The development of the horse in the fossil record shows
The horse walked upright
The horse started out the size of a small dog and evolved to the larger modern horse
The modern horse evolved from mules
The modern horse was once related to bears

For forgetting a specific memory, the light is activated to control the neurons that release certain chemicals, such as alpha-CaM kinase II, that erase memories. After the traumatic memory is removed, and the good memory is implanted, the PTSD patients are able to escape from the previous event, and restore their life.