Biological determinism, also known as genetic
determinism is the belief that human behaviour
is controlled by an individual's genes or
some component of their physiology, generally
at the expense of the role of the environment,
whether in embryonic development or in learning.
Genetic reductionism is a similar concept,
but it is distinct from genetic determinism
in that the former refers to the level of
understanding, while the latter refers to
the supposedly causal role of genes. It has
been associated with movements in science
and society including eugenics, scientific
racism, the debate around the heritability
of IQ, the biological basis for gender roles,
and the sociobiology debate.
In 1892 August Weismann proposed in his germ
plasm theory that heritable information is
transmitted only via germ cells, which he
thought contained determinants (genes). Francis
Galton, supposing that undesirable traits
such as club foot and criminality were inherited,
advocated eugenics, aiming to prevent supposedly
defective people from breeding. Samuel George
Morton and Paul Broca attempted to relate
the cranial capacity (internal skull volume)
to skin colour, intending to show that white
people were superior. Other workers such as
H. H. Goddard, and Robert Yerkes attempted
to measure people's intelligence and to show
that the resulting scores were heritable,
again to demonstrate the supposed superiority
of people with white skin.
Galton popularized the phrase nature and nurture,
later often used to characterize the heated
debate over whether genes or the environment
determined human behavior. Scientists such
as ecologists and behavioural geneticists
now see it as obvious that both factors are
essential, and that they are intertwined.Late
in the 20th century, the determinism of gender
roles was debated by geneticists and others.
Biologists such as John Money and Anke Ehrhardt
attempted to describe femininity and homosexuality
according to then-current social standards;
against this, the evolutionary biologist Richard
Lewontin and others argued that clothing and
other preferences vary in different societies.
The biologist E. O. Wilson founded the discipline
of sociobiology, founded on observations of
animals such as social insects, controversially
suggesting that its explanations of social
behaviour might apply to humans.
== History ==
=== 
Roots ===
Biological determinism is the belief that
a human’s behavior is controlled by a person’s
genes and inherited traits. It dates back
to the 1800s. Stephen Jay Gould has spent
his career tracing the roots of this “western”
thought because it is more involved than anyone
could have assumed. Gould suggests that the
main theories of biological determinism are
based on bad biology and bad use of the scientific
method. When a scientist says they used the
scientific method to gather their data, the
readers automatically assume that the information
given must be correct.
Gould presents three key ideas that have influenced
biological determinism. The first is that
measurement and quantification have changed
science over the past century and without
context, these measurements are useless. If
something is assigned a number, then it must
be real, true, and scientific. If these numbers
and measurements are given without context,
then the data can be given many different
meanings. The second is that reinfication,
the idea that certain qualities (intelligence,
race) are valid because we put a name on it.
One could separate a group into different
components and give a name to these divided
groups and have it be true, but actually,
there is nothing scientific about intelligence
being used as a unitary quality. The third
problem is that the main thought behind biological
determinism is that traits are inherited.
Scientists have traced certain traits through
families lines and found that some are inherited.
Gould suggests that these studies merely restate
the original assumption. Gould points out
that various theories of biological determinism
have no evidence or science to back them up,
and even though these ideas are very flawed,
people still widely accept them.
However, Gould is thought to be flawed in
his own way because readers believe he is
simply disregarding certain aspects of science.
Gould questions that since the scientific
aspects of the works themselves are so flawed
that why is it so widespread accepted. Gould
suggests that there could be some social,
political, and economic forces which could
explain why these biological determinism theories
are so widely accepted, but he fails to go
further deep into the topic. Gould shows that
these biological determinism theories have
many consequences for human life and scientists
in the future can see these and use his book
to continue trying to show the people that
biological determinism, is in fact, false.
In this review of Gould’s essay by Garland
E. Allen, Allen writes that Gould has helped
future scientists examine social, economic,
and political values of this time regarding
biological determinism. Biological determinism
is still prominent in scientific works, past
and present, that have been regarded by the
public as true and believable. Gould wants
his readers to understand that biological
determinism has roots all throughout science,
even though it has been proven false.
=== Germ plasm ===
In 1892, the Austrian biologist August Weismann
proposed that multicellular organisms consist
of two separate types of cell: somatic cells,
which carry out the body's ordinary functions,
and germ cells, which transmit heritable information.
He called the material that carried the information,
now identified as DNA, the germ plasm, and
individual components of it, now called genes,
determinants. Weismann argued that there is
a one-way transfer of information from the
germ cells to somatic cells, so that nothing
acquired by the body during an organism's
life can affect the germ plasm and the next
generation. This effectively denied that Lamarckism
(inheritance of acquired characteristics)
was a possible mechanism of evolution. The
modern equivalent of the theory, expressed
at molecular rather than cellular level, is
the central dogma of molecular biology.
=== Eugenics ===
Early ideas of biological determinism centred
on the inheritance of undesirable traits,
whether physical such as club foot or cleft
palate, or psychological such as alcoholism,
bipolar disorder and criminality. The belief
that such traits were inherited led to the
desire to solve the problem with the eugenics
movement, led by a follower of Darwin, Francis
Galton (1822–1911), by forcibly reducing
breeding by supposedly defective people. By
the 1920s, many U.S. states brought in laws
permitting the compulsory sterilization of
people considered genetically unfit, including
inmates of prisons and psychiatric hospitals.
This was followed by similar laws in Germany,
and throughout the Western world, in 
the 1930s.
=== Scientific racism ===
Under the influence of determinist beliefs,
the American craniologist Samuel George Morton
(1799–1851), and later the French anthropologist
Paul Broca (1824–1880), attempted to measure
the cranial capacities (internal skull volumes)
of people of different skin colours, intending
to show that whites were superior to the rest,
with larger brains. All the supposed proofs
from such studies were invalidated by methodological
flaws. The results were used to justify slavery,
and to oppose women's suffrage.
=== Heritability of IQ ===
Alfred Binet (1857–1911) designed tests
specifically to measure performance, not innate
ability. From the late 19th century, the American
school, led by researchers such as H. H. Goddard
(1866–1957), Lewis Terman (1877–1956),
and Robert Yerkes (1876–1956), transformed
these tests into tools for measuring inherited
mental ability. They attempted to measure
people's intelligence with IQ tests, to demonstrate
that the resulting scores were heritable,
and so to conclude that people with white
skin were superior to the rest. It proved
impossible to design culture-independent tests
and to carry out testing in a fair way given
that people came from different backgrounds,
or were newly arrived immigrants, or were
illiterate. The results were used to oppose
immigration of people from southern and eastern
Europe to America.
=== Human gender roles ===
Lynda Birke argues in her 1992 book In Pursuit
of Difference that biology explains sexual
differences by the mechanisms of chromosomes,
genetics, and inheritance. However, hormonal
differences are not absolute, and people can
be born with intersex characteristics, for
example as a genetic mosaic. Homosexuality
can be attributed to both biological and social
causes. Dean Hamer has studied the so-called
"gay gene". The neuroscientist Simon LeVay
in 1991 studied the difference in hypothalamic
structures between homosexual and heterosexual
men, finding that the INAH-3 suggested a partial
cause for homosexuality.Richard Lewontin,
Steven Rose, and Leon Kamin's book Not in
Our Genes discussed a study of girls who were
relatively "masculinized". The biologists
John Money and Anke Ehrhardt looked for ways
to describe femininity that fitted their own
social standards, such as clothing preference
or using makeup. The experiment, in Lewontin's
words, "ignores the existence of societies
in which women wear pants, or in which men
wear skirts, or in which men enjoy and appropriate
jewelry to themselves." Gender differences
in work are becoming less pronounced, suggesting
that these are imposed by society. In contrast,
the standard model of sex and gender indicates
a clear-cut dichotomy between males and females,
with no overlap, a cultural model followed
by professionals such as doctors when they
deal with gender assignment.
=== Sociobiology ===
