Snippets From Science

• Does the nose, know? There is growing evidence that subtle odor molecules given off by humans can influence the behavior of others. Some of these are so subtle they can’t be perceived by our olfactory system. These airborne molecules are called pheromones, and they are detected by a different patch of sensory cells in our nasal chamber. Pheromones are airborne chemicals we release that affect the behavior or physiology of others, especially at close range. Can pheromones influence mate selection in humans? Yes. It appears that pheromones subconsciously program females to favor males whose immune systems are least like their own. This occurs in other animals as well. Why? Scientists argue that this favors survival of offspring since their “hybrid” immune systems will have a more diverse arsenal to ward off disease and infection. (Moran, Jafek, and Rowley, 1991, J. Steroid Biochem. & Mol. Biology, pp. 522-545; Jones and Lopez, Human Reproductive Biology; Tim Friend, Animal Talk, and other sources)

• Speaking of pheromones, when a honeybee dies, it releases a “death pheromone,” which signals surviving bees to drag it out of the hive. If a living bee is dabbed with a tiny drop of this pheromone (oleic acid), other bees drag it, “kicking and screaming,” out of the hive.

• By isolating DNA from preserved hair of a wooly mammoth, two scientists at Penn State managed to read out the genetic code of this 20,000 year-old relative of the elephant. Since all cells of an organism have the same genetic code, they know the genetic make-up of every cell of an animal that went extinct thousands of years ago. Considering the recent flu epidemic, it’s worth noting that scientists have established the genetic code of the deadly 1918 flu virus, and they used the code to reassemble this dangerous virus. By studying the recreated virus, clues may be obtained that would aid in developing vaccines for the flu viruses of today. (from J. Craig Venter, who helped sequence the human gene sequence)

• Believe it or not, there are records of large dragonflies attacking birds. In England a dragonfly attacked a sparrow, and the observer noted:  “Bird was briefly towed by dragonfly.” In the U.S., a hungry Common Green Darner captured a ruby-throated hummingbird. The observer said:  “Both animals fell to the ground locked together, then the dragonfly flew away with the dead bird.” Don’t expect this to happen very often! (P.S. Corbet, Dragonflies, Behavior and Ecology of Odonata, 1999)

• Circuits in the nervous system are established by chains of neurons that communicate with each other in two ways – electrically and chemically. The signal that sweeps from one end of a neuron to the other is electrical. But the signal that is transmitted between neurons is a chemical that is released into the tiny space (synapse) between the neurons. These chemicals are called neurotransmitters. One neuron in the circuit releases its neurotransmitter into the synapse, causing the adjacent neuron to “fire” and carry the signal along its length to the next neuron in the series. There are over 100 of these chemicals that allow us to move, think, and solve problems. It’s difficult to accept that they are responsible for who we are intellectually and emotionally, and that the brain is driven by electrical impulses and the release of chemicals.

• “Levels of carbon dioxide are the highest in at least 800,000 years, and up by a third since the industrial revolution.” (Alistair Doyle in Reuters News, Feb. 12, 2009)