Mother Clucker

Marveling at the red feather’s of his backyard chickens, Darwin wrote:

The chickens...were just black in the first plumage, but late in autumn to my astonishment red feather after red feather very strangely appeared in the Cocks and now one of the Cocks is nearly as splendid as the wild Gallus Bankiva.

This 1860 observation would result in a debate lasting nearly one hundred and fifty years --what is the origin of the chicken? Darwin maintained that the Red Jungle Fowl (Gallus Gallus) of Southern Asia was the mother of all chickens based on the red feather reversion in his simple breeding experiments. However, body size data, archeological findings and even linguistic evidence made a case for multiple lineages. Is the ancestor for Darwin‘s chicken different than the one I had for dinner? How many times has domestication occurred over the past 8000 years?

Two studies in the mid 1990’s utilizing mitochondrial DNA technology supported the idea that one subspecies of the red jungle fowl (Gallus gallus gallus) was the mother of the domestic chicken--seeming to put an end to the long lasting argument. These initial experiments, however, were critiqued for using an insufficient data set. A 2006 report once again resolves the dispute after improving the experiment by using a greater sample size. They concluded, “Chickens have multiple maternal origins and that domestications occurred in at least three regions of South and Southeast Asia”.

So... there's more than one mother clucker.

Fumihito et al. 1994
Fumihito et al. 1996
Liu et al. 2006

Glowing Parasites

I'm always fascinated by how scientists can manipulate the green fluorescent protein from a jelly fish to learn about another creature.

Now, green fluorescent parasites are being used to infect rodents with malaria and the infection can be tracked throughout the life cycle of the parasites. Green fluorescent blood cells, green fluorescent mosquito eggs and green fluorescent sporozoites (cells that infect new hosts devoloping in the mosquito's salivary glands) are glowing life phases of the protozoa that causes malaria.

Ono et al., 2007
Franke-Fayard et al., 2004
Natarajan et al., 2001

Left Handed Smile

How many times had I handed my toddler her spoon when I realized that I only gave it to her left hand? I’d heard stories about people forcing left-handers to be right, but could I coerce a right-hander to be a lefty. Looking down at the high chair, I noticed the spoon, the cup and even the bite sized strawberry pieces all poised on the left side of the tray -right where I placed them -with my right hand. Pushing everything to the other side, I watched her reach with her already red left hand -the right remaining motionless at her side.

Teasing out the nature verses nurture part of handedness is an enduring goal for scientists. The idea that handedness has something to do with brain function draws intrigue. Many studies (some more reputable than others) have correlated handedness with mental illness, sexual orientation and most recently, life span. But a non-biased indicator of true handedness is needed to make any association meaningful.

Hair whorl--that is the direction hair swirls on the head--has held long-time hopes for the field. While the clockwise nature of the swirl seems to match the rate of right-handedness (and counterclocwise, lefty-ness), a distinct association is missing. The order that teeth erupt on the other hand, does parallel handedness… maybe.

A Turkish group, reported a relationship between teething and handedness “there was a statistical difference between sequence of the tooth eruption and handedness”. The reports maintains that the down side to using dentition as a marker, as I also quickly came to realize, is that parents are not so good at keeping track of this specific milestone. The mouth schematic in our baby book has lines radiating from each tooth on one side only. The time of eruption and the type of tooth that broke first (the only data that I recorded), however, have no significance (with respect to side dominance that is). I peered over early baby pictures for a snap of the first toothy smile but to no avail. Likewise, the experiment consisted of few data points (92 individuals). More importantly, to me at least, was the puzzling way the data was analyzed and presented. After doing a few calculations myself, it seemed that the predictability of handedness with respect to tooth eruption was not much better than 50%. Now, I’m no statistician but I can usually read a table.

Orbak et al., 2007
Jansen et al., 2006

Brush with a Caterpillar

The first confirmed case of human hemolysis resulting from the venomous caterpillar, Lonomia, of Southern Brazil was reported in the American Journal of Tropical Medicine and Hygiene, Malaque et al. 2006. Eight hours after a brush with the Lonomia obliqua caterpillar (literally, his hand brushed it); a 64 year old man began vomiting and urinating blood (among other things). He was diagnosed with "caterpillar induced hemorrhagic syndrome".

Even though it was the first case of hemolysis, the caterpillar is associated with hemorrhagic syndrome (364 cases in 2004). What made this case different were lab reports indicating the patient's red blood cells burst open within the vessels.