一是动物身体变小，因为人类偏向捕猎大体积动物作为食物。比如鱼，当人们把大鱼捞走，小鱼能够留下来并且pass their genes to the next generation;
听力：lecture;动物的 evolution 与人类活动有关。第一，动物体格越变越小。比如鱼，人们会把大鱼捕走，只有小鱼能存活下来，所以鱼就 pass their genes to the next generation，鱼就变小了。第二，动物大脑越变变大。比如 mice，mice 学会了在城市里生活和寻找食物，脑子聪明的会活下来，所以就 pass their genes to the next generation。
The professor talks about two ways how human activities affect animal evolution.
Firstly, it causes animals to grow smaller. This is because human tend to hunt those animals bigger in size as food source. Take fish as an example, when people caught huge number of big fish, smaller fish sustain and they are able to pass their genes to the next generation;
Secondly, animals began to have larger brain, since they have to adapt to changeable environment and survive. The professor then gives an example of mice, in order to survive in the city and search for food, mice evolve to be smarter, and only the smarter ones will survive and pass their gene to the next generation.