The Two Assumptions of Heritability Studies

Evolution cannot occur without at least some traits being heritable. Heritability is a measure of parent-offspring resemblance; so a trait with high heritability has a high genetic component to it, right?
No.

This is one strange and paradoxical thing about heredity studies: heritability is defined as something specific to a certain population in certain circumstances. It is neither a property of an individual nor a property of a trait.

In parent-offspring correlation studies, heritability is simply the slope that measures the resemblance between the average trait value of the two parents and the trait value of the offspring. In twin studies, heritability is the correlation between the trait values of the twins.

From my reading about scientific and philosophical articles on heritability, I figured that two assumptions are implied in those studies without even being mentioned:
(1) Parents and offspring always resemble, instead of differ from, each other. (In other word, the slope of heritability on the parent-offspring graph is always positive.)
(2) Heritability can never equal to zero. This is because of how the math works out. Heritability is a correlation: a covariance over the product of two standard deviations. Covariances and standard deviations are always positive numbers.

Think about it: pick any measurable trait, its heritability will be a non-zero positive number, even if in reality it does not have genetic component. So what does heritability really tell us?

What would our evolution looks like if parents and offspring always tend to differ, not resemble, each other? Would we evolve backwards? Within one generation, the evolutionary response in the offspring will shift in the opposite direction as the selective pressure; however, the response will be cancelled in the grand-offspring generation under the same selective pressure. Just thinking about this weird scenario gave me a giggle fit in my philosophy-biology class.

Crazy Start

It's the second week of school. I already have homework piled up and a bunch of books to read. Isn't that crazy? I slept too less last night, spent the free period between classes to read The Origin of Species, got back home and insisted not to sleep until midnight.

I'm happy with the history of science and philosophy biology classes I chose. Although they require more readings than straight science classes, the content is interesting and the instructors are knowledgeable and friendly. I've got an official reason to read The Origin of Species.

I haven't got exercise so I'm stiff, but I'm so tired that I don't feel anything. I want ice-cream and going to sleep. A paper is due after tomorrow. At least I have ice-cream now.

(Surprisingly, it has been raining heavily at night in Madison in the past two days. The snow has melted because of the rain.)

Review on Wassily Kandinsky’s Black Triangle

Just some parts from my 5-page-long art history final paper. Taking the components of the painting apart, I felt like studying the anatomy of an organism. I should have started it a few weeks ago, however finished it in the last day. Whether it's good writing or junk, it's done now! Consider how much time I put in, I'm satisfied. Hope prof. MC will like it.

Wassily Kandinsky, Black Triangle, 1925

Source: Paul Overy, Kandinsky: The Language of the Eye 

New York, N.Y., Praeger Publishers, Inc., 1969, p. 91

Best Logic Question Ever

 "If I ate myself would I become twice as big or disappear completely?"

 Saw it somewhere on Tumblr. They should totally teach this in philosophy class!

Is That Philosophic?

My art history professor was trying to explain how surrealist artists produce the sense of uncanny by making familiar things seem strange and unfamiliar.

Prof. MC, "One of my favorite things to do is to look at myself in the mirror. Hehehe. The more you look, the stranger and more alien the familiar face becomes. Believe me, just give yourself a minute. I give myself a minute every hour."

LOL I can't tell if Prof. MC was being philosophic and psychoanalytic or just plain narcissistic.