Evolution—The Theory and Its Supporting Evidence - The Changing Earth: Exploring Geology and Evolution - page 473

Geo-Focus

The Tragic Lysenko Affair

When Jean-Baptiste de Lamarck (1744-
1829) proposed his theory of inheritance
of acquired characteristics , many scientists
accepted it as a viable explanation to ac-
count for evolution. In fact, it was not
fully refuted for several decades, and
even Charles Darwin, at least for a time,
accepted some kind of Lamarckian in-
heritance. Nevertheless, the notion that
acquired characteristics could be inher-
ited is now no more than an interesting
footnote in the history of science. There
was, however, one instance in recent
times when the idea enjoyed some popu-
larity, but with tragic consequences.
One of the most notable examples
of adherence to a disproved scientifi c
theory involved Trofi m Denisovich
Lysenko (1898-1976), who became
president of the Soviet Academy of
Agricultural Sciences in 1938. He lost
this position in 1953, but in the same
year was appointed director of the In-
stitute of Genetics, a post he held until
1965. Lysenko endorsed Lamarck's
theory of inheritance of acquired

characteristics: He thought plants and
animals could be changed in desirable
ways by exposing them to a new envi-
ronment. Lysenko reasoned that seeds
exposed to dry conditions or to cold
would acquire a resistance to drought or
cold weather, and these traits would be
inherited by future generations.
Lysenko accepted inheritance of
acquired characteristics because he
thought it was compatible with Marxist-
Leninist philosophy. Beginning in 1929,
Soviet scientists were encouraged to
develop concepts consistent with this
philosophy. As president of the Academy
of Agricultural Sciences and with the
endorsement of the Central Committee
of the Soviet Union, Lysenko did not
allow any other research concerning in-
heritance. Those who publicly disagreed
with him lost their jobs or were sent to
labor camps.
Unfortunately for the Soviet people,
inheritance of acquired characteristics
had been discredited more than 50 years
earlier. The results of Lysenko's belief in

the political correctness of this theory
and its implementation were wide-
spread crop failures and famine and the
thorough dismantling of Soviet genetic
research in agriculture. In fact, it took
decades for the Soviet genetic research
programs to fully recover from this set-
back, after scientists fi nally became free
to experiment with other theories of
inheritance.
Lysenko's ideas on inheritance were
not mandated in the Soviet Union
because of their scientifi c merit, but
rather because they were deemed com-
patible with a belief system. The fact that
Lysenko retained power and only his
type of genetic research was permitted
for more than 25 years is a testament to
the absurdity of basing scientifi c theo-
ries on philosophic or political beliefs.
In other words, a government mandate
does not validate a scientifi c theory, nor
does a popular vote or a decree by some
ecclesiastic body. Legislating or decreeing
that acquired traits are inheritable does
not make it so.

and fastest are likely to survive. In some circumstances these
attributes may indeed be favorable, but under different cir-
cumstances natural selection may favor the smallest, the
most easily concealed, or those having the ability to detoxify
some natural or human-made substance.

always display the same trait, such as fl ower color). He con-
cluded from these experiments that traits are controlled by
a pair of factors, or what we now call genes , and that these
factors (genes) controlling the same trait occur in alternative
forms, or alleles . He further realized that one allele may be
dominant over another and that offspring receive one allele
of each pair from each parent. For example, in

Figure 18.4,
R represents the allele for red flower color, and r represents
white, so any offspring may inherit the combinations of alleles
symbolized as RR, Rr, or rr. And since R is dominant over r,
only those offspring with the rr combination will have white
fl owers.
We can summarize the most important aspects of Men-
del's work as follows: The factors (genes) that control traits
do not blend during inheritance, and even though traits may
not be expressed in each generation, they are not lost. There-
fore, alternative expressions of genes account for some varia-
tion in populations because traits do not blend, as previously
thought.
Mendelian genetics explains much about heredity, but
we now know the situation is much more complex than he
realized. Our discussion focused on a single gene controlling

◗

MENDEL AND THE BIRTH
OF GENETICS
Critics of natural selection were quick to point out that
Darwin and Wallace could not account for the origin of
variations or explain how variations were maintained in
populations. The critics reasoned that should a variant trait
arise, it would blend with other traits and would be lost. Ac-
tually, the answers to these criticisms existed even then, but
they remained in obscurity until 1900.

Mendel's Experiments
During the 1860s, Gregor Mendel, an Austrian monk,
performed a series of controlled experiments with true-
breeding strains of garden peas (strains that when self-fertilized