Half Brother by Kenneth Oppel

I gave this book a rating of four out of five. Ben's parents are scientists, and they decide that they're going to "adopt" a baby chimpanzee and teach it to learn sign language. They tell Ben that Zan, the chimpanzee, is part of their family, and that Ben will be like his big brother. Zan learns many words very quickly, but he still acts like a wild animal at times. Ben starts to think of Zan as his little brother and gets upset when his parents treat Zan like a specimen in an experiment. Ben's dad is under pressure to receive grant money to fund his projects, and some people start to question his methods. There are many things going on in Ben's life, and they all seem to add to his stress. The plot takes a serious turn when Ben's father decides to end the experiment. What will happen to Zan?

The conflict is enjoyable, because Zan is an adorable character. We are able to learn about his thoughts and feelings through sign language, although some people think of him as experimental animal. The dad's experimental methods, the animal rights activists, and Ben's personal life all add to the conflict to make things worse.