Scientists at the University of Wisconsin-Madison identified the Pax6 gene as a very important regulator in the development of the human brain. It represses some genes while activating others. Interestingly mice do not require Pax6 for brain development nor do zebrafish. This discovery will lead to the ability to customize brain cells in vitro. (1)
"The fact that Pax6 is uniformly expressed in all human neuroectoderm cells was a surprise," Zhang [a professor of anatomy in the UW School of Medicine and Pubic Health] explains. "This is a phenomenon that is a departure from what we see in animals. It seems that in the earliest stages of development, human cells are regulated by different processes" . . . In practical terms, the new finding will help scientists refine and improve techniques for making specific types of neural cells. Such cells will be critical for future research, developing new models for disease, and may one day be used in clinical settings to repair the damaged cells that cause such conditions as Parkinson's disease and amyotrophic lateral sclerosis or Lou Gehrig's disease. (2)
As I have said, human-based research, when performed properly, always gives data relevant to humans. Animal-based research does not. This is a good example of animals being different from humans even in very fundamental properties. The only way to discover this was by studying humans and human tissues.
1. X. Zhang et al., Cell Stem Cell 7, 90 (July 2, 2010).
2. University_of_Wisconsin-Madison. (ScienceDaily, 2010).