Kin selection

This is a common pattern throughout the animal kingdom of individuals sacrificing a certain amount of their resources, including their own safety or even their entire reproductive potential, to benefit closely related other individuals.

Such a phenomenon is called kin selection.

Kin selection occurs because it's beneficial to not only preserve your own genes but also the genes of close relatives in order to pass on the genes that you and your relatives have in common.

If you and your relatives have a certain characteristic that gives you an advantage over others in your population, looking out for yourselves will increase the chances of that characteristic being passed on to the next generation on top of the advantage that the characteristic initially bestowed.

So, to trot out a very old cliche, if Big Brother Giraffe pulls down some branches for Little Brother to eat because Little Brother hasn't grown his new long neck enough, both will survive to maturity to pass on their big-necked genes.

Place yourself between me and harm.

Sorry to do this to you, but I am, after all, incredibly gorgeous.'" Well, I don't know much about human pheromones, but I do know a little about bee pheromones.

Bee colonies are fantastic examples of kin selection in action, an altruistic place where the sisters are doing it for each other.