One thing that does not yet seem to have been mentioned is that it’s unfavourable evolutionarily to have anything other than a 50⁄50 mix of males/females, as if there is a preponderance of one gender then if you are the opposite gender you’ll tend to have more babies. Of course there are exceptions to this due to things like infanticide but on the whole it’s a good approximation.
This does not explain how the first male came about of course, but it does explain how it only had to evolve once by chance and then immediately took over from there.
There are cases where artificially skewed gender balance can get corrected in a few generations:
Not quite sure that part about a tungsten rod being equivalent to a nuclear weapon is correct.
Earth orbital velocity is 7.8km/s. so if all the mass in a starship launch went into one tungsten rod then that rod would have an energy of 0.5 * 100000 * 7800^2 = 3 terajoules, or 3⁄4 of a kiloton of TNT. Nuclear weapons are tens of kilotons at a minimum and single digit megatons often, so I don’t think this is a fair comparison.
This actually makes a great deal of sense if you think about it for a little bit. The energy that the tungsten rod has is given to it by the fuel in the starship. So if a nuclear bomb can have a yield in tons of TNT that is much greater than the mass of the starship, then you should be suspicious of claims that it can impart more energy than it has fuel.
I would argue further that a tungsten rod might just disappear into the ground unlike a nuclear airburst, but that’s just conjecture on my part.