New Guinea map: Map of New Guinea, showing location of discoveries.

Scientists exploring a remote mountain rainforest in New Guinea report discovering a surprising number of animal and plant species—some quite rare, and others never seen before. Among their discoveries were 20 new species of frogs, four new types of butterflies, five new species of palms, and a newly-discovered bird. Many other plants and animals found in the region are extremely rare—in some cases, this was the first time they were ever seen inside Indonesia.

To see photos of some of the newly-discovered species, go here

The area has no native human population. In fact, the scientists believe their expedition may have been the first time humans ever visited this particular place. Many of the animals walked right into the camp, indicating they had not learned to fear human presence.

Indonesia is a hotspot for biodiversity. In fact, the country of Indonesia has more different species of animals than the entire continent of Africa! Why is Indonesia's wildlife so rich?

1. It's tropical, lying right on the Equator. Sunlight provides energy for tremendous plant growth, which provides abundant resources for animals.
2. It's a chain of islands, more than 13,000 in all. Plants and animals isolated on islands often evolve into new species, found nowhere else on Earth.
3. It's also mountainous. Mountains and valleys create barriers that prevent plants and animals from spreading out. Again, isolated populations will sometimes evolve into new species.
4. It straddles Wallace's line. Alfred Wallace, a contemporary of Darwin's, and sometimes credited as the co-discoverer of natural selection, noticed that animals in eastern Indonesia were similar to those in Australia, while animals in western Indonesia were more similar to those in Asia. Later scientists realized that plate tectonics and high sea levels had kept those two continents separate for millions of years, allowing entirely different types of animals to evolve. It's only been fairly recently—in geological terms—that the two landmasses came close together in the country we now call Indonesia.