is a little advice:

1. Guys generally want a mate who is kind and trustworthy, too. We’re not that different; so don’t act a little crazy because you think he likes it. He doesn’t.

2. Guys also prefer women who display dominance toward other women (non- family/friend). Don’t be afraid to put that random girl with the prying eyes in her place.

Contrary to the hypotheses predicting female mate preferences, male mate preferences may have developed as a way to take advantage of strong female-based social hierarchies. No matter what the reasoning, however, if you can
1) be kinder and more trustworthy towards that special someone than anyone else and
2) display dominance over other same-sex people, then feel free to say good-bye to the friend zone!


For further details, check out the original experiment:

Lukaszewski, A., & Roney, J. (2010). Kind toward whom? Mate preferences for personality traits are target specific Evolution and Human Behavior, 31 (1), 29-38 DOI: 10.1016/j.evolhumbehav.2009.06.008

Tuesday, September 25, 2018

Caught in My Web: We Are Primates

Image by Luc Viatour at Wikimedia Commons
If the news cycle these days has you wondering about our own humanity, take a moment to reflect on our primate nature. For this edition of Caught in My Web, let's explore primate behavior in the news.

1. Elizabeth Preston at Discover writes about lemur "stink flirting" in High-Ranking Male Primates Keep Wafting Their Sex Stink at Females, Who Hate It.

2. Janelle Weaver discusses how primates grant favors for their own social benefit at Nature in Monkeys Go Out on a Limb to Show Gratitude.

3. Roxanne Khamsi at NewScientist reports that Envious Monkeys Can Spot a Fair Deal.

4. Writing for The Verge, Angela Chen explains how we discovered that bonobos prefer to befriend bullies in For Bonobos, Nice Guys Finish Last.

5. In Those Lying Apes, Dale Peterson of Psychology Today discusses chimpanzee deception.

Sound familiar?

Tuesday, September 18, 2018

Epigenetics: The Fusion of Nature and Nurture (A Guest Post)

A reposting of an original article by Tricia Horvath on August 14, 2013.

For decades scientists have been debating what makes a person who they are. Is someone’s personality, appearance, and medical history determined by their nature (their hardwired genes with the environment playing no role) or nurturing (how they were raised, and what they encountered in their environment growing up)? Many scientists were convinced that only one of these things, nature or nurture, could be responsible for determining a person’s fate. For instance, those who believed in nurture as the prevailing force thought that a person’s specific genes had nothing to do with how they behaved. Although ample evidence has been built up on both sides, scientists now know that the answer is actually both!

If you need convincing, just think about identical twins. Identical twins are genetic clones (all of their genes are exactly the same). These twins are very similar to each other in many ways such as physical appearance and personalities, even if they are separated at birth and raised apart from one another. However, anyone who has spent significant time with identical twins knows that each twin is their own person, and as they get older and spend less time together the personalities of the twins will continue to diverge. If nature (just genes) was in charge, identical twins would be the same in every respect. If nurture (just environment) was in charge, identical twins would be no more similar than any pair of siblings.

Genes are like pages in an
instruction manual for ourselves.
If genes are the pages in our
instruction manual, then DNA
is the actual book. Image by
tungphoto at freedigitalfotos.net.
So how is any of this possible? The answer lies in a field called epigenetics. Epigenetics studies how the environment interacts with genes to change their expression. Genes are like pages in an instruction manual for ourselves. In order for certain traits to be expressed, these genes/pages need to be read. If a gene cannot be read, then the trait it represents will not be expressed.

The environment plays a large role in determining which genes can be read, and therefore what traits are expressed. However, if a person does not have the genes for a specific trait (their book does not have those pages) that trait could never be expressed. For example, no matter how much time you spend in the water growing up, you will never grow a mermaid tail because you don’t have the genes for a mermaid tail. In this example, spending a lot of time in the water growing up would be part of your nurturing, and the lack of genes for a mermaid tail would be part of your nature. Even though having a mermaid tail would be beneficial in the water, the environment cannot interact with your genes to give you a mermaid tail because you simply don’t have the genes. Therefore epigenetics only works if you have the right genes.


How does epigenetics work?


DNA is the long strings of genetic material that are found in every cell (and every cell has exactly the same DNA). Genes are strung together on the DNA strings: If genes are the pages in our instruction manual, then DNA is the actual book. Each gene has a section with “read” or “don’t read” signs. The gene will be read, or not read depending on which of these signs is showing. The environment can determine which genes are read (and therefore which traits are expressed) by covering up these signs.
You’re less likely to stop if you don’t see the sign.
Photo by Nicholas A. Tonelli at Flickr.

The first player in covering up one of these signs is a methyl mark. Methyl marks are little chemical tags that get attached to certain parts of DNA. Methyl marks have two jobs. First, they partially cover up one of the signs (“read” or “don’t read”). Second, they help attract proteins that can help completely cover up the sign.

Before we talk about these other factors, it is important to understand a few structural aspects of DNA. DNA exists in cells loosely wrapped around proteins called histones. This looks like beads (histones) on a string (DNA). DNA wraps around histones easily because DNA is negatively charged and histones are positively charged, and oppositely charged things attract one another. (Think about magnets that stick together when the opposite poles are facing each other, but repel each other when the same poles are facing each other.) In order to keep the DNA from wrapping too tightly around the histones, acetyl groups are added to the histones. Acetyl groups cover up the positive charges on the histones. This makes the histones less positively charged so they don’t attract the DNA as strongly. (This would be like making one of the magnets less strong. It is easier to pull apart two magnets that aren’t strongly attracted to each other.)

This diagram of epigenetic mechanisms is by NIH at Wikimedia Commons.

When methyl marks are present on DNA they attract proteins that remove the acetyl groups. This causes the DNA to wrap around the now more positively-charged histones very tightly. (The magnet is stronger now). When a whole section of a gene becomes wound up this tightly it leads to a complete covering up of the “read” or “don’t read” sign. Sometimes this can also happen on part of the gene that would normally be read (the actual page of the instruction manual). If enough of the gene is covered up by the DNA wrapping too tightly around the histones, then the gene cannot be read (imagine if there was a large object covering the page you wanted to read in the instruction manual).

Once a “read” or “don’t read” sign is covered up, it is not necessarily covered up for the rest of your life. Instead, the environment can remove methyl marks from DNA and add acetyl groups back onto the histones (covering up the positive charge on the histones, making them attract the DNA less strongly). This would uncover the sign and allow it to be read once more.

All of this means that traits (including behavior) may be influenced by both genes and the environment. Although the genes we are born with only make it possible for us to express certain traits, our environment helps determine which of those traits are actually expressed. If our environment changes, the traits we express can change! Because we can change our environments, we have the power to change ourselves!

Tuesday, September 11, 2018

Exploring How Predators Hunt

By Jon Clark

A "Lion King" in his natural habitat. Photo by Jon Clark.
Predatory animals are a huge obsession for most children at some point. From that picture book about the cool T-Rex to watching “The Lion King” millions of times, we’re fascinated with the kings of the food chain. And let’s be honest, even as adults they’re still pretty neat to us. Why else take a grand safari adventure to see lions and other animals in their natural habitat? So to fuel that curiosity, below is a guide to how predators hunt. It might just help you understand animal movements and behavior for watching wildlife.


The basics of how predators hunt


Predators are, of course, animals that feed on other animals. These predators rely on the flesh of other animals as a resource for their survival and are highly skilled at finding and catching it. Predators sit at the top of a delicate food web, all components of which fit together to keep the environment balanced over time.

Different types of predators have four main hunting strategies for finding their prey. According to an article from Idaho Public Television, they are:

  • Chase: Think of an eagle diving for a mouse. This is chase behavior in predators. This method requires a delicate balance of hunting down food that provides enough energy and nutrition to offset the energy cost of running that food source down.

  • Stalk: For this method, think of an egret or crane standing motionless or walking slowly in water, and then lunging as a tasty morsel goes by. This method is a huge time sink for the animal as it moves from cover to cover getting incrementally closer to it’s prey. It also takes far less energy, however, as only a small burst of speed is required at the end. This means that these predators can often live off of smaller prey. 

  • Ambush: Lion researcher, George Schaller, watched a group of gazelles in the Serengeti. In order to access water, there was a patch of thick brush they would need to cross. As the gazelles entered the brush, Schaller watched as the lions hiding in wait, instantly ambushed and ate one of the gazelles. Due to their long manes and tan color, lions are nearly undetectable in such cover. The ambush requires a great deal of time, as it relies on other animals to wander into the area. For predators that have the patience, the success rates are quite high.

  • Teamwork: Think of wolves working as a pack to take down a deer. This is one of the most exciting ways of how predators hunt. Teamwork allows the animals to pursue large and fast prey, scoring large amounts of food for the group. This is arguably one of the most successful tactics as seasoned hunters can quickly steer their prey in the direction of the other party. Additionally, the energy required for the chase and kill can be dispersed across the collective group. 


Lions on the hunt


One of the coolest and most popular things to see on a safari is a lion in its own natural habitat. This mighty “King of the Jungle” hunts both independently and as part of groups. Lions hunt some of the fastest animals in the world, like the wildebeest, which can run at speeds of 50 mph. Lions themselves are not incredibly fast, so they’ve had to get smart through a variety of hunting strategies.

Because lions are also relatively lazy animals, they tend to eat larger animals – which sustain them for longer periods. These animals include antelopes, zebras and wildebeest.

A lioness. Photo by Jon Clark.

The female lionesses hunt the most often for both themselves and for the males. A lioness will stalk from cover to cover to get close to the prey animal, and then pounce at the last minute. Their prey usually has slower reaction times, so this is a solid method. If the prey sees them, the lion will act innocent by sitting up and staring off into the distance, as if to say, “I wasn’t doing anything.”

Another method lions use is to find a bush near where the prey goes often, like a watering hole, and wait until they can strike. Lions have been known to actually nap while awaiting their deadly ambush.

To catch large or fast prey, lions leverage their group numbers to help each other cut off the escape of fleeing prey. When lions decide to hunt in pairs and groups their success rate goes up from about 18 percent to 30 percent while hunting alone and in daylight, according to the African Lion & Environmental Research Trust.

When hunting in groups, lions stalk in a pattern to encircle the prey. Then some attack, driving the prey to other waiting lions. As the prey animal tires from the constant running, one or two lionesses will try to jump on the back of the animal or hang by their claws from a zebra's or gnu's or buffalo's back. This certainly makes it very hard for the poor animal to run away from the next lion, who goes for the throat to complete the hunt. It’s one of the smartest and most effective ways for how predators hunt.

Hungry cubs waiting for lunch. Photo by Jon Clark.

Lions are known for their advanced hunting skills and have mastered the art of teamwork in all of their hunting strategies, including chasing, stalking, and ambushing their prey. Embarking on an African safari will be your best chance to experience these master hunters in real life.

Tuesday, September 4, 2018

Why Ask for Directions? (A Guest Post)

A reposting of an original article by Anna Schneider on Feburary 8, 2016.

For the iconic monarch butterfly, the shorter days in fall mean it’s time to pack up and head south to a warmer climate! Just like clockwork, the Eastern population of monarch butterflies makes a 2000 mile journey to their winter paradise roosts in central Mexico. The journey in itself is one of the greatest migrations among all animals.

But here’s the catch: none of these butterflies has made this trip before. Several generations of monarchs have come and gone over the course of a summer, but the generation born in late August and early September are genetically prepared for months of survival without feeding or breeding. But their predecessors didn’t exactly leave them with a map. How do they know where to go? Do they have a map and compass inside their heads? The answer: yes! Well, sort of…

Think about this: if you were lost in the woods and needed to find south, what would you do? Here’s a hint: look up! The sun can be a great resource when you’re lost, and I’m not talking about just asking it for directions. As the Earth rotates on its axis throughout the day, the sun appears to travel overhead. By knowing approximately what time of day it is, you can determine the cardinal directions. Monarchs use specialized cells or organs called photoreceptors that respond to light to establish the position of the sun.

Representation of time compensated sun compass orientation used by monarchs;
Image created by Anna Schneider.
Until recently, it was thought that monarchs simply used the photoreceptors on the top portion of their compound eyes, called the dorsal rim. Past studies have shown that the signals are passed from the photoreceptors on to the “sun compass” region in their brains and the butterflies change direction based on that information. Like most animals, it was assumed that their internal clock was located inside their brains. However, recent research has demonstrated that individuals whose antennae have been painted or removed altogether become disoriented when placed in flight simulators. These monarchs do not adjust for the time of day when trying to fly south. When those same antennae that were removed were placed in a petri dish, they continued to respond to light and showed signs that they continued the pattern of time. This indicates that antennae and the brain are both needed for the monarchs to correctly determine their direction.

Diagram of features on the head of a monarch butterfly; Image created by Anna Schneider.
Now, estimating which way is South might be fine and dandy on a bright sunny day, but what happens when it’s cloudy? Not a problem for these super-insects! In another recent study, researchers tethered monarchs to flight simulators and altered the magnetic field conditions to see what would happen. When the magnetic field was reversed so magnetic North was in the opposite direction, the butterflies altered their bearings and flew exactly opposite as well. This suggests that monarchs could have some sort of way to detect the earth’s magnetic field, called magnetoreception, which could enhance the photoreception capabilities.

Many of the mechanisms behind the migration of these incredible creatures are yet to be discovered, but much progress has been made in the past decade. So next time you see a monarch butterfly, take a second look. There is more than meets the eye.

Sources:

Gegear, R., Foley, L., Casselman, A., & Reppert, S. (2010). Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism Nature, 463 (7282), 804-807 DOI: 10.1038/nature08719

Guerra, P., Gegear, R., & Reppert, S. (2014). A magnetic compass aids monarch butterfly migration Nature Communications, 5 DOI: 10.1038/ncomms5164

Merlin, C., Gegear, R., & Reppert, S. (2009). Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies Science, 325 (5948), 1700-1704 DOI: 10.1126/science.1176221

Steven M. Reppert. The Reppert Lab: Migration. University of Massachusetts Medical School: Department of Neurobiology.