On the 4th of August 2016, Man created a synthetic mineral they call Thulionite. When large amounts of energy passed through the material, it could replicate itself and grow. It was first used in prosthetic medicine before gaining applications in robotics.
The first prosthetic brain was developed for a lab mouse named Angel. The synthetic brain developed from Thulionite grew within Angel throughout her lifetime in a fashion indistinguishable from her natural kin. The technology was duplicated and many more synthetic mice brains were tested.
The first synthetic brain was birthed. A male and female mouse both with Thulionite brains were able to reproduce. A single male mouse they called Andy was born with a mechanical brain. Andy survived only for a couple of days, but much was to become from this one very important mouse.
The first experiments giving the synthetic brains capabilities beyond their natural counterparts were undertaken. A few mice were given an additional 5% processing power, and performed better in intelligence based tests. Unfortunately the mice's metabolism would falter, leading to much lower body mass and consequently much shorter life span.
Four fields of study were established, focusing on solving the four overarching issues faced by creatures with synthetic brains.
Dr Akbar Cealvin and his team focused on improving performance and handling biological overheating.
Dr Felicia Watson and her team were dedicated to generating stable power within the body from biological means.
Dr Gregory Willem and his team studied the manipulation of dna, in attempt to grow synthetic organs, bones and other anatomy.
Dr Marcel Porbay and his team experimented controlling and reducing the corrosive properties of the synthetic creatures.
Each of these four fields lead to the four traits we see in Mech Beasts theses days, being heat, shock, iron and corrosion respectively.