We propose a method of measuring the human genomic deleterious mutatio
n rate based on comparison of the rate of evolution per nucleotide per
generation of neutral sequences, mu(N), with the overall rate of evol
ution of unique sequence DNA, mu(O). Data on mu(N), which are based on
pseudogenes, permit an estimate of the total zygotic (twice the genom
ic) mutation rate, U(T) = 2mu(N)n = 2(2 x 10(-8))(3 x 10(9)) almost-eq
ual-to 10(2), where n is the number of nucleotides per genome. Data on
mu(O), can be obtained by comparison of representative samples of rel
atively short homologous sequences from the genomes of Homo and a rela
ted species. The fraction of the genome that is controlled by negative
selection is f(S) = (mu(N) -mu(O))/mu(N) and the deleterious zygotic
mutation rate, the expected number of new deleterious alleles carried
by a zygote, is U(S) = U(T)f(S). If f(S) > 0.01, U(S) > 1, which would
have important implications for human genetics and evolutionary biolo
gy. (C) 1993 Wiley-Liss, Inc.