Organisms possess various characteristics, or traits, that develop over a lifetime rather than being present from birth. These are known as acquired traits, arising from an organism’s experiences or environmental influences.
Defining Acquired Traits
Acquired traits are characteristics that an organism develops after birth, throughout its life, as a result of environmental factors, personal experiences, or deliberate actions. These traits are not encoded in the organism’s original genetic blueprint.
For example, a person who spends a lot of time outdoors might develop a suntan, which is a change in skin pigmentation caused by exposure to ultraviolet radiation. Similarly, a musician might develop calluses on their fingertips from playing an instrument, or an athlete might build significant muscle mass through rigorous exercise and diet.
Other examples of acquired traits include scars resulting from injuries, the ability to speak a foreign language, or learned skills such as riding a bicycle or swimming. Mental traits, such as learned sentiments or object recognition, are also acquired through experience. These changes reflect an organism’s interaction with its surroundings.
Acquired Traits Versus Inherited Traits
The distinction between acquired and inherited traits is fundamental to understanding how characteristics are passed between generations. Inherited traits are characteristics determined by genetic information, or DNA, passed directly from parents to their offspring. These traits are present from birth or develop naturally as part of an organism’s lifecycle. Examples in humans include eye color, natural hair color and texture, blood type, and genetic predispositions to conditions like sickle cell anemia.
In contrast, acquired traits are not part of an organism’s genetic makeup. They do not involve changes to the DNA sequence in reproductive cells (sperm or egg cells). Therefore, while an individual might develop significant muscle strength, learn a complex language, or gain a scar, these modifications are not genetically transmitted to their children. Offspring must acquire these traits themselves.
Inheritance of Acquired Traits
Historically, there was a belief, notably associated with Jean-Baptiste Lamarck, that acquired traits could be passed down through generations, a concept known as Lamarckian inheritance. Lamarck proposed that if an organism developed a characteristic through use or disuse during its lifetime, that trait could be inherited by its offspring. For instance, he suggested that a blacksmith’s sons might inherit the strong muscles their father developed from his work, or that giraffes developed long necks by stretching for leaves, and this longer neck trait was then passed on.
Modern genetics, based on the understanding of DNA and heredity, largely disproved this idea, establishing that changes to an organism’s body cells (somatic cells) during its lifetime generally do not alter the genetic information in its germline cells (sperm or egg cells), which are responsible for heredity. Therefore, physical changes or learned behaviors acquired by an individual are typically not reflected in the DNA passed to the next generation. While the historical Lamarckian view is not generally accepted, epigenetics explores complex and rare exceptions. This field examines how gene expression can be modified without altering the underlying DNA sequence, and some research suggests certain environmentally induced epigenetic changes might, in limited cases, be passed down to subsequent generations. However, these instances are distinct from the broad Lamarckian theory and represent intricate biological mechanisms, not a general rule for the inheritance of acquired traits.