Encephalization

[TigerLilly]

I was wondering if someone could explain what encephalization is in not-so-complicated terms. I thought it was how brain weight and body weight related to each other when compared to a reference variable. In a bio article that I'm reading, it says this but later it refers to brain mass in realtion to diet and hatchling development in birds. I'm confused. Can someone help me out please? Here are 2 quote from the article:

"Alternatively, comparisons are more often made after controlling statistically for the effects of body weight or some other size-related reference variable. encephalization, a comparative concept, is measured as a specie's deviation from some observed or expected relation between brain mass and body mass in a reference group."

"In summary, encephalization in mammals is often associated with dietary differences, whereas in birds it is associated with varying patterns of hatchling development."

Any help is appreciated, thanks a lot!

[Monique]

Well, from what you wrote done it seems that with encephalization is meant the amount of brain that an organism has, in comparison with other species.

In which case you have to control for the body weight of the animal, since a human brain would hardly fit into the skull of a rabbit :P Basically, you'd expect the ratio to be the same across species, hypothetically.

Apparently it turns out that meat eaters (hunters) have a differently sized brain, compared to plant eaters (gatherers). The same deviation exists for hatchling development (not sure what is meant with that, maybe the faster developing birds have larger brains).

[Monique]

Or simply stated:

encephalization quotient : a number reflecting the increase in brain size over and beyond that explainable by an increase in body size (ratio of brain weight to body weight).