Darwin’s theories repetitively appear throughout this book and in this chapter it mentioned his “Origins of Species”. It prompted me to research more about the origins of tetrapods. Johnson mentioned how a fish evolved to now how feet to be able to walk on land. According to this website I found, it all began with ray-finned fish that slowly evolved into bony fish such as Eusthenopteron. These fish eventually continued evolving until they developed forelimbs and hindlimbs with fingers.
Organisms evolve based on their need for survival. Harsh weather can prompt an organism to use a body part, even if it wasn’t designed for that specific reason, in order to survive. The example Johnson gave was the birds feathers. The feathers were made for warmth but then they became useful for flying.
Its interesting to see how organisms keep evolving based on the environmental pressures. It makes me wonder if humans are done evolving or are we going to look different in the 22nd century? Or are we going to be extinct? I wonder.