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We present the results of a study investigating the sizes and morphologies ofredshift 4 < z < 8 galaxies in the CANDELS GOODS-S, HUDF and HUDF parallelfields. Based on non-parametric measurements and incorporating a carefultreatment of measurement biases, we quantify the typical size of galaxies ateach redshift as the peak of the log-normal size distribution, rather than thearithmetic mean size. Parameterizing the evolution of galaxy half-light radiusas $r_{50} \propto (1+z)^n$, we find $n = -0.20 \pm 0.26$ at brightUV-luminosities ($0.3L_{*(z=3)} < L < L_*$) and $n = -0.47 \pm 0.62$ at faintluminosities ($0.12L_* < L < 0.3L_*$). Furthermore, simulations based onartificially redshifting our z~4 galaxy sample show that we cannot reject thenull hypothesis of no size evolution. We show that this result is caused by acombination of the size-dependent completeness of high-redshift galaxy samplesand the underestimation of the sizes of the largest galaxies at a given epoch.To explore the evolution of galaxy morphology we first compare asymmetrymeasurements to those from a large sample of simulated single S\'ersicprofiles, in order to robustly categorise galaxies as either `smooth' or`disturbed'. Comparing the disturbed fraction amongst bright ($M_{UV} \leq-20$) galaxies at each redshift to that obtained by artificially redshiftingour z~4 galaxy sample, while carefully matching the size and UV-luminositydistributions, we find no clear evidence for evolution in galaxy morphologyover the redshift interval 4 < z < 8. Therefore, based on our results, a bright($M_{UV} \leq -20$) galaxy at z~6 is no more likely to be measured as`disturbed' than a comparable galaxy at z~4, given the current observationalconstraints.

Non-parametric analysis of the rest-frame UV sizes and morphological disturbance amongst L* galaxies at 4