A new form of altruism in the insect world has been discovered. Older individuals of a species of termite have the ability to create a toxic goo via a chemical reaction which kills both themselves and their attackers. This is another variant of autothysis (Greek: auto-, self; -thysis, sacrifice) in which an insect ruptures an organ to release a defensive substance when attacked.
Of course, we all know that a bee that stings in defense of its hive dies soon after. Likewise, human soldiers sacrifice themselves in defense of their families. A question to ask is how is insect altruism different from human altruism.
As far as I know, insects never need to be conscripted. Humans, however, are frequently less inclined to lay down their lives on behalf of others without some external persuasion.
A key difference might be that humans engage in within-species competition. Ants are designated as either workers, soldiers, or royalty at an early age. Humans, due to their increased intelligence, have the potential to be be any or all of these things, depending on their competitive interactions with their fellow humans.
As part of this within-species competition, humans are also intelligent enough to be able to exploit the altruism of others. Rather than merely acting instinctively to preserve the species, individual humans can imagine and implement a chain of causes and effects which lead to reaping benefits for themselves at the expense of their more generous and gullible brethren.
This might explain why humans have evolved to be so much smarter than other species. By evolving past a certain critical threshold of intelligence, humans not only have to contend with the tooth and claw of lions, tigers, and bears, but also the force and fraud of their siblings. Those individuals that are able to deceive while not being deceived produce more offspring. Instead of males evolving bigger antlers to fight off other males for mates, humans are in a runaway arms race for bigger brains.