That's the opposite of my understanding; Sandberg and Bostrom discusses this and at least as far as compute resources go, simulating the brain is by far the harder problem.
That may be true of the body, although our nervous system in our body is quite large, not to mention the spinal chord. But it's certainly not true of the developmental environment. For one thing, simulating that would require simulated thousands of other human brains.
http://www.fhi.ox.ac.uk/selected_outputs/fohi_publications/b...