2011 Stories
When fighting leukemia, evolutionary history matters
In the next few months, college students across the country will be offered the chance to save a life by swabbing cells from the insides of their cheeks and registering as a potential marrow donor with Be The Match®. The Give A Spit About Cancer campaign, which launched in October, helps college students organize marrow donor registry drives. The cells collected in these drives are used to figure out who might be able to donate marrow or blood stem cells to a patient with a life-threatening disease like leukemia. While ethnicity is irrelevant to most medical procedures, marrow and blood stem cell transplants are an exception to this rule. Registering potential donors of non-Caucasian descent and mixed ethnicity is particularly important in these drives. Evolutionary theory helps us understand why …
Read more »An antibiotic that exploits evolutionary history
This month, the World Health Organization announced that tuberculosis cases are on the decline for the first time in at least 20 years. We seem finally to be winning what has been a very long battle. Tuberculosis bacteria have been attacking us since modern humans began to migrate out of Africa around 40,000 years ago. If you enjoy classic literature, you’ll be familiar with the cough, fever, and weight loss of consumption (the old-fashioned term for tuberculosis), which used to be a near certain death sentence. That changed when the aminoglycoside antibiotic streptomycin was discovered in 1943. In combination with other drugs, streptomycin could cure tuberculosis. Though the medical community has been reconsidering how frequently it and other antibiotics of the same class should be deployed, streptomycin remains an important weapon in the fight against tuberculosis. Understanding how this drug works takes us on a fascinating evolutionary journey that begins some 1.8 billion years ago …
Read more »The evidence lines up in early mammal evolution
Back in the Jurassic, dinosaurs may have dominated terrestrial ecosystems, but they were not alone. Scurrying around their feet and clinging to the trees above them were the fuzzy ancestors of their successors. When most of the dinosaurs perished, the surviving mammals diversified into the dinosaurs’ niches, where they remain today. Last month, scientists reported on the discovery of a fossil mammal from China that would have lived alongside the dinosaurs and that, at 160 million years old, represents one of the earliest mammals known. Juramaia sinensis may not have been much to look at — a furry rodent-like animal just a few centimeters long — but it’s made big news. Is this tiny critter really the “missing link” in mammal evolution and the “mother of us all,” as many articles have suggested?
Read more »“Error. Greed does not compute.”
Swarms of tiny robots have given up their selfish ways and started sharing resources for the greater good. Though this might sound like the plot of a bad summer blockbuster, it is real news. This month, a team of Swiss researchers announced that they’ve used robots to simulate biological evolution. The simple, mobile robots — each a little larger than a sugar cube — began their lives directionless, meandering aimlessly into walls. But after a few generations of natural selection, their computer programs evolved so that they became efficient foragers, purposefully collecting disks that represent food. None of that is particularly surprising. Scientists have long been able to simulate evolution through computer programs that mimic the processes of genetic inheritance, mutation, recombination, and reproduction. What is noteworthy is that many of these robots eventually evolved to help one another, sacrificing personal success to aid other robots in their group. Such altruistic behaviors — which we observe in all sorts of organisms, from humans to slime molds — are a topic of debate among evolutionary biologists, and these big-hearted robots are allowing scientists to test ideas about how such behaviors evolve.
Read more »Gender-biased bacteria throw off an evolutionary balance
This month, biologists reported that a bacterial infection has run rampant in populations of a major crop pest in the Southwest. The bacterium (called Rickettsia) is a close relative of the species that causes typhus in humans. Its host is the sweet potato whitefly, a tiny bug that can occur in large enough numbers to form visible clouds. Whiteflies suck the sap from plants and spread crop diseases, causing hundreds of millions of dollars of damage in a single season. In just a few years, the percentage of southwestern whiteflies infected with Rickettsia has skyrocketed from 1% to more than 90%. Unfortunately, this is not the boon for local farmers that it might seem. Rickettsia don’t sicken the whitefly; instead, the bacterium actively helps the pest spread and increase in numbers. Evolutionary theory accounts for this surprising observation and highlights how we might turn it in our favor.
Read more »Toxic river means rapid evolution for one fish species
Though we often think of evolution as occurring at a snail’s pace, one fish species is highlighting just how quickly evolution occurs — in the right circumstances. Between 1947 and 1976, General Electric released more than a million pounds of PCBs into the Hudson River. PCBs can kill fish and seabirds and have been linked to cancer and other serious health problems in humans. PCBs were banned in 1979, but the toxins have remained at high levels in the Hudson because they settle into the sediments on the bottom of the river and don’t break down. Now, scientists have discovered that, over the past 60 years, one bottom-feeding fish species, the Atlantic tomcod, has evolved resistance to PCBs. Though this evolutionary shift is good news for tomcod, it may put the rest of the food web, which depends on this species, in jeopardy.
Read more »Bad at estimating? Blame evolution
The next time you are in the kitchen, try this experiment: pick up a box of butter (four sticks) in one hand and a box of saltines (four packets) in the other. Which is heavier? If you said the butter, you are not alone. Most people would identify the box of butter as the heavier object — even though, if you look at the labels, you’ll see that they both weigh exactly one pound! This is an example of the size-weight illusion, and it is incredibly common. Most people — very young children, people from different cultures, and even people who know ahead of time that the two object weigh the same — report that the smaller of two objects of equal mass just “feels” heavier. Why is this? Recent research suggests that the roots of this modern party trick (as well as our penchant for sports like baseball and football) can be traced back to the evolutionary origins of Homo sapiens and to the opportunities provided by a well thrown rock or spear.
Read more »¿Eres un mal estimador? La culpa es de la evolución
La próxima vez que estés en la cocina, prueba este experimento: toma una caja de manteca en una mano y una caja de galletas saladas en tu otra mano. ¿Cuál es más pesada? Si dijiste la manteca, no estás solo. La mayoría de las personas identifica la caja de manteca como el objeto mas pesado — a pesar de que si miras la etiqueta ¡verás que ambas pesan exactamente una libra! Este es un ejemplo de la ilusión tamaño-peso, que es increíblemente común. La mayoría de la gente — niños pequeños, gente de diferentes culturas, y aun gente que sabe de antemano que ambos objetos pesan lo mismo — advierten que el más pequeño de dos objetos de igual masa “se siente” mas pesado. ¿Por qué ocurre esto? Recientes investigaciones sugieren que la raíz de este truco moderno (así como nuestra afición por deportes como el beisbol y el futbol) se remonta a los orígenes evolutivos del Homo sapiens y a las oportunidades que un buen tiro con una roca o una lanza ofrecen.
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