1. Detail of animals in a 36,0000-year-old cave painting, Lascaux, France.

2. A 30,000-year-old ivory carving of a water bird, found in Germany.

3. Biologist Carlos Rivera Gonzales examining a tiny tree frog in Peru.

Harvard biologist E. O. Wilson believes that humans have evolved an innate affinity for natural environments rich in biodiversity - biophilia.