Spider Alert

(Arachnophobes may not want to read on).

A species of spider, Anelosimus studiosus, is highly social. Instead of each female building her own nest and defending it (or not) as in most spiders, Anelosimus studiosus breeds in colonies.

But here's the interesting thing. You can split these spiders into two broad personality types - aggressive and docile. Colonies made of all aggressive spiders or all docile spiders don't raise nearly as many young as those with both.

Essentially, instead of specializing by physical caste like most insects, they specialize by personality - and in an interesting way. The aggressive spiders defend the nest, attack intruders and do most of the hunting. The docile spiders raise the babies.

Docile spiders don't have the aggression to hunt successfully and catch only half the number of prey. Aggressive spiders, on the other hand, tend to forget that the babies are theirs and...yeah. Dinner time.

So, what does all of this imply? It implies first that variation in personality occurs in some quite simple animals.

It also implies that a mix of aggressive and docile personalities may be desirable in other animals. Especially ones that form larger groups.

Like, you know, humans. There's a Brave New World style idea in there somewhere.