Where earlier phases of the hybrid program had as their goal dealing with basic requirements like digestion, reproduction, and intelligence, our recent goals have addressed details like appearance, the senses, and memory.
Skin tone has been improved to where it is neither a reddish blush or a pallor, and as we could not perfect a proper head of hair, we went in the other direction - hairless. Far better bald than with a strand here or there. Breasts are small, but functional, a high priority goal of ours due to the bonding that occurs during nursing. The sex drive in the hybrids remains as varied as it does in the human animal. Sight and sound reception is closer to what the Zetas are capable of, vastly higher ranges than humans have ever experienced, due to our dim Sun and relatively inhospitable planet. Those who could not peek through the gloom or follow a faint sound simply did not survive to reproduce. Where the human animal has many memory levels - short term, long term, subconscious, conscious, and others unknown and thus not labeled by humans - the target hybrid has a cohesive memory, much like the Zetas. Having perfected our 90's model, we are now into mass production, as the cataclysms are fast approaching.