Many criminal investigations, including “cold cases, ” do not have a suspect but do have DNA evidence. In these cases, a genetic profile can be obtained from the forensic specimens at the crime scene and electronically compared to profiles listed in ...
‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ ‌ 

OUPblog » Earth & Life Sciences

 

Searching DNA databases: cold hits and hot-button issues

Searching DNA databases: cold hits and hot-button issues

Many criminal investigations, including “cold cases,” do not have a suspect but do have DNA evidence. In these cases, a genetic profile can be obtained from the forensic specimens at the crime scene and electronically compared to profiles listed in criminal DNA databases. If the genetic profile of a forensic specimen matches the profile of someone in the database, depending on other kinds of evidence, that individual may become the prime suspect in what was heretofore a suspect-less crime.

Searching DNA databases to identify potential suspects has become a critical part of criminal investigations ever since the FBI reported its first “cold hit” in July 1999, linking six sexual assault cases in Washington, D.C., with three sexual assault cases in Jacksonville, Florida. The match of the genetic profiles from the evidence samples with an individual in the national criminal database ultimately led to the identification and conviction of Leon Dundas.

How the statistical significance of a match obtained with a database search is presented to the jury should, in my view, be straightforward but, given the adversarial nature of our criminal justice system, remains contentious. One view is that if the profiles of the evidence and a suspect who had been identified by the database search match, then the estimated population frequency of that particular genetic profile (equivalent to the Random Match Probability in a non-database search case) is still the relevant statistic to be presented to the jury. The Random Match Probability (RMP) is an estimate of the probability that a randomly chosen individual in a given population would also match the evidence profile. The RMP is estimated as the population frequency of the specific genetic profile, which is calculated by multiplying the probabilities of a match at each individual genetic marker (the “Product Rule”).

An alternative view, often invoked by the defense, is that the size of the database should be multiplied by the RMP. For example, if the RMP is 1/100 million and the database that was searched is 1 million, this perspective argues that the number 1/100 is the one that should be presented to the jury. This calculation, however, represents the probability of getting a “hit” (match) with the database and not the probability of a coincidental match between the evidence and suspect (1/100 million), the more relevant metric for interpreting the probative significance of a DNA match. Although these arguments may seem arcane, the estimates that result from these different statistical metrics could be the difference between conviction and acquittal.

There are many different kinds of DNA databases. Ethnically defined population databases are used to calculate genotype frequencies and, thus, to estimate RMPs but are not useful for searching. The first DNA searches were of databases of convicted felons. In some jurisdictions, databases of arrestees have also been established and searched. These searches have recently been expanded to include “partial matches,” potentially implicating relatives of the individuals in the database. This strategy, known as “familial searching,” has been very effective but contentious, with discussions typically focused on the “trade-offs” between civil liberties and law enforcement. In some jurisdictions, the “trade-off” has been between two different controversial criminal database programs. In Maryland, for example, an arrestee database (albeit one specifying arraignment) was allowed but familial searching was outlawed. Familial searching has been critiqued as turning relatives of people in the database into “suspects.” A more accurate description is that these partial matches revealed by familial searching identify “persons of interest” and that they provide potential leads for investigation.

Recently, searching for partial matches in the investigation of suspect-less crimes has expanded from criminal databases to genealogy databases, as applied in the Golden State Killer case in 2018. These databases consist of genetic profiles from people seeking information about their ancestry or trying to find relatives. Genetic genealogy involves constructing a large family tree going back several generations based on the individuals identified in the database search and on genealogical records. Identifying several different individuals in the database whose profile shares a region of DNA with the evidence profile allows a family tree to be constructed. The shorter the shared region between two individuals or between the evidence and someone in the database, the more distant the relationship. This is because genetic recombination, the shuffling of DNA regions that occurs in each generation, reduces the length of shared DNA segments over time. So, in the construction of a family tree, the length of the shared region indicates how far back in time you have to go to locate the common ancestor. Tracing the descendants in this family tree who were in the area when the crime was committed identifies a set of potential suspects.

The DNA technologies used in investigative genetic genealogy (IGG) are different from those typically used in analyzing the evidence samples or the criminal database samples, which are based on around 25 short tandem repeat markers (STRs). The genotyping technology used to generate profiles in genealogy databases is based on analyzing thousands of single nucleotide polymorphisms (SNPs). With the recent implementation of Next Generation Sequencing technology to sequence the whole genome, even more informative searching for shared DNA regions can be accomplished. (Next Generation Sequencing of the whole genome is so powerful that it can now distinguish identical (monozygotic) twins!)

Investigative genetic genealogy (IGG) has completely upended the trade-offs and guidelines proposed for familial searching as well as many of the arguments. Many of the rationales justifying familial searching of criminal databases, such as the recidivism rate, and the presumed relinquishing by convicts of certain rights do not apply to genealogical databases. Also, the concerns about racial disparities in criminal databases don’t apply to these non-criminal databases either. In general, it’s very hard to draw lines in the sand when the sands are shifting so rapidly and the technology is evolving so quickly. And it is particularly difficult when dramatic successes in identifying the perpetrators of truly heinous unsolved crimes are lauded in the media, making celebrities of the forensic scientists who carried out the complex genealogical analyses that finally led to the arrest of the Golden State Killer and, shortly thereafter, to many others.

It’s still possible and desirable to set some guidelines for IGG, a complex and expensive procedure. It should be restricted to serious crimes. The profiles in the database should be restricted to those individuals who have consented to have their personal genomic data searched for law enforcement purposes. With the appropriate guidelines, the promise of DNA database searching to solve suspect-less crimes can truly transform our criminal justice system.

Featured image by TanyaJoy via iStock.

OUPblog - Academic insights for the thinking world.

Nature’s landscape artists

Nature’s landscape artists

Claude Monet, c. 1899. Public Domain via Wikimedia Commons.

Claude Monet once said, “I perhaps owe having become a painter to flowers.” Perhaps he should have given bees equal credit for his occupation. Without them, the dialectical coevolutionary dance with flowers that has lasted 125 million years would not have produced the colorful landscapes he so cherished. For Darwin, it was an abominable mystery; for Monet, an endless inspiration.

Bees, like Monet, paint the landscape. Their tool kit, however, is not one of canvas, paint pigments, and brushes, but consists of special body parts and behavior. Their bodies, covered with branched hairs, trap pollen when they rub against floral anthers and transfer it to the stigma—pollination. Their visual spectrum is tuned to the color spectrum of flowers, not an adaptation of the bees to flowers but an adaptation of flowers to attract the pollinators. Insects evolved their color sensitivities long before flowering plants exploited them.

Monet’s ‘Le jardin de l’artiste à Giverny,’ 1900. Public Domain via Wikimedia Commons.

The behavioral toolkit of honey bees is expansive. Bees learn the diurnal nectar delivery rhythms of the flowers; they also learn their colors, shapes, odors, and where they are located. Honey bees are central-place foragers, meaning they have a stationary nest from which they explore their surroundings. They can travel more than 300 km2 in search of rewarding patches of flowers. To do this, they have a navigational tool kit. First, they need to know how far they have flown: an odometer. This they accomplish by measuring the optical flow that traverses the nearly 14,000 individual facets that make up their compound eyes, similar to us driving through a city and noting how much city flows by in our periphery. They calculate how far they have flown and the angle of their trajectory relative to the sun, requiring a knowledge of the sun’s location and a compass. Then they integrate the individual paths they took and determine a straight-line direction and distance from the nest. Equipped with this information, they return to the nest and tell their sisters the location of the bonanza they discovered.

Bee dance diagram. Emmanuel Boutet, CC BY-SA 2.5 via Wikimedia Commons.

Communication among honey bees is not done with airborne sounds, as they have no organs for detecting them. Information is conveyed through a dance performed by returning foragers on the vertical surface of a comb in a dark nest. New recruits gather on the comb dance floor, attend the dances, and learn the direction and distance to the patch of flowers. How they perceive the information in the dance is not known, but to us as observers, we can decipher the direction by the orientation of the dance, and the distance by timing one part of it. Because the dance is done on a vertical comb inside a dark cavity, perhaps a hollow tree or a box hive provided by a beekeeper, the forager has two challenges. First, she must perform a bit of analytical geometry and translate the angle of the food source relative to the location of the sun from a horizontal to a vertical plane, then she must represent the direction of the sun at the top of comb. This is a constant like north at the top of our topographical maps.

Walker canyon wildflowers. Mike’s Birds, CC BY-SA 2.0 via Wikimedia Commons.

Equipped with this information, recruits fly out of the nest in the direction of the resource for the distance indicated by the dance and seek the flowers. The flowers lure them in with attractive colors, shapes, odors, and sweet nectar that the bees imbibe and in the process transfer pollen onto the stigma, fertilizing the ova. The seeds develop, drop to the ground and wait until the following spring when the plants emerge and paint the fresh landscape with a kaleidoscope of colors that rivals Claude Monet.

Featured image by JLGutierrez on iStock.

OUPblog - Academic insights for the thinking world.

Understanding fossil-fuel propaganda: a Q&A with Genevieve Guenther

Understanding fossil-fuel propaganda: a Q&A with Genevieve Guenther

2024’s UN climate summit in Azerbaijan is a key moment for world leaders to express their convictions and plans to address the escalating stakes of the climate crisis. This month we sat down with Genevieve Guenther—author of The Language of Climate Politics, and founder of End Climate—to discuss the current state of climate activism and how propaganda from the fossil fuel industry has shaped the discourse.

Sarah Butcher: How did you first get involved in climate change activism?

Genevieve Guenther: I got really concerned about climate change after I had a child and started to worry about what kind of world he would inherit after I died. So I utilized my training as a scholar to master the field of climate communication, while learning about climate science and economics, in the hopes of using my expertise in the political effects of language to help move our climate politics forward. Eventually I began working on The Language of Climate Politics, and while I was writing it I also founded the group End Climate Silence to help push the news media to cover climate change with the urgency it deserves.

SB: How did you come to recognize that the language people–and more importantly the media—use was having an impact on efforts to actually create change?

GG: As recently as 2018, public-opinion surveys showed that even many Democrats felt some doubt that climate change was real. I could see that this doubt tracked very neatly onto the rise of the disinformation that there was a lot of scientific “uncertainty” around the issue. (Scientists were projecting a range of possible outcomes from rising carbon emissions, but they were definitely not saying that climate change was fake.) I realized that voters had heard about this supposed uncertainty because, at the time, news outlets were platforming so-called “climate skeptics” to provide what they called “a balance of opinion” about climate change. Later I discovered that most Americans learn everything they know about climate change from the news media. So it became apparent to me that how journalists talk about climate change had, and still has, a great deal of influence over America’s climate politics!

SB: Do you have any examples of fossil-fuel propaganda that you share with people to illustrate the scope of the problem?

Guenther presented her book The Language of Climate Politics at the book’s launch event at The UN bookshop.
Image courtesy of Genevieve Guenther, used with permission.

GG: Fossil-fuel propaganda is a huge phenomenon! There are many lies about climate change and clean energy floating around. You may have heard that developing off-shore wind turbines is killing whales (it isn’t), or that fossil fuels are the most reliable form of energy (they aren’t), or that focusing on your personal carbon footprint is the most important thing you can do to fight climate change (it definitely isn’t). But the propaganda I investigate in my book is the complex of lies, myths, and incorrect assumptions that create the false and dangerous belief that we can keep using coal, oil, and gas but still deal with climate change anyway. We cannot! So I expose the scientists, economists, lobbyists, and journalists who propagate this false belief, illuminating the bankruptcy of their ideas and giving readers clear, actionable messages to counter mis- and disinformation in their own conversations about climate change. Focus-group polling shows that these messages increase concerned Democrats’ and Republicans’ support for phasing out fossil fuels by up to ten points.

SB: What are the biggest misconceptions you see around fossil-fuel propaganda?

GG: That it spreads only among the uneducated or the right wing. My book shows how some scientists, economists, journalists, and even climate advocates sometimes inadvertently echo the core fossil-fuel propaganda and thereby normalize it, shaping mainstream views about climate change.

SB: What sets your book on the climate change crisis apart?

GG: I think my book is personal and accessible, but also has a real scope. I try to sort out the whole kaleidoscope of climate disinformation, so we can see and counter it clearly. The book discusses what the science says will happen to the US and the UK if we don’t phase out fossil fuels; how past economic models have low-balled climate damages and what the new economic models project for the future; the promise and challenges of climate technologies; the recent history of US and international climate politics; advice for coping with climate change emotionally and helping to build a more powerful climate movement; and more! The climate journalist Amy Westervelt said in her endorsement that the book “takes the whole overwhelming universe of fossil-fuel propaganda and distills it,” providing “one of the best explanations I’ve read of how the heck the climate crisis has gone unchecked for so long.” And Kieran Setiya, who’s not even a climate person, but a Professor of Philosophy at MIT, said: “if you want to understand the climate crisis and you only have time to read one book, this should be it.” I’m pretty proud of that, honestly.

SB: What was the most surprising thing you discovered working on this book?

GG: That China has enacted a whole-of-government, whole-of-society climate policy, called the “1 + N” policy, to achieve net-zero emissions by 2060. That was a huge surprise! I hadn’t known that China had passed comprehensive climate legislation. I don’t think many people in the West know this either. But I describe the provisions of China’s climate policies in Chapter 4, so hopefully now more people will understand the depth of China’s commitment to decarbonization.

SB: Is there anything in the current debate that gives you hope about our climate future?

GG: I try not to deal in hope. Hope keeps my focus on things I cannot control. Instead, I try to embrace what I think of as intellectual humility—I don’t know what’s going to happen politically, because no one does—and I try to accept what I take to be my duty. That is, I feel like, being alive with relative privilege at this historical moment, I have a responsibility to help resolve the climate crisis, so that at the end of the day I can say I did my best. I mean, that’s all that can be asked of us, right?

SB: What do you hope readers take away from your book?

GG: I hope they feel equipped to resist the dominant forms of climate disinformation in public discourse and feel empowered to talk about the climate crisis in ways that will focus the conversation on phasing out fossil fuels. And I hope they feel fortified and inspired to do that work!

Featured image by USGS on Unsplash.

OUPblog - Academic insights for the thinking world.

Charles Darwin the geologist

Charles Darwin the geologist

Who was Charles Darwin the geologist? Was he a nephew, or maybe a cousin, of the illustrious naturalist, who first published the theory of evolution by natural selection? I know they had big families… But no, this is the one and the same. It is often forgotten that, early in his career, Charles Darwin was a ‘card-carrying’ geologist.

It did not start well. Aged 17, he assessed the Edinburgh University geology lectures he dropped in on, while studying Medicine, so ‘incredibly dull’, that he would ‘never attend to the subject of geology’.

His lecturer was Robert Jameson, who was on the wrong side in the dispute about the origin of dolerite. As dolerite could be found as a layer among strata of sandstone and limestone, he believed it had somehow precipitated out of water. It turned out a sill could be intruded between the layers as red-hot basaltic magma.

In the spirit of student rebellion Charles also assessed all but one of his lecturers in medicine as ‘intolerably dull’. Squeamish about anatomy, he ostensibly switched to the University of Cambridge to study theology. By the summer of 1831 he needed to prove some rapid geological acumen in applying to become the geologist/naturalist on a round-the-world voyage on the survey ship HMS Beagle.

Charles convinced Cambridge Professor Adam Sedgwick to allow him to spend a few weeks as a field assistant while the professor mapped the geology of North Wales. The learning was intensive, but it worked.

While on the Beagle, Darwin’s notes on geology were four times longer than those reporting natural history. He wrote to his sister that ’the pleasure of the first day’s partridge shooting …. cannot be compared to finding a fine group of fossil bones’—there were some great bones to be found in Patagonia.

On returning after almost five years away on the Beagle, Darwin became the society secretary to the Geological Society of London where he remained for three years. He published four scientific papers on geology, including how coral reefs formed above sinking volcanoes.

Less known was Darwin’s solo expedition to investigate the ‘parallel roads’ contouring Glen Roy in the Scottish Highlands. This was a real adventure. From London one could only get as far as Liverpool by train. Like the raised beach deposits he had mapped on the coast of Chile, he visited Glen Roy to record former sea levels.

Another facet of Darwin’s geology emerged on the long walks he took around his wife’s family’s house at Maer near Stoke on Trent. (His own family life was hectic, with ten children.) On one of these walks he discovered an igneous dyke, now named Butterton Dyke, which intruded around the time of the Hebridean volcanoes (one date gives 54 million years ago) but which chemically and by orientation is of mystery origin. To commemorate Darwin, again as a geologist, a fragment of the dyke was sent into orbit on the Mir space station and then flown to a last resting place on the Moon.

Although no longer collecting bones, or dolerite samples, after the 1859 publication of The Origin of Species, he summoned geological evidence to manifest the time needed to allow for evolution. He proposed sluggish rates of erosion of 500-foot-tall Sussex cliffs, such as an inch per century, to explain how much geological time had passed to enable evolution. His estimates for erosion have proved to be perhaps a hundred times too slow and he came under much criticism from physicists who calculated the age of the habitable earth from simple thermal decay. However, by the beginning of a new century, twenty years after his death, the discovery of heating accompanying radioactive decay vindicated his projection of the duration of geological time.

If you were scoring Charles Darwin as a geologist the results would be mixed. Always concocting hypotheses, he was ready to change his theories as new evidence arrived. He admitted there was only one such area of theorizing (the explanation for coral reefs) where he hadn’t had to change his mind. And it was Darwin the geologist who could give Darwin the evolutionist the eons of time required to realise his theory of natural selection.

Featured image via © Getty Images; iStock.com (Used with Permission).

OUPblog - Academic insights for the thinking world.

The art of the bee

The art of the bee

In June 1799, Alexander von Humboldt departed Spain on a five-year expedition that traversed what was known in the New World as New Granada and New Spain. Along the way, he made extensive collections and observations of geography, geology, climate, atmospheric science, astronomy, magnetic flux, botany, zoology, biogeography, ecology, and anthropology. He converted his 4,000 pages of notes into a collection of volumes called the Cosmos. His most popular work, however, was a book called Ansichten der Natur (Views of Nature), a condensed version of the Cosmos. In this book, von Humboldt organized chapters around themes and brought into each chapter a consilience of disciplines that spanned botany to anthropology. Woven together into a narrative, the book painted a view that reflected both an opinion and a glimpse of nature.

Humboldt appealed to artists and poets to interpret and paint nature. He believed that they would be better at conveying views of nature to the public than would science-oriented naturalists. The nineteenth century philosopher Henry David Thoreau was strongly influenced by Humboldt when he wrote his most noted work, Walden, weaving a tapestry of science and imagination. The American painter Edwin Church accepted Humboldt’s challenge and, beginning in 1853, retraced his expedition across South America. The result was 1.7 x 3 meter canvas painting, The Heart of the Andes (1859), now hanging in the New York Metropolitan Museum of Art. The painting, like the chapters of Ansichten Der Natur, is a composite interpretation of the natural history of the Andes, showing amazingly accurate details of the flora and includes geography, geology, and even an element of anthropology.

The Heart of Andes by Frederic Edwin Church, Metropolitan Museum of Art via Wikimedia Commons. Public domain.

As I set out to write a book on honey bee biology, I kept Humboldt as an aspirational model. Rather than write the typical biology text that reflected an excavation of levels of biological organization like taxonomy, biogeography, physiology, anatomy, etc., I built chapters around themes relating to honey bee impacts, behavior, and ecology.

Portrait of Alexander von Humboldt by Fredrich Georg Weitsch, Alte Nationalgalerie via Wikimedia Commons. Public domain.

The impact of bees on our world is immeasurable. Bees are responsible for the evolution of the vast array of brightly colored flowers and for engineering the niches of multitudes of plants, animals, and microbes. They’ve painted our landscapes with flowers through their pollination activities and have evolved the most complex societies to aid their exploitation of the environment. The biology of the honey bee is one that reflects their role in transforming environments with their anatomical adaptations and a complex language that together function to exploit floral resources. A complex social system that includes a division of labour builds, defends, and provisions nests containing tens of thousands of individuals, only one of whom reproduces.

My book, The Art of the Bee: Shaping the Environment from Landscapes to Societies, presents fundamental biology, not in layers, but wrapped in interesting themes and concepts, and in ways designed to explore and understand each concept and learn fundamental bee biology. It examines the coevolution of bees and flowering plants, bees as engineers of the environment, the evolution of sociality, the honey bee as a superorganism and how it evolves, and the mating behaviour of the queen.

We will explore the wonderful biology and behavior of honey bees in future installments, each related to a different chapter painting a view, an opinion and a glimpse, of the wonderful world of bees.

Feature image by John Pons via Wikimedia Commons. CC4.0.

OUPblog - Academic insights for the thinking world.


Contact UsPast IssuesJoin This ListUnsubscribe

Safely Unsubscribe ArchivesPreferencesContactSubscribePrivacy