cells, reproduce quickly. Other cells, like nerve cells, grow slowly. Both normal cells and cancer cells go through a sequence of steps, or phases, when they form new cells. This is called the cell cycle.
On a cold, foggy morning, an army wakes on the banks of a river. A tall soldier named Jim Conklin begins his day by washing his shirt, and rushes back to camp to report a rumor he has overheard: the regiment will move into battle the next day.
Stulp, who is Dutch, studies why his fellow citizens are so tall. Today, the Dutch are on average the tallest people on the planet. Just 150 years ago, they were relatively short. In 1860, the average Dutch soldier in the Netherlands was 5-foot-5. American men were 2.7 inches taller. Since 1860, average heights have increased in many parts of the world, but no people have shot up like the Dutch. The average Dutchman now stands more than 6 feet tall. And while the growth spurt in the United States has stopped in recent years, the Dutch continue to get taller.