What is meant by acquired trait?

An acquired trait is a characteristic that develops during an organism's lifetime due to environmental influences or experiences, rather than being inherited from its parents. It's a change in the phenotype (physical characteristics) that's not encoded in the organism's genes and therefore cannot be passed on to offspring.

Here are some examples:

* Muscle growth from exercise: A bodybuilder's increased muscle mass is a result of physical training, not a change in their genes. Their children will not inherit those larger muscles.

* Calluses on hands: These toughened areas of skin develop from repeated friction and are not passed down genetically.

* Tanning: Exposure to sunlight causes the skin to produce more melanin, resulting in a tan. This is a temporary change and not a trait passed down to offspring.

* Learning a new language: The ability to speak a particular language is acquired through experience, not inherited.

* Scarring: Injuries that leave scars are not encoded in genes and cannot be passed on.

Important Note: The idea of acquired traits being passed down was a central tenet of Lamarckism, an earlier theory of evolution that has been largely discredited. While acquired traits are important for an individual's adaptation to its environment, they are not the basis of evolution. Evolution is driven by changes in the genetic makeup of populations, which are then passed down to offspring.