The behavior of this waspis fascinating and involves what amounts to complex, multi-step predation behavior on cockroaches. All this has to be wired into a “ganglion/brain” structure no bigger than the head of a pin. As a general question how would such precise and complex (seemingly almost knowingly intelligent) multi-step behavior like this develop as function of evolution?
Find roach
sting for limb paralysis
locate precise ganglia center - sting again
chew off half of antenna and “steer” to burrow
lay egg on roach
cover burrow
You think that’s impressive? How about complex behavior where there’s even less of a brain involved?
There’s the parasitic flatworm that causes the host snail’s eyestalks to take on the color, banding, and movement behavior of a caterpillar, thereby guaranteeing that it will be eaten by a bird (which then spreads the flatworm’s young):
There are other complex behavior-altering capabilities exhibited by parasitic fungi, which don’t have brains at all.
I look at it as a pretty long road of evolutionarily shaped changes. The wasps, parasitic worms, and fungi don’t think any of this out – they’re simply the most successful of a series of random changes that, pared by the statistics of survival, effectively programmed in every link of this complex behavior.
I think the the first thing to recognize is the massive varieties of behaviors that are out there. For example, I’m always reminded of a story about a poor Peregrine falcon that failed to mate because he insisted on offering the females a dead mouse when they wanted a dead bird. Even in a population with an established behavior, there are still a lot of individual outliers contained in a few fringe percentage points.
An example from my personal experience with gold fish: In every batch of 100 gold fish, 98 of them school like normal, but there’s 2 who want to be off doing their own thing. 90 of them will eat flakes or pellets, but there are 5 who will only eat pellets and 5 who will only eat flakes. In the wild, these outliers would probably die off or fail to reproduce.
If it so happens that a one in a million outlier reproduces more successfully than their peers, it won’t take long for that to become the standard behavior throughout the population, especially when many species have offspring in the thousands each generation. It’s not like humans where your two kids lead to four grand kids… it’s a case where their thousand kids lead to a million grand kids and a billion great grand kids. It might take longer to spread that mutation geographically than for it to dominate the genes in a particular local population. As long as conditions remain the same, that particular behavior dominates the population. The behavior remains the standard until some outlier does better or until an external change to the environment favors something else.