awards involving human subjects and those without human subjects involvement differs slightly (overall, 43 for human subjects, 41 without).

Some gender differential exists across various NIH grant programs. Although men are, on average, a half-year younger than women (42.26 for men vs. 42.82 for women) at receipt of first award, the difference is reversed—and more pronounced—for the R15 and R21 awards. For the R21, in particular, women are over 2 years younger than their male colleagues at receipt of first award (40.45 for women, 42.60 for men). PhD holders are, on average, younger (41.38±7.30) than either MD/PhD (43.79±6.49) or MD (43.83±6.54) holders at receipt of first NIH research award (data provided by NIH).

Not only chronological age demonstrates the difficulties for new investigators. For instance, in its 1997 survey, the American Society for Cell Biology (ASCB) found that 71 percent of those receiving PhDs before 1970 obtained grant funding from the NIH, NSF, or American Cancer Society on their first attempt. That number drops to 43 percent of those graduating in the 1980s and 25 percent of those graduating in the 1990s (Marincola and Solomon, 1998a; http://www.ascb.org/survey/survey.htm).

A demographic analysis of available data² provides some insight on why the number of awards to new investigators is so low and has declined over time (see Figure 1-3). How have PhDs ages 35 and younger and educated in the United States fared in recent years? Data presented by Paula Stephan about U.S. PhD recipients from 1993 to 2001 reveal the following:

• The number of life scientists ages 35 and younger increased 59 percent (see Figure 2-8)

• The number of life scientists ages 35 and younger in tenure-track positions increased 6.7 percent, and

• The number of life scientists ages 35 and younger in tenure-track positions in Research I institutions³ declined 12.1 percent (from 618 to 543).