They converted carbon dioxide to oxygen. The increased oxygen levels allowed for cellular respiration to occur instead of only glycolysis. The atmosphere became thinner, decreasing temperatures of the planet as well.
Why are they being abused?
Does a animal that is going to be used for human consumption deserve to be treated cruelly?
Does the USDA regulate pig farms and treatment of the pigs?
Are there sanctions for cruelty?
How are the pigs slaughtered, humanly or not?
Answer:
the blood gets oxygen in the lungs its called oxy-rich blood (im pretty sure this is correct)
Explanation: