  We calculate the major pair fraction and derive the major merger fraction and
rate for 82 massive ($M_{*}>10^{11}M_{\odot}$) galaxies at $1.7 < z < 3.0$
utilising deep HST NICMOS data taken in the GOODS North and South fields. For
the first time, our NICMOS data provides imaging with sufficient angular
resolution and depth to collate a sufficiently large sample of massive galaxies
at z $>$ 1.5 to reliably measure their pair fraction history. We find strong
evidence that the pair fraction of massive galaxies evolves with redshift. We
calculate a pair fraction of $f_{m}$ = 0.29 +/- 0.06 for our whole sample at
$1.7 < z < 3.0$. Specifically, we fit a power law function of the form
$f_{m}=f_{0}(1+z)^{m}$ to a combined sample of low redshift data from Conselice
et al. (2007) and recently acquired high redshift data from the GOODS NICMOS
Survey. We find a best fit to the free parameters of $f_{0}$ = 0.008 +/- 0.003
and $m$ = 3.0 +/- 0.4. We go on to fit a theoretically motivated
Press-Schechter curve to this data. This Press-Schechter fit, and the data,
show no sign of levelling off or turning over, implying that the merger
fraction of massive galaxies continues to rise with redshift out to z $\sim$ 3.
Since previous work has established that the merger fraction for lower mass
galaxies turns over at z $\sim$ 1.5 - 2.0, this is evidence that higher mass
galaxies experience more mergers earlier than their lower mass counterparts,
i.e. a galaxy assembly downsizing. Finally, we calculate a merger rate at z =
2.6 of $\Re$ $<$ 5 $\times$ 10$^{5}$ Gpc$^{-3}$ Gyr$^{-1}$, which experiences
no significant change to $\Re$ $<$ 1.2 $\times$ 10$^{5}$ Gpc$^{-3}$ Gyr$^{-1}$
at z = 0.5. This corresponds to an average $M_{*}>10^{11}M_{\odot}$ galaxy
experiencing 1.7 +/- 0.5 mergers between z = 3 and z = 0.
