584 CHAPTER 22major processes of long-term evolution, anagenesis (changes in characters within lin-
eages) and cladogenesis (origin of two or more lineages from a common ancestor), are
abundantly supported by evidence from every possible source, ranging from molecu-
lar biology to paleontology. Over the past century we have certainly learned of evolu-
tionary processes that were formerly unknown: we now know, for example, that some
DNA sequences are mobile and can cause mutations in other genes. But no scientific
observations have ever cast serious doubt on the reality of the basic mechanisms
of evolution, such as natural selection, or on the reality of the basic historical pat-
terns of evolution, such as transformation of characters and the origin of all known
forms of life from common ancestors. Contrast this mountain of evidence with the
evidence for supernatural creation or intelligent design: there is no such evidence.The uses and implications of Evolutionary Science
Like any other science, evolutionary biology has practical applications—in health
science, food production, and other areas—that can affect our lives. And to a far
greater degree than most other sciences, it has enormous implications for under-
standing ourselves as individuals, as societies, as a species. No other subject in
biology has more profound philosophical implications. We touch here on some of
these topics, although only superficially; hundreds of books have been written on
these subjects.Evolution by natural selection: A broad and flexible concept
Darwin already recognized that evolution—that is, descent with modification
from common ancestors—doesn’t describe only the history of species: languages
and other cultural elements also evolve. Since Darwin’s time, the basic idea of
evolution, as well as the specific concept of evolution by natural selection of vari-
ants, has been widely applied [94]. Karl Popper, David Hull, and other philoso-
phers have proposed that knowledge, especially scientific knowledge, changes
by a process of selection among competing ideas or schools of thought—an idea
that is at the core of evolutionary epistemology [60]. There exist academic fields
of evolutionary social science, evolutionary political science, evolutionary eco-
nomics, evolutionary anthropology, and applications of the ideas of evolution and
selection to technological innovation and even to literature and creative thought
[79, 116]. In many of these areas, the analogy to biological evolution by natu-
ral selection of random variation is inexact and perhaps forced; for example, the
variations that may or may not survive are often not random in the sense that
describes gene mutations. Still, evolution by natural selection, in a broad sense,
can describe a great range of human experiences and activities [35], and in some
areas, it has a real payoff. An enormous field of evolutionary computation, founded
on the principle that complex adaptations can evolve by natural selection among
randomly generated variations, uses genetic algorithms that mimic natural selec-
tion to address a huge range of real-world problems. There even exist evolutionary
algorithms that enable robots to adapt to unforeseen changes [1].Practical applications of evolutionary science
Almost all of the principles and methods of evolutionary biology bear on a range of
practical applications [56]. Among these are human use of other organisms’ adapta-
tions, food production, management of natural resources, conservation, and human
health.
Many of the methods and theoretical models developed to study evolution have
been broadly useful. Evolutionary geneticists developed the concept of linkage
disequilibrium and the dynamics of association between genes or markers; these22_EVOL4E_CH22.indd 584 3/22/17 1:49 PM