2017-09-01 Coral Magazine

ALL: D. KNOP

ern evolutionary biology. At the time it was believed that

a species was a fixed entity, a divine creation unchanging

over time. In 1838, Darwin proposed a radically differ-

ent theory: that all organisms arise and develop through

the natural selection of small, inherited variations that

increase a plant or animal’s ability to compete, survive,

and reproduce. In 1859 he published his groundbreaking

work On the Origin of Species.

The eye, with its immense complexity, was a kind of

test of Darwin’s theory, even during his lifetime. It devel-

oped, he believed, through natural selection by offering a

survival and reproductive advantage. The notion that the

eye was created by God was widely accepted in Darwin’s

time and provided evangelical critics much fodder to at-

tack his theories. Countering the prevailing wisdom,

Darwin devoted a whole chapter of his book to the

eye and its genesis. His explanation was simple:

Early in the history of development there

must have been a very simple construc-

tion of two cells, a pigment cell and a

nerve cell (photoreceptor), that en-

abled the organism to perceive

direction and was therefore ad-

vantageous. He believed that

the more highly developed

eyes arose over time

from this this primi-

tive eye.

The horseshoe crab, with its compound

eye, has not changed significantly for

about 440 million years.

Trilobites, an extinct class of marine

arthropods that lived about 520 million

years ago, had compound eyes.

As curious a humanas ever lived, Brit-
ish naturalist Charles Darwin spent five years exploring
the world on the ship HMS Beagle and came home with
the first explanation of how coral reefs are formed. He
also brought with him a trove of fossils, bones, and ani-
mal specimens that would form the basis of his theory of
evolution, which provides a scientific explanation for the
biodiversity of all life and is still the foundation of mod-