The species of primates called mandrills have evolved to have bright blue rear ends, because brightly colored rumps help them attract mates and give them a reproductive advantage. Porcupines evolved to have quills, because quills help them to avoid predators and reproduce. This gives porcupines a survival advantage.

In 1831, Darwin joined a naval expedition on a ship called the HMS Beagle as the unofficial naturalist onboard. Darwin collected many specimens during the ship’s five-year expedition around the world. After returning to England, he began developing his ideas about evolution. In 1859, Darwin published his great work, On the Origin of Species.

Human beings have a genetic preference for fatty foods, which explains why fried chicken, french fries, and buttery popcorn are so popular. Evolutionary psychologists say that the preference for fatty foods derives from the days when people hunted and gathered and food was scarce. Eating high-fat foods was important because fat gave people the calories they needed. In other words, the preference for fat was adaptive. Today, in wealthy countries with abundant food and sedentary lifestyles, the preference for fat remains, despite the fact that it no longer has beneficial effects. In fact, consuming fatty foods can lead to health problems.