June 07, 2011

Cavemen Stayed Local while Women Left Home

23 minutes

We talk with Sandi Copeland, Adjunct Professor of Anthropology at CU, about this story:

Two million years ago, two-legged apes roamed the African landscape. Many of these ancient hominins, lived in limestone caves in what is now South Africa. We know this through fossilized skull fragments and teeth from those caves.

But fossils only tell us where an individual died—not where it grew up, or where it traveled during its life. Or do they? New research from the University of Colorado that’s been published in the journal Nature, reveals that male hominins in South Africa grew up in the caves where they died, while the females who died there grew up elsewhere and migrated to the caves as adults.

The research not only sheds light on the behaviors of early human relatives; it makes use of a new technique, pioneered by the CU researchers, to quickly and cheaply analyze the birthplace of fossilized creatures.

Producer: Shelley Schlender

Co-hosts: Joel Parker, Ted Burnham

Engineer: Shelley Schlender

For Headline Features, read on . . .

STORY 1 {Virtual water cannot remedy freshwater shortage}:

We all know what it’s like to drink or bathe in “real” water. But what about “virtual” water? “Virtual Water” is an economic calculation of the water needed to produce a certain amount of product. For instance, producing one kilogram of beef generally requires 15 thousand litres of water. It also takes water to grow crops such as juicy oranges. Virtual water transfers occur through trade. When desert destinations such as Quatar, or Las Vegas, buy oranges and beef they are indirectly importing water. And as the world’s population grows, virtual water transfer could, in theory, provide more equal water use between nations, insuring that everyone’s water needs are met.

However, according to a study published today in the journal Environmental Research Letters, banking on virtual water as a solution to global water problems could spell disaster. The study’s lead author, David Seekell, of the University of Virginia, points out that 80% of the people on Earth are already threatened by water shortages. Seekell warns that there’s not enough virtual water transfer to provide future, larger populations have enough water. What’s more, recent theoretical work shows that these transfers make societies more vulnerable to droughts. Without addressing population growth, Seekell says that efforts to equalize water supplies through global trade or a formal government-based virtual water market are likely end up high and dry.

STORY 2 {Bat hibernation and rabies}:

For North American wildlife, it’s often hard to survive the winter. Many bats solve this problem through hibernation, but at a cost. Hibernation allows some pathogens, such as rabies, to survive as well. To figure out the costs and benefits of hibernation, Colorado State University biologist Dylan George and colleagues designed a mathematical model to analyze data from a five year study of Colorado’s big brown bats. Matching data about birth, mortality and rabies infection, they’ve concluded that during the chilly months of a bat’s winter hibernation, the bat’s slowed-down metabolism slows viral development enough that it doesn’t make the bats sick just yet, and this allows plenty of bat babies to be born in the spring — already infected with rabies. Many of these young bats then live long enough to produce more generations of infected babies. In contrast, when the scientists ran simulations that eliminated hibernation, the rabies virus killed bats so fast, populations crashed. The authors say this gives insights into how hibernation and cooler temperatures may influence many diseases in bats.

STORY 3 {Glimpse Into Uncertainty}:

We’re not completely certain how to explain this next story, because – well – it’s based on the “Uncertainty Principle.” The Uncertainty Principle is one of the more well-known consequences of quantum mechanics, but in case you are uncertain about what the principle is, it is usually defined as: you can’t measure both the position and speed of a particle simultaneously, because as soon as you measure one, you irrevocably interfere with getting an accurate measure of the other. It is also related to the other well-known concept of quantum mechanics: the mysterious particle-wave duality. One classic demonstration of these phenomena is called Young’s double-slit experiment, where particles pass through a pair of slits and interact with each other and create an interference pattern even if you send them through one particle at a time. That raises the spooky question: what is a particle interfering with if it is traveling alone unless it – somehow – passes through both slits simultaneously and interferes with itself? And if you tried to measure the position or momentum of the particles or which slit a particle went through, the very act of measuring destroys the interference pattern.

Now, Sacha Kocsis and colleagues at the University of Toronto have devised an experiment that may provide a peek at the path, or the typical path, taken by photons in the double-slit experiment. They make what are called “weak measurements” of a photon’s momentum to create an average trajectory for the particle. These weak measurements don’t disturb the particles enough to destroy the interference effect; they also don’t allow for precise measurements of individual particles, but they do make good measurements of the average paths for many particles. The researchers suggest that the power of these weak measurements might bring a better perspective to the quantum behavior of particles than trying to pin one down and see what happens. Though precisely how this will help our understanding of quantum mechanics is…uncertain.

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