EvoluTIonARy BIology 17
were discovered. Since James Watson and Francis Crick established the structure of
DNA in 1953, advances in genetics, molecular biology, and molecular and informa-
tion technology have revolutionized the study of evolution.
New molecular and computational technology has enabled new fields of
evolutionary study to develop, among them molecular evolution (analysis of the
processes and history of changes in genes). The leaders of the evolutionary syn-
thesis had maintained that almost all features of organisms are adaptive, and
evolved by natural selection. But this principle was challenged by the neutral
theory of molecular evolution, developed by Motoo Kimura (1983, [13]), who
argued that most of the evolution of DNA sequences occurs by chance (genetic
drift) rather than by natural selection. Evolutionary developmental biology, growing
out of comparative embryology and based partly on molecular genetics, is devoted
to understanding how the evolution of developmental processes underlies the
evolution of morphological features at all levels, from cells to whole organisms.
Because the entire genome—the full DNA complement of an organism—can now
be sequenced, molecular evolutionary studies have expanded into evolutionary
genomics, which is concerned with variation and evolution in multiple genes or
even entire genomes. Genomic data are enabling biologists to determine phylo-
genetic relationships with ever-greater confidence; they are revealing the genetic
bases of adaptive characteristics of species and how and when they were modified
by natural selection, and they are revealing the history of populations and their
distributions over the globe. The histories of species are written in their genes.
The advances in these new fields are complemented by vigorous research, new
discoveries, and new ideas about long-standing topics in evolutionary biology,
such as the evolution of adaptations and of new species. Since the mid-1960s,
evolutionary theory has expanded into areas such as ecology, animal behavior,
and reproductive biology. Detailed theories that explain the evolution of particular
kinds of characteristics such as life span, ecological distribution, and social behav-
ior were pioneered by the evolutionary theoreticians William Hamilton and John
Maynard Smith in England and George Williams in the United States. The study
of macroevolution has been renewed by provocative interpretations of the fossil
record and by new methods for studying phylogenetic relationships. Research in
evolutionary biology is progressing more rapidly than ever before.
Since Darwin’s time, research on evolution, and in biology more broadly, has
transformed evolutionary biology. Were Darwin to reappear today, he would
understand very few scientific papers about evolution. Modern evolutionary biologyG. Ledyard Stebbins, George Gaylord Simpson, and Theodosius DobzhanskyMotoo Kimura01_EVOL4E_CH01.indd 17 3/23/17 8:43 AM