I found this small article on The Conversation. It is similar to a concise summary of the underlying theme of The Selfish Gene book. I like it because it brings in examples of altruism and quickly explains them in simplistic terms to reveal the hidden selfishness.
There is also a new theory mentioned for altruism that is not mentioned in The Selfish Gene: altruistic punishment. The theory states that some people have a “gene” that makes them want to punish selfish animals by confronting them. Such punishment is an “altruistic” act because it provides a public good at some cost to the punisher in the form of time, effort, and possible risk of retaliation. The risk of suffering altruistic punishment therefore functions as a social pressure to be kind. Therefore, the rebel risks being ostracized and losing the support network of the community and is less likely to survive. So, the gene for displaying kindness increases in the gene pool and kinder animals are more likely to survive with the support of the community.
There is also and article in nature about this theory of altruistic punishment which cna be found here http://www.nature.com/nature/journal/v415/n6868/full/415137a.html
Not as intellectually rigorous as Dawkins’ writing but a neat explanation to the puzzle of altruism. The Conversation article can be found here: https://theconversation.com/why-is-it-nice-to-be-nice-solving-darwins-puzzle-of-kindness-85055
Learning in Parallel 