Pop Up Flash to the Rescue
Quick Tip: The pop up flash is actually a very useful tool if used in close quarters. It doesn't have a big reach, so stay no more than six feet from the subject. Not only will it soften shadows, but it can help to reveal more detail. Here with these Wolf Monkeys it also added a nice light in the eyes. For a subtle look, try lowering the output on the flash to -1.7. This gives just enough light without being overpowering.