I'm sure it's possible, but it's like a human being developing a resistance to a hammer to the skull. It would take much more than few generations of selective pressure to do that.

Your skull IS such an adaptation. Not hammer, but it does protect your CNS from many physical harms, and was evolutionarily gifted to you back in the days of early vertebrates

I'm not saying it's not an adaptation. Think about the scale of time you just referenced and compare it to the frame of time of the study and my comment.

Read my comment again.

Thank you.

The speed of evolution is mainly a function of the length of a generation (and also of the amount of pressure from the environment). Consider how long human generations are compared to cockroaches, and how little evolutionary pressure humans face today. Read my comment again. Thank you

I did read your comment. You're wrong. A few generations (1.5 years) would not plausibly have this effect. I doubt even a hundred generations would be able to select for something so significant since it's a weakness that all exoskeleton insects have. Insects have remained largely the same for millions of years.

I never said it wasn't possible, I said it wasn't plausible for it happen on short scales of time such as this study.

You're being pedantic, but you're still wrong.

Different humans have skulls of different thicknesses and if there was a situation where hammer skullings became major cause of death I'm sure that over time those with thicker skulls or other features that made them less susceptible to skullings would survive and flourish.

how many generations will roaches have passed through within the space of one year? tens? hundreds? thousands?

American cockroaches take 6 months to a year to reach reproductive maturity