Encyclopedia of Evolution.pdf - Online Reading Center

anamensis in 1995, and Kenyanthropus platyops in 2001. K.
platyops has some characteristics that appear very modern
despite its ancient age. Thus for the third time, a member of
the Leakey family has discovered evidence that the australopithecines
may not be on the main line of human evolution.
Meave Leakey has been head of the Division of Paleontology
at the Kenya National Museum since 1982 and has directed
the museum’s Turkana field projects since 1989.
Richard and Meave Leakey’s daughter Louise completed
a Ph.D. in paleontology in 2001 and may continue the Leakey
family tradition of important contributions to evolutionary
science.
Further Reading
Leakey, Richard E. One Life: An Autobiography. Salem, N.H.: Salem
House, 1984.
Morell, V. Ancestral Passions: The Leakey Family and the Quest for
Humankind’s Beginnings. New York: Simon and Schuster, 1995.
Willis, Delta. The Leakey Family: Leaders in the Search for Human
Origins. New York: Facts On File, 1992.
Lewontin, Richard (1929– ) American Geneticist Born
March 29, 1929, Richard Charles Lewontin has contributed
greatly to an understanding of the connection between genetics
and the evolutionary process. He pioneered the application
of molecular techniques to the study of population
genetics and evolutionary change. He has also been one of
the most outspoken critics of what he considers the misapplication
of genetic and evolutionary concepts to the complexities
of human individuality and society.
After receiving a doctorate from Columbia University,
Lewontin held faculty positions at North Carolina State University,
the University of Rochester, and the University of Chicago.
In 1966 Lewontin and geneticist J. L. Hubby published
two papers that introduced the use of gel electrophoresis into
the study of population genetics (see bioinformatics). He
joined the faculty of Harvard University in 1973.
One of Lewontin’s major contributions has been to criticize
the overapplication of natural selection in evolutionary
concepts. While natural selection has produced many
evolutionary adaptations, there are many biological characteristics
that are not the product of selection. Lewontin has
made three contributions to this line of thought. First, his
studies of population genetics revealed a great deal of DNA
and protein variation that was not connected to survival or
reproduction in wild populations. Second, together with a
Harvard colleague (see Gould, Stephen Jay), he pointed
out that many characteristics were not themselves adaptations
but were the indirect consequences of natural selection
acting upon some other characteristic. This concept was formalized
as exaptation by Gould and paleontologist Elisabeth
Vrba (see adaptation). Third, Lewontin has also been a tireless
critic of sociobiology. Lewontin believes that while the
human brain and its mental capacities evolved, its particular
characteristics did not, therefore it is useless to look for a
genetic basis or an evolutionary reason for such characteristics
as religion, fear of strangers, or intelligence. Lewontin
sees belief in a genetic basis for differences in intelligence as
the first step toward injustice. He was elected to, and resigned
from, the National Academy of Sciences during the 1970s.
Further Reading
Gould, Stephen Jay, and Richard Lewontin. “The spandrels of San
Marco and the Panglossian paradigm: A critique of the adaptationist
programme.” Proceedings of the Royal Society of London
B 205 (1979): 581–598.
Hubby, John L., and Richard Lewontin. “A molecular approach to
the study of genic heterozygosity in natural populations. I. The
number of alleles at different loci in Drosophila pseudoobscura.”
Genetics 54 (1966): 577–594.
Levins, Richard, and Richard Lewontin. The Dialectical Biologist.
Cambridge, Mass.: Harvard University Press, 1987.
Lewontin, Richard. The Genetic Basis of Evolutionary Change. New
York: Columbia University Press, 1974.
———. It Ain’t Necessarily So: The Dream of the Human Genome
and Other Illusions. New York: New York Review Books, 2000.
———. The Triple Helix: Gene, Organism, and Environment. Cambridge
Mass.: Harvard University Press, 2000.
———, Steven Rose, and Leon J. Kamin. Not in Our Genes: Biology,
Ideology, and Human Nature. New York: Pantheon, 1985.
———, and John L. Hubby. “A molecular approach to the study of
genic heterozygoisty in natural populations. II. Amount of variation
and degree of heterozygosity in natural populations of Drosophila
pseudoobscura.” Genetics 54 (1966): 595–609.
life, origin of See origin of life.
life history, evolution of
life history, evolution of Life history refers to the patterns
of growth, reproduction, and death in organisms. Evolutionary
scientists study the life histories of organisms, attempting
to explain them in terms of natural selection, relative
to particular environments and ways of persisting in these
environments. Certain sets of characteristics, called strategies,
function successfully together; however, seldom does an
environment or habitat have a single best life history strategy.
Below are examples, rather than a complete overview.
Physiology and Growth
Organisms have limits. In particular, they have limited
resources and must allocate those resources among functions.
Frequently, to do more of one thing means to do less
of another. Organisms accordingly invest resources into those
functions that will allow them to obtain more resources and
to reproduce more successfully.
Consider this simplified example of plant growth. The
plant uses its food resources to produce leaves; this is an
investment, because the leaves then allow the plant to make
more food. However, it must also produce stems, to supply
the leaves with water, and to hold the leaves up higher than
the leaves of other plants; and roots, which obtain water
and minerals for the leaves. If the plant allocates most of the
food that the leaves make into the production of new leaves,
neglecting its stems (for example, by making them flimsy) and
producing few new roots, it may be able to grow very fast
but will probably be unable to survive the winter. This is part
of the life history strategy of a weed; it grows fast because