Why do adult humans not explore their environment by biting things but infant humans do? How do adults investigate things if not by using their mouth?
Good question! In fact, a now-debunked theory by orangutan scientists Greatall, Badall, Okayall, et al speculated that humans do gradually lose their ability to sense their environment as, over time, they stop shoving their mouth at things.
However, in this enlightened 21st century of science, we now know that these ornithocentric perspectives have been unfairly forced onto humans - they are still capable of sensing objects by compensating with other limbs as their shoving-things-at-mouth-sense sharply declines. A landmark study found that some humans are even capable of using their appendages to send one another messages through “phones” in order to explore the world. Remember, just because a human behavior does not mirror yours does not mean it isn’t important to that species! Someday we may even discover the value of their tradition called “planking.” Inspirational.