Our Solar System’s Formation Was A Lot Messier Than You Think

By Korey Haynes | January 16, 2019 11:30 am
planets superimposed on each other

The early solar system was a violent place: it wasn’t just asteroids, but whole planets that veered on strange courses. (Photo credit: NASA)

When most of us learn about the solar system, it seems like a pretty well-ordered place. Our sun formed first, about five billion years ago, and the planets appeared a little later. As a very general trend, these planets grew larger and less dense the farther from the sun they formed.  

But this story leaves out the chaotic dynamics and frenetic reshuffling that occurred when our solar system was young. Nature may like order eventually, but that order evolves out of pure chance. Our solar system may be settled down now, but in its youth, it was a wild place.

Creating Order Out of Chaos

cloud of gas with planets

The planets formed out of an initial disk of gas and dust. (Credit: NASA)

The basic story does sound ordered. Any star system begins as a vast disk of gas with a baby star forming in the center. The star absorbs the vast majority of the material in this disk, but there’s some left over. Those remnants coalesces into dust grains, which become pebbles, which become boulders and eventually planets. Meanwhile, the young star is turning on and starting to shine, creating a solar wind that starts to blow out the leftover gas. Only heavy materials are left near the star, leading to small, dense planets close by. Physics also tells us these closer planets have smaller orbits, limiting the amount of material they can encounter and nab with their growing gravitational bulk. Farther out, gas giants can form, sucking in large amounts of hydrogen and helium gas. And beyond that, you find the snow line, where ices can exist without being melted or baked away by the sun’s heat. These get incorporated into the ice giants.

That sounds very tidy and quaint, a cosmic “just-so story”, if you will. But the solar system is more messy and more complex than that. There’s the Kuiper Belt and Oort Cloud for example, swaths of detritus that aren’t collected into any one object. Mars is suspiciously tiny, and why is there an asteroid belt in the middle of the solar system anyway?

We also know that Earth was struck by some monstrous object in its early history, though where it came from is still a mystery. In any case, that planet-sized impactor gave us a moon — which turns out to be helpful in all kinds of ways. But it certainly wasn’t destined to be that way.

Planets Don’t Stay in One Place

solar system, with clouds of asteroids leading and trailing Jupiter

Jupiter still has a lot of sway in the solar system, with entire families of asteroids called Greeks and Trojans under its gravitational influence. (Credit: Roen Kelly)

Remember that Nature starts most chains of events pretty randomly. So sometimes planets will form on orbits that aren’t stable over the countless millennia of the planets’ lifetimes. Occasionally that instability means planets crash into each other. More often, it means they veer cosmically close — not colliding, but close enough for gravity and momentum to send them careening off on strange orbits. We use this “slingshot effect” all the time with spacecraft to great benefit, but random encounters result in random slingshotting. Sometimes planets may fling themselves out of the solar system entirely — like the Mars-sized object that collided with Earth to form our moon, and now is nowhere to be found. Scientists have found a few of these rogue planets, unattached to any identifiable star, drifting in the cosmos.

And our moon’s birth isn’t the only example of planets roving. Back when the solar system was young, our sun hadn’t yet blown away all the extra gas. Instead, it remained scattered throughout the planets, denser in some areas than others. Jupiter, cruising around the sun, interacted with these waves of gas and began to lose angular momentum and spiral in. As it migrated in toward the sun, it also nudged in closer to its inner neighbor, Mars, and sucked in material that by rights should have belonged to the Red Planet. This could explain why Mars somehow ended up with less material than Earth, despite having a bigger orbital path that therefore should have fed it richly enough to grow much larger. To get back where we see it in the modern era, Jupiter would then have had to reverse course, in a move researchers call a “grand tack” (as in a sailboat tacking to change direction). But why should a planet suddenly change directions?

Jupiter and Saturn still have a lot of sway in today’s solar system, thanks to their large bulks. Researchers think it’s possible that eons ago, as Jupiter spiraled in toward the sun, Saturn came chasing after. The two became locked in a resonance that spiraled them back out and cast an even stronger pull on the objects around them. Such a gravitational shove might have pushed Neptune farther out, which in turn scattered icy Kuiper Belt objects inwards. Jupiter then flung these objects all over, forming the Oort Cloud that still surrounds us.

Looking Farther From Home

planet trailing gas around a star

WASP-12b is another planet so hot it’s losing its atmosphere to its star. (Credit: ESA/Hubble)

It might help to look at these events from a more distant perspective. Since astronomers discovered the first planets outside our solar system a few decades ago, it’s been clear that other solar systems don’t look much like ours. Some of that is observational bias — it’s actually quite difficult to see planets as small as Earth orbiting as far from their star as we do from the sun.

But even the larger planets we do see look different. Astronomers have found numerous hot Jupiters, gas giants traveling on sizzling orbits close to their stars. They’ve discovered scores of super-Earths, sub-Neptune sized objects that appear to be the most common type of planet — and one that doesn’t exist in our home system. And with more systems to look at, they’ve noticed what there was evidence for in our own system the whole time: that planets often go roving.

Hot Jupiters have been confusing since astronomers first found them. It doesn’t make physical sense for a giant ball of gas to form next to a brilliantly hot star. The star will strip away that gas faster than the nascent planet’s gravity can pull it close. In fact, we can see this happening around some of the hottest exoplanets, like HD209458b. Astronomers can actually observe its atmosphere streaming away behind it, being boiled off.

Perhaps even more telling is WASP-17b, another hot Jupiter. This one orbits retrograde (backwards) to its host star, a sure sign that something wonky happened in its past, as planets can’t start out rotating the wrong way.

Astronomers also know that both of these planets are loners, like other hot Jupiters. This might have been our solar system’s fate, if Saturn hadn’t pulled Jupiter out of its downward spiral. Without that rescue mission, Jupiter might have herded the rest of the solar system into deep space. We don’t know if systems with hot Jupiters had more planets in their pasts, but we do know it would be unlikely for those hypothetical planets to survive a Jupiter-like planet’s sunward plunge.

Since we don’t have dashcam footage of the long-ago joyrides from our own solar system, it’s difficult for researchers to “prove” any of these scenarios. But the more we look at the universe around us, the more evidence we see for disrupted systems and roving planets, and the more we learn about how unique our own solar system’s history seems to be.

CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: solar system

Nobel Prize Winner: Give Scientists Time to Make ‘Curiosity-Driven’ Discoveries

By Donna Strickland, University of Waterloo | January 14, 2019 1:30 pm
Donna Stickland nobel prize award

Donna Stickland was awarded the Nobel Prize in Physics in December 2018 in Stockholm, Sweden. Her work “paved the way toward the most intense laser pulses ever created.” (Credit: Bengt Nyman/Wikimedia Commons)

Since the announcement that I won the Nobel Prize in physics for chirped pulse amplification, or CPA, there has been a lot of attention on its practical applications.

It is understandable that people want to know how it affects them. But as a scientist, I would hope society would be equally interested in fundamental science. After all, you can’t have the applications without the curiosity-driven research behind it. Learning more about science — science for science’s sake — is worth supporting.

Gérard Mourou, my co-recipient of the Nobel Prize, and I developed CPA in the mid-1980s. It all started when he wondered if we could increase laser intensity by orders of magnitude — or by factors of a thousand. He was my doctoral supervisor at the University of Rochester back then. Mourou suggested stretching an ultrashort pulse of light of low energy, amplifying it and then compressing it. As the graduate student, I had to handle the details.

Read More

CATEGORIZED UNDER: Space & Physics, Technology, Top Posts
MORE ABOUT: physics

Where Static Electricity Comes From and How It Works

static electricity

Static electricity can cause more than just a bad hair day. (Credit: Ken Bosma, CC BY)

Static electricity is a ubiquitous part of everyday life. It’s all around us, sometimes funny and obvious, as when it makes your hair stand on end, sometimes hidden and useful, as when harnessed by the electronics in your cellphone. The dry winter months are high season for an annoying downside of static electricity – electric discharges like tiny lightning zaps whenever you touch door knobs or warm blankets fresh from the clothes dryer.

Static electricity is one of the oldest scientific phenomena people observed and described. Greek philosopher Thales of Miletus made the first account; in his sixth century B.C. writings, he noted that if amber was rubbed hard enough, small dust particles will start sticking to it. Three hundred years later, Theophrastus followed up on Thales’ experiments by rubbing various kinds of stone and also observed the “power of attraction.” But neither of these natural philosophers found a satisfactory explanation for what they saw.

It took almost 2,000 more years before the English word “electricity” was first coined, based on the Latin “electricus,” meaning “like amber.” Some of the most famous experiments were conducted by Benjamin Franklin in his quest to understand the underlying mechanism of electricity – which is one of the reasons why his face smiles from the US$100 bill. People quickly recognized electricity’s potential usefulness.

Flying Boy

The amazing flying boy relies on static electricity to wow the crowd. (Credit: Frontispiece of Novi profectus in historia electricitatis, post obitum auctoris, by Christian August Hausen (1746))

Of course, in the 18th century people mostly made use of static electricity in magic tricks and other performances. For instance, Stephen Gray’s “flying boy experiment” became a popular public demonstration: He’d use a Leyden jar to charge up the youth, suspended from silk cords, and then show how he could turn book pages via static electricity, or lift small objects just using the static attraction.

Building on Franklin’s insights – including his realization that electric charge comes in positive and negative flavors, and that total charge is always conserved – we nowadays understand at the atomic level what causes the electrostatic attraction, why it can cause mini lightning bolts and how to harness what can be a nuisance for use in various modern technologies.

What are These Tiny Sparks?

Static electricity comes down to the interactive force between electrical charges. At the atomic scale, negative charges are carried by tiny elementary particles called electrons. Most electrons are neatly packed inside the bulk of matter, whether it be a hard and lifeless stone or the soft, living tissue of your body. However, many electrons also sit right on the surface of any material. Each different material holds on to these surface electrons with its own different characteristic strength. If two materials rub against each other, electrons can be ripped out of the “weaker” material and find themselves on the material with stronger binding force.

This transfer of electrons – what we know as a spark of static electricity – happens all the time. Infamous examples are children sliding down a playground slide, feet shuffling along a carpet or someone removing wool gloves in order to shake hands.

But we notice its effect more frequently in the dry months of winter, when the air has very low humidity. Dry air is an electrical insulator, whereas moist air acts as a conductor. This is what happens: In dry air, electrons get trapped on the surface with the stronger binding force. Unlike when the air is moist, they can’t find their way to flow back to the surface where they came from, and they can’t make the distribution of charges uniform again.

A static electric spark occurs when an object with a surplus of negative electrons comes close to another object with less negative charge – and the surplus of electrons is large enough to make the electrons “jump.” The electrons flow from where they’ve built up – like on you after walking across a wool rug – to the next thing you contact that doesn’t have an excess of electrons – such as a doorknob.

doorknob static electricity

You’ll feel the electrons jump. (Credit: Muhammed Ibrahim CC BY-ND)

When electrons have nowhere to go, the charge builds up on surfaces – until it reaches a critical maximum and discharges in the form of a tiny lightning bolt. Give the electrons a place to go – such as your outstretched finger – and you will most certainly feel the zap.

The Power of the Mini Sparks

Though sometimes annoying, the amount of charge in static electricity is typically quite little and rather innocent. The voltage can be about 100 times the voltage of typical power outlets. However, these huge voltages are nothing to worry about, since voltage is just a measure of the charge difference between objects. The “dangerous” quantity is current, which tells how many electrons are flowing. Since typically only a few electrons are transmitted in a static electric discharge, these zaps are pretty harmless.

Nevertheless, these little sparks can be fatal to sensitive electronics, such as the hardware components of a computer. Small currents carried by only few electrons can be enough to accidentally fry them. That’s why workers in electronic industries have to remain “grounded.” Being grounded just means maintaining a wired connection to the ground, which for the electrons looks like an empty highway “home.” Grounding yourself is easily done by touching a metal component or holding a key in your hand. Metals are very good conductors, and so electrons are quite happy to go there.

A more serious threat is an electric discharge in the vicinity of flammable gases. This is why it’s advisable to ground yourself before touching the pumps at gas stations; you don’t want a stray spark to combust any stray gasoline fumes. Or you can invest in the kind of anti-static wristband widely used by workers in the electronic industries to safely ground individuals before they work on very sensitive electronic components. They prevent static buildups using a conductive ribbon that coils around your wrist.

static electricity wristband

In settings where a few electrons can do big damage, workers wear anti-static wrist straps. (Credit: Shutterstock)

In everyday life, the best method to reduce charge buildups is running a humidifier to raise the amount of moisture in the air. Also keeping your skin moist by applying moisturizer can make a big difference. Dryer sheets prevent charges from building up as your clothes tumble dry by spreading a small amount of fabric softener over the cloth. These positive particles balance out loose electrons, and the effective charge nullifies, meaning your clothes won’t emerge from the dryer clingy and stuck to one another. You can rub fabric softener on your carpets to prevent charge buildup too. Last but not least, wearing cotton clothes and leather-soled shoes are the better choice, rather than wool clothing and rubber-soled shoes, if you’ve really had it with static electricity.

Harnessing Static Electricity

Despite the nuisance and possible dangers of static electricity, it definitely has its benefits.

Many everyday applications of modern technology crucially rely on static electricity. For instance, Xerox machines and photocopiers use electric attraction to “glue” charged tone particles onto paper. Air fresheners not only make the room smell nice, but they really do eliminate bad odors by discharging static electricity onto dust particles, thus dissembling the bad smell.

Similarly, the smokestacks found in modern factories use charged plates to reduce pollution. As smoke particles move up the stack, they pick up negative charges from a metal grid. Once charged, they are attracted to plates on the other sides of the smokestack that are positively charged. Finally, the charged smoke particles are collected onto a tray from the collecting plates and can be disposed of.

static electricity smokestacks

Static electricity can attract and trap charged pollution particles before they’re emitted from factories. (Credit: Muhammed Ibrahim, CC BY-ND)

Static electricity has also found its way into nanotechnology, where it is used, for instance, to pick up single atoms by laser beams. These atoms can then be manipulated for all kinds of purposes as in various computing applications. Another exciting application in nanotechnology is the control of nanoballoons, which through static electricity can be switched between an inflated and a collapsed state. These molecular machines could one day deliver medication to specific tissues within the body.

Static electricity has seen two and a half millennia since its discovery. Still it’s a curiosity, a nuisance – but it’s also proven to be important for our everyday lives.


This article was coauthored by Muhammed Ibrahim, a system engineer at an environmental software company. He is conducting collaborative research with Dr. Sebastian Deffner on reducing computational errors in quantum memories.The Conversation

Sebastian Deffner, Assistant Professor of Physics, University of Maryland, Baltimore County

This article is republished from The Conversation under a Creative Commons license. Read the original article.

CATEGORIZED UNDER: Space & Physics, Technology, Top Posts

With A Genetic Tweak, Crops That Grow 40 Percent Larger

tractor spraying crops

(Credit: Fotokostic/Shutterstock)

What if your ability to feed yourself was dependent on a process that made a mistake 20 percent of the time?

We face this situation every day. That’s because the plants that produce the food we eat evolved to solve a chemistry problem that arose billions of years ago. Plants evolved to use carbon dioxide to make our food and the oxygen we breathe – a process called photosynthesis. But they grew so well and produced so much oxygen that this gas began to dominate the atmosphere. To plants, carbon dioxide and oxygen look very similar, and sometimes, plants use an oxygen instead of carbon dioxide. When this happens, toxic compounds are created, which lowers crop yields and costs us 148 trillion calories per year in unrealized wheat and soybean yield – or enough calories to feed an additional 200 million people for a whole year.

Improving crop yields to grow more food on less land is not a new challenge. But as the global population grows and diets change, the issue is becoming more urgent. It seems likely that we will have to increase food production by between 25 and 70 percent by 2050 to have an adequate supply of food.

As a plant biochemist, I have been fascinated by photosynthesis for my whole career, because we owe our entire existence to this single process. My own interest in agricultural research was spurred by this challenge: Plants feed people, and we need to quickly develop solutions to feed more people.

tobacco plants

Amanda Cavanagh tests modified tobacco plants in a specialized greenhouse to select ones with genetic designs that boost the yield of key food crops. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Supercharging Photosynthesis to Grow More Food

It can take decades for agricultural innovations such as improved seeds to reach growers’ fields, whether they are created via genetic approaches or traditional breeding. The high-yielding crop varieties that were bred during the first green revolution helped prevent food shortages in the 1960s by increasing the proportion of grain-to-plant biomass. It’s the grain that contains most of the plant’s consumable calories, so having more grain instead of straw means more food. But most crops are now so improved that they are close to their theoretical limit.

I work on an international project called Realizing Increased Photosynthetic Efficiency (RIPE), which takes another approach. We are boosting harvests by increasing the efficiency of photosynthesis – the solar-powered process that plants use to turn carbon dioxide and water into greater crop yields. In our most recent publication, we show one way to increase crop yield by up to 40 percent by rerouting a series of chemical reactions common to most of our staple food crops.

Photorespiration Costs a Lot of Energy

Two-thirds of the calories we consume across the globe come directly or indirectly from just four crops: rice, wheat, soybean and maize. Of these, the first three are hindered by a photosynthetic glitch. Typically the enzyme that captures carbon dioxide from the atmosphere, called Rubisco, converts carbon dioxide into sugar and energy. But in one out of every five chemical reactions, Rubisco makes a mistake. The enzyme grabs an oxygen molecule instead. Rather than producing sugars and energy, the chemical reaction yields glycolate and ammonia, which are toxic to plants. To deal with this problem, plants have evolved an energy-expensive process called photorespiration that recycles these toxic compounds. But toxin recycling requires so much energy that the plant produces less food.

photosynthesis

In the process of photosynthesis, carbon dioxide and water are transformed into sugars and oxygen. Sunlight powers this chemical reaction. (Credit: BlueRingMedia/Shutterstock)

Photorespiration uses so much energy that some plants, like maize, as well as photosynthetic bacteria and algae, have evolved mechanisms to prevent Rubisco’s exposure to oxygen. Other organisms, like bacteria, have evolved more efficient ways to remove these toxins.

These natural solutions have inspired many researchers to try to tweak photorespiration to improve crop yields. Some of the more efficient naturally occurring recycling pathways have been genetically engineered in other plants to improve growth and photosynthesis in greenhouse and laboratory conditions. Another strategy has been to modify natural photorespiration and speed up the recycling.

Chemical detour improves crop yield

photosynthesis pathway

The red car represents unmodified plants who use a circuitous and energy-expensive process called photorespiration that costs yield potential. The blue car represents plants engineered with an alternate route to shortcut photorespiration, enabling these plants to save fuel and reinvest their energy to boost productivity by as much as 40 percent. (Credit: RIPE, CC BY-SA)

These direct manipulations of photorespiration are crucial targets for future crop improvement. Increased atmospheric carbon dioxide from fossil fuel consumption boosts photosynthesis, allowing the plant to use more carbon. You might assume that that this will solve the oxygen-grabbing mistake. But, higher temperatures promote the formation of toxic compounds through photorespiration. Even if carbon dioxide levels more than double, we expect harvest yield losses of 18 percent because of the almost 4 degrees Celsius temperature increase that will accompany them. We cannot rely on increasing levels of carbon dioxide to grow all the food we will need by 2050.

I worked with Paul South, a research molecular biologist with the U.S. Department of Agriculture, Agricultural Research Service and professor Don Ort, who is a biologist specializing in crop science at the University of Illinois, to explore whether modifying the chemical reactions of photorespiration might boost crop yields. One element that makes recycling the toxin glycolate so inefficient is that it moves through three compartments inside the plant cell. That’s like taking an aluminum can into three separate recycling plants. We engineered three new shortcuts that could recycle the compound in one location. We also stopped the natural process from occurring.

modified plants experiment

Four unmodified plants (left) grow beside four plants (right) engineered with alternate routes to shortcut photorespiration. The modified plants are able to reinvest their energy and resources to boost productivity by 40 percent. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Designed in Silico; Tested in Soil

Agricultural research innovations can be rapidly tested in a model species. Tobacco is well-suited for this since it is easy to genetically engineer and grow in the field. The other advantage of tobacco is that it has a short life cycle, produces a lot of seed and develops a leafy canopy similar to other field crops so we can measure the impact of our genetic alterations in a short time span. We can then determine whether these modifications in tobacco can be translated into our desired food crops.

We engineered and tested 1,200 tobacco plants with unique sets of genes to find the genetic combination that recycled glycolate most efficiently. Then we starved these modified plants of carbon dioxide. This triggered the formation of the toxin glycolate. Then we identified which plants grew best – these have the combination of genes that recycled the toxin most efficiently. Over the next two years, we further tested these plants in real-world agricultural conditions. Plants with the best combination of genes flowered about a week earlier, grew taller and were about 40 percent larger than unmodified plants.

Field Trials

Over two years of field trials, scientists Donald Ort (right), Paul South (center) and Amanda Cavanagh (left) found tobacco plants engineered to modify photorespiration are more productive in real-world field conditions. Now they are translating this technology hoping to boost the yield of key food crops, including soybeans, rice, cowpeas and cassava. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Having shown proof of concept in tobacco, we are beginning to test these designs in food crops: soybean, cowpea, rice, potato, tomato and eggplant. Soon, we will have a better idea of how much we can increase the yield of these crops with our modifications.

Once we demonstrate that our discovery can be translated into food crops, the Food and Drug Administration and the USDA will rigorously test these modified plants to make sure they are safe for human consumption and pose no risk to the environment. Such testing can cost as much as US$150 million and take more than 10 years.

Since the process of photorespiration is common across plant species, we are optimistic that our strategy will increase crop yields by close to 40 percent and help find a way to grow more food on less land to be able to feed a hungry global population by 2050.

 

Amanda Cavanagh, Postdoctoral Research Associate at the Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

CATEGORIZED UNDER: Environment, Living World, Top Posts

Why We Still Can’t Read the Writing of the Ancient Indus Civilization

By Bridget Alex | January 4, 2019 1:11 pm

Seals and their impressions from the Indus Valley Civilization, showing undeciphered symbols (Credit: Wikimedia commons)

Today, when we’ve unlocked the secrets of Egyptian hieroglyphs, Maya writing and hosts of far lesser known scripts, it seems as though there’s nothing left for enterprising epigraphers. Fear not, for there are actually a number of ancient writing systems still to be cracked. They include texts of the Olmec and Zapotec (Mesoamerican cultures preceding the Classic Maya), Proto-Elamite (writings of the earliest civilization of present-day Iran) and Rongorongo of Easter Island.

But if it’s fame you’re after (as well as intense scrutiny and even death threats) there’s no better challenge than the symbols of the Indus Valley Civilization, which flourished some 4,000 years ago in present-day Pakistan and northwest India.

From this culture, archaeologists have recovered several thousand short inscriptions, most with just 4 or 5 signs. There is no consensus on how to read them, although dozens of speculative decipherments have been proposed over the past century.

Complicating efforts, the underlying language the script is tied to is disputed, and there are complex modern-day political ramifications to the question. Rival ethnic groups claim to descend from this once-great civilization and knowing its language would help cement cultural ties. Hence the reported threats to scholars immersed in the matter.

Furthermore, some researchers go so far as to deny the existence of an underlying language. That is, they argue the Indus inscriptions were not true writing — visible signs that unambiguously represent speech — but an alternate symbolic system similar to emblems, conveying more general meanings.

Despite naysayers and challenges, decipherment efforts have progressed in the past decade, thanks to better databases of texts and new computational methods for finding patterns among the signs. Here’s what we know, for now.

That Lesser-known Great Civilization

4,000 years ago the Indus Valley civilization held an estimated one million people spread over a Texas-sized region, twice the area of contemporary Egypt or Mesopotamia. Its largest excavated cities, Harappa and Mohenjo-daro, exhibit levels urban planning that rival modern standards, including grid-like streets, water management and the oldest toilets. Yet there’s no suggestion of royal, religious or military might — no grand palaces, temples or defensive fortifications. And after flourishing between 1900-2600 BC, it’s unclear what happened to the people, or if any populations today can count themselves as their descendants.

One reason archaeologists, and average people, don’t know much about the Indus, is that it was only discovered in the 1920s. Since then, researchers have identified more than 1,000 settlements, which from the surface appear to belong to the culture. But less than 10 percent have been systematically excavated, due in part to unrest along the India-Pakistan border.

Another reason the Indus is elusive: that undeciphered script.

The Indus Inscriptions

Several thousand Indus texts have been discovered, mostly from Harappa and Mohenjo-daro, but also in far-flung lands of trading partners along the Persian Gulf and in Mesopotamia (and it’s probable the Indus were exposed to the idea of writing by these literate Mesopotamians). The majority are engraved on small stone seals, about one inch squared, above the image of an animal, such as a bull, elephant or unicorn-like creature. Fewer inscriptions are found on clay tablets, pottery and metal objects.

Characters from Indus inscriptions (Credit: Rao et al 2009, A Markov Model of the Indus Script, PNAS vol 106, adapted from Mahadevan 1977)

With an average of just 4 or 5 signs, the brevity of most inscriptions poses a challenge for decipherment efforts. It’s also among the reasons that some scholars argue these characters are not true writing. Most other civilizations with a writing system have left examples that are hundreds of characters long. The longest example of Indus script, by contrast, is less than 30 characters.

Since 2004, there’s even been a standing $10,000 prize for anyone who discovers an Indus text over 50 characters, offered by an anonymous donor and valid through the lifetime of historian Steve Farmer, a vocal opponent of the view that the Indus civilization was literate.

Tallying all the characters appearing on all known texts, researchers count between 400 and 700 distinct Indus signs. In part, their estimates differ because of subjectivity in judging how much variation is permissible for a single sign. For instance, my handwritten “a” probably looks different than your “a,” but they are the same character. Regardless, having several hundred characters suggests the script — if it was writing — was likely logosyllabic, meaning signs represented full words as well as syllabic sounds. Other logosyllabic systems we’ve deciphered include Mesopotamian cuneiform (~600 signs) and Mayan glyphs (~800 signs).

How to Read Long-lost Scripts

Scholars have deciphered many extinct writing systems, such as Egyptian hieroglyphs, Mesopotamian cuneiform and, most recently, a considerable portion of Maya glyphs. Aside from the short inscriptions, why does Indus give us so much trouble?

Successful decipherment efforts have followed similar courses (Part 3). Researchers cataloged the possible characters and their variations to infer the nature of the system — alphabetic, syllabic, logographic, etc. Then they found patterns in the distribution and frequency of signs. For instance, some characters may commonly occur at the beginning of lines or others may usually cluster together.

Though there’s some disagreement, we’re probably at that point for the Indus script. But serious decipherment breakthroughs have relied on three key elements so far absent from the Indus corpus:

1) Proper names, such as kings or cities, known from records of contemporaneous cultures. During the process of deciphering Egyptian hieroglyphs, scholars benefited from the mention of rulers like Ptolemy and Cleopatra in ancient Greek texts, understood at the time. As for the Indus, we don’t know any historical figures or certain place names.

2) A bi- or trilingual inscription, which records the same text in both known and unknown writing systems. For Egypt, that was the famous Rosetta stone, a fractured slab transcribing a priestly decree in two Egyptian scripts and ancient Greek. No such thing has been found for the Indus.

3) The language the script transcribes. For Egypt, successful translators correctly reasoned that hieroglyphs represented Coptic, a language still used by the Egyptian Coptic Church. And indigenous people of Mesoamerica continue to speak the words of Maya glyphs.

But the actual identity of the Indus language (or languages) is contested and clouded by modern politics. Presently, many scholars (here, here) argue for an ancient form of Dravidian, a family of languages found today in mostly southern India, but also pockets of northern India and Pakistan, near the heart of the Indus Valley Civilization. Alternatively, some favor an Indo-European language, related to ancient Sanskrit, which supports Hindu nationalist claims to the culture. Still others propose different indigenous language families, like Munda, or no language at all.

Where We Stand

As early as 1966, archaeologist Shri B. B. Lal concluded the texts were normally read from right to left. But, as Indus scholar Bryan K. Wells wrote in 2015, that is “about the only fact that most researchers can agree on” (page 7). This conclusion is based on spacing of characters: rightmost signs are aligned comfortably at the edge, whereas leftmost signs hang, get squeezed or pushed lower.

The degree of disorder in different sequences. Indus inscriptions fall near writing systems, between DNA (top) and computer code (bottom) (Credit: Rao, Probabilistic Analysis of an Ancient Undeciphered Script, Computer, April 2010)

The degree of disorder in different sequences. Indus inscriptions fall near writing systems, between DNA (top) and computer code (bottom) (Credit: Rao, Probabilistic Analysis of an Ancient Undeciphered Script, Computer, April 2010)

For decades, researchers have used statistical analyses to show that certain signs often cluster together, suggesting words and/or word-order (what we would call syntax) exist in the texts (here, here, here) — an important counter to claims that Indus signs are not true writing. More recently, computer scientists have reinvigorated efforts. One approach analyzes how random or predictable the order of signs is within a text. By this measure, known as conditional entropy, Indus inscriptions appear like known writing systems, which fall between highly ordered sequences like computer code and disordered ones like DNA code. Other methods using statistics and probability theory have brought similar conclusions: Indus inscriptions exhibit a degree of predictability characteristic of true writing.

Reading that putative writing will take future research. Ancient DNA may soon shed light on the ancestry of the Indus people, providing clues about their language. And there’s always hope that future excavations will uncover more informative texts, a Rosetta stone of the Indus.

CATEGORIZED UNDER: Living World, Technology

What the Earliest Texts Say About the Invention of Writing

By Bridget Alex | January 2, 2019 3:59 pm
Early Chinese characters on an ox scapula used in divination rituals (Credit: wikipedia https://en.wikipedia.org/wiki/Oracle_bone)

Early Chinese characters on an ox scapula used in divination rituals (Credit: Wikimedia Commons)

Though we call the last several decades of computational invention the Information Age, we might better look thousands of years in the past to see its true beginnings. That’s when writing, a system that has served as the basis for our collective store of information ever since, began.

This revolutionary idea likely emerged four times in human history: in ancient Mesopotamia, Egypt, China and Mesoamerica. In each case, it seems that people with no prior exposure to writing invented symbolic systems that would eventually transcribe anything that could be said.

My last story discussed how these scripts developed through broadly similar stages. To sum it up in one sentence: the original writing systems began with mostly pictorial characters that resembled their referent, and over time became more efficient and abstract, including a greater number of signs that represented sounds and semantic information.

Although the different scripts followed similar patterns of development, the initial causes and contexts of their inventions differed. Here, let’s delve into those differences.

Shopping Receipts from 3200 BC

What we know about ancient scripts is biased by the durability of various forms of media. Early texts written on perishable materials, like parchment or wood, mostly deteriorated over time. Words carved in clay or stone endured. So, to begin, we must understand that archaeologists are working with an incomplete record.

They’ve made the most progress for Mesopotamia because — conveniently — its earliest texts seem to have been inscribed onto baked clay tablets (chapter 4).

Examples of proto-cuneiform discovered at Uruk (Credit: http://cdli.ox.ac.uk/wiki/doku.php?id=proto-cuneiform)

Proto-cuneiform tablets discovered at Uruk. (Credit: http://cdli.ox.ac.uk/wiki/doku.php?id=proto-cuneiform)

Mesopotamian characters, which first appeared around 3200 BC, had a wedge-like appearance, leading later scholars to call the system cuneiform, after the Latin word cuneus for “wedge.” The earliest-known cuneiform (technically proto-cuneiform) texts were discovered in the temple precinct of Uruk, arguably the world’s first city, on the Euphrates River in present-day Iraq. This is likely where cuneiform originated, and it seems to be a case of necessity being the mother of invention.

In the centuries surrounding the earliest texts (3100-3350 BC), Sumerian-controlled Uruk underwent substantial population growth from about 20,000 to 50,000 residents. Urbanization required sophisticated bookkeeping, so scholars think writing was devised to log transactions of goods and services. Though the idea of representing words with signs was novel, cuneiform built upon earlier methods of record keeping, including numerals, seals of authenticity and tokens, small clay pieces shaped into cones, crescents, and other geometric shapes, likely used for counting commodities during transactions.

Supporting the hypothesis that writing began out of economic necessity: Of the 5,000-plus texts recovered from this period, around 90 percent are administrative receipts and expenditures (chapter 2). They are clay tags or tablets, documenting exchanges of goats, barley and so forth — the hot items of the day. The remaining 10-ish percent of early texts includes scribes’ exercises to learn writing and lexical lists, or glossaries of words organized by theme like professions, animals or cities.

None of the early texts are page-turners (figuratively and literally … they didn’t have pages). That took time. Over the ages, cuneiform expanded beyond its initial accounting purposes and was used for writing letters, history and more. It also spread to other tongues. Cuneiform probably first transcribed Sumerian, the now-lost language spoken in Uruk. But during its 3,000-year existence, the script was adopted by many peoples, including speakers of Akkadian (the earliest written Semitic language, the family that includes Arabic and Hebrew) and Hittite (the earliest written Indo-European language, the family that includes most present-day languages of Europe and southwest Asia).

Inventions Elsewhere

The impetus for writing is less clear in Egypt, China and Mesoamerica. In these cases the oldest surviving texts, on durable materials, were almost certainly not the first created. Most scholars contend earlier records were made on perishable media, lost to the ages. Their reasoning: The earliest-known examples seem too developed in form and structure to be a society’s first stab at writing. Or they’re too restricted in use to necessitate a full writing system and literate folks to perpetuate it.

But here’s what we’ve got:

In Egypt, the claim of earliest-known texts belongs to about 200 postage-stamp sized tags made of ivory and bone, discovered in the late 1980s in an elite tomb called U-j in Abydos (chapters 5 and 6). Dating to around 3300 BC, the perforated tags were likely attached to commodities, subsequently nabbed by grave robbers. Each tag contained a simple inscription, a few signs resembling people, animals, geographic features, numerals and more. In total, about 50 distinct signs appear. Some are similar enough to classic hieroglyphs of later periods that many researchers accept these tags as early Egyptian writing.

Tags from tomb U-j, Abydos, which could represent the earliest Egyptian hieroglyphs (Credit: Lawer 2001 Science, http://science.sciencemag.org/content/292/5526/2418)

Tags from tomb U-j, Abydos, which could represent the earliest Egyptian hieroglyphs (Credit: Lawer 2001 /Science, http://science.sciencemag.org/content/292/5526/2418)

This discovery pushed Egyptian script back two centuries, to about the same time cuneiform emerged. And like Mesopotamia, during this period Egyptian society got more complex. Bureaucratic needs may have stimulated writing in Egypt, but it likely had other uses as well. Given the effort required to produce these fine tags and other early texts, writing may have also served religious or social functions — perhaps to distinguish the elite from commoners.

As for China, the oldest surviving texts are objectively cooler than those from Egypt and Mesopotamia. They come from contexts of divination and ancestor tribute, dating to around 1200 BC at the Anyang site in north China, the capital of the Shang dynasty. The inscriptions adorn bronze vessels containing offerings to deceased ancestors and oracle bones: cracked ox shoulder blades and turtle shells covered with text.

From Anyang, more than 133,000 inscribed oracle bone fragments have been recovered. They were used in divination rituals pertaining to matters such as harvests, birth and war. Royal parties would pose questions to the gods, like “Lady Hao’s childbearing lucky?” or “Week without disaster?” The oracle bones were then fractured; their cracks foretold the answer. Sometime later, scribes would return to the cracked surface and record the question, prognostication and outcome.

An incised turtle shell used as an oracle bone (Credit: Boltz 1986 World Archaeology, Vol 17)

An incised turtle shell used as an oracle bone (Credit: Boltz 1986 World Archaeology, Vol 17)

This Anyang writing was fully developed, with about 4000 standardized characters and the capacity to transcribe speech. The oracle bones and vessels would have been seen by few, just members of the royal inner circle. Consequently, scholars doubt this was the first Chinese writing. It was just the first to last.

Finally in Mesoamerica, the earliest surviving texts, which remain undeciphered, were carved onto monuments by the Olmec (roughly 500-900 BC) and Zapotec (by about 500 BC). Due to their rarity, we can’t say much about the origins of writing here. However these systems are thought to have inspired the Maya, whose ancient script is now mostly deciphered.

Example of Maya glyphs (Credit Kwamikagami, Wikipedia)

Example of Maya glyphs. (Credit: Kwamikagami/Wikipedia)

The Classic Maya civilization peaked around 1,500 years ago in the Yucatan region of Mesoamerica. Long before this golden age, the earliest uncontested Maya characters or glyphs appeared around 200-400 BC, carved or painted onto elite structures, including thrones, altars and palace walls, like at San Bartolo, Guatemala. Attempting to emulate their powerful, literate predecessors, Maya elite may have developed writing to adorn their buildings and goods as a status symbol. But then again, this view may be a consequence of preservation. If texts on perishable materials, like palm leaves, survived we would have a better understanding of the origins of Maya script and its antecedents.

There’s a lesson here for writers dreaming of achieving immortality through their work: Whatever you write about, what you write on matters too.

CATEGORIZED UNDER: Living World, Technology
MORE ABOUT: archaeology, writing

Do Our Odds of Dying Ever Stop Increasing With Age? Scientists Disagree

By Lacy Schley | January 2, 2019 12:06 pm
elderly couple sitting together

(Credit: Pressmaster/Shutterstock)

As we get older, our chances of dying go up. To that, you might say, well, duh. But, when we hit around 80 years old or so, a funny thing seems to happen: Our odds of dying stop increasing and instead start leveling out. So you’ve got the same shot — about 50/50 — of croaking at, say, 110 (an age that would classify you as a so-called supercentenarian) as you would at 95.

It’s an odd phenomenon that’s left experts puzzled for years. Researchers have floated many theories to try and explain it. For instance, some think maybe there’s some evolutionary quirk that allows this to happen. Others posit that maybe there’s some cellular funniness afoot, allowing people of extreme old age to somehow accumulate damage more slowly in their cells.

But some experts contend that maybe this human mortality plateau isn’t happening at all. A new paper in PLOS Biology argues that most — if not all — of the proposed observations of so-called late-life mortality plateaus could be chalked up to scientific error.

Read More

CATEGORIZED UNDER: Health & Medicine, Top Posts

How We Found Jupiter’s 79 (At Least) Moons

By Korey Haynes | December 27, 2018 4:18 pm
a tiny moon in front of jupiter

The moon Io is tiny compared to mighty Jupiter, but still among the easiest of Jupiter’s many moons to spot. (Credit: Cassini Imaging Team/SSI/JPL/ESA/NASA)

Jupiter is king of the planets. It’s huge, it’s bright in our night skies, and even four of its comparatively tiny moons are bright enough to see with the most basic of telescopes. We’ve sent nine probes either into orbit or on a close flyby of the planet. And yet, as recently as this past year, we discovered not one, but twelve new moons around Jupiter, bringing the total to 79. How haven’t we exhausted this particular moon mine yet? Read More

CATEGORIZED UNDER: Space & Physics, Top Posts
MORE ABOUT: solar system

Gut Microbes Could Soon Diagnose and Explain The Cause of IBS and IBD

By Anna Groves | December 20, 2018 4:18 pm
IBD and IBS

(Credit: sedat seven/shutterstock)

Doctors have long scratched their heads over the causes and cures for two common diseases of the digestive system: IBS and IBD. But research out today in Science Translational Medicine takes a leap forward in explaining these conditions, thanks to a major undertaking to sequence the gut microbiomes of almost 2,000 people.

Difference Between IBS and IBD

Irritable Bowel Syndrome, or IBS, is thought to affect as much as 20 percent of the world’s population, while its cousin, Inflammatory Bowel Disease or IBD, is less common (fewer than 1 percent of the population) but more severe. The two have similar symptoms, but because one is characterized by its namesake inflammation (IBD) and the other isn’t (IBS), their treatments are very different.

When a patient reports abdominal pain, constipation or diarrhea, doctors conduct invasive tests like blood samples and colonoscopies to look for signs of inflammation. If they find it, the patient has IBD, and treatments are aimed at reducing that inflammation. Crohn’s disease and ulcerative colitis are both types of IBD.

But if doctors find nothing? That’s IBS. IBS is a bit of a catch-all diagnosis for when there’s no inflammation — and really no other abnormalities that might explain a patient’s symptoms. Current IBS treatments revolve around alleviating symptoms and hoping for the best.

Although scientists recently identified a possible genetic trigger of IBD in mice, the root causes of both diseases are currently unknown.

Poop Microbes Reflect Colon Microbes

Mounting evidence shows that microbes play a role in gut health, and previous research has showed that IBS and IBD patients have different microbiota than healthy people. That’s why a research team in the Netherlands wondered how the two would compare to each other, and if they could be used for diagnosis.

“We thought, let’s see if the microbiome, or gut composition, can become a biomarker so we can design new tests in order to distinguish these two diagnoses,” says Arnau Vich Vila, computational biologist at the University Medical Center Groningen in the Netherlands.

“We would reduce the number of colonoscopies; saving time, saving money and also improving the diagnosis so that the patient doesn’t have to go through this kind of procedure,” says Vich Vila.

The team set about sequencing the microbiomes from almost 1,800 people: 350 with IBD, 410 with IBS, and 1,000 healthy people as a comparison. But to do this, they needed to collect 1,800 microbiomes. That’s a lot of poop.

They found their participants through three different established banks of volunteers with well-established medical information for use in population studies. If you’ve ever peed in a cup at the doctor’s office, you can use your imagination to figure out how fecal samples are collected. But as an added challenge, fecal samples can’t be kept at room temperature, because that would allow certain bacteria to grow, interfering with the study results.

“So we asked all of them to collect the sample at home, put it in the freezer, and then we were driving around the Netherlands to pick up these samples,” says Vich Vila.

They used a genetic tool called shotgun metagenomic sequencing to sequence the DNA of the bacteria living in each sample, a common technique used to identify bacteria species in big samples. But they didn’t just identify the species – they looked at how abundant each was, how fast each grew, and what functions each performs in the gut.

upset stomach IBD and IBS symptoms

(Credit: Emily Frost/shutterstock)

IBD Bacteria, Different from IBS Bacteria

They found that people with IBD and IBS had substantial overlap in which microbes they had in their guts, and both were different than their healthy peers. And Vich Vila says the group was surprised to find such an overlap in the IBS and IBD microbes, because of how fundamentally different the two diseases are.

But the researchers also found consistent microbial differences between IBS and IBD patients, suggesting microbiome analysis could soon be used to diagnose IBS and IBD – and could start to explain the differences in the conditions.

For instance, both IBS and IBD patients had reduced numbers of some known beneficial gut bacteria, while only patients with Crohn’s disease had increases in bacteria like Escherichia, known to invade the gut’s mucus lining and cause problems (you know this one from the “E” in E. coli.) Likewise, there were certain bacteria that only the IBS patients had in increased amounts.

The microbiomes were different in other ways, too. The genetic diversity within individual bacteria species was sometimes different, as were the growth rates. Patients with IBS and IBD also had much more virulent bacteria than people with healthy guts – bacteria that do things like evade or suppress their host’s immune system. And patients with Crohn’s, specifically, had more bacteria that had antibiotic resistance genes than any of the other groups.

They also compared the diagnostic abilities of their new microbiome data to that of a currently used diagnostic test for IBD: whether a patient’s stool contains a biomarker of inflammation called calprotectin. Their microbiome test did better at predicting whether a patient had IBS or IBD than did the old test.

What Bacteria Do In Your Gut

What a bacterium does is programmed in its DNA just like any other living organism. So the researchers also wanted to know if their huge genomic dataset could tell us not just which bacteria are in which person’s gut, but what they are up to – especially if what they’re up to is making people sick. Figuring this out would really blow open the possibilities for understanding these two rather mysterious conditions.

They found many functional changes between the IBS, IBD, and healthy patients. For instance, in patients with Crohn’s disease, there were more bacteria breaking down sugars and fewer kickstarting fermentation. That causes the inflammation. Meanwhile, in patients with IBS, there were more bacteria than normal focused on fermentation and breaking down carbs.

This latter point caught the attention of William Chey, University of Michigan professor and practicing IBS specialist, who was not involved in this study. “It’s something I’ve been wondering about for quite a while,” says Chey, explaining that IBS patients often complain of bloating, and bloating is often caused by fermentation. “A question’s always been, could the microbiome provide an explanation for that?”

“So what they found – alterations in the microbiome which would explain increased levels of fermentation or altered fermentation in IBS patients – is really interesting,” says Chey.

Gut Solutions For The Future?

Valerie Collij, co-lead on the study, researches and practices medicine at University Medical Center Groningen. “As a clinician, I would say that this is the base for future treatments,” she says. “We can use this information to get dietary interventions, or pro- and prebiotics, or even fecal transplants that are based on the gut microbiome composition. That would be great. But we are nowhere near there, yet, I would say.”

“But what we are really close to now is using microbiota as a diagnostic tool,” adds Vich Vila.

Chey is excited about where these findings could lead IBS and IBD research in the future. “It’s really been the Holy Grail, looking for the characteristics of the microbiomes that might be linked to the pathology that we see in the clinic,” he says.

CATEGORIZED UNDER: Health & Medicine, Top Posts
MORE ABOUT: personal health

In Praise of Parasites

By Kenneth R. Weiss | December 20, 2018 2:08 pm
Kevin Lafferty

Kevin Lafferty emerges from the waters off Anacapa Island near Ventura, California, after spearing fish in March 2018. He’s advising a UCSB PhD student on research to determine if reef fish inside protected marine reserves have more or fewer parasites than depleted fish populations outside the reserve. It’s to test a pattern that has emerged in other studies: that parasites thrive with richness and abundance of marine life. (Credit: Kenneth R. Weiss)

Kevin Lafferty gets more than his share of intimate disclosures from strangers about their anatomy and bodily functions.

Graphic details and pictures arrive steadily via email, from people all over the world — a prison inmate in Florida, a social psychologist in Romania, a Californian afraid he picked up a nasty worm in Vietnam — begging for help, often after explaining that doctors will no longer listen. Do I have bugs burrowing into my brain? Insects poking around under my skin? Creatures inching through my intestines?

Lafferty has learned to open letters and packages carefully. On occasion, they contain skin or other suspect samples in alcohol-filled vials.

“Sorry to hear about your health troubles,” Lafferty wrote recently to one man who asked him to help identify a worm found wriggling in the toilet bowl. “Undercooked fish (and squid) can expose you to many different types of larval parasites that … can accidentally infect humans, sometimes making people sick.”

“The photo that you sent does not look like a tapeworm (or a parasite) to me, but it is not sufficient quality for identification,” he gently informed another, whose email included extreme close-up pictures of a white, bumpy tongue and noted that emergency hospitals keep referring the stricken man to “psychiatry.”

Lafferty is not a medical doctor — he’s a PhD ecologist who studies parasites, mostly in fish and other marine creatures, a fact he’s always careful to explain to his correspondents. He’s sympathetic to these desperate people, even if what ails them is more imagined than real. Parasites, after all, have wormed into every corner of the tapestry of life, including hooking up with human beings in the most unpleasant of ways.

Lafferty lab dissection

It’s dissection day in the lab at UCSB. Kevin Lafferty examines a slide of a parasitic copepod found in the gills of a horn shark. The copepod had its own parasitic worm attached to an egg sac. “That’s beautiful,” Lafferty says, complimenting PhD student Dana Morton (not pictured), who found the parasites and prepared the slide. “There are not a lot of illustrations of parasites on parasites.” Technician Ronny Young and PhD student Marisa Morse look on from the background. (Credit: Kenneth R. Weiss)

Yet his own view of parasites is more expansive than that of veterinarians, physicians and public health researchers, who tend to vilify these freeloading worms, bugs and protozoans as nasty culprits behind outbreaks of disease. Lafferty reminds us that parasites are not lesser life forms hell-bent on exploiting the weak and degraded, but rather an overlooked, misunderstood and even glorious part of nature. He celebrates them.

“Don’t get me wrong, I don’t want to be parasitized and I wouldn’t wish it on others,” he says in his laboratory at the University of California, Santa Barbara. But over three decades of studying parasites he has grown to admire their ingenious and complex lifestyles as they hitch rides on hosts that swim, run, crawl, climb or fly around the globe. He cut his scientific teeth studying parasitic worms that castrate their hosts (and thus, from an evolutionary standpoint, transform them into the living dead). In recent years, he’s become enthralled by tiny parasites that brainwash those they infect, turning them into zombies or pushing the hosts to engage in crazy, life-threatening behavior.

“Many of them are fabulous examples of evolution,” he says, “and sometimes incredibly beautiful in terms of the things they do to make a living on this planet.”

Parasites have an underappreciated importance, he adds — as indicators and shapers of healthy ecosystems. They thrive where nature remains robust, their richness and abundance keeping pace with biodiversity. They can serve important roles in maintaining ecosystem equilibrium. For all these reasons and others, he urges fellow scientists to take a more neutral view of them and adopt well-established theoretical approaches for studying diseases on land to better understand how marine parasites operate. If scientists want to better predict when infections and infestations will recede, remain innocuous or spiral out of control, he says, they need to start thinking like parasites.

Up From the Mud

On a cold winter day, Lafferty is wading in the black muck of the Carpinteria Salt Marsh, about a 20-minute drive down the coast from his Santa Barbara home and laboratory. Despite the frigid air that has dipped into California, he is wearing his typical uniform:  surfer board shorts, flip-flops and a light gray hoodie sweatshirt emblazoned with the logo of the US Geological Survey (USGS), his employer of two decades. Introduced by mutual friends years ago, I’ve gotten to know Lafferty as a friend at dinner parties and as a fellow surfer.

He picks up a handful of horn snails from the sucking mud. Lafferty began collecting these small mud snails three decades ago, and found that about half are chockablock with parasitic flatworms called trematodes, which eat the snail’s gonad and transform the mollusk into a neutered, hard-shelled meat wagon. They ride around inside for the rest of the snail’s natural life — a dozen years or more — feeding on the infertile gastropod while pumping out trematode larvae into brackish waters. The snails in Lafferty’s hands are likely infected with one of 20 different trematode species, he says: “For the host horn snail, it’s a bad outcome, a fate worse than death. For the parasite, it’s an awesome and sophisticated strategy.”

snail collecting

Lafferty collects California horn snails at Carpinteria Salt Marsh, where he has spent decades studying the roles that parasites play in marine ecology. (Credit: Kenneth R. Weiss)

The flatworms in these snails may not be destined for a lowly existence in the mud, though: Their future holds an opportunity to swim, and even fly. Larvae of the most common species go on to penetrate the gills of a California killifish, then attach themselves by the hundreds to the fish’s brain, manipulating the new host to dart to the surface or roll on its side and flash its silvery belly.

That conspicuous behavior makes the infected fish 10 to 30 times more likely to be eaten by a predatory heron or egret. And it’s in that bird’s intestine that the trematode finally matures, excreting eggs that are dispersed with guano all over the salt marsh or in other estuaries — before being picked up, again, by horn snails.

Parasites have altered the way Lafferty sees the salt marsh and beyond. A great egret flies by, flashing its brilliant, white wings. Sure, it’s gorgeous, but it’s a lightweight in this neighborhood compared to the parasites. Lafferty and colleagues once determined that the collective weight — or biomass — of trematodes in this salt marsh and two others in Baja California, Mexico, is greater than the collective weight of all the birds that live in the same three estuaries.

Lafferty spots an osprey in the distance, and trains his spotting scope to watch as the fishing hawk rips apart and bolts down chunks of a mullet held in its talons. “We’re watching a transmission event,” he says. “That mullet had hundreds of larval trematodes in it. It’s like eating a bad piece of sushi.”

By some estimates, nearly half of the species in the animal kingdom are parasites. Most of them remain largely out of sight because they are small, even microscopic. Their ancestors didn’t always start with a parasitic lifestyle: Researchers have so far found 223 incidents where parasitic insects, worms, mollusks or protozoans evolved from non-parasitic predecessors. Some ate dead things. Others killed their prey and consumed it. Then their life strategy evolved because they proved more successful if they kept their prey alive, kept their victims close — so they could feed on them longer. It’s a strategy distinct from those of parasitoids, which outright kill their hosts, Lafferty explains, a glint of mischief in his eye. “Think about the movie Alien. Remember when the alien sock puppet bursts its head out of John Hurt’s chest? That’s a classic parasitoid.”

Lafferty revels in such parasite talk, enjoying the reaction from lecture audiences or gatherings of friends. From personal experience, I can attest that he’s not beyond rolling a pre-dinner video for surf buddies in which one moment he’s landing a five-foot wahoo in the tropical Pacific — and in the next, he’s in the lab extracting thumb-sized, blood-engorged parasitic worms from the fish’s stomach. He squeezes the dark, congealed blood from the worms, fries them up with a little garlic and butter, pops one in his mouth and then, with a smirk, holds out the skillet and dares a grad student to give it a try.

He is also a serious marine ecologist who holds passionately that parasites are worthy of study for how they influence ecological systems and how ecosystems influence them. For years, it was a fairly lonely position to take:  “Ecologists have built hundreds of food webs and they haven’t put parasites in them. And what we’ve lost from that is the ability to even think about parasites and their role in ecology,” Lafferty says. Ecology conferences used to struggle with where to place Lafferty’s talks in their schedules, but nowadays the meetings have dedicated sessions on wildlife infectious diseases. And ecologists, especially younger ones, are starting to recognize that they are missing part of the story if the food webs they model don’t include parasites that can influence predator-prey relationships and competition for resources. As illustrated by the trematode in the killifish, Lafferty says, “parasites are determining who lives and who dies in a way that benefits them.”

Moreover, parasites are a useful way to explore broader ecological questions: How does energy flow through those food webs? What forces maintain ecological stability and keep one species from overrunning all others? What are the implications of robust and healthy biodiversity on human health? Ecologists debate all sorts of competing theories, Lafferty says. What’s clear to him and other like-minded parasitologists: “We cannot answer these questions if we are going to ignore the parasite part of the equation.”

But first, a scientist needs to overcome the ick factor — just as Lafferty did 30 years ago. He calls himself an “accidental parasitologist” to this day.

The Making of a Model Surfer

Born in Glendale, California, in 1963, Kevin Dale Lafferty was raised in nearby La Cañada, the son of a mother who wrote a book and taught classes on earthquake preparedness and a father who was an aeronautical engineer at NASA’s Jet Propulsion Laboratory. He fell in love with the ocean during boyhood vacations in nearby Newport Beach and Laguna Beach.

He bodysurfed. He snorkeled. He caught mackerel off the pier and pried mussels and crabs off its pilings — matching his discoveries to those described in Ed “Doc” Ricketts’ classic guidebook, Between Pacific Tides.  At 13, he knew his destiny: become a marine biologist. At 15, he learned to scuba dive and, while in high school, built underwater camera housings out of Plexiglas.

Once enrolled in aquatic biology at UCSB, he learned he could walk from the dorms with a board under his arm to surf.  Tanned and fit, he modeled bathing suits (“It was a good way to meet girls”) and wasn’t a particularly serious student until he reached the more interesting upper-division courses in marine ecology.

giant sea bass

A rare giant sea bass surprised Lafferty while he was collecting fish to look for parasites in waters off Santa Cruz Island in the Channel Islands National Park. Lafferty says the close encounter with this protected giant fish made this one of his Top 10 dives. (Credit: David Kushner/National Park Service)

His youthful passions most certainly did not involve parasites. But while on a student field trip to nearby mudflats, he met UCSB parasitologist Armand Kuris. Kuris was so impressed with Lafferty’s smarts and their easy flow of conversation that he tracked Lafferty down on campus and recruited him to join his lab as a PhD student. Lafferty agreed on one condition: He would study marine ecology, but not parasites. “I found them disgusting.”

The Santa Barbara campus, situated on a cliff overlooking the Pacific Ocean, has a powerful allure to marine scientists, beach lovers and surfers. It has three premier surf breaks, substantial waves in the fall and winter, and glorious weather nearly year-round. It also has a laid-back style that makes even the most hard-charging professors more collaborative than cutthroat.

Graduate students, particularly those in the marine sciences who surf, never want to leave. Those who manage a rewarding surf-adjacent career can be the targets of considerable envy.  When Lafferty’s work, years after his student days, was featured in the Canadian television series The Nature of Things, video images showed him catching and riding a wave with a classic surf rock song, “California Baby,” filling the soundtrack. Show host David Suzuki introduced him this way: “Kevin Lafferty… has a rough life.”

California horn snail

Lafferty holds a California horn snail, Cerithideopsis californica, which has an even chance of being infected with one of 20 species of parasitic flatworms called trematodes. As parasitic castrators, these trematodes consume the snail’s gonad and then ride around in the host for the rest of its natural life. (Credit: Kenneth R. Weiss)

Suzuki didn’t know the half of it. Not only did Lafferty manage to stay at UCSB after grad school (by snagging a job with the USGS that permitted him to work from the university), but he ultimately took up residence in the only home on a 170-acre protected area next to campus, the Coal Oil Point Natural Reserve. And it just happens to have an unobstructed view of 30 miles of coastline and unrivaled access to the surf he loves so much (he self-published a guidebook, The Essentials of Surfing, in 2013). “It looks like he has it all, but he did it piece by piece,” says Kuris, who has now collaborated with Lafferty for nearly three decades. “You only do that if you have a high level of self-confidence. Kevin was committed to his geography. I knew he was serious when he gave up a two-year postdoc in Cambridge.”

One critical life piece fell into place soon after Lafferty joined Kuris’s lab to pursue his PhD. It so happened that the only job available to fund his graduate work was as a teaching assistant in the parasitology class, the topic that so revolted him. As he was learning about parasites so he could teach the course, he realized that all of the marine creatures he thought he knew so well — ever since his boyhood curled up with Between Pacific Tides — were full of parasites. And in many cases, the parasites were having their way with his beloved abalone, sea stars and sand crabs.

It hit him that here was an opportunity to break new ground. “Although lots of people had studied parasites for their own sake, or as problems to be solved, it seemed like an open playing field to start asking how parasites fit into natural ecosystems,” he says. He spent the next two years cracking horn snails with a hammer to collect trematodes in estuaries from San Francisco to Baja. His work solidified how the parasites were affecting the snails’ abundance and evolution — finding, for example, that snails in areas with high infection rates have evolved to mature and reproduce early, before they get castrated.

fish dissection

Pursuing parasites in the lab: Step one: discard the filet from this ling cod. Step two: place the gills, gonad, liver, intestines and other organs on glass plates to be squashed for examination under the microscope. Parasites are ubiquitous in nature; many of these freeloaders hitch a ride without seriously impairing their host. (Credit: Kenneth R. Weiss)

Another life piece emerged in his second year of grad school, when a new PhD student arrived from Brazil. She’d recently completed a master’s on social spiders that cooperate to weave webs the size of volleyball nets. Cristina Sandoval moved into the office across the corridor in Noble Hall, which housed the usual assortment of beach-casual grad students studying ecology and evolutionary biology. She showed up every day wearing high heels, stockings, gloves and pillbox hats. “No one knew what to make of her,” Lafferty recalls. She needed help to learn English. He volunteered.

One marriage, two children and three decades later, they live in a blufftop doublewide trailer in the Coal Oil Point reserve. Sandoval, a PhD evolutionary biologist, has spent more than 20 years as the reserve’s director, managing a small army of docents and volunteers who protect the shoreline, dunes, estuary and the western snowy plover, a fluffy little shorebird threatened with extinction. She’s celebrated for innovative approaches, such as grabbing marauding skunks by the tail before they can eat plover eggs. Once hoisted aloft, skunks are incapable of spraying. Or so she says.

In addition to the USGS job, Lafferty codirects the Parasite Ecology Group at UCSB, which provides him an office and lab space. Although he doesn’t teach regularly, he mentors a half-dozen PhD students and a couple of post-doctoral researchers. The USGS, which once tolerated his parasitology work, now embraces it because of its value in managing natural resources, including rare and threatened species such as abalone, sea otters and island foxes in the nearby Channel Islands National Park.

Lafferty’s day begins at dawn as he walks the family dog, Hubble, and checks the surf from the bluff. Forget that image of the slacker surfer: Lafferty is as disciplined with his surfing as he is with his science. At age 55, he surfs more than he did when he was 40. He knows this because he tracks every surf session, as well as every session in the gym, and every pound of weight he’s carrying, in an Excel spreadsheet. Pie charts and fever graphs reveal, through an elaborate point system, if he has met his goal for the week, the month, the year. He refuses desserts with sugar. Beer gets banished any time he tips the scale above 160 pounds. His wife finds his discipline a bit strange; his colleagues find it enviable, an extension of his intense work focus.

surfing

Lafferty catches a wave near Santa Barbara, California, where he lives and works studying marine creatures from microscopic parasites to great white sharks. (Credit: Kenneth R. Weiss)

Colleagues point to how Lafferty can quickly size up the science, map out the fieldwork and then plow ahead without distraction. “I’ve worked with finishers before, but he’s quite remarkable,” says Peter Hudson, a wildlife disease ecologist at Pennsylvania State University. “He does it. He finishes it and he publishes it. He’s a machine.”

All told, Lafferty has published more than 200 articles in Science, Nature, Proceedings of the National Academy of Sciences and other peer-reviewed journals. Much of his work focuses on parasitology. He and colleagues worked out how to halt an epidemic of schistosomiasis in Senegal by reintroducing freshwater river prawns that eat the intermediate host of the blood fluke that causes the disease. He discovered how the eradication of rats on Palmyra Atoll in the Central Pacific had a second benefit: the local extinction of the Asian tiger mosquito, a vector for the dengue and Zika viruses. His work often veers into other topics of marine ecology and conservation biology, such as recently detecting the presence of white sharks near Santa Barbara by collecting seawater samples with telltale environmental DNA.

Hudson and other collaborators say that Lafferty is an astute naturalist as well as a solid scientist who understands theory and how to design an experiment that will yield the data needed to test a hypothesis.

“He’s one of the top people in both areas, and that is rare,” says Andrew P. Dobson, an infectious disease ecologist at Princeton University. “We have had tremendous fun together. It’s as much fun writing down equations on a blackboard as it is digging through the mud looking for creatures.”

Lafferty also is one of the few federal researchers to be promoted to senior scientist in the USGS, with a rank and pay grade similar to that of a brigadier general in the Army.  “He’s unusual as a federal scientist,” says James Estes, a former USGS researcher and emeritus ecologist at UC Santa Cruz. “There are not many as creative and productive. He’s a top scientist by any metric.”

Although he comes across as even-keeled and dispassionate, Lafferty’s not afraid of calling out a faulty scientific argument, or sticking up for the lowly parasite. Many marine-disease experts come from veterinarian or wildlife-welfare backgrounds. Their mission, as they see it, is to minimize the impact of parasites on wildlife. Lafferty, as an ecologist, views parasites as part of nature, not a scourge to be wiped off the planet.

He doesn’t mind ruffling feathers. In 2015, he wrote a paper, “Sea Otter Health: Challenging a Pet Hypothesis,” that questioned a well-publicized scientific theory that polluted urban runoff carrying domestic cat feces was infecting the adorable, button-nosed otters with toxoplasmosis. The data showed the opposite was true: More otters were infected with toxoplasmosis along the lightly populated Big Sur coast than near the city of Monterey. “I expect,” Lafferty admonished, “that future directions in sea otter health research will continue this recognition that marine diseases are part of nature, and that sea otter parasites might, ironically, indicate wilderness, not a dirty ocean.”

Lafferty has a particular affinity for Toxoplasma gondii, the single-celled protozoan behind toxoplasmosis. It’s his favorite, he says, among the hundreds of parasites known to hijack the brains of their hosts. T. gondii tricks rats into being unafraid and even aroused by the smell of cat urine, which seems to make them more likely to get eaten by a cat. This phenomenon, dubbed “feline fatal attraction,” allows the protozoan to reach its primary host, where it can reproduce and complete its lifecycle.

toxoplasma gondii

An image of a cyst of Toxoplasma gondii, taken with a transmission electron microscope. Within the cyst, one can see the parasites developing. T. gondii infects many warm-blooded animals, including human beings, usually without obvious symptoms. The parasite alters the behavior of infected rodents; Lafferty is among those investigating whether asymptomatic infections might affect human behavior as well. (Credit: CDC)

T. gondii infects warm-blooded animals of all kinds, including as many as two-thirds of the human population in some countries, and nearly no one in others. In the United States, about one in eight is infected. It encysts in the human brain and, although it can cause serious eye and brain damage in a human fetus, is mostly asymptomatic in adults with healthy immune systems.

Or is it? Some studies have suggested that the parasite may have subtle, mind-manipulating effects on unintended human hosts — on traits such as guilt or impulsiveness. Other studies have noted slower reaction times or diminished ability to focus, suggesting these may be why infected people have a nearly threefold higher chance of being involved in a car accident. Lafferty has run with this idea to ask if parasite-triggered personality traits might explain differences in cultures around the globe. He concludes, for example, that T. gondii might explain a third of the variation of neuroticism among different countries.

Lafferty explored these ideas in a TEDx Talk, “A Parasite’s Perspective,” delivered in California’s Sonoma County in 2016. He ended with a personal note that his blood test was negative for T. gondii, but that about 100 members of the audience were likely infected. How would they react if they were? “You’ve just learned that in your brain is a parasite that would like nothing better than for you to be eaten by a cat,” he deadpanned. “How do you feel about that shared personality?”

anglerfish

In his UCSB office, Lafferty holds a plush-toy anglerfish knitted by former post-doctoral researcher Julia Buck. The toy is sufficiently anatomically correct to show how the tiny parasitic male anglerfish, colored red, implants himself into the female’s body. The male feeds off his mate’s circulatory system while supplying sperm. (Credit: Kenneth R. Weiss)

Off the stage, Lafferty says he recognizes that these can be considered wild ideas but he finds them a good way help people think about the role parasites play in the broad ecological picture. He has a healthy skepticism about extrapolating effects in rodent brains to humans, and well understands that correlation between parasites and behaviors does not equal causation. “It’s hard to prove,” he says. But what if there were something to the car crash data? “If that’s true, that’s a big deal. We are talking about thousands of deaths around the world.”

Fair Play for Parasites

Lafferty is acutely aware that he has a privileged, wealthy worldview of parasites, making it too easy to enjoy such thought experiments or view them as cute little study subjects. “I’ve never lost a child to a parasitic infection or suffered a debilitating illness because of one,” he says, horrible circumstances that occur too often in poor countries.

Still, he hopes that, at least in scientific circles, attitudes toward parasites will evolve the way they have for other threatening creatures such as sharks, wolves and mountain lions — ones that, until recently, we rushed out to exterminate without considering the ramifications.

In an “us versus them” view of the natural world, parasites will usually be put on the other team, he says. But that’s not the only way to think about it. “The key to doing science is you don’t want to be rooting for a team, because it takes the objectivity away,” he says.

“That’s how we are going to understand them: by not taking a side.”

 

This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews.

Knowable Magazine | Annual Reviews

CATEGORIZED UNDER: Environment, Living World, Top Posts
MORE ABOUT: animals, Ecology, ocean
NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+