Although scientists understood the role of chromosomes in
inheritance from the mid-1880s, the work of Gregor Mendel was not
rediscovered until 1900. Chromosomes were visible in microscopes,
but genes could be observed only indirectly. A gene corresponds to
a section of the deoxyribonucleic acid molecule (DNA) that forms
the nucleus of each cell in the body. The DNA is tightly packed to
form chromosomes. The structure of the DNA molecule was not
discovered until 1953.
Based on his observation that his mutant fruit fly with
white eyes was the offspring of red-eyed parents, Thomas Hunt
Morgan argued that eugenics was not entirely scientific.
Understanding the genetic effects of X-rays led Sturtevant and
Muller to warn of the dangers of radioactive fallout from nuclear
testing and nuclear war. But Sturtevant and Muller did not agree
on the value of eugenics.
The pseudo-science of eugenics is intermingled with the
development and demise of the eugenics movement, which co-opted
many well-meaning scientists with the hope of improving humankind,
and degenerated into brutal and stupid acts of racial and ethnic
hatred, including the genocidal crimes of the Nazis.
The key problems with eugenics are our inability to
objectively determine what genetic differences are improvements,
and our weakness for using coersion and brutality to get what we
See also in The book of science:
Readings on wikipedia: