We happened to purchase the game Evolution to play with the kids a few days ago, not realizing that it was designed around real science! The players “manage” simple animals with up to three adaptations (like Fertile, Climbing, Intelligence, etc). The Herbivores and Omnivores have to avoid being driven to extinction by the Carnivores, while the Carnivores have to manage their population and carefully select prey with large enough body size or population to provide adequate nutrition. They “adapt” by swapping out traits that have become obsolete for new ones. For example, the Fertile trait provides for the animal’s population to grow by 1 each turn, so long as there is food available. When food grows scarce, the Fertile trait becomes useless and can be exchanged for Defensive Herding or Scavenger… an Herbivore can even evolve into a Carnivore!
The box says ages 12+, but my 9- and 11-year-old had no trouble understanding it. I think if your kids have played Settlers of Catan or Magic: the Gathering, they’ll grasp the mechanics of the game quickly.
One caveat: while the game definitely fosters intuition about why evolution/adaptation happens, I needed to remind my kids that in nature the process is involuntary–the animals can’t “choose” which adaptation to develop next. Rather, environmental pressures drive obsolete organisms to adaptation or extinction depending largely on happenstance.
There’s also a version for younger kids, Evolution: The Beginning, that we’ve enjoyed. Same basic theory from what I’ve read about the two games, just less complicated for the Beginning version. And yes, I agree that it absolutely bears mentioning to the small people that evolution happens via natural selection / survival of the fittest, as opposed to consciously picking and choosing traits.