Science News for the Science Classroom
Skewed Bird Gender Ratios
Humans aren’t the only species to face relationship problems. In a recent study of 187 bird species, scientist found that populations which exhibit skewed gender ratios- more males than females, or vice versa- are more likely to result in divorce, infidelity, or polygamy in mated pairs.
While 90% of bird species remain monogamous for life, having one gender more popular than another can break these norms. In populations with more females than males, divorce is twice as more likely to occur than in populations with more males. Consequently, male-dominated populations practice infidelity more often. In both cases, the rarer sex tends to be more susceptible to practicing polygamy.
Interestingly enough, these relationship behaviors featured in correlate surprisingly close to humans’ behaviors in similar population disparities.
Why Do Zebras Have Stripes?
It’s an age old question: why do zebras have stripes? Hypothesis have varied, from being used as camouflage to confusing predators to reducing body temperature, but a new study seems to point in a different direction: that Zebras evolved striped to ward away biting insects.By using a model that compares the seven living species of the equid group- including horses, asses, and zebras- researchers discovered that the presence of striping directly correlates with the number of biting flies in an environment.
While this is a huge step in figuring out the mystery behind a Zebra’s stripes, scientists are still unsure exactly how these stripes ward away flies, in part because Zebras are notoriously difficult to thoroughly study in the wild.
Read more: http://goo.gl/FM7n6d
The Oceans of Enceladus
Not too long ago, it was believed that Earth was the only body in the solar system with liquid water and, therefore, the only planet capable of harboring life. Recent evidence has proved otherwise: from the dried riverbeds and lakes that prove that water once flowed on Mars to the oceans that lie beneath Europa’s ice, liquid water- and the possibility of life- is becoming more and more prevalent in our solar neighborhood. Now, another moon of Saturn, tiny Enceladus, may very well be our best candidate for extraterrestrial life.
After witnessing plums of water-vapor ejecting from “tiger stripe” formations on Enceladus’ south pole, Scientists at NASA have concluded the presence of an ocean the size of lake Superior trapped beneath the ice of the frozen moon. Even more exciting is that fact that the plums ejected from Enceladus’ tiger stripes contain organic molecules. Should the moon’s interior be warm enough, microbial life isn’t out of the picture.
Learn more here: http://goo.gl/RyaSnb
RicochetScience Article: Endeladus and Water – What this Means for Life
The Microbe That (Almost) Killed All Life
250 million years ago, the Permian extinction resulted in the loss of 90%of ocean species and nearly 70% of land-dwelling species, making it the closest life has ever come to being completely eradicated on planet Earth. Theories have ranged from a gamma ray burst to intense volcanic activity, though the true culprit may be much smaller: small enough to be invisible to the naked eye.
Methanosarcina is a member of a group of single-celled organisms called archaea – organisms that are adapted for life in extreme environments. While it had been present before the Permian extinction, sometime around 250 million years ago it developed the ability to produce methane, probably borrowing the ability from another kind of microbe through a process known as “gene transfer”. Methanosarcina would go on to explode in the ocean biome, releasing massive amounts of methane into the atmosphere and making the planet inhospitable to almost all life.
Methanosarcina may explain why the Permian mass extinction lasted nearly ten thousand years, as opposed to the relatively short extinction period that occurred after the dinosaur’s own demise by the hands of an asteroid.
Black Death Airborne?
The Black Death- or the bubonic plague- hit London in 1349, killing 6 out of every 10 people. It’s perhaps the most devastating disease in human history, yet according to the findings of at least a few scientists, our commonly held beliefs that the disease was carried by fleas living on rats may be completely false.
While researching several newly uncovered bodies of plague victims from London’s 1349 outbreak and comparing them to a recent outbreak of bubonic plague in Madagascar, these scientists found that the DNA of the plague strains were exactly the same, over 600 years later. Because of this, they determined that a flea-borne disease could not have spread so fast as the Black Death that ravaged London. The plague, therefore, would have to be pneumonic- airborne- rather than bubonic. Rats and fleas would have very little to do with the plague’s spread.
The findings are still rather controversial, but at the very least it is an interesting theory that sheds a different light on the nature of the Black Death.
Read more here: http://goo.gl/c8xZIg
Human Sense of Smell is Better than Predicted
How good is your sense of smell? Scientists used to say that people could smell over 10,000 different scents. They were definitely right with the over part because they have now found that we can smell over one trillion scents!
It may not always seem like we can smell that many different things because different molecules are mixed together making one final scent. Yet, each molecule has its own scent when apart!
This week we released the third part of our Mendelian genetics tutorials – The Dihybrid Cross. This short video explains the basic principles of a two-trait cross with an emphasis on probability. You can view the entire set of videos from our Biology 101 page.
This article was edited on April 15th to correct for a statement that Methanosarcina possessed a nucleus.