Simplify the following text for a Grade 4 native English-speaking person.
Original: The zoo was founded in 1868 , when the Lincoln Park Commissioners were given a gift of a pair of swans from Central Park in New York City In 1874 , the swans were joined by a bear cub , the first animal purchased for the zoo .
Simplified: This was when the Lincoln Park Commissioners were given a gift of a pair of swans . In 1874 , the swans were joined by a bear cub .