Evolution has fundamentally shaped psychological processes because it favors genetic variations that produce adaptive behavior.
Just as fish have an inborn knack for swimming and most birds are built for flight, we humans also have innate (inborn) abilities.
At birth, the human brain emerges already “pro- grammed” for language, social interaction, self-preserva- tion, and many other functions—as we can readily see in the interaction between babies and their caregivers.
Babies “know,” for example, how to search for the breast, how to communicate rather effectively through coos and cries, and, surprisingly, how to imitate a person sticking out her tongue.
How did such potential come to be woven into the brain’s fabric?
The answer rests on the concept of evolution, the process by which succeeding generations of organisms change as they adapt to changing environments.
We can observe evo- lution in action even on a microscopic level, when an anti- biotic fails to work on a strain of bacteria that has evolved a resistance.
When it comes to larger and more complex organisms, change occurs over much longer periods of time as these organisms adapt to changing climates, preda- tors, diseases, and food supplies.
In our own species, for example, change has favored large brains suited to lan- guage, complex problem solving, and social interaction.
The core concept for this section makes this evolution- ary process the link between genetics and behavior.
Evolution has fundamentally shaped psychological pro- cesses because it favors genetic variations that produce adaptive behavior.
Our explanation of evolution begins in this section with the story of Charles Darwin, who contributed the concept of evolutionary change to the world. Next, we will build on Darwin’s insight with a look at genetics, which involves the molecular machinery that makes evolution work.
Finally, we will explore the fascinating new science of epigenetics, which is beginning to reveal how our environment acts upon our genetic framework to shape our outcomes in areas ranging from intelligence to health and disease—and ultimately influencing our very longevity.
By the end of this section, you will be able to:
1. 2.1 Describe Darwin’s theory of evolution and natural selection
2. 2.2 Illustrate the role of the genotype and the phenotype in making each person a unique individual
3. 2.3 Explain how the science of epigenetics illuminates the way environmental forces alter gene expression
