> growth=c(17,20,22,64,170,190,315)
> gap=c(6,13,14,15,16,18,22,29)
> wilcox.test(growth,gap)

        Wilcoxon rank sum test with continuity correction

data:  growth and gap 
W = 49.5, p-value = 0.01500
alternative hypothesis: true location shift is not equal to 0 

Warning message:
In wilcox.test.default(growth, gap) :
  cannot compute exact p-value with ties