2 poks in natural science ”what we know something to be” is not necessarily the same as ”what...

2 PoKs in natural science

• ”What we know something to be”

is not necessarily the same as

”What it is”.

• Influence of social-cultural context

on scientists: claims accepted as knowlege in one context, and

unacceptable in another.

What carries genetic information?What is its structure?

• Late 1800s: DNA (de-oxyribose nucleic acid) found in the nucleus (together with proteins).

• Is DNA the hereditary material? (maybe proteins are?)

• What is the structure of DNA?

The structure of DNA

Evidence from:• Biochemistry: phosphate groups, water, 4

different nitrogenous bases in equal ratios (Chargaff):

Adenine, Thymine

Cytosine, Guanine

Physics, X-Ray diffraction images: a helical structure (Pauling – nobel laureate – 3

helices).

Watson & Crick (in 1959)

W & C present a first model

• Watson had listened to a presentation by Rosalind Franklin in which she estimated the amount of water based on her X-Ray diffraction patterns. They then built a model and presented it for peer review.

• But Watson did not take notes, remembered incorrectly, and when Franklin saw the model, her comments falsified it immediately.

• 1953: a revised model ..

The original model (1953)

DNA structure

Biochemistry: bases in equal ratios

W & C: what can this mean?

Ce n est pas un pipe ..

The map is not the territory,the thing is not the thing named.

Bateson

Methods of verification .. The inevitability of uncertainty

T. S. Eliot, The Hollow Men

Between the idea and the reality;

between the motion and the act,

Falls the shadow.

Between the conception and the creation;

between the emotion and the response,

Falls the shadow.

Binomial system of nomenclature

• Carolus Linneaus (1707-1778).

• Kingdom (Animalia), Phylum (Vertebrata), Class (Mammalia), Order (Primates)

(genus) Homo, (species) sapiens

While modified, remains the standard over 200 yrs.

Humans classified into sub-groups:

• Within Homo sapiens Linneaus proposed four taxa: americanus, asiaticus, africanus, europeanus, each race with characteristics endemic to individuals belonging to it:

Native Americans: reddish, stubborn, anger easily.

Africans: black, relaxed, negligent.

Asians: yellow, avaricious, easily distracted.

Europeans: white, gentle, and inventive.

Linneaus now regarded as a father of scientific racism; subspecies (race) rejected.

J. Marks, U. Calif. (1999) personal.uncc.edu/.../aaa/marksaaa99.htm

• “The claim that we are apes is not a fact of nature, but an artifact of the way we organize and divide nature”.

• “As a consequence, that claim has a lot more to do with the work of Durkheim and Mauss than with Darwin and Huxley. This is an obvious site for a biological anthropology – a field both anthropologically-informed and biologically meaningful. And it’s vacant at the moment. “