Hello, I am maintaining a blog in my native language defending evolution. Before, every time I felt there was a questionable aspect in the theory, I would soon find an answer that just make me fall deeper in love with the subject. However, there is one single thing that has been bugging me: the mechanisms for the evolution of instincts.
How could natural selection manage to write this command "stand up/find any solid mass in the surrounding/spread your wings/use your feet to gain strength to push backward/push until you feel light on your back/repeat until there is no more solid mass" to the blind cuckoo hatchling for the instinct to murder foster siblings? Maybe it was just me being unimaginative, but I have not been able envision how that behavior got into a baby's genes, or how could that be selected for. Maybe each hatchling were given a random command for a set of actions, and the moonwalk murdering ones got selected over the tap dancing and hip hop ones. Still I am having a hard time thinking of a plausible way nature has crafted genes, which afterall just make protein based commands, can act like evil voices in their heads telling them exactly what to do.

Because I have not been able to find a satisfactory response, I am feeling inauthentic in the claims I give out on my blog (about evolution being accepted by scientists because they have carefully considerred its merits and not because they conveniently took the whole package of "currently accepted scientific theories"). I believe if most of that curious bunch have actually scrutinised such important theory, I would come accross more and deeper questions and answers, rather than the standard resources in reply to tedious stuff like "Why are there still monkeys???".

Thank you in advance for  answering :)

Great question - the short answer is that we don't know but have some sensible hypotheses relating to, for instance the Baldwin effect described by Dawkins here

https://richarddawkins.net/2015/04/darw … -instinct/

I think two sources of difficulty around this topic are 1) defining exactly what constitutes "instinctual behaviour"  and 2) a general lack of recognition that complex behavioural routines can potentially be generated by a small set of simple decision rules or heuristics. To give you a very simple example, hatchling turtles emerge onto a beach and head for the sea right? How do they know this is the right thing to do since nobody "told" them? Well basically they don't, they seem to just orientate to and move towards light (and -in the absence of light pollution this means the water). So a very simple sensory bias in this case produces an "instinctual behaviour".