Natural life is the first level of the Present difficulty in the Genesis/Mega Drive port of Lemmings.
Strategy[]
Have the first Lemming bash through the sign to the right of the entrance. Turn the second Lemming into a Blocker once he's at the top of the hill at raise the release rate to 99. Have the Trailblazer bash through the well and drop down below. Don't worry, he will survive the fall.
Bash through the bottom of the pillar then have him build at the edge of the platform. The idea is to connect his ramp to the two small thorns sprouting from the mount of dirt across the water. Once the Builder collides with the thorns, he will turn back to the left so make him build to the exit. Bomb the Blocker holding the other Lemmings back. They should walk across the level, collide with the right edge of the map and turn left towards the Exit portal.