Microbiology and Immunology

Darwin, Charles Robert WORLD OF MICROBIOLOGY AND IMMUNOLOGY

150

•

dysentery, cholera, plague, and staphylococcus and strepto-

coccus infections. Such treatment was widespread for a time,

especially in the Soviet Union. However, use of bacteriophage

for this purpose was superseded by the use of chemical drugs

and antibioticseven within d’Hérelle’s lifetime. Today bacte-

riophage is employed primarily as a diagnostic ultravirus. Of

the many honors d’Hérelle received, his perhaps most notable

is the Leeuwenhoek Medal given to him by the Amsterdam

Academy of Science in 1925; before d’Hérelle, Louis Pasteur

had been the only other French scientist to receive the award.

D’Hérelle was presented with honorary degrees from the

University of Leiden and from Yale, Montreal, and Laval

Universities. He died after surgery in Paris at the age of 75.

See alsoBacteriophage and bacteriophage typing

DDarwin, Charles RobertARWIN, CHARLESROBERT(1809-1882)

English naturalist

Charles Robert Darwin is credited with popularizing the con-

cept of organic evolution by means of natural selection.

Though Darwin was not the first naturalist to propose a model

of biological evolution, his introduction of the mechanism of

the “survival of the fittest,” and discussion of the evolution of

humans, marked a revolution in both science and natural phi-

losophy.

Darwin was born in Shrewsbury, England and showed

an early interest in the natural sciences, especially geology.

His father, Robert Darwin, a wealthy physician, encouraged

Charles to pursue studies in medicine at the University of

Edinburg. Darwin soon tired of the subject, and his father sent

him to Cambridge to prepare for a career in the clergy. At

Cambridge, Darwin rekindled his passion for the natural sci-

ences, often devoting more time to socializing with

Cambridge scientists than to his clerical studies. With guid-

ance from his cousin, entomologist William Darwin Fox

(1805–1880), Darwin became increasingly involved in the

growing circle of natural scientists at Cambridge. ox intro-

duced Darwin to clergyman and biologist John Stevens

Henslow (1796–1861). Henslow became Darwin’s tutor in

mathematics and theology, as well as his mentor in his per-

sonal studies of botany, geology, and zoology. Henslow pro-

foundly influenced Darwin, and it was he who encouraged

Darwin to delay seeking an appointment in the Church of

England in favor of joining an expedition team and venturing

overseas. After graduation, Darwin agreed to an unpaid posi-

tion as naturalist aboard the H.M.S. Beagle. The expedition

team was initially chartered for a three year voyage and sur-

vey of South America’s Pacific coastline, but the ship pursued

other ventures after their work was complete and Darwin

remained part of H.M.S.Beagle’s crew for five years.

Darwin used his years aboard theBeagleto further his

study of the natural sciences. In South America, Darwin

became fascinated with geology. He paid close attention to

changes in the land brought about by earthquakes and volca-

noes. His observations led him to reject catastrophism (a the-

ory that land forms are the result of single, catastrophic

events), and instead espoused the geological theories of grad-

ual development proposed by English geologist Charles Lyell

(1797–1875) in his 1830 work, Principles of Geology. Yet,

some of his observations in South America did not fit with

Lyell’s theories. Darwin disagreed with Lyell’s assertion that

coral reefs grew atop oceanic volcanoes and rises, and con-

cluded that coral reefs built upon themselves. When Darwin

returned to England in 1836, he and Lyell became good

friends. Lyell welcomed Darwin’s new research on coral reefs,

and encouraged him to publish other studies from his voyages.

Darwin was elected a fellow of the Geological Society

in 1836, and became a member of the Royal Society in 1839.

That same year, he published his Journal of Researches into

the Geology and Natural History of the Various Countries

Visited by H.M.S. Beagle. Though his achievements in geol-

ogy largely prompted his welcoming into Britain’s scientific

community, his research interests began to diverge from the

discipline in the early 1840s. Discussions with other natural-

ists prompted Darwin’s increasing interest in population diver-

sity of fauna, extinct animals, and the presumed fixity of

species. Again, he turned to notes of his observations and var-

ious specimens he gathered while on his prior expedition. The

focus of his new studies was the Galápagos Islands off the

Pacific coast of Ecuador. While there, Darwin was struck by

the uniqueness of the island’s tortoises and birds. Some neigh-

boring islands had animal populations, which were largely

similar to that of the continent, while others had seemingly

different variety of species. After analyzing finch specimen

from the Galápagos, Darwin concluded that species must have

some means of transmutation, or ability of a species to alter

over time. Darwin thus proposed that as species modified, and

as old species disappeared, new varieties could be introduced.

Thus, Darwin proposed an evolutionary model of animal pop-

ulations.

The idea of organic evolution was not novel. French

naturalist, Georges Buffon (1707–1788) had theorized that

species were prone to development and change. Darwin’s own

grandfather, Erasmus Darwin, also published research regard-

ing the evolution of species. Although the theoretical concept

of evolution was not new, it remained undeveloped prior to

Charles Darwin. Just as he had done with Lyell’s geological

theory, Darwin set about the further the understanding of evo-

lution not merely as a philosophical concept, but as a practical

scientific model for explaining the diversity of species and

populations. His major contribution to the field was the intro-

duction of a mechanism by which evolution was accom-

plished. Darwin believed that evolution was the product of an

ongoing struggle of species to better adapt to their environ-

ment, with those that were best adapted surviving to reproduce

and replace less-suited individuals. He called this phenome-

non “survival of the fittest,” or natural selection. In this way,

Darwin believed that traits of maximum adaptiveness were

transferred to future generations of the animal population,

eventually resulting in new species.

Darwin finished an extensive draft of his theories in

1844, but lacked confidence in his abilities to convince others

of the merits of his discoveries. Years later, prompted by

rumors that a colleague was about to publish a theory similar

womi_D 5/6/03 2:09 PM Page 150