This month the U.S. Postal Service debuts a new commemorative stamp set celebrating four American scientists. Over the next four weeks I'll share with you the achievement of each scientist. I begin with the first stamp: Barbara McClintock.
No one knew more about a cob of corn than Barbara McClintock. Each spring this scientist rose very early in the morning to plant corn on Long Island Sound, carefully fertilizing each stock throughout the summer, then harvesting them at the end of the season. She spend the long, quiet winter months analyzing her harvest. Unlike most scientists she worked completely alone, so much so that if a visitor showed up in the afternoon she often had to speak softly, saying she hadn't yet used her vocal cords that day. She studied the color of the corn kernels, which varied from dark to light. In the 1940s she noticed distinct and regular patterns in the colors of the kernels. McClintock knew that these patterns reflected the genetic make-up of the corn. A set of genes controls the appearance of every plant and animal; this is, of course, the genetic code that we use in DNA testing to determine paternity or to solve crimes. So, McClintock realized that the rapid change in the corn's appearance meant something revolutionary: No longer were genes the fixed, stable things always though by scientists, instead they could spontaneously change.
She spent the next three years checking and double-checking her results before she revealed to her colleagues the existence of these "jumping genes."
What does McClintock's work mean for us today?
Her work led to greater understanding of human diseases. For example, how jumping genes can pass on resistance to antibiotics, or how they let African sleeping sickness evade the defenses of the human immune system.
Her work was so far ahead of its time that only 40 years after she did her ground breaking research did she receive a Nobel Prize. At age 81 all she had to say was "Oh Dear" - and then she walked out in to the brisk air of Long Island Sound and spent all morning picking walnuts. She returned, dressed in her dungarees and carrying tongs for grappling with the walnuts, to address the press. "It might seem unfair," she said, "to reward a person for having so much pleasure over the years, asking the maize plant [as she called corn] to solve specific problems and then watching its responses."
The world, though, is richer today because Barbara McClintock hear what the corn said back.
Copyright 2005 William S. Hammack Enterprises
