Adaptation (biology)

In the field of evolutionary biology, adaptation refers to the process by which plant and animal species become suited to their environment or the world around them. This occurs through the process of natural selection, which influences heritable variations in organisms. Even the simplest of organisms must adapt in myriad ways, such as in their structure, physiology, genes, reproduction, development, and many other aspects. The concept of adaptation is used in many fields other than the biological sciences, such as in the social sciences, psychology, cognitive sciences, environmental sciences, and even in literacy, literature, and the arts. Its meanings depend upon the particular field and research context in which it is employed. There is a rich history of meanings and applications within the field of evolutionary biology, where it originated. The concept of adaptation has played a crucial role since Charles Darwin (1809–1882) published The Origin of Species in 1859.

Brief History

The term “adaptation,” as understood in the sciences, originated in the seventeenth century. It refers to both the process and to its outcome. This, in turn, has led to many interpretations and much debate. The origin of this dual understanding, of process and outcome, is related to the rupture that occurred during the nineteenth century when the incipient theory of evolution collided with the established belief in creationism. Therefore, adaptation, or the way organisms change to fit their environments, has played a central role in scientific research for centuries, predating even the idea of evolution in biology. The study of natural selection is a central concept related to adaptation. Natural selection refers to how a plant or animal population becomes suited to its surroundings in order to survive and reproduce in the particular environment in which it lives.

There are many points of contention about the concept of biological adaptation; even the definition of the term is not agreed upon by all scholars and scientists. The ways by which adaptations occur and develop—and the impact on the evolutionary trajectory of a particular organism’s lineage or ancestry—have been the subject of much scientific study and debate for over a century. Throughout its history, the idea of adaptation has undergone a great many important shifts and been enriched by a vast amount of scientific findings. These have both deepened and diversified the concept. In his work The Origin of Species, Charles Darwin helped propagate the idea of adaptation of the species, an idea that was not his alone. The expression “survival of the fittest” was first used to refer to competition between organisms by Herbert Spencer (1820–1903) in his 1864 Principles of Biology. J. B. S. Haldane (1892–1964) was the first scientist to apply quantified fitness in his theory of natural and artificial selection in 1924. In time, adaptation became a central concept in several major social disciplines, as well as in many fields of biology. In both the contemporary social and physical sciences, adaptation and environment are strongly linked together.

Adaptation Today

When the concept of adaptation first originated, it was used to denote the relation between design and function. Biologists today tend to agree that an organism’s traits typically reflect adaptations to the environment. From a physiological standpoint, an organism—animal or plant—can adapt to the world around it by adjusting to it. For example, it can do so by changing its metabolism with an increase or decrease in altitude.

More commonly, however, adaptation refers to the propagation of certain characteristics that enable reproductive success. In the latter, adaptation is driven by genetic variations among organisms that become adapted to a particular environment. That is, they evince greater reproductive and survival success in that natural world. A common example is the peppered moth in Britain, which were originally most commonly light-colored, with only a few darker individuals. However, the proportion of dark-tinted moths significantly increased following the Industrial Revolution in the nineteenth century. The dark-tinted moths blended against trees covered in soot emanating from surrounding factories, thus escaping detection by birds, their natural predators. After efforts were made to reduce pollution in the later twentieth century, the proportion of lighter-colored moths again began to rise.

Adaptation is a process that occurs gradually. It takes place through changes in the gene frequency. These genetic changes are driven by the advantages provided by a specific characteristic, such as the dark pigmentation of the peppered moth’s wings—since the darker-colored moths were more likely to survive, they had more opportunity to reproduce and pass on their genes than did their lighter-colored counterparts. The most popular view of adaptation is related to how an organism’s characteristic or feature has evolved, by a process of natural selection, in order to perform a specific function. There are many examples in the natural world, such as the light bones of birds that fly, the long necks of giraffes for feeding from treetops, the frontal positioning of eyes in predators in order to hunt more efficiently, and the long, sharp canine teeth of carnivores, among others.

Contemporary biologists agree that the traits of organisms commonly reflect adaptations. However, there is much disagreement over whether certain traits arose from common behaviors of the organism or whether the behaviors arose from the traits, as well as whether given traits are truly adaptations or whether they evolved by chance or for other purposes and later became useful in an unexpected manner. For example, giant pandas have a thumb-like bone called the “radial sesamoid bone.” Rather than a digit, it is an enlarged wrist bone that giant pandas employ as an opposable thumb, allowing them to hold bamboo stems more easily. However, it is not clear whether this enlarged bone became a common trait in pandas (or their evolutionary ancestors) before or after they began eating bamboo rather than a carnivorous diet. It is possible that the opposable radial sesamoid bone originally evolved as an adaptation for tree climbing and only later began to be used for feeding. This kind of shift in the function of a previously developed trait is called “exaptation.”

Evolutionary biology experts work with a catalog of meanings for the concept of adaptation that responds to its rich history and research findings. Some different applications for adaptation among interdisciplinary research interests today are individual fitness, population adaptation, adaptation as natural selection, adaptive traits, molecular adaptation, adaptation as structural improvement, and plasticity or capacity of variation. Evolutionary biologists, however, seldom use one sole meaning while eschewing all others.

Bibliography

"Adaptation." National Geographic, 19 Oct. 2023, education.nationalgeographic.org/resource/adaptation/. Accessed 14 Oct. 2024.

Bomblies, Kirsten, and Catherine L. Peichel. "Genetics of Adaption." PNAS, vol. 119, no. 30, 18 July 2022, doi.org/10.1073/pnas.2122152119. Accessed 27 Dec. 2022.

Brandon, Robert N. Adaptation and Environment. Princeton: Princeton UP, 2014. Print.

Brooker, Robert. Biology: Evolution, Diversity and Ecology. New York: McGraw, 2010. Print.

Corning, Peter A. “Biological Adaptation in Human Societies: A ‘Basic Needs’ Approach.” Journal of Bioeconomics. 2 (2000): 41–86. Print.

Cunningham, Joseph T. Hormones and Heredity: A Discussion of the Evolution of Adaptations and the Evolution of the Species. Amazon, 2012. Digital file.

Futuyma, Douglas. Evolution. Sunderland: Sinauer, 2009. Print.

Hoefnagels, Marielle. Biology: Concepts and Investigations. McGraw, 2014. Print.

Werner, Carl. Evolution: The Grand Experiment. New Leaf, 2014. Print.

Wong, Kate. "How Scientists Discovered the Staggering Complexity of Human Evolution." Scientific American, 1 Sept. 2020, www.scientificamerican.com/article/how-scientists-discovered-the-staggering-complexity-of-human-evolution/. Accessed 27 Dec. 2022.

Zimler, Carl, and Douglas Emlen. Evolution: Making Sense of Life. Greenwood Village: Roberts, 2012. Print.